# Patent

## Title
Zoom lens system, imaging device and camera

## Abstract

A high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and the conditions: −2.3<f2/fW<−1.5, ωW≧36 and fT/fW>4.5 (f2: a composite focal length of the second lens unit, ωW: a half view angle at a wide-angle limit, fT: a focal length of the entire system at a telephoto limit, fW: a focal length of the entire system at a wide-angle limit) are satisfied; an imaging device; and a camera are provided.

## Background
TECHNICAL FIELD
The present invention relates to a zoom lens system, an imaging device and a camera. In particular, the present invention relates to: a high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner; an imaging device employing the zoom lens system; and a thin and compact camera employing the imaging device.
BACKGROUND ART
There are extremely strong demands for size reduction and performance improvement in digital still cameras and digital video cameras (simply referred to as digital cameras, hereinafter) having an image sensor for performing photoelectric conversion. In particular, from a convenience point of view, digital cameras are strongly requested that employ a zoom lens system having a high zooming ratio and still covering a wide focal-length range from a wide angle condition to a highly telephoto condition. On the other hand, in recent years, zoom lens systems are also desired that have a wide angle range where the photographing field is large.
As zoom lens systems having a high zooming ratio and zoom lens systems having a wide angle range as described above, various kinds of zoom lenses having a four-unit construction of positive, negative, positive and positive have conventionally been proposed, which each comprises, in order from the object side to the image side, a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power.
Japanese Laid-Open Patent Publication No. 2008-146016 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which at the time of magnification change from a wide-angle limit to a telephoto limit, at least a first lens unit, a second lens unit, and a third lens unit are moved and thereby the intervals between the respective lens units are changed, the second lens unit is composed of at most three lenses, and the relation between the ratio of the values of lateral magnification of the second lens unit at a telephoto limit and a wide-angle limit and the ratio of the values of lateral magnification of the third lens unit at a telephoto limit and a wide-angle limit is set forth.
Japanese Laid-Open Patent Publication No. 2008-122880 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, and having a zooming ratio of 3 to 12, in which a second lens unit is composed of at most three lenses, a bi-concave negative lens is arranged on the most object side in the second lens unit, and the shape factor of the bi-concave negative lens is set forth.
Japanese Laid-Open Patent Publication No. 2008-122879 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of a negative lens and a positive lens, and the shape factor of the positive lens is set forth.
Japanese Laid-Open Patent Publication No. 2008-052116 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of a positive lens and a negative lens, a second lens unit is composed of, in order from the object side, a negative lens and a positive lens, and a refractive index and an Abbe number of the negative lens in the second lens unit are set forth.
Japanese Laid-Open Patent Publication No. 2008-052113 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, and having a zooming ratio of 3.8 to 10, in which a second lens unit includes a bi-concave negative lens on the most object side, the entire second lens unit is composed of at most two negative lenses and a positive lens, and the shape factor of the bi-concave negative lens is set forth.
Japanese Laid-Open Patent Publication No. 2008-052110 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a second lens unit is composed of, in order from the object side, a negative lens and a positive lens, and a refractive index and an Abbe number of the positive lens are set forth.
Japanese Laid-Open Patent Publication No. 2007-328178 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of, in order from the object side, a negative lens and a positive lens, a second lens unit is composed of, in order from the object side, a negative lens and a positive lens, a third lens unit is composed of at most three lenses including a positive lens and a negative lens, and a fourth lens unit is composed of a positive lens.
Japanese Laid-Open Patent Publication No. 2007-256452 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a third lens unit is composed of, in order from the object side, a first positive lens, a second bi-concave negative lens, and a third negative lens, and at the time of magnification change, the interval between a first lens unit and a second lens unit is greater and the interval between the second lens unit and the third lens unit is smaller at a telephoto limit than at a wide-angle limit.
Japanese Laid-Open Patent Publication No. 2007-240747 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is composed of, in order from the object side, two lenses, i.e., a negative lens and a positive lens; a second lens unit is composed of, in order from the object side, two lenses, i.e., a negative lens and a positive lens; a third lens unit is composed of, in order from the object side, three lenses, i.e., a positive lens, a positive lens, and a negative lens; a fourth lens unit is composed of a positive lens; at the time of magnification change, the interval between the first lens unit and the second lens unit is greater at a telephoto limit than at a wide-angle limit, and the third lens unit is located closer to the object side so that the interval between the third lens unit and the second lens unit decreases; a brightness diaphragm, which moves in the direction along the optical axis at the time of magnification change, is arranged between the second lens unit and the third lens unit; and the brightness diaphragm is located closer to the object side at a telephoto limit than at a wide-angle limit.
Japanese Laid-Open Patent Publication No. 2007-171371 discloses a zoom lens having the above-mentioned four-unit construction of positive, negative, positive and positive, in which a first lens unit is located closer to the object side at a telephoto limit than at a wide-angle limit; the interval between the first lens unit and a second lens unit is greater, the interval between the second lens unit and a third lens unit is smaller, and the interval between the third lens unit and a fourth lens unit is greater at a telephoto limit than at a wide-angle limit; the first lens unit is composed of a negative lens and a positive lens; the second lens unit is composed of, in order from the object side to the image side, a negative lens and a positive lens; and the ratio between the focal length of the negative lens in the second lens unit or the focal length of the second lens unit, and the focal length of the entire lens system at a wide-angle limit is set forth.
Japanese Laid-Open Patent Publication No. 2008-172321 discloses an imaging device comprising: a zoom lens which includes the above-mentioned four-unit construction of positive, negative, positive and positive, and performs zooming from a wide-angle limit to a telephoto limit with the intervals between a plurality of lens units being varied; an image sensor; and an image recovery unit, in which the relations among the maximum length of the zoom lens along the optical axis from its most-object-side refractive surface to its imaging surface, the focal lengths of the entire system at a wide-angle limit and a telephoto limit, the minimum F-number at a telephoto limit, and the half of the diagonal length of an effective imaging range on the imaging surface, are set forth.
CITATION LIST
Patent Literature


    [PTL 1] Japanese Laid-Open Patent Publication No. 2008-146016
    [PTL 2] Japanese Laid-Open Patent Publication No. 2008-122880
    [PTL 3] Japanese Laid-Open Patent Publication No. 2008-122879
    [PTL 4] Japanese Laid-Open Patent Publication No. 2008-052116
    [PTL 5] Japanese Laid-Open Patent Publication No. 2008-052113
    [PTL 6] Japanese Laid-Open Patent Publication No. 2008-052110
    [PTL 7] Japanese Laid-Open Patent Publication No. 2007-328178
    [PTL 8] Japanese Laid-Open Patent Publication No. 2007-256452
    [PTL 9] Japanese Laid-Open Patent Publication No. 2007-240747
    [PTL 10] Japanese Laid-Open Patent Publication No. 2007-171371
    [PTL 11] Japanese Laid-Open Patent Publication No. 2008-172321


SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
Each of the zoom lenses disclosed in the respective patent literatures is miniaturized to such an extent that it can be applied to a thin and compact digital camera, but cannot meet the recent demands in terms of achieving a good balance between the view angle at a wide-angle limit and the zooming ratio.
The object of the present invention is to provide: a high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner; an imaging device employing the zoom lens system; and a thin and compact camera employing the imaging device.
Solution to the Problems
(I) One of the above-described objects is achieved by the following zoom lens system. That is, the present invention relates to:
a zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (2-1), (a-1) and (b-2) are satisfied:

−2.3<f2/fW<−1.5  (2-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
f2 is a composite focal length of the second lens unit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
One of the above-described objects is achieved by the following imaging device. That is, the present invention relates to:
an imaging device capable of outputting an optical image of an object as an electric image signal, comprising:
a zoom lens system that forms an optical image of the object; and
an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (2-1), (a-1) and (b-2) are satisfied:

−2.3<f2/fW<−1.5  (2-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
f2 is a composite focal length of the second lens unit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
One of the above-described objects is achieved by the following camera. That is, the present invention relates to:
a camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:
an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (2-1), (a-1) and (b-2) are satisfied:

−2.3<f2/fW<1.5  (2-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
f2 is a composite focal length of the second lens unit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
(II) One of the above-described objects is achieved by the following zoom lens system. That is, the present invention relates to:
a zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (3-1), (a-1) and (b-2) are satisfied:

0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit,
β3W is a lateral magnification of the third lens unit at a wide-angle limit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
One of the above-described objects is achieved by the following imaging device. That is, the present invention relates to:
an imaging device capable of outputting an optical image of an object as an electric image signal, comprising:
a zoom lens system that forms an optical image of the object; and
an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (3-1), (a-1) and (b-2) are satisfied:

0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit,
β3W is a lateral magnification of the third lens unit at a wide-angle limit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
One of the above-described objects is achieved by the following camera. That is, the present invention relates to:
a camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:
an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (3-1), (a-1) and (b-2) are satisfied:

0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit,
β3W is a lateral magnification of the third lens unit at a wide-angle limit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
(III) One of the above-described objects is achieved by the following zoom lens system. That is, the present invention relates to:
a zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (4-1), (a-1) and (b-2) are satisfied:

0.6<M1/M3<1.5  (4-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
One of the above-described objects is achieved by the following imaging device. That is, the present invention relates to:
an imaging device capable of outputting an optical image of an object as an electric image signal, comprising:
a zoom lens system that forms an optical image of the object; and
an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (4-1), (a-1) and (b-2) are satisfied:

0.6<M1/M3<1.5  (4-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
One of the above-described objects is achieved by the following camera. That is, the present invention relates to:
a camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:
an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system, in order from an object side to an image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (4-1), (a-1) and (b-2) are satisfied:

0.6<M1/M3<1.5  (4-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
Effects of the Invention
According to the present invention, it is possible to provide: a high-performance zoom lens system which is compact and has a wide view angle at a wide-angle limit and a high zooming ratio in a balanced manner; an imaging device employing the zoom lens system; and a thin and compact camera employing the imaging device.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-1 (Example I-1).
FIG. 2 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-1.
FIG. 3 is a lateral aberration diagram of a zoom lens system according to Example I-1 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 4 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-2 (Example I-2).
FIG. 5 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-2.
FIG. 6 is a lateral aberration diagram of a zoom lens system according to Example I-2 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 7 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-3 (Example I-3).
FIG. 8 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-3.
FIG. 9 is a lateral aberration diagram of a zoom lens system according to Example I-3 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 10 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-4 (Example I-4).
FIG. 11 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-4.
FIG. 12 is a lateral aberration diagram of a zoom lens system according to Example I-4 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 13 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-5 (Example I-5).
FIG. 14 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-5.
FIG. 15 is a lateral aberration diagram of a zoom lens system according to Example I-5 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 16 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-6 (Example I-6).
FIG. 17 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-6.
FIG. 18 is a lateral aberration diagram of a zoom lens system according to Example I-6 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 19 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-7 (Example I-7).
FIG. 20 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-7.
FIG. 21 is a lateral aberration diagram of a zoom lens system according to Example I-7 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 22 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-8 (Example I-8).
FIG. 23 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-8.
FIG. 24 is a lateral aberration diagram of a zoom lens system according to Example I-8 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 25 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment I-9 (Example I-9).
FIG. 26 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example I-9.
FIG. 27 is a lateral aberration diagram of a zoom lens system according to Example I-9 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 28 is a schematic construction diagram of a digital still camera according to Embodiment I-10.
FIG. 29 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-1 (Example II-1).
FIG. 30 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-1.
FIG. 31 is a lateral aberration diagram of a zoom lens system according to Example II-1 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 32 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-2 (Example II-2).
FIG. 33 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-2.
FIG. 34 is a lateral aberration diagram of a zoom lens system according to Example II-2 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 35 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-3 (Example II-3).
FIG. 36 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-3.
FIG. 37 is a lateral aberration diagram of a zoom lens system according to Example II-3 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 38 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-4 (Example II-4).
FIG. 39 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-4.
FIG. 40 is a lateral aberration diagram of a zoom lens system according to Example II-4 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 41 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-5 (Example II-5).
FIG. 42 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-5.
FIG. 43 is a lateral aberration diagram of a zoom lens system according to Example II-5 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 44 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment II-6 (Example II-6).
FIG. 45 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example II-6.
FIG. 46 is a lateral aberration diagram of a zoom lens system according to Example II-6 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 47 is a schematic construction diagram of a digital still camera according to Embodiment II-7.
FIG. 48 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-1 (Example III-1).
FIG. 49 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-1.
FIG. 50 is a lateral aberration diagram of a zoom lens system according to Example III-1 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 51 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-2 (Example III-2).
FIG. 52 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-2.
FIG. 53 is a lateral aberration diagram of a zoom lens system according to Example III-2 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 54 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-3 (Example III-3).
FIG. 55 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-3.
FIG. 56 is a lateral aberration diagram of a zoom lens system according to Example III-3 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 57 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-4 (Example III-4).
FIG. 58 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-4.
FIG. 59 is a lateral aberration diagram of a zoom lens system according to Example III-4 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 60 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-5 (Example III-5).
FIG. 61 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-5.
FIG. 62 is a lateral aberration diagram of a zoom lens system according to Example III-5 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 63 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-6 (Example III-6).
FIG. 64 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-6.
FIG. 65 is a lateral aberration diagram of a zoom lens system according to Example III-6 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 66 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-7 (Example III-7).
FIG. 67 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-7.
FIG. 68 is a lateral aberration diagram of a zoom lens system according to Example III-7 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 69 is a lens arrangement diagram showing an infinity in-focus condition of a zoom lens system according to Embodiment III-8 (Example III-8).
FIG. 70 is a longitudinal aberration diagram of an infinity in-focus condition of a zoom lens system according to Example III-8.
FIG. 71 is a lateral aberration diagram of a zoom lens system according to Example III-8 at a telephoto limit in a basic state where image blur compensation is not performed and in a blur compensation state.
FIG. 72 is a schematic construction diagram of a digital still camera according to Embodiment III-9.



EMBODIMENTS OF THE INVENTION
Embodiments I-1 to I-9
FIGS. 1, 4, 7, 10, 13, 16, 19, 22 and 25 are lens arrangement diagrams of zoom lens systems according to Embodiments I-1 to I-9, respectively.
Each of FIGS. 1, 4, 7, 10, 13, 16, 19, 22 and 25 shows a zoom lens system in an infinity in-focus condition. In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length fW), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length fM=√(fW*fT)), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length fT). Further, in each Fig., an arrow of straight or curved line provided between part (a) and part (b) indicates the movement of each lens unit from a wide-angle limit through a middle position to a telephoto limit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.
The zoom lens system according to each embodiment, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having positive optical power, and a fourth lens unit having positive optical power. Then, in zooming, the individual lens units move in a direction along the optical axis such that intervals between the lens units, that is, the interval between the first lens unit and the second lens unit, the interval between the second lens unit and the third lens unit, and the interval between the third lens unit and the fourth lens unit should all vary. In the zoom lens system according to each embodiment, since these lens units are arranged in the desired optical power configuration, high optical performance is maintained and still size reduction is achieved in the entire lens system.
Further, in FIGS. 1, 4, 7, 10, 13, 16, 19, 22 and 25, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. In each Fig., the straight line located on the most right-hand side indicates the position of the image surface S. On the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P equivalent to an optical low-pass filter or a face plate of an image sensor is provided.
Further, in FIGS. 1, 4, 7, 10, 13, 16, 19, 22 and 25, an aperture diaphragm A is provided on the most object side in the third lens unit G3. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, the aperture diaphragm A moves along the optical axis integrally with the third lens unit G3.
As shown in FIG. 1, in the zoom lens system according to Embodiment I-1, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other.
In the zoom lens system according to Embodiment I-1, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-1, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-1, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8.
In the zoom lens system according to Embodiment I-1, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-1, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves approximately monotonically to the image side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 4, in the zoom lens system according to Embodiment I-2, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment I-2, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-2, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-2, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-2, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-2, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 7, in the zoom lens system according to Embodiment I-3, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment I-3, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-3, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-3, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-3, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-3, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 10, in the zoom lens system according to Embodiment I-4, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment I-4, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-4, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-4, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-4, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-4, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 13, in the zoom lens system according to Embodiment I-5, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment I-5, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-5, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-5, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-5, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-5, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 16, in the zoom lens system according to Embodiment I-6, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment I-6, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-6, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-6, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-6, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 19, in the zoom lens system according to Embodiment I-7, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment I-7, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-7, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-7, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-7, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-7, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 22, in the zoom lens system according to Embodiment I-8, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.
In the zoom lens system according to Embodiment I-8, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-8, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-8, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-8, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment I-8, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 25, in the zoom lens system according to Embodiment I-9, the first lens unit G1 comprises solely a positive meniscus first lens element L1 with the convex surface facing the object side.
In the zoom lens system according to Embodiment I-9, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave second lens element L2; and a positive meniscus third lens element L3 with the convex surface facing the object side. The second lens element L2 has two aspheric surfaces.
In the zoom lens system according to Embodiment I-9, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fourth lens element L4; a bi-concave fifth lens element L5; and a bi-convex sixth lens element L6. Among these, the fourth lens element L4 and the fifth lens element L5 are cemented with each other. Further, the fourth lens element L4 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-9, the fourth lens unit G4 comprises solely a bi-convex seventh lens element L7. The seventh lens element L7 has an aspheric object side surface.
In the zoom lens system according to Embodiment I-9, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the seventh lens element L7).
In the zoom lens system according to Embodiment I-9, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
In the zoom lens systems according to Embodiments I-1 to I-9, the first lens unit G1 comprises one or two lens elements, the second lens unit G2 comprises two lens elements, and the third lens unit G3 comprises three lens elements. Thus, the lens system has a short overall optical length (overall length of lens system).
In the zoom lens systems according to Embodiments I-1 to I-8, the first lens unit G1, in order from the object side to the image side, is composed of the negative meniscus lens element L1 with the convex surface facing the object side, and the positive lens element L2. These two lens elements are cemented with each other to constitute a cemented lens element. Thus, a compact lens system is realized. Further, such a construction permits favorable compensation of chromatic aberration. Furthermore, in the zoom lens system according to Embodiment I-9, the first lens unit G1 is composed of solely the positive meniscus first lens element L1 with the convex surface facing the object side. Thus, a more compact and lightweight lens system is realized. In this case, it is difficult to compensate chromatic aberration and spherical aberration by the first lens unit G1 alone. Therefore, it is necessary to make the F-number at a telephoto limit relatively great (to make the lens system relatively dark).
In the zoom lens systems according to Embodiments I-1 to I-9, in the second lens unit G2, the third lens element L3 or the second lens element L2, which is an object side lens element, has an aspheric surface. Therefore, aberrations, particularly distortion at a wide-angle limit, can be compensated more favorably. Further, in the third lens unit G3, the fifth lens element L5 or the fourth lens element L4, which is an object side positive lens element, has an aspheric surface. Therefore, aberrations, particularly spherical aberration, can be compensated more favorably.
In the zoom lens systems according to Embodiments I-1 to I-8, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fifth lens element L5 having positive optical power, the sixth lens element L6 having negative optical power, and the seventh lens element L7 having positive optical power. The fifth lens element L5, which is an object side positive lens element, and the sixth lens element L6 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements. Further, in the zoom lens system according to Embodiment I-9, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fourth lens element L4 having positive optical power, the fifth lens element L5 having negative optical power; and the sixth lens element L6 having positive optical power. The fourth lens element L4, which is an object side positive lens element, and the fifth lens element L5 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements.
In the zoom lens systems according to Embodiments I-1 to I-9, the fourth lens unit G4 is composed of a single lens element, and the lens element has positive optical power. Thus, the lens system has a short overall optical length (overall length of lens system). Further, at the time of focusing from an infinite-distance object to a close-distance object, as shown in each Fig., the fourth lens unit G4 is drawn out to the object side so that rapid focusing is achieved easily.
Further, in the zoom lens systems according to Embodiments I-1 to I-9, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1, the second lens unit G2, the third lens unit G3, and the fourth lens unit G4 are moved individually along the optical axis so that zooming is achieved. Then, any lens unit among the first lens unit G1, the second lens unit G2, the third lens unit G3 and the fourth lens unit G4, or alternatively, a sub lens unit consisting of a part of a lens unit is moved in a direction perpendicular to the optical axis, so that image point movement caused by vibration of the entire system is compensated, that is, image blur caused by hand blurring, vibration and the like can be compensated optically.
When image point movement caused by vibration of the entire system is to be compensated, for example, the third lens unit G3 is moved in a direction perpendicular to the optical axis. Thus, image blur is compensated in a state that size increase in the entire zoom lens system is suppressed to realize a compact construction and that excellent imaging characteristics such as small decentering coma aberration and small decentering astigmatism are maintained.
In a case that a lens unit is composed of a plurality of lens elements, the above-mentioned sub lens unit consisting of a part of a lens unit indicates any one lens element or alternatively a plurality of adjacent lens elements among the plurality of lens elements.
Embodiments II-1 to II-6
FIGS. 29, 32, 35, 38, 41 and 44 are lens arrangement diagrams of zoom lens systems according to Embodiments II-1 to II-6, respectively.
Each of FIGS. 29, 32, 35, 38, 41 and 44 shows a zoom lens system in an infinity in-focus condition. In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length fW), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length fM=√(fW*fT)), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length fT). Further, in each Fig., an arrow of straight or curved line provided between part (a) and part (b) indicates the movement of each lens unit from a wide-angle limit through a middle position to a telephoto limit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.
The zoom lens system according to each embodiment, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power; a second lens unit G2 having negative optical power; a third lens unit G3 having positive optical power; and a fourth lens unit having positive optical power. Then, in zooming, the individual lens units move in a direction along the optical axis such that intervals between the lens units, that is, the interval between the first lens unit and the second lens unit, the interval between the second lens unit and the third lens unit, and the interval between the third lens unit and the fourth lens unit should all vary. In the zoom lens system according to each embodiment, since these lens units are arranged in the desired optical power configuration, high optical performance is maintained and still size reduction is achieved in the entire lens system.
Further, in FIGS. 29, 32, 35, 38, 41 and 44, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. In each Fig., the straight line located on the most right-hand side indicates the position of the image surface S. On the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P equivalent to an optical low-pass filter or a face plate of an image sensor is provided.
Further, in FIGS. 29, 32, 35, 38, 41 and 44, an aperture diaphragm A is provided on the most object side in the third lens unit G3. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, the aperture diaphragm A moves along the optical axis integrally with the third lens unit G3.
As shown in FIG. 29, in the zoom lens system according to Embodiment II-1, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.
In the zoom lens system according to Embodiment II-1, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment II-1, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-1, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-1, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment II-1, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 32, in the zoom lens system according to Embodiment II-2, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other.
In the zoom lens system according to Embodiment II-2, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment II-2, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-2, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8.
In the zoom lens system according to Embodiment II-2, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment II-2, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves approximately monotonically to the image side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 35, in the zoom lens system according to Embodiment II-3, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment II-3, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment II-3, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-3, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-3, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment II-3, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 38, in the zoom lens system according to Embodiment II-4, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment II-4, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment II-4, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-4, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-4, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment II-4, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 41, in the zoom lens system according to Embodiment II-5, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment II-5, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment II-5, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-5, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-5, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment II-5, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 44, in the zoom lens system according to Embodiment II-6, the first lens unit G1 comprises solely a positive meniscus first lens element L1 with the convex surface facing the object side.
In the zoom lens system according to Embodiment II-6, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave second lens element L2; and a positive meniscus third lens element L3 with the convex surface facing the object side. The second lens element L2 has two aspheric surfaces.
In the zoom lens system according to Embodiment II-6, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fourth lens element L4; a bi-concave fifth lens element L5; and a bi-convex sixth lens element L6. Among these, the fourth lens element L4 and the fifth lens element L5 are cemented with each other. Further, the fourth lens element L4 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-6, the fourth lens unit G4 comprises solely a bi-convex seventh lens element L7. The seventh lens element L7 has an aspheric object side surface.
In the zoom lens system according to Embodiment II-6, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the seventh lens element L7).
In the zoom lens system according to Embodiment II-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
In the zoom lens systems according to Embodiments II-1 to II-6, the first lens unit G1 comprises one or two lens elements, the second lens unit G2 comprises two lens elements, and the third lens unit G3 comprises three lens elements. Thus, the lens system has a short overall optical length (overall length of lens system).
In the zoom lens systems according to Embodiments II-1 to II-5, the first lens unit G1, in order from the object side to the image side, is composed of the negative meniscus lens element L1 with the convex surface facing the object side, and the positive lens element L2. These two lens elements are cemented with each other to constitute a cemented lens element. Thus, a compact lens system is realized. Further, such a construction permits favorable compensation of chromatic aberration. Furthermore, in the zoom lens system according to Embodiment II-6, the first lens unit G1 is composed of solely the positive meniscus first lens element L1 with the convex surface facing the object side. Thus, a more compact and lightweight lens system is realized. In this case, it is difficult to compensate chromatic aberration and spherical aberration by the first lens unit G1 alone. Therefore, it is necessary to make the F-number at a telephoto limit relatively great (to make the lens system relatively dark).
In the zoom lens systems according to Embodiments II-1 to II-6, in the second lens unit G2, the third lens element L3 or the second lens element L2, which is an object side lens element, has an aspheric surface. Therefore, aberrations, particularly distortion at a wide-angle limit, can be compensated more favorably. Further, in the third lens unit G3, the fifth lens element L5 or the fourth lens element L4, which is an object side positive lens element, has an aspheric surface. Therefore, aberrations, particularly spherical aberration, can be compensated more favorably.
In the zoom lens systems according to Embodiments II-1 to II-5, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fifth lens element L5 having positive optical power, the sixth lens element L6 having negative optical power, and the seventh lens element L7 having positive optical power. The fifth lens element L5, which is an object side positive lens element, and the sixth lens element L6 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements. Further, in the zoom lens system according to Embodiment II-6, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fourth lens element L4 having positive optical power, the fifth lens element L5 having negative optical power; and the sixth lens element L6 having positive optical power. The fourth lens element L4, which is an object side positive lens element, and the fifth lens element L5 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements.
In the zoom lens systems according to Embodiments II-1 to II-6, the fourth lens unit G4 is composed of a single lens element, and the lens element has positive optical power. Thus, the lens system has a short overall optical length (overall length of lens system). Further, at the time of focusing from an infinite-distance object to a close-distance object, as shown in each Fig., the fourth lens unit G4 is drawn out to the object side so that rapid focusing is achieved easily.
Further, in the zoom lens systems according to Embodiments II-1 to II-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1, the second lens unit G2, the third lens unit G3, and the fourth lens unit G4 are moved individually along the optical axis so that zooming is achieved. Then, any lens unit among the first lens unit G1, the second lens unit G2, the third lens unit G3 and the fourth lens unit G4, or alternatively, a sub lens unit consisting of a part of a lens unit is moved in a direction perpendicular to the optical axis, so that image point movement caused by vibration of the entire system is compensated, that is, image blur caused by hand blurring, vibration and the like can be compensated optically.
When image point movement caused by vibration of the entire system is to be compensated, for example, the third lens unit G3 is moved in a direction perpendicular to the optical axis. Thus, image blur is compensated in a state that size increase in the entire zoom lens system is suppressed to realize a compact construction and that excellent imaging characteristics such as small decentering coma aberration and small decentering astigmatism are maintained.
In a case that a lens unit is composed of a plurality of lens elements, the above-mentioned sub lens unit consisting of a part of a lens unit indicates any one lens element or alternatively a plurality of adjacent lens elements among the plurality of lens elements.
Embodiments III-1 to III-8
FIGS. 48, 51, 54, 57, 60, 63, 66 and 69 are lens arrangement diagrams of zoom lens systems according to Embodiments III-1 to III-8, respectively.
Each of FIGS. 48, 51, 54, 57, 60, 63, 66 and 69 shows a zoom lens system in an infinity in-focus condition. In each Fig., part (a) shows a lens configuration at a wide-angle limit (in the minimum focal length condition: focal length fW), part (b) shows a lens configuration at a middle position (in an intermediate focal length condition: focal length fM=√(fW*fT)), and part (c) shows a lens configuration at a telephoto limit (in the maximum focal length condition: focal length fT). Further, in each Fig., an arrow of straight or curved line provided between part (a) and part (b) indicates the movement of each lens unit from a wide-angle limit through a middle position to a telephoto limit. Moreover, in each Fig., an arrow imparted to a lens unit indicates focusing from an infinity in-focus condition to a close-object in-focus condition. That is, the arrow indicates the moving direction at the time of focusing from an infinity in-focus condition to a close-object in-focus condition.
The zoom lens system according to each embodiment, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having positive optical power, and a fourth lens unit having positive optical power. Then, in zooming, the individual lens units move in a direction along the optical axis such that intervals between the lens units, that is, the interval between the first lens unit and the second lens unit, the interval between the second lens unit and the third lens unit, and the interval between the third lens unit and the fourth lens unit should all vary. In the zoom lens system according to each embodiment, since these lens units are arranged in the desired optical power configuration, high optical performance is maintained and still size reduction is achieved in the entire lens system.
Further, in FIGS. 48, 51, 54, 57, 60, 63, 66 and 69, an asterisk “*” imparted to a particular surface indicates that the surface is aspheric. In each Fig., symbol (+) or (−) imparted to the symbol of each lens unit corresponds to the sign of the optical power of the lens unit. In each Fig., the straight line located on the most right-hand side indicates the position of the image surface S. On the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P equivalent to an optical low-pass filter or a face plate of an image sensor is provided.
Further, in FIGS. 48, 51, 54, 57, 60, 63, 66 and 69, an aperture diaphragm A is provided on the most object side in the third lens unit G3. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, the aperture diaphragm A moves along the optical axis integrally with the third lens unit G3.
As shown in FIG. 48, in the zoom lens system according to Embodiment III-1, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.
In the zoom lens system according to Embodiment III-1, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-1, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-1, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-1, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-1, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 51, in the zoom lens system according to Embodiment III-2, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment III-2, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-2, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-2, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-2, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-2, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 54, in the zoom lens system according to Embodiment III-3, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment III-3, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-3, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. The fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-3, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-3, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-3, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 57, in the zoom lens system according to Embodiment III-4, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment III-4, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-4, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-4, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-4, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-4, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 60, in the zoom lens system according to Embodiment III-5, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment III-5, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-5, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-5, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-5, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-5, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 63, in the zoom lens system according to Embodiment III-6, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a bi-convex second lens element L2. The first lens element L1 and the second lens element L2 are cemented with each other. Further, the second lens element L2 has an aspheric image side surface.
In the zoom lens system according to Embodiment III-6, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-6, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fifth lens element L5; a bi-concave sixth lens element L6; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-6, the fourth lens unit G4 comprises solely a positive meniscus eighth lens element L8 with the convex surface facing the image side. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-6, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-6, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 66, in the zoom lens system according to Embodiment III-7, the first lens unit G1, in order from the object side to the image side, comprises a negative meniscus first lens element L1 with the convex surface facing the object side; and a positive meniscus second lens element L2 with the convex surface facing the object side. The first lens element L1 and the second lens element L2 are cemented with each other.
In the zoom lens system according to Embodiment III-7, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave third lens element L3; and a positive meniscus fourth lens element L4 with the convex surface facing the object side. The third lens element L3 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-7, the third lens unit G3, in order from the object side to the image side, comprises a positive meniscus fifth lens element L5 with the convex surface facing the object side; a negative meniscus sixth lens element L6 with the convex surface facing the object side; and a bi-convex seventh lens element L7. Among these, the fifth lens element L5 and the sixth lens element L6 are cemented with each other. Further, the fifth lens element L5 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-7, the fourth lens unit G4 comprises solely a bi-convex eighth lens element L8. The eighth lens element L8 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-7, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the eighth lens element L8).
In the zoom lens system according to Embodiment III-7, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
As shown in FIG. 69, in the zoom lens system according to Embodiment III-8, the first lens unit G1 comprises solely a positive meniscus first lens element L1 with the convex surface facing the object side.
In the zoom lens system according to Embodiment III-8, the second lens unit G2, in order from the object side to the image side, comprises a bi-concave second lens element L2; and a positive meniscus third lens element L3 with the convex surface facing the object side. The second lens element L2 has two aspheric surfaces.
In the zoom lens system according to Embodiment III-8, the third lens unit G3, in order from the object side to the image side, comprises a bi-convex fourth lens element L4; a bi-concave fifth lens element L5; and a bi-convex sixth lens element L6. Among these, the fourth lens element L4 and the fifth lens element L5 are cemented with each other. Further, the fourth lens element L4 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-8, the fourth lens unit G4 comprises solely a bi-convex seventh lens element L7. The seventh lens element L7 has an aspheric object side surface.
In the zoom lens system according to Embodiment III-8, a plane parallel plate P is provided on the object side relative to the image surface S (between the image surface S and the seventh lens element L7).
In the zoom lens system according to Embodiment III-8, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1 and the third lens unit G3 move to the object side, the second lens unit G2 moves to the image side with locus of a convex to the image side, and the fourth lens unit G4 moves to the image side with locus of a convex to the object side. That is, in zooming, the individual lens units move along the optical axis such that the interval between the second lens unit G2 and the third lens unit G3 should decrease.
In the zoom lens systems according to Embodiments III-1 to III-8, the first lens unit G1 comprises one or two lens elements, the second lens unit G2 comprises two lens elements, and the third lens unit G3 comprises three lens elements. Thus, the lens system has a short overall optical length (overall length of lens system).
In the zoom lens systems according to Embodiments III-1 to III-7, the first lens unit G1, in order from the object side to the image side, is composed of the negative meniscus lens element L1 with the convex surface facing the object side, and the positive lens element L2. These two lens elements are cemented with each other to constitute a cemented lens element. Thus, a compact lens system is realized. Further, such a construction permits favorable compensation of chromatic aberration. Furthermore, in the zoom lens system according to Embodiment III-8, the first lens unit G1 is composed of solely the positive meniscus first lens element L1 with the convex surface facing the object side. Thus, a more compact and lightweight lens system is realized. In this case, it is difficult to compensate chromatic aberration and spherical aberration by the first lens unit G1 alone. Therefore, it is necessary to make the F-number at a telephoto limit relatively great (to make the lens system relatively dark).
In the zoom lens systems according to Embodiments III-1 to III-8, in the second lens unit G2, the third lens element L3 or the second lens element L2, which is an object side lens element, has an aspheric surface. Therefore, aberrations, particularly distortion at a wide-angle limit, can be compensated more favorably. Further, in the third lens unit G3, the fifth lens element L5 or the fourth lens element L4, which is an object side positive lens element, has an aspheric surface. Therefore, aberrations, particularly spherical aberration, can be compensated more favorably.
In the zoom lens systems according to Embodiments III-1 to III-7, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fifth lens element L5 having positive optical power, the sixth lens element L6 having negative optical power, and the seventh lens element L7 having positive optical power. The fifth lens element L5, which is an object side positive lens element, and the sixth lens element L6 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements. Further, in the zoom lens system according to Embodiment III-8, the third lens unit G3 is composed of three lens elements, i.e., in order from the object side to the image side, the fourth lens element L4 having positive optical power, the fifth lens element L5 having negative optical power; and the sixth lens element L6 having positive optical power. The fourth lens element L4, which is an object side positive lens element, and the fifth lens element L5 are cemented with each other to constitute a cemented lens element. Therefore, axial aberration, which occurs in the positive lens element, is compensated in the negative lens element, and thus excellent optical performance is achieved with a small number of lens elements.
In the zoom lens systems according to Embodiments III-1 to III-8, the fourth lens unit G4 is composed of a single lens element, and the lens element has positive optical power. Thus, the lens system has a short overall optical length (overall length of lens system). Further, at the time of focusing from an infinite-distance object to a close-distance object, as shown in each Fig., the fourth lens unit G4 is drawn out to the object side so that rapid focusing is achieved easily.
Further, in the zoom lens systems according to Embodiments III-1 to III-8, in zooming from a wide-angle limit to a telephoto limit at the time of image taking, the first lens unit G1, the second lens unit G2, the third lens unit G3, and the fourth lens unit G4 are moved individually along the optical axis so that zooming is achieved. Then, any lens unit among the first lens unit G1, the second lens unit G2, the third lens unit G3 and the fourth lens unit G4, or alternatively, a sub lens unit consisting of a part of a lens unit is moved in a direction perpendicular to the optical axis, so that image point movement caused by vibration of the entire system is compensated, that is, image blur caused by hand blurring, vibration and the like can be compensated optically.
When image point movement caused by vibration of the entire system is to be compensated, for example, the third lens unit G3 is moved in a direction perpendicular to the optical axis. Thus, image blur is compensated in a state that size increase in the entire zoom lens system is suppressed to realize a compact construction and that excellent imaging characteristics such as small decentering coma aberration and small decentering astigmatism are maintained.
In a case that a lens unit is composed of a plurality of lens elements, the above-mentioned sub lens unit consisting of a part of a lens unit indicates any one lens element or alternatively a plurality of adjacent lens elements among the plurality of lens elements.
The following description is given for conditions preferred to be satisfied by a zoom lens system like the zoom lens systems according to Embodiments I-1 to I-9, II-1 to II-6 and III-1 to III-8. Here, a plurality of preferable conditions are set forth for the zoom lens system according to each embodiment. A construction that satisfies all the plural conditions is most desirable for the zoom lens system. However, when an individual condition is satisfied, a zoom lens system having the corresponding effect is obtained.
In a zoom lens system like the zoom lens systems according to Embodiments I-1 to I-9, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, and the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power (this lens configuration is referred to as basic configuration I of the embodiments, hereinafter), the following conditions (2-1), (a-1) and (b-2) are satisfied.

−2.3<f2/fW<−1.5  (2-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
f2 is a composite focal length of the second lens unit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
The condition (2-1) sets forth a suitable focal length of the second lens unit. When the value exceeds the upper limit of the condition (2-1), the focal length of the second lens unit becomes excessively long, and the amount of movement of the second lens unit increases in zooming, which might result in difficulty in achieving a compact zoom lens system having a zooming ratio exceeding 4.5. On the other hand, when the value goes below the lower limit of the condition (2-1), the focal length of the second lens unit becomes excessively short, which might result in difficulty in compensating variation in aberration caused by movement of the second lens unit.
When at least one of the following conditions (2-1)′ and (2-1)′′ is satisfied, the above-mentioned effect is achieved more successfully.

−2.1<f2/fW  (2-1)′

f2/fW<−1.7  (2-1)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, it is preferable that the following condition (3-1) is satisfied.

0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)

where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit, and
β3W is a lateral magnification of the third lens unit at a wide-angle limit.
The condition (3-1) sets forth the ratio between lateral magnification change in the second lens unit and lateral magnification change in the third lens unit. When the value exceeds the upper limit of the condition (3-1), variable magnification load to the second lens unit becomes excessively great, which might result in difficulty in suppressing occurrence of aberration due to increase in the power, particularly, occurrence of abaxial aberration such as curvature of field at a telephoto limit or magnification chromatic aberration. On the other hand, when the value goes below the lower limit of the condition (3-1), it might be difficult to suppress increase in the size of the lens system due to increase in the amount of movement of the third lens unit, and occurrence of aberration due to increase in the power of the third lens unit, particularly, occurrence of axial aberration such as spherical aberration at a telephoto limit.
When the following condition (3-1)′ is satisfied, the above-mentioned effect is achieved more successfully.

0.5<(β2T/β2W)/(β3T/β3W)  (3-1)′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, it is preferable that the following condition (4-1) is satisfied.

0.6<M1/M3<1.5  (4-1)

where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive), and
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive).
The condition (4-1) sets forth the ratio between the amount of movement of the first lens unit in the direction along the optical axis and the amount of movement of the third lens unit in the direction along the optical axis. When the value exceeds the upper limit of the condition (4-1), the amount of movement of the first lens unit increases and then, the overall optical length increases. As a result, a lens barrel at the time of retraction increases in size, which might result in difficulty in achieving a compact zoom lens system. On the other hand, when the value goes below the lower limit of the condition (4-1), the amount of movement of the third lens unit becomes excessively great, which might result in difficulty in compensating curvature of field or magnification chromatic aberration.
When at least one of the following conditions (4-1)′ and (4-1)′′ is satisfied, the above-mentioned effect is achieved more successfully.

0.8<M1/M3  (4-1)′

M1/M3<1.2  (4-1)′′

In a zoom lens system like the zoom lens systems according to Embodiments II-1 to II-6, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, and the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power (this lens configuration is referred to as basic configuration II of the embodiments, hereinafter), the following conditions (3-1), (a-1) and (b-2) are satisfied.

0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit,
β3W is a lateral magnification of the third lens unit at a wide-angle limit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
The condition (3-1) sets forth the ratio between lateral magnification change in the second lens unit and lateral magnification change in the third lens unit. When the value exceeds the upper limit of the condition (3-1), variable magnification load to the second lens unit becomes excessively great, which might result in difficulty in suppressing occurrence of aberration due to increase in the power, particularly, occurrence of abaxial aberration such as curvature of field at a telephoto limit or magnification chromatic aberration. On the other hand, when the value goes below the lower limit of the condition (3-1), it might be difficult to suppress increase in the size of the lens system due to increase in the amount of movement of the third lens unit, and occurrence of aberration due to increase in the power of the third lens unit, particularly, occurrence of axial aberration such as spherical aberration at a telephoto limit.
When the following condition (3-1)′ is satisfied, the above-mentioned effect is achieved more successfully.

0.5<(β2T/β2W)/(β3T/β3W)  (3-1)′

In a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, it is preferable that the following condition (2-1) is satisfied.

−2.3<f2/fW<−1.5  (2-1)

where,
f2 is a composite focal length of the second lens unit, and
fW is a focal length of the entire system at a wide-angle limit.
The condition (2-1) sets forth a suitable focal length of the second lens unit. When the value exceeds the upper limit of the condition (2-1), the focal length of the second lens unit becomes excessively long, and the amount of movement of the second lens unit increases in zooming, which might result in difficulty in achieving a compact zoom lens system having a zooming ratio exceeding 4.5. On the other hand, when the value goes below the lower limit of the condition (2-1), the focal length of the second lens unit becomes excessively short, which might result in difficulty in compensating variation in aberration caused by movement of the second lens unit.
When at least one of the following conditions (2-1)′ and (2-1)′′ is satisfied, the above-mentioned effect is achieved more successfully.

−2.1<f2/fW  (2-1)′

f2/fW<−1.7  (2-1)′′

In a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, it is preferable that the following condition (4-1) is satisfied.

0.6<M1/M3<1.5  (4-1)

where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive), and
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive).
The condition (4-1) sets forth the ratio between the amount of movement of the first lens unit in the direction along the optical axis and the amount of movement of the third lens unit in the direction along the optical axis. When the value exceeds the upper limit of the condition (4-1), the amount of movement of the first lens unit increases and then, the overall optical length increases. As a result, a lens barrel at the time of retraction increases in size, which might result in difficulty in achieving a compact zoom lens system. On the other hand, when the value goes below the lower limit of the condition (4-1), the amount of movement of the third lens unit becomes excessively great, which might result in difficulty in compensating curvature of field or magnification chromatic aberration.
When at least one of the following conditions (4-1)′ and (4-1)′′ is satisfied, the above-mentioned effect is achieved more successfully.

0.8<M1/M3  (4-1)′

M1/M3<1.2  (4-1)′′

In a zoom lens system like the zoom lens systems according to Embodiments III-1 to III-8, in order from the object side to the image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein the first lens unit is composed of at most two lens elements, the second lens unit is composed of two lens elements, and the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power (this lens configuration is referred to as basic configuration III of the embodiments, hereinafter), the following conditions (4-1), (a-1) and (b-2) are satisfied.

0.6<M1/M3<1.5  (4-1)

ωW≧36  (a-1)

fT/fW>4.5  (b-2)

where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.
The condition (4-1) sets forth the ratio between the amount of movement of the first lens unit in the direction along the optical axis and the amount of movement of the third lens unit in the direction along the optical axis. When the value exceeds the upper limit of the condition (4-1), the amount of movement of the first lens unit increases and then, the overall optical length increases. As a result, a lens barrel at the time of retraction increases in size, which might result in difficulty in achieving a compact zoom lens system. On the other hand, when the value goes below the lower limit of the condition (4-1), the amount of movement of the third lens unit becomes excessively great, which might result in difficulty in compensating curvature of field or magnification chromatic aberration.
When at least one of the following conditions (4-1)′ and (4-1)′′ is satisfied, the above-mentioned effect is achieved more successfully.

0.8<M1/M3  (4-1)′

M1/M3<1.2  (4-1)′′

In a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, it is preferable that the following condition (2-1) is satisfied.

−2.3<f2/fW<−1.5  (2-1)

where,
f2 is a composite focal length of the second lens unit, and
fW is a focal length of the entire system at a wide-angle limit.
The condition (2-1) sets forth a suitable focal length of the second lens unit. When the value exceeds the upper limit of the condition (2-1), the focal length of the second lens unit becomes excessively long, and the amount of movement of the second lens unit increases in zooming, which might result in difficulty in achieving a compact zoom lens system having a zooming ratio exceeding 4.5. On the other hand, when the value goes below the lower limit of the condition (2-1), the focal length of the second lens unit becomes excessively short, which might result in difficulty in compensating variation in aberration caused by movement of the second lens unit.
When at least one of the following conditions (2-1)′ and (2-1)′′ is satisfied, the above-mentioned effect is achieved more successfully.

−2.1<f2/fW  (2-1)′

f2/fW<−1.7  (2-1)′′

In a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, it is preferable that the following condition (3-1) is satisfied.

0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)

where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit, and
β3W is a lateral magnification of the third lens unit at a wide-angle limit.
The condition (3-1) sets forth the ratio between lateral magnification change in the second lens unit and lateral magnification change in the third lens unit. When the value exceeds the upper limit of the condition (3-1), variable magnification load to the second lens unit becomes excessively great, which might result in difficulty in suppressing occurrence of aberration due to increase in the power, particularly, occurrence of abaxial aberration such as curvature of field at a telephoto limit or magnification chromatic aberration. On the other hand, when the value goes below the lower limit of the condition (3-1), it might be difficult to suppress increase in the size of the lens system due to increase in the amount of movement of the third lens unit, and occurrence of aberration due to increase in the power of the third lens unit, particularly, occurrence of axial aberration such as spherical aberration at a telephoto limit.
When the following condition (3-1)′ is satisfied, the above-mentioned effect is achieved more successfully.

0.5<(β2T/β2W)/(β3T/β3W)  (3-1)′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, in which the second lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, in which the second lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, in which the second lens unit includes a lens element having positive optical power, it is preferable that the following condition (5) is satisfied.

1.88<nd2p<2.20  (5)

where,
nd2p is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.
The condition (5) sets forth the refractive index of the lens element having positive optical power, which is included in the second lens unit. When the value exceeds the upper limit of the condition (5), it might be difficult to realize mass production of the lens material. On the other hand, when the value goes below the lower limit of the condition (5), it might be difficult to compensate curvature of field and distortion at a wide-angle limit, and coma aberration in the entire zooming range from a wide-angle limit to a telephoto limit.
When at least one of the following conditions (5)′ and (5)′′ is satisfied, the above-mentioned effect is achieved more successfully.

1.90<nd2p  (5)′

nd2p<2.15  (5)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, in which the second lens unit includes a lens element having negative optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, in which the second lens unit includes a lens element having negative optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, in which the second lens unit includes a lens element having negative optical power, it is preferable that the following condition (6) is satisfied.

0.35<(r2na+r2nb)/(r2na−r2nb)<1.20  (6)

where,
r2na is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.
The condition (6) sets forth the shape factor of the lens element having negative optical power, which is included in the second lens unit. When the value exceeds the upper limit of the condition (6), it might be difficult to compensate curvature of field and distortion at a wide-angle limit. On the other hand, when the value goes below the lower limit of the condition (6), it might be difficult to compensate coma aberration in the entire zooming range from a wide-angle limit to a telephoto limit.
When at least one of the following conditions (6)′ and (6)′′ is satisfied, the above-mentioned effect is achieved more successfully.

0.59<(r2na+r2nb)/(r2na−r2nb)  (6)′

(r2na+r2nb)/(r2na−r2nb)<0.90  (6)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, in which the second lens is composed of two lens elements, i.e., in order from the object side to the image side, a lens element having negative optical power and a lens element having positive optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, in which the second lens unit is composed of two lens elements, i.e., in order from the object side to the image side, a lens element having negative optical power and a lens element having positive optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, in which the second lens unit is composed of two lens elements, i.e., in order from the object side to the image side, a lens element having negative optical power and a lens element having positive optical power, it is preferable that the following condition (7) is satisfied.

−8.5<(r2nb+r2pa)/(r2nb−r2pa)<−3.5  (7)

where,
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.
The condition (7) sets forth the shape factor of an air lens between the two lens elements constituting the second lens unit. When the value exceeds the upper limit of the condition (7), it might be difficult to compensate curvature of field and distortion at a wide-angle limit. On the other hand, when the value goes below the lower limit of the condition (7), it might be difficult to compensate coma aberration in the entire zooming range from a wide-angle limit to a telephoto limit.
When at least one of the following conditions (7)′ and (7)′′ is satisfied, the above-mentioned effect is achieved more successfully.

−8.0<(r2nb+r2pa)/(r2nb−r2pa)  (7)′

(r2nb+r2pa)/(r2nb−r2pa)<−5.0  (7)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, in which the first lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, in which the first lens unit includes a lens element having positive optical power, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, in which the first lens unit includes a lens element having positive optical power, it is preferable that the following condition (8) is satisfied.

−1.8<(r1pa+r1pb)/(r1pa−r1pb)<0.0  (8)

where,
r1pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and
r1pb is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.
The condition (8) sets forth the shape factor of the lens element having positive optical power, which is included in the first lens unit. When the value exceeds the upper limit of the condition (8), it might be difficult to compensate coma aberration at a telephoto limit. On the other hand, when the value goes below the lower limit of the condition (8), it might be difficult to compensate curvature of field at a wide-angle limit.
When at least one of the following conditions (8)′ and (8)′′ is satisfied, the above-mentioned effect is achieved more successfully.

−1.2<(r1pa+r1pb)/(r1pa−r1pb)  (8)′

(r1pa+r1pb)/(r1pa−r1pb)<−0.2  (8)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, it is preferable that the following condition (9) is satisfied.

1.87<f3/fW<3.00  (9)

where,
f3 is a composite focal length of the third lens unit, and
fW is a focal length of the entire system at a wide-angle limit.
The condition (9) sets forth a suitable focal length of the third lens unit. When the value exceeds the upper limit of the condition (9), the focal length of the third lens unit becomes excessively long, which might result in difficulty in achieving a compact zoom lens system. Further, when the value exceeds the upper limit of the condition (9), the amount of movement of, for example, the third lens unit becomes excessively great when the third lens unit is moved in a direction perpendicular to the optical axis for blur compensation. Such a situation is not desirable. On the other hand, when the value goes below the lower limit of the condition (9), the focal length of the third lens unit becomes excessively short. Then, the aberration compensation capability of the third lens unit becomes excessively high, and compensation of various aberrations is not well-balanced, which might result in difficulty in achieving a compact zoom lens system.
When at least one of the following conditions (9)′ and (9)′′ is satisfied, the above-mentioned effect is achieved more successfully.

1.90<f3/fW  (9)′

f3/fW<2.10  (9)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, it is preferable that the following condition (10) is satisfied.

0.5<f3IL/f3<1.5  (10)

where,
f3IL is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.
The condition (10) sets forth a suitable focal length of the image side lens element having positive optical power, which is included in the third lens unit. When the value exceeds the upper limit of the condition (10), it might be difficult to compensate spherical aberration and coma aberration in a balanced manner by other lens elements, although the overall optical length can be reduced. On the other hand, when the value goes below the lower limit of the condition (10), it might be difficult to reduce the overall optical length, although spherical aberration and coma aberration can be compensated in a balanced manner by other lens elements.
When at least one of the following conditions (10)′ and (10)′′ is satisfied, the above-mentioned effect is achieved more successfully.

1.0<f3IL/f3  (10)′

f3IL/f3<1.3  (10)′′

In a zoom lens system having the basic configuration I like the zoom lens systems according to Embodiments I-1 to I-9, and in a zoom lens system having the basic configuration II like the zoom lens systems according to Embodiments II-1 to II-6, and in a zoom lens system having the basic configuration III like the zoom lens systems according to Embodiments III-1 to III-8, it is preferable that the following condition (11) is satisfied.

−1.00<f3n/f3<−0.25  (11)

where,
f3n is a focal length of the lens element having negative optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.
The condition (11) sets forth a suitable focal length of the lens element having negative optical power, which is included in the third lens unit. When the value exceeds the upper limit of the condition (11), it might be difficult to compensate spherical aberration and coma aberration in a balanced manner by other lens elements, although the overall optical length can be reduced. On the other hand, when the value goes below the lower limit of the condition (11), it might be difficult to reduce the overall optical length, although spherical aberration and coma aberration can be compensated in a balanced manner by other lens elements.
When at least one of the following conditions (11)′ and (11)′′ is satisfied, the above-mentioned effect is achieved more successfully.

−0.50<f3n/f3  (11)′

f3n/f3<−0.35  (11)′′

Each of the lens units constituting the zoom lens system according to any of Embodiments I-1 to I-9, II-1 to II-6 and III-1 to III-8 is composed exclusively of refractive type lens elements that deflect the incident light by refraction (that is, lens elements of a type in which deflection is achieved at the interface between media each having a distinct refractive index). However, the present invention is not limited to this. For example, the lens units may employ diffractive type lens elements that deflect the incident light by diffraction; refractive-diffractive hybrid type lens elements that deflect the incident light by a combination of diffraction and refraction; or gradient index type lens elements that deflect the incident light by distribution of refractive index in the medium. In particular, in the refractive-diffractive hybrid type lens elements, when a diffraction structure is formed in the interface between media having mutually different refractive indices, wavelength dependence in the diffraction efficiency is improved. Thus, such a configuration is preferable.
Moreover, in each embodiment, a configuration has been described that on the object side relative to the image surface S (that is, between the image surface S and the most image side lens surface of the fourth lens unit G4), a plane parallel plate P such as an optical low-pass filter and a face plate of an image sensor is provided. This low-pass filter may be: a birefringent type low-pass filter made of, for example, a crystal whose predetermined crystal orientation is adjusted; or a phase type low-pass filter that achieves required characteristics of optical cut-off frequency by diffraction.
Embodiment I-10
FIG. 28 is a schematic construction diagram of a digital still camera according to Embodiment I-10. In FIG. 28, the digital still camera comprises: an imaging device having a zoom lens system 1 and an image sensor 2 composed of a CCD; a liquid crystal display monitor 3; and a body 4. The employed zoom lens system 1 is a zoom lens system according to Embodiment I-1. In FIG. 28, the zoom lens system 1 comprises a first lens unit G1, a second lens unit G2, an aperture diaphragm A, a third lens unit G3, and a fourth lens unit G4. In the body 4, the zoom lens system 1 is arranged on the front side, and the image sensor 2 is arranged on the rear side of the zoom lens system 1. On the rear side of the body 4, the liquid crystal display monitor 3 is arranged, and an optical image of a photographic object generated by the zoom lens system 1 is formed on an image surface S.
A lens barrel comprises a main barrel 5, a moving barrel 6 and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens unit G1, the second lens unit G2, the aperture diaphragm A and the third lens unit G3, and the fourth lens unit G4 move to predetermined positions relative to the image sensor 2, so that zooming from a wide-angle limit to a telephoto limit is achieved. The fourth lens unit G4 is movable in an optical axis direction by a motor for focus adjustment.
In this way, when the zoom lens system according to Embodiment I-1 is employed in a digital still camera, a small digital still camera is obtained that has a high resolution and high capability of compensating the curvature of field and that has a short overall length of lens system at the time of non-use. Here, in the digital still camera shown in FIG. 28, any one of the zoom lens systems according to Embodiments I-2 to I-9 may be employed in place of the zoom lens system according to Embodiment I-1. Further, the optical system of the digital still camera shown in FIG. 28 is applicable also to a digital video camera for moving images. In this case, moving images with high resolution can be acquired in addition to still images.
Here, the digital still camera according to Embodiment I-10 has been described for a case that the employed zoom lens system 1 is a zoom lens system according to any of Embodiments I-1 to I-9. However, in these zoom lens systems, the entire zooming range need not be used. That is, in accordance with a desired zooming range, a range where satisfactory optical performance is obtained may exclusively be used. Then, the zoom lens system may be used as one having a lower magnification than the zoom lens systems described in Embodiments I-1 to I-9.
Further, Embodiment I-10 has been described for a case that the zoom lens system is applied to a lens barrel of so-called barrel retraction construction. However, the present invention is not limited to this. For example, the zoom lens system may be applied to a lens barrel of so-called bending construction where a prism having an internal reflective surface or a front surface reflective mirror is arranged at an arbitrary position within the first lens unit G1 or the like. Further, in Embodiment I-10, the zoom lens system may be applied to a so-called sliding lens barrel in which a part of the lens units constituting the zoom lens system like the entirety of the second lens unit G2, the entirety of the third lens unit G3, or alternatively a part of the second lens unit G2 or the third lens unit G3 is caused to escape from the optical axis at the time of retraction.
Further, an imaging device comprising a zoom lens system according to any of Embodiments I-1 to I-9 described above and an image sensor such as a CCD or a CMOS may be applied to a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera, a vehicle-mounted camera or the like.
Embodiment II-7
FIG. 47 is a schematic construction diagram of a digital still camera according to Embodiment II-7. In FIG. 47, the digital still camera comprises: an imaging device having a zoom lens system 1 and an image sensor 2 composed of a CCD; a liquid crystal display monitor 3; and a body 4. The employed zoom lens system 1 is a zoom lens system according to Embodiment II-1. In FIG. 47, the zoom lens system 1 comprises a first lens unit G1, a second lens unit G2, an aperture diaphragm A, a third lens unit G3, and a fourth lens unit G4. In the body 4, the zoom lens system 1 is arranged on the front side, and the image sensor 2 is arranged on the rear side of the zoom lens system 1. On the rear side of the body 4, the liquid crystal display monitor 3 is arranged, and an optical image of a photographic object generated by the zoom lens system 1 is formed on an image surface S.
A lens barrel comprises a main barrel 5, a moving barrel 6 and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens unit G1, the second lens unit G2, the aperture diaphragm A and the third lens unit G3, and the fourth lens unit G4 move to predetermined positions relative to the image sensor 2, so that zooming from a wide-angle limit to a telephoto limit is achieved. The fourth lens unit G4 is movable in an optical axis direction by a motor for focus adjustment.
In this way, when the zoom lens system according to Embodiment II-1 is employed in a digital still camera, a small digital still camera is obtained that has a high resolution and high capability of compensating the curvature of field and that has a short overall length of lens system at the time of non-use. Here, in the digital still camera shown in FIG. 47, any one of the zoom lens systems according to Embodiments II-2 to II-6 may be employed in place of the zoom lens system according to Embodiment II-1. Further, the optical system of the digital still camera shown in FIG. 47 is applicable also to a digital video camera for moving images. In this case, moving images with high resolution can be acquired in addition to still images.
Here, the digital still camera according to Embodiment II-7 has been described for a case that the employed zoom lens system 1 is a zoom lens system according to any of Embodiments II-1 to II-6. However, in these zoom lens systems, the entire zooming range need not be used. That is, in accordance with a desired zooming range, a range where satisfactory optical performance is obtained may exclusively be used. Then, the zoom lens system may be used as one having a lower magnification than the zoom lens systems described in Embodiments II-1 to II-6.
Further, Embodiment II-7 has been described for a case that the zoom lens system is applied to a lens barrel of so-called barrel retraction construction. However, the present invention is not limited to this. For example, the zoom lens system may be applied to a lens barrel of so-called bending construction where a prism having an internal reflective surface or a front surface reflective mirror is arranged at an arbitrary position within the first lens unit G1 or the like. Further, in Embodiment II-7, the zoom lens system may be applied to a so-called sliding lens barrel in which a part of the lens units constituting the zoom lens system like the entirety of the second lens unit G2, the entirety of the third lens unit G3, or alternatively a part of the second lens unit G2 or the third lens unit G3 is caused to escape from the optical axis at the time of retraction.
Further, an imaging device comprising a zoom lens system according to any of Embodiments II-1 to II-6 described above and an image sensor such as a CCD or a CMOS may be applied to a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera, a vehicle-mounted camera or the like.
Embodiment III-9
FIG. 72 is a schematic construction diagram of a digital still camera according to Embodiment III-9. In FIG. 72, the digital still camera comprises: an imaging device having a zoom lens system 1 and an image sensor 2 composed of a CCD; a liquid crystal display monitor 3; and a body 4. The employed zoom lens system 1 is a zoom lens system according to Embodiment III-1. In FIG. 72, the zoom lens system 1 comprises a first lens unit G1, a second lens unit G2, an aperture diaphragm A, a third lens unit G3, and a fourth lens unit G4. In the body 4, the zoom lens system 1 is arranged on the front side, and the image sensor 2 is arranged on the rear side of the zoom lens system 1. On the rear side of the body 4, the liquid crystal display monitor 3 is arranged, and an optical image of a photographic object generated by the zoom lens system 1 is formed on an image surface S.
A lens barrel comprises a main barrel 5, a moving barrel 6 and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens unit G1, the second lens unit G2, the aperture diaphragm A and the third lens unit G3, and the fourth lens unit G4 move to predetermined positions relative to the image sensor 2, so that zooming from a wide-angle limit to a telephoto limit is achieved. The fourth lens unit G4 is movable in an optical axis direction by a motor for focus adjustment.
In this way, when the zoom lens system according to Embodiment III-1 is employed in a digital still camera, a small digital still camera is obtained that has a high resolution and high capability of compensating the curvature of field and that has a short overall length of lens system at the time of non-use. Here, in the digital still camera shown in FIG. 72, any one of the zoom lens systems according to Embodiments III-2 to III-8 may be employed in place of the zoom lens system according to Embodiment III-1. Further, the optical system of the digital still camera shown in FIG. 72 is applicable also to a digital video camera for moving images. In this case, moving images with high resolution can be acquired in addition to still images.
Here, the digital still camera according to Embodiment III-9 has been described for a case that the employed zoom lens system 1 is a zoom lens system according to any of Embodiments III-1 to III-8. However, in these zoom lens systems, the entire zooming range need not be used. That is, in accordance with a desired zooming range, a range where satisfactory optical performance is obtained may exclusively be used. Then, the zoom lens system may be used as one having a lower magnification than the zoom lens systems described in Embodiments III-1 to III-8.
Further, Embodiment III-9 has been described for a case that the zoom lens system is applied to a lens barrel of so-called barrel retraction construction. However, the present invention is not limited to this. For example, the zoom lens system may be applied to a lens barrel of so-called bending construction where a prism having an internal reflective surface or a front surface reflective mirror is arranged at an arbitrary position within the first lens unit G1 or the like. Further, in Embodiment III-9, the zoom lens system may be applied to a so-called sliding lens barrel in which a part of the lens units constituting the zoom lens system like the entirety of the second lens unit G2, the entirety of the third lens unit G3, or alternatively a part of the second lens unit G2 or the third lens unit G3 is caused to escape from the optical axis at the time of retraction.
Further, an imaging device comprising a zoom lens system according to any of Embodiments III-1 to III-8 described above and an image sensor such as a CCD or a CMOS may be applied to a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera, a vehicle-mounted camera or the like.
Numerical examples are described below in which the zoom lens systems according to Embodiments I-1 to I-9, II-1 to II-6 and III-1 to III-8 are implemented. Here, in the numerical examples, the units of length are all “mm”, while the units of view angle are all “°”. Moreover, in the numerical examples, r is the radius of curvature, d is the axial distance, nd is the refractive index to the d-line, and vd is the Abbe number to the d-line. In the numerical examples, the surfaces marked with * are aspherical surfaces, and the aspherical surface configuration is defined by the following expression.




  Z
  =
  
    
      
        
          h
          2
        
        /
        r
      
      
        1
        +
        
          
            1
            -
            
              
                (
                
                  1
                  +
                  κ
                
                )
              
              ⁢
              
                
                  (
                  
                    h
                    /
                    r
                  
                  )
                
                2
              
            
          
        
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      4
      ⁢
      
        
      
      ⁢
      
        h
        4
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      6
      ⁢
      
        
      
      ⁢
      
        h
        6
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      8
      ⁢
      
        
      
      ⁢
      
        h
        8
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      10
      ⁢
      
        
      
      ⁢
      
        h
        10
      
    
  




Here, κ is the conic constant, A4, A6, A8 and A10 are a fourth-order, sixth-order, eighth-order and tenth-order aspherical coefficients, respectively.

FIGS. 2, 5, 8, 11, 14, 17, 20, 23 and 26 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments I-1 to I-9, respectively.
FIGS. 30, 33, 36, 39, 42 and 45 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments II-1 to II-6, respectively.
FIGS. 49, 52, 55, 58, 61, 64, 67 and 70 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments III-1 to III-8, respectively.
In each longitudinal aberration diagram, part (a) shows the aberration at a wide-angle limit, part (b) shows the aberration at a middle position, and part (c) shows the aberration at a telephoto limit. Each longitudinal aberration diagram, in order from the left-hand side, shows the spherical aberration (SA (mm)), the astigmatism (AST (mm)) and the distortion (DIS (%)). In each spherical aberration diagram, the vertical axis indicates the F-number (in each Fig., indicated as F), and the solid line, the short dash line and the long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each astigmatism diagram, the vertical axis indicates the image height (in each Fig., indicated as H), and the solid line and the dash line indicate the characteristics to the sagittal plane (in each Fig., indicated as “s”) and the meridional plane (in each Fig., indicated as “m”), respectively. In each distortion diagram, the vertical axis indicates the image height (in each Fig., indicated as H).
FIGS. 3, 6, 9, 12, 15, 18, 21, 24 and 27 are lateral aberration diagrams of the zoom lens systems at a telephoto limit according to Embodiments I-1 to I-9, respectively.
FIGS. 31, 34, 37, 40, 43 and 46 are lateral aberration diagrams of the zoom lens systems at a telephoto limit according to Embodiments II-1 to II-6, respectively.
FIGS. 50, 53, 56, 59, 62, 65, 68 and 71 are lateral aberration diagrams of the zoom lens systems at a telephoto limit according to Embodiments III-1 to III-8, respectively.
In each lateral aberration diagram, the aberration diagrams in the upper three parts correspond to a basic state where image blur compensation is not performed at a telephoto limit, while the aberration diagrams in the lower three parts correspond to an image blur compensation state where the entirety of the third lens unit G3 is moved by a predetermined amount in a direction perpendicular to the optical axis at a telephoto limit. Among the lateral aberration diagrams of a basic state, the upper part shows the lateral aberration at an image point of 70% of the maximum image height, the middle part shows the lateral aberration at the axial image point, and the lower part shows the lateral aberration at an image point of −70% of the maximum image height. Among the lateral aberration diagrams of an image blur compensation state, the upper part shows the lateral aberration at an image point of 70% of the maximum image height, the middle part shows the lateral aberration at the axial image point, and the lower part shows the lateral aberration at an image point of −70% of the maximum image height. In each lateral aberration diagram, the horizontal axis indicates the distance from the principal ray on the pupil surface, and the solid line, the short dash line and the long dash line indicate the characteristics to the d-line, the F-line and the C-line, respectively. In each lateral aberration diagram, the meridional plane is adopted as the plane containing the optical axis of the first lens unit G1 and the optical axis of the third lens unit G3.
Here, in the zoom lens system according to each example, the amount of movement of the third lens unit G3 in a direction perpendicular to the optical axis in the image blur compensation state at a telephoto limit is as follows.















Amount of movement



Example
(mm)









I-1
0.055



I-2
0.063



I-3
0.066



I-4
0.066



I-5
0.085



I-6
0.086



I-7
0.085



I-8
0.081



I-9
0.061



II-1
0.060



II-2
0.055



II-3
0.066



II-4
0.065



II-5
0.086



II-6
0.061



III-1
0.060



III-2
0.063



III-3
0.066



III-4
0.065



III-5
0.065



III-6
0.085



III-7
0.081



III-8
0.061










Here, when the shooting distance is infinity, at a telephoto limit, the amount of image decentering in a case that the zoom lens system inclines by 0.3° is equal to the amount of image decentering in a case that the entirety of the third lens unit G3 displaces in parallel by each of the above-mentioned values in a direction perpendicular to the optical axis.
As seen from the lateral aberration diagrams, satisfactory symmetry is obtained in the lateral aberration at the axial image point. Further, when the lateral aberration at the +70% image point and the lateral aberration at the −70% image point are compared with each other in the basic state, all have a small degree of curvature and almost the same inclination in the aberration curve. Thus, decentering coma aberration and decentering astigmatism are small. This indicates that sufficient imaging performance is obtained even in the image blur compensation state. Further, when the image blur compensation angle of a zoom lens system is the same, the amount of parallel translation required for image blur compensation decreases with decreasing focal length of the entire zoom lens system. Thus, at arbitrary zoom positions, sufficient image blur compensation can be performed for image blur compensation angles up to 0.3° without degrading the imaging characteristics.
Numerical Example I-1
The zoom lens system of Numerical Example I-1 corresponds to Embodiment I-1 shown in FIG. 1. Table I-1 shows the surface data of the zoom lens system of Numerical Example I-1. Table I-2 shows the aspherical data. Table I-3 shows various data.







TABLE I-1







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
34.84177
0.80000
1.84666
23.8


 2
22.99333
3.20000
1.72916
54.7


 3
−7811.04900
Variable


 4*
−58.44512
1.20000
1.85976
40.6


 5*
5.19121
1.67940


 6
8.20411
1.70000
1.94595
18.0


 7
16.41950
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.44243
2.50000
1.77377
47.2


10
793.42870
0.40000
1.80518
25.5


11
4.01346
0.50000


12
15.48439
1.80000
1.72916
54.7


13
−12.85234
Variable


14
121.92800
1.80000
1.58913
61.3


15
−16.82223
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-2





(Aspherical data)

















Surface No. 4



K = 0.00000E+00, A4 = 9.54547E−05, A6 = −6.85975E−07,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 5



K = −3.14137E+00, A4 = 2.36281E−03, A6 = −5.94676E−05,



A8 = 1.73729E−06 A10 = −2.29781E−08



Surface No. 9



K = −2.74176E−01, A4 = −2.89782E−04, A6 = −1.87247E−05,



A8 = 1.84381E−06 A10 = 2.49143E−07

















TABLE I-3





(Various data)


Zooming ratio 4.80270





















Wide-angle
Middle
Telephoto




limit
position
limit







Focal length
4.5807
9.4609
21.9997



F-number
3.33997
4.26195
6.23446



View angle
42.9736
21.6329
9.7950



Image height
3.8300
3.8300
3.8300



Overall length
40.0369
43.5052
49.5867



of lens system



BF
0.51919
0.46391
0.50046



d3
0.5000
7.9401
13.0837



d7
15.4856
7.7577
1.4500



d13
1.8860
6.9437
15.4487



d15
5.0667
3.8205
2.5245



Entrance pupil
10.9762
21.7930
28.9202



position



Exit pupil
−14.4240
−25.5869
−98.9580



position



Front principal
14.1528
27.8180
46.0536



points position



Back principal
35.4562
34.0443
27.5870



points position











Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−82.4113


2
2
31.4469


3
4
−5.4975


4
6
15.7497


5
9
5.7657


6
10
−5.0110


7
12
9.8968


8
14
25.2137









Numerical Example I-2
The zoom lens system of Numerical Example I-2 corresponds to Embodiment I-2 shown in FIG. 4. Table I-4 shows the surface data of the zoom lens system of Numerical Example I-2. Table I-5 shows the aspherical data. Table I-6 shows various data.







TABLE I-4





(Surface data)



















Surface number
r
d
nd
vd





Object surface
∞


 1
42.20045
0.80000
1.84666
23.8


 2
24.97099
2.90000
1.72916
54.7


 3*
−75.26600
Variable


 4*
−30.93809
0.90000
1.85976
40.6


 5*
5.39301
1.48910


 6
7.94718
1.70000
1.94595
18.0


 7
16.31084
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.79974
2.50000
1.85976
40.6


10
−14.66516
0.40000
1.84666
23.8


11
4.21186
0.60000


12
35.77043
1.70000
1.88300
40.8


13
−12.04398
Variable


14*
217.18110
1.80000
1.58913
61.3


15
−13.09408
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
51.72567
4.00000
−0.10347
1.61339


2
4
−9.29681
4.57940
0.03326
1.40517


3
8
10.04351
5.20000
−0.17000
1.52851


4
14
25.21371
1.80000
1.00018
1.66201










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.23531
−0.28990
−0.34528


3
8
−0.50392
−0.79018
−1.45189


4
14
0.74684
0.79846
0.84841
















TABLE I-5





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.11021E−05, A6 = 5.76903E−08,



A8 = −1.20097E−09 A10 = 7.11123E−12



Surface No. 4



K = 0.00000E+00, A4 = 2.30985E−04, A6 = −2.75552E−06,



A8 = 1.66601E−08 A10 = −7.35706E−11



Surface No. 5



K = −3.84341E+00, A4 = 2.62504E−03, A6 = −6.59135E−05,



A8 = 2.01477E−06 A10 = −2.90630E−08



Surface No. 9



K = −3.34609E−01, A4 = −2.42708E−04, A6 = −1.34729E−05,



A8 = 2.29294E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −7.38521E−05, A6 = 2.41783E−05,



A8 = −1.21687E−06 A10 = 2.41573E−08

















TABLE I-6





(Various data)


Zooming ratio 4.80618



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
4.5741
9.4586
21.9840


F-number
3.17859
3.86582
5.42033


View angle
42.9885
21.6541
9.9636


Image height
3.8300
3.8300
3.8300


Overall length
38.0091
39.1967
46.9950


of lens system


BF
0.50369
0.48002
0.48548


d3
0.5000
6.5541
13.4853


d7
14.2364
6.0247
1.4500


d13
2.0453
5.1834
13.2422


d15
4.9347
5.1654
2.5429


Entrance pupil
10.2416
18.5093
32.3551


position


Exit pupil
−15.2779
−24.0293
−119.2210


position


Front principal
13.4899
24.3176
50.3017


points position


Back principal
33.4350
29.7382
25.0110


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−73.8101


2
2
26.0324


3
4
−5.2811


4
6
14.9110


5
9
4.4716


6
10
−3.8275


7
12
10.3771


8
14
21.0233










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.40143
3.70000
0.74496
2.30550


2
4
−8.92286
4.08910
−0.07408
1.17904


3
8
9.99157
5.20000
0.00641
1.72344


4
14
21.02326
1.80000
1.07139
1.73540










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.30086
−0.37802
−0.53517


3
8
−0.53235
−0.88850
−1.23765


4
14
0.70689
0.69703
0.82152









Numerical Example I-3
The zoom lens system of Numerical Example I-3 corresponds to Embodiment I-3 shown in FIG. 7. Table I-7 shows the surface data of the zoom lens system of Numerical Example I-3. Table I-8 shows the aspherical data. Table I-9 shows various data.







TABLE I-7







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
41.02146
0.80000
1.84666
23.8


 2
22.94949
2.90000
1.72916
54.7


 3*
−67.14728
Variable


 4*
−29.93103
0.90000
1.85976
40.6


 5*
5.46456
1.36330


 6
7.77602
1.70000
1.94595
18.0


 7
15.86423
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.80894
2.50000
1.85976
40.6


10
−17.74441
0.40000
1.84666
23.8


11
4.20335
0.60000


12
31.08621
1.70000
1.88300
40.8


13
−13.05352
Variable


14*
−351.70210
1.80000
1.58913
61.3


15
−13.85677
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-8





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.28200E−05, A6 = 4.77959E−08,



A8 = −1.86769E−09 A10 = 1.77279E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.18900E−04, A6 = −2.69906E−06,



A8 = 1.79580E−08 A10 = −8.75673E−11



Surface No. 5



K = −3.91033E+00, A4 = 2.61805E−03, A6 = −6.55634E−05,



A8 = 2.01069E−06 A10 = −2.88747E−08



Surface No. 9



K = −3.23663E−01, A4 = −2.30616E−04, A6 = −5.24116E−06,



A8 = 7.79597E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −3.12216E−05, A6 = 2.03557E−05,



A8 = −1.20427E−06 A10 = 2.70800E−08

















TABLE I-9





(Various data)


Zooming ratio 4.71121



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1452
11.1841
24.2400


F-number
3.42188
4.22392
5.78635


View angle
39.6255
18.5721
8.9850


Image height
3.8300
3.8300
3.8300


Overall length
37.9988
39.3104
46.9908


of lens system


BF
0.50333
0.49039
0.48704


d3
0.5000
6.5774
12.9775


d7
13.7284
5.1752
1.4500


d13
2.0537
5.2917
13.8767


d15
5.5502
6.1124
2.5363


Entrance pupil
10.3440
18.4859
31.7927


position


Exit pupil
−15.3270
−23.3750
−79.0858


position


Front principal
13.8169
24.4288
48.6485


points position


Back principal
32.8536
28.1263
22.7507


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−62.8019


2
2
23.7796


3
4
−5.3122


4
6
14.6288


5
9
4.6384


6
10
−3.9805


7
12
10.6028


8
14
24.4372










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
38.39690
3.70000
0.79630
2.35434


2
4
−8.99282
3.96330
−0.01055
1.26577


3
8
10.19180
5.20000
−0.11865
1.64853


4
14
24.43722
1.80000
1.17683
1.84637










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.32619
−0.41844
−0.59589


3
8
−0.56490
−0.98777
−1.24463


4
14
0.72720
0.70473
0.85120









Numerical Example I-4
The zoom lens system of Numerical Example I-4 corresponds to Embodiment I-4 shown in FIG. 10. Table I-10 shows the surface data of the zoom lens system of Numerical Example I-4. Table I-11 shows the aspherical data. Table I-12 shows various data.







TABLE I-10







(Surface data)











Surface number
r
d
nd
vd














Object surface
∞





 1
77.48544
0.70000
2.14422
17.5


 2
42.37542
2.50000
1.88300
40.8


 3*
−54.64303
Variable


 4*
−24.97959
0.90000
1.85976
40.6


 5*
5.48270
0.96780


 6
7.81948
1.70000
2.00170
20.6


 7
20.38775
Variable


 8 (Diaphragm)
∞
0.00000


 9*
4.85241
2.50000
1.85976
40.6


10
−19.04782
0.40000
1.84666
23.8


11
4.26231
0.60000


12
37.18501
1.50000
1.88300
40.8


13
−13.66920
Variable


14*
−136.73890
1.80000
1.80420
46.5


15
−14.90167
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-11





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.47762E−05, A6 = 5.09518E−08,



A8 = −1.94970E−09 A10 = 1.59565E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.31527E−04, A6 = −2.90013E−06,



A8 = 1.68839E−08 A10 = −5.66432E−11



Surface No. 5



K = −3.52458E+00, A4 = 2.23158E−03, A6 = −4.53310E−05,



A8 = 1.14427E−06 A10 = −1.66385E−08



Surface No. 9



K = −3.07449E−01, A4 = −2.44430E−04, A6 = −4.77575E−06,



A8 = 7.41211E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −6.50732E−05, A6 = 1.34430E−05,



A8 = −7.09989E−07 A10 = 1.38939E−08

















TABLE I-12





(Various data)







Zooming ratio 4.71152













Wide-angle
Middle
Telephoto




limit
position
limit







Focal length
5.1466
11.1810
24.2483



F-number
3.33816
4.20129
6.20279



View angle
39.6377
18.5711
9.0207



Image height
3.8300
3.8300
3.8300



Overall length
37.7216
39.2545
46.7249



of lens system



BF
0.51113
0.48442
0.49197



d3
0.5000
6.7559
11.8660



d7
14.5217
5.5731
1.4500



d13
1.9080
6.0145
15.8554



d15
5.7131
5.8587
2.4937



Entrance pupil
9.9785
17.5384
25.2778



position



Exit pupil
−15.2007
−27.1412
−894.2331



position



Front principal
13.4393
24.1941
48.8689



points position



Back principal
32.5751
28.0734
22.4766



points position











Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−82.6114


2
2
27.3598


3
4
−5.1588


4
6
11.8601


5
9
4.7266


6
10
−4.0816


7
12
11.4782


8
14
20.6601










Zoom lens unit data















Overall
Front
Back





length
principal
principal


Lens
Initial
Focal
of lens
points
points


unit
surface No.
length
unit
position
position





1
1
40.76881
3.20000
1.00946
2.53622


2
4
−9.96079
3.56780
−0.07786
1.19845


3
8
10.69375
5.00000
−0.39913
1.39101


4
14
20.66011
1.80000
1.11237
1.92123










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.33513
−0.42447
−0.54264


3
8
−0.55997
−0.96877
−1.32146


4
14
0.67269
0.66693
0.82944









Numerical Example I-5
The zoom lens system of Numerical Example I-5 corresponds to Embodiment I-5 shown in FIG. 13. Table I-13 shows the surface data of the zoom lens system of Numerical Example I-5. Table I-14 shows the aspherical data. Table I-15 shows various data.







TABLE I-13







(Surface data)











Surface number
r
d
nd
vd














Object surface
∞





 1
32.96612
0.70000
2.00170
20.6


 2
22.83794
2.80000
1.72916
54.7


 3*
−69.62549
Variable


 4*
−22.07623
0.90000
1.85976
40.6


 5*
5.75481
0.86420


 6
7.35601
1.70000
1.94595
18.0


 7
15.40257
Variable


 8 (Diaphragm)
∞
0.00000


 9*
4.47675
2.00000
1.85976
40.6


10
−30.92880
0.75000
1.84666
23.8


11
3.86195
0.65000


12
37.07756
1.70000
1.88300
40.8


13
−13.24229
Variable


14*
−53.65745
1.75000
1.72916
54.7


15
−10.92395
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-14





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.10641E−05, A6 = 4.57255E−08,



A8 = −8.67085E−10 A10 = 5.11073E−12



Surface No. 4



K = 0.00000E+00, A4 = 2.91216E−04, A6 = −3.21053E−06,



A8 = 1.77359E−08 A10 = −2.22730E−11



Surface No. 5



K = −4.07185E+00, A4 = 2.40517E−03, A6 = −5.39975E−05,



A8 = 1.54921E−06 A10 = −1.98020E−08



Surface No. 9



K = −3.22033E−01, A4 = −2.27689E−04, A6 = −5.46309E−06,



A8 = 1.38100E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −1.14847E−04, A6 = 1.94114E−05,



A8 = −9.80977E−07 A10 = 1.87787E−08

















TABLE I-15





(Various data)







Zooming ratio 5.65255













Wide-angle
Middle
Telephoto




limit
position
limit







Focal length
5.1474
12.2494
29.0958



F-number
3.29148
4.19974
5.64552



View angle
39.6524
17.0575
7.5686



Image height
3.8300
3.8300
3.8300



Overall length
37.4155
39.4580
47.4088



of lens system



BF
0.51923
0.48599
0.48733



d3
0.5000
6.6544
14.2072



d7
13.9561
5.0650
1.4500



d13
2.0691
6.3617
13.8957



d15
5.5569
6.0767
2.5544



Entrance pupil
10.6264
19.3044
38.9535



position



Exit pupil
−16.4307
−33.4938
17791.8698



position



Front principal
14.2106
27.1380
68.0969



points position



Back principal
32.2681
27.2086
18.3130



points position











Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−76.8672


2
2
23.8899


3
4
−5.2312


4
6
13.4990


5
9
4.6706


6
10
−4.0154


7
12
11.2282


8
14
18.4919










Zoom lens unit data















Overall
Front
Back





length
principal
principal


Lens
Initial
Focal
of lens
points
points


unit
surface No.
length
unit
position
position





1
1
34.93433
3.50000
0.57704
2.07781


2
4
−8.79494
3.46420
0.22280
1.54666


3
8
10.51843
5.10000
−0.37852
1.36836


4
14
18.49195
1.75000
1.24919
2.00432










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.36654
−0.49299
−0.85494


3
8
−0.61890
−1.14128
−1.19737


4
14
0.64952
0.62321
0.81361









Numerical Example I-6
The zoom lens system of Numerical Example I-6 corresponds to Embodiment I-6 shown in FIG. 16. Table I-16 shows the surface data of the zoom lens system of Numerical Example I-6. Table I-17 shows the aspherical data. Table I-18 shows various data.







TABLE I-16







(Surface data)











Surface number
r
d
nd
vd














Object surface
∞





 1
29.91925
0.70000
2.00170
20.6


 2
19.98281
2.80000
1.76802
49.2


 3*
−103.25020
Variable


 4*
−22.49507
0.90000
1.85976
40.6


 5*
5.57366
0.90550


 6
7.37692
1.70000
1.94595
18.0


 7
16.02009
Variable


 8 (Diaphragm)
∞
0.00000


 9*
4.61199
2.00000
1.85976
40.6


10
−24.88350
0.75000
1.84666
23.8


11
4.01400
0.65000


12
37.05789
1.70000
1.88300
40.8


13
−13.32109
Variable


14*
−53.65745
1.75000
1.72916
54.7


15
−10.88388
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-17





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 8.49664E−06, A6 = 8.32166E−08,



A8 = −1.86812E−09 A10 = 1.35563E−11



Surface No. 4



K = 0.00000E+00, A4 = 3.21225E−04, A6 = −3.69715E−06,



A8 = 1.31982E−08 A10 = 7.49330E−11



Surface No. 5



K = −3.85293E+00, A4 = 2.46791E−03, A6 = −5.22942E−05,



A8 = 1.46924E−06 A10 = −2.07319E−08



Surface No. 9



K = −3.41482E−01, A4 = −2.06492E−04, A6 = −4.06797E−06,



A8 = 1.45582E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −1.53654E−04, A6 = 2.28406E−05,



A8 = −1.19750E−06 A10 = 2.33325E−08

















TABLE I-18





(Various data)







Zooming ratio 5.65218













Wide-angle
Middle
Telephoto




limit
position
limit







Focal length
5.1467
12.2494
29.0902



F-number
3.27980
4.14117
5.61334



View angle
39.6446
17.0676
7.5838



Image height
3.8300
3.8300
3.8300



Overall length
37.3937
39.5062
47.4016



of lens system



BF
0.51662
0.48573
0.48730



d3
0.5000
6.7890
14.0599



d7
13.7902
4.9612
1.4500



d13
2.0482
6.1467
13.9872



d15
5.6833
6.2680
2.5617



Entrance pupil
10.5854
19.8135
39.4360



position



Exit pupil
−16.5628
−32.6546
1650.8359



position



Front principal
14.1812
27.5353
69.0390



points position



Back principal
32.2470
27.2568
18.3114



points position











Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−62.2622


2
2
22.0170


3
4
−5.1196


4
6
13.1930


5
9
4.6720


6
10
−4.0344


7
12
11.2755


8
14
18.4072










Zoom lens unit data















Overall
Front
Back





length
principal
principal


Lens
Initial
Focal
of lens
points
points


unit
surface No.
length
unit
position
position





1
1
34.46402
3.50000
0.35636
1.89994


2
4
−8.71102
3.50550
0.17113
1.48371


3
8
10.59742
5.10000
−0.27952
1.44857


4
14
18.40715
1.75000
1.24804
2.00315










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.37097
−0.50667
−0.87796


3
8
−0.62790
−1.14806
−1.18357


4
14
0.64112
0.61103
0.81229









Numerical Example I-7
The zoom lens system of Numerical Example I-7 corresponds to Embodiment I-7 shown in FIG. 19. Table I-19 shows the surface data of the zoom lens system of Numerical Example I-7. Table I-20 shows the aspherical data. Table I-21 shows various data.







TABLE I-19







(Surface data)











Surface number
r
d
nd
vd














Object surface
∞





 1
28.71329
0.70000
2.00170
20.6


 2
19.42508
2.80000
1.76802
49.2


 3*
−115.20360
Variable


 4*
−21.87243
0.90000
1.85976
40.6


 5*
5.39818
0.92440


 6
7.35762
1.70000
1.94595
18.0


 7
16.90012
Variable


 8 (Diaphragm)
∞
0.00000


 9*
4.55090
2.00000
1.85976
40.6


10
32.15726
0.75000
1.92286
20.9


11
4.10556
0.65000


12
28.55014
1.70000
1.88300
40.8


13
−13.03525
Variable


14*
−56.93994
1.75000
1.77377
47.2


15
−11.83795
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-20





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 8.25518E−06, A6 = 8.05537E−08,



A8 = −1.83404E−09 A10 = 1.36190E−11



Surface No. 4



K = 0.00000E+00, A4 = 3.76370E−04, A6 = −5.54490E−06,



A8 = 4.02068E−08 A10 = −8.60389E−11



Surface No. 5



K = −3.69163E+00, A4 = 2.59884E−03, A6 = −5.44387E−05,



A8 = 1.45475E−06 A10 = −2.17379E−08



Surface No. 9



K = −4.14883E−01, A4 = −9.21666E−05, A6 = −2.91362E−07,



A8 = 1.60430E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −1.24204E−04, A6 = 2.14219E−05,



A8 = −1.13415E−06 A10 = 2.25228E−08

















TABLE I-21





(Various data)







Zooming ratio 5.65625













Wide-angle
Middle
Telephoto




limit
position
limit







Focal length
5.1459
12.2513
29.1062



F-number
3.30007
4.13787
5.63730



View angle
39.6542
17.0649
7.5694



Image height
3.8300
3.8300
3.8300



Overall length
37.3809
39.5083
47.4075



of lens system



BF
0.51436
0.48968
0.49235



d3
0.5000
6.8693
13.9472



d7
13.6634
4.9010
1.4500



d13
2.0228
5.9040
14.0872



d15
5.8060
6.4698
2.5563



Entrance pupil
10.4667
20.0406
39.5259



position



Exit pupil
−16.4143
−30.4506
−1223.4949



position



Front principal
14.0484
27.4408
67.9400



points position



Back principal
32.2350
27.2570
18.3013



points position











Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−62.2976


2
2
21.8405


3
4
−4.9602


4
6
12.6774


5
9
5.9660


6
10
−5.1661


7
12
10.3331


8
14
18.9932










Zoom lens unit data















Overall
Front
Back





length
principal
principal


Lens
Initial
Focal
of lens
points
points


unit
surface No.
length
unit
position
position





1
1
34.07693
3.50000
0.29738
1.84285


2
4
−8.59236
3.52440
0.11198
1.40959


3
8
10.58063
5.10000
−0.21934
1.49499


4
14
18.99322
1.75000
1.22482
2.00464










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.37011
−0.51005
−0.87962


3
8
−0.63165
−1.15123
−1.18680


4
14
0.64593
0.61228
0.81818









Numerical Example I-8
The zoom lens system of Numerical Example I-8 corresponds to Embodiment I-8 shown in FIG. 22. Table I-22 shows the surface data of the zoom lens system of Numerical Example I-8. Table I-23 shows the aspherical data. Table I-24 shows various data.







TABLE I-22







(Surface data)











Surface number
r
d
nd
vd














Object surface
∞





 1
26.24654
0.80000
1.92286
20.9


 2
19.47359
2.90000
1.77250
49.6


 3
109.68850
Variable


 4*
−124.53210
0.95000
1.85976
40.6


 5*
5.25923
1.75650


 6
8.20781
1.70000
2.14422
17.5


 7
12.83109
Variable


 8 (Diaphragm)
∞
0.00000


 9*
4.65332
2.45000
1.80139
45.4


10
14.95742
0.50000
1.92286
20.9


11
4.24062
0.48000


12
13.11167
1.50000
1.80420
46.5


13
−19.34140
Variable


14*
18.34229
1.70000
1.82080
42.7


15
−317.88590
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE I-23





(Aspherical data)

















Surface No. 4



K = 0.00000E+00, A4 = 1.07024E−04, A6 = −1.68199E−06,



A8 = 1.05423E−08 A10 = 0.00000E+00



Surface No. 5



K = −2.21584E+00, A4 = 1.55616E−03, A6 = −1.26061E−05,



A8 = 2.01423E−07 A10 = −1.53348E−09



Surface No. 9



K = −4.25982E−01, A4 = −7.34038E−06, A6 = 2.29644E−05,



A8 = −6.67959E−06 A10 = 7.69046E−07



Surface No. 14



K = 0.00000E+00, A4 = 5.76025E−05, A6 = 1.05741E−06,



A8 = 0.00000E+00 A10 = 0.00000E+00

















TABLE I-24





(Various data)







Zooming ratio 5.64641













Wide-angle
Middle
Telephoto




limit
position
limit







Focal length
5.1434
12.2384
29.0417



F-number
3.16726
3.84698
5.55779



View angle
39.9424
17.6011
7.5082



Image height
3.8300
3.8300
3.8300



Overall length
40.6659
43.5886
54.5657



of lens system



BF
0.49444
0.50779
0.49981



d3
0.5000
9.9099
17.8974



d7
15.7039
5.4929
1.4500



d13
3.8122
6.0562
16.2028



d15
4.4189
5.8852
2.7792



Entrance pupil
11.4804
26.4000
46.7566



position



Exit pupil
−16.2416
−23.5842
−223.5063



position



Front principal
15.0431
32.4214
72.0331



points position



Back principal
35.5225
31.3502
25.5239



points position











Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−86.6861


2
2
30.2265


3
4
−5.8494


4
6
16.6426


5
9
7.6225


6
10
−6.5602


7
12
9.9213


8
14
21.1761










Zoom lens unit data















Overall
Front
Back





length
principal
principal


Lens
Initial
Focal
of lens
points
points


unit
surface No.
length
unit
position
position





1
1
47.77654
3.70000
−0.84574
0.84735


2
4
−9.55092
4.40650
0.14386
1.58661


3
8
10.80176
4.93000
−0.72013
1.19828


4
14
21.17606
1.70000
0.05105
0.81526










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.27501
−0.37722
−0.55107


3
8
−0.56320
−1.08618
−1.42840


4
14
0.69506
0.62519
0.77224









Numerical Example I-9
The zoom lens system of Numerical Example I-9 corresponds to Embodiment I-9 shown in FIG. 25. Table I-25 shows the surface data of the zoom lens system of Numerical Example I-9. Table I-26 shows the aspherical data. Table I-27 shows various data.







TABLE I-25







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
31.86466
2.50000
1.72916
54.7


 2
134.84140
Variable


 3*
−248.26680
1.20000
1.85976
40.6


 4*
5.75364
1.94000


 5
8.39253
1.70000
1.94595
18.0


 6
14.57504
Variable


 7(Diaphragm)
∞
0.00000


 8*
4.61391
2.50000
1.77377
47.2


 9
−92.73069
0.40000
1.80518
25.5


10
4.14814
0.50000


11
16.83120
1.80000
1.72916
54.7


12
−14.51842
Variable


13*
165.08590
1.80000
2.00170
20.6


14
−32.87752
Variable


15
∞
1.00000
1.51680
64.2


16
∞
(BF)


Image surface
∞
















TABLE I-26





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.34480E−04, A6 = −9.96145E−07,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 4



K = −3.36150E+00, A4 = 2.01372E−03, A6 = −3.87027E−05,



A8 = 1.15749E−06 A10 = −1.46790E−08



Surface No. 8



K = −2.95367E−01, A4 = −2.26495E−04, A6 = 2.36597E−05,



A8 = −8.11256E−06 A10 = 8.89822E−07



Surface No. 13



K = 0.00000E+00, A4 = 3.02355E−05, A6 = 2.23022E−06,



A8 = −5.36111E−08 A10 = 0.00000E+00

















TABLE I-27





(Various data)


Zooming ratio 4.70823



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1685
11.2200
24.3347


F-number
3.26820
4.15816
6.23804


View angle
38.1988
18.9234
9.0070


Image height
3.8300
3.8300
3.8300


Overall length
42.0225
44.1238
50.1723


of lens system


BF
0.51010
0.48494
0.50099


d2
0.6000
8.7177
12.8658


d6
17.4325
7.1763
1.3000


d12
2.4468
7.1761
17.7813


d14
5.6931
5.2289
2.3842


Entrance pupil
11.3010
21.9379
26.1297


position


Exit pupil
−15.2274
−25.3743
−112.2135


position


Front principal
14.7720
28.2896
45.2106


points position


Back principal
36.8540
32.9039
25.8377


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
56.6431


2
3
−6.5263


3
5
18.4496


4
8
5.7447


5
9
−4.9222


6
11
10.9553


7
13
27.4958










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
56.64310
2.50000
−0.44284
0.62602


2
3
−10.93149
4.84000
0.09096
1.50158


3
7
11.09254
5.20000
−0.43515
1.35811


4
13
27.49578
1.80000
0.75332
1.64997










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
3
−0.25336
−0.31207
−0.35399


3
7
−0.48346
−0.83216
−1.40202


4
13
0.74496
0.76276
0.86564









The following Table I-28 shows the corresponding values to the individual conditions in the zoom lens systems of each of Numerical Examples.







TABLE I-28







(Values corresponding to conditions)









Example
















Condition
I-1
I-2
I-3
I-4
I-5
I-6
I-7
I-8
I-9




















(2-1)
f2/fW
−2.03
−1.95
−1.75
−1.94
−1.71
−1.69
−1.67
−1.86
−2.12


(a-1)
ωW
42.98
42.99
39.63
39.66
39.68
39.67
39.68
39.94
38.20


(b-2)
fT/fW
4.80
4.81
4.71
4.71
5.65
5.65
5.66
5.65
4.71


(3-1)
(β2T/β2W)/(β3T/β3W)
0.51
0.77
0.83
0.69
1.21
1.26
1.26
0.79
0.48


(4-1)
M1/M3
0.87
1.02
1.02
0.84
1.14
1.14
1.14
1.29
0.68


(5)
nd2p
1.946
1.946
1.946
2.002
1.946
1.946
1.946
2.144
1.946


(6)
(r2na + r2nb)/(r2na − r2nb)
0.84
0.70
0.69
0.64
0.59
0.60
0.60
0.92
0.95


(7)
(r2nb + r2pa)/(r2nb − r2pa)
−4.45
−5.22
−5.73
−5.69
−8.19
−7.18
−6.51
−4.57
−5.36


(8)
(r1pa + r1pb)/(r1pa − r1pb)
−0.99
−0.50
−0.49
−0.13
−0.51
−0.68
−0.71
−1.43
−1.62


(9)
f3/fW
2.19
2.18
1.98
2.08
2.04
2.06
2.06
2.10
2.15


(10) 
f3IL/f3
0.97
1.02
1.04
1.13
1.10
1.11
1.01
0.97
1.08


(11) 
f3n/f3
−0.50
−0.38
−0.39
−0.38
−0.38
−0.38
−0.49
−0.61
−0.44









Numerical Example II-1
The zoom lens system of Numerical Example II-1 corresponds to Embodiment II-1 shown in FIG. 29. Table II-1 shows the surface data of the zoom lens system of Numerical Example II-1. Table II-2 shows the aspherical data. Table II-3 shows various data.







TABLE II-1







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
34.17398
0.80000
1.84666
23.8


 2
23.28840
3.20000
1.72916
54.7


 3
5217.68300
Variable


 4*
−101.29280
1.20000
1.85976
40.6


 5*
5.58800
1.94000


 6
8.33970
1.70000
1.94595
18.0


 7
14.57504
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.49421
2.50000
1.77377
47.2


10
49.59507
0.40000
1.80518
25.5


11
4.00635
0.50000


12
15.55736
1.80000
1.72916
54.7


13
−14.61304
Variable


14*
33.73569
1.80000
1.58913
61.3


15
−33.83382
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE II-2





(Aspherical data)

















Surface No. 4



K = 0.00000E+00, A4 = 1.31031E−04, A6 = −1.09009E−06,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 5



K = −3.29074E+00, A4 = 2.12847E−03, A6 = −4.41308E−05,



A8 = 1.38765E−06 A10 = −1.96733E−08



Surface No. 9



K = −3.35821E−01, A4 = −1.87980E−04, A6 = 2.72768E−05,



A8 = −8.64444E−06 A10 = 9.43500E−07



Surface No. 14



K = 0.00000E+00, A4 = 6.36985E−05, A6 = 2.61378E−06,



A8 = −4.23871E−08 A10 = 0.00000E+00

















TABLE II-3





(Various data)


Zooming ratio 4.70670



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1677
11.2241
24.3226


F-number
3.26552
3.95949
6.17921


View angle
38.2451
18.4933
8.9525


Image height
3.8300
3.8300
3.8300


Overall length
42.0558
44.3663
50.2027


of lens system


BF
0.49262
0.49148
0.49424


d3
0.6000
9.2713
11.8247


d7
16.3737
6.6282
1.3000


d13
2.4277
5.0960
17.3459


d15
5.3218
6.0394
2.3979


Entrance pupil
11.9231
24.8818
26.5373


position


Exit pupil
−14.8030
−20.5171
−84.7163


position


Front principal
15.3448
30.1092
43.9172


points position


Back principal
36.8881
33.1422
25.8801


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−89.3631


2
2
32.0735


3
4
−6.1279


4
6
18.1963


5
9
6.2362


6
10
−5.4342


7
12
10.6008


8
14
28.9594










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
50.88919
4.00000
−0.12750
1.59066


2
4
−10.02146
4.84000
0.08964
1.49662


3
8
10.73240
5.20000
−0.44561
1.35068


4
14
28.95942
1.80000
0.57117
1.22717










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.26534
−0.34441
−0.37754


3
8
−0.50578
−0.87494
−1.47619


4
14
0.75668
0.73194
0.85759









Numerical Example II-2
The zoom lens system of Numerical Example II-2 corresponds to Embodiment II-2 shown in FIG. 32. Table II-4 shows the surface data of the zoom lens system of Numerical Example II-2. Table II-5 shows the aspherical data. Table II-6 shows various data.







TABLE II-4







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
34.84177
0.80000
1.84666
23.8


 2
22.99333
3.20000
1.72916
54.7


 3
−7811.04900
Variable


 4*
−58.44512
1.20000
1.85976
40.6


 5*
5.19121
1.67940


 6
8.20411
1.70000
1.94595
18.0


 7
16.41950
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.44243
2.50000
1.77377
47.2


10
793.42870
0.40000
1.80518
25.5


11
4.01346
0.50000


12
15.48439
1.80000
1.72916
54.7


13
−12.85234
Variable


14
121.92800
1.80000
1.58913
61.3


15
−16.82223
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE II-5





(Aspherical data)

















Surface No. 4



K = 0.00000E+00, A4 = 9.54547E−05, A6 = −6.85975E−07,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 5



K = −3.14137E+00, A4 = 2.36281E−03, A6 = −5.94676E−05,



A8 = 1.73729E−06 A10 = −2.29781E−08



Surface No. 9



K = −2.74176E−01, A4 = −2.89782E−04, A6 = −1.87247E−05,



A8 = 1.84381E−06 A10 = 2.49143E−07

















TABLE II-6





(Various data)


Zooming ratio 4.80270



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
4.5807
9.4609
21.9997


F-number
3.33997
4.26195
6.23446


View angle
42.9736
21.6329
9.7950


Image height
3.8300
3.8300
3.8300


Overall length
40.0369
43.5052
49.5867


of lens system


BF
0.51919
0.46391
0.50046


d3
0.5000
7.9401
13.0837


d7
15.4856
7.7577
1.4500


d13
1.8860
6.9437
15.4487


d15
5.0667
3.8205
2.5245


Entrance pupil
10.9762
21.7930
28.9202


position


Exit pupil
−14.4240
−25.5869
−98.9580


position


Front principal
14.1528
27.8180
46.0536


points position


Back principal
35.4562
34.0443
27.5870


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−82.4113


2
2
31.4469


3
4
−5.4975


4
6
15.7497


5
9
5.7657


6
10
−5.0110


7
12
9.8968


8
14
25.2137










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
51.72567
4.00000
−0.10347
1.61339


2
4
−9.29681
4.57940
0.03326
1.40517


3
8
10.04351
5.20000
−0.17000
1.52851


4
14
25.21371
1.80000
1.00018
1.66201










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.23531
−0.28990
−0.34528


3
8
−0.50392
−0.79018
−1.45189


4
14
0.74684
0.79846
0.84841









Numerical Example II-3
The zoom lens system of Numerical Example II-3 corresponds to Embodiment II-3 shown in FIG. 35. Table II-7 shows the surface data of the zoom lens system of Numerical Example II-3. Table II-8 shows the aspherical data. Table II-9 shows various data.







TABLE II-7







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
77.48544
0.70000
2.14422
17.5


 2
42.37542
2.50000
1.88300
40.8


 3*
−54.64303
Variable


 4*
−24.97959
0.90000
1.85976
40.6


 5*
5.48270
0.96780


 6
7.81948
1.70000
2.00170
20.6


 7
20.38775
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.85241
2.50000
1.85976
40.6


10
−19.04782
0.40000
1.84666
23.8


11
4.26231
0.60000


12
37.18501
1.50000
1.88300
40.8


13
−13.66920
Variable


14*
−136.73890
1.80000
1.80420
46.5


15
−14.90167
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE II-8





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.47762E−05, A6 = 5.09518E−08,



A8 = −1.94970E−09 A10 = 1.59565E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.31527E−04, A6 = −2.90013E−06,



A8 = 1.68839E−08 A10 = −5.66432E−11



Surface No. 5



K = −3.52458E+00, A4 = 2.23158E−03, A6 = −4.53310E−05,



A8 = 1.14427E−06 A10 = −1.66385E−08



Surface No. 9



K = −3.07449E−01, A4 = −2.44430E−04, A6 = −4.77575E−06,



A8 = 7.41211E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −6.50732E−05, A6 = 1.34430E−05,



A8 = −7.09989E−07 A10 = 1.38939E−08

















TABLE II-9





(Various data)


Zooming ratio 4.71152



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1466
11.1810
24.2483


F-number
3.33816
4.20129
6.20279


View angle
39.6377
18.5711
9.0207


Image height
3.8300
3.8300
3.8300


Overall length
37.7216
39.2545
46.7249


of lens system


BF
0.51113
0.48442
0.49197


d3
0.5000
6.7559
11.8660


d7
14.5217
5.5731
1.4500


d13
1.9080
6.0145
15.8554


d15
5.7131
5.8587
2.4937


Entrance pupil
9.9785
17.5384
25.2778


position


Exit pupil
−15.2007
−27.1412
−894.2331


position


Front principal
13.4393
24.1941
48.8689


points position


Back principal
32.5751
28.0734
22.4766


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−82.6114


2
2
27.3598


3
4
−5.1588


4
6
11.8601


5
9
4.7266


6
10
−4.0816


7
12
11.4782


8
14
20.6601










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.76881
3.20000
1.00946
2.53622


2
4
−9.96079
3.56780
−0.07786
1.19845


3
8
10.69375
5.00000
−0.39913
1.39101


4
14
20.66011
1.80000
1.11237
1.92123










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.33513
−0.42447
−0.54264


3
8
−0.55997
−0.96877
−1.32146


4
14
0.67269
0.66693
0.82944









Numerical Example II-4
The zoom lens system of Numerical Example II-4 corresponds to Embodiment II-4 shown in FIG. 38. Table II-10 shows the surface data of the zoom lens system of Numerical Example II-4. Table II-11 shows the aspherical data. Table II-12 shows various data.







TABLE II-10







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
97.05992
0.70000
2.14422
17.5


 2
46.46025
2.50000
1.88300
40.8


 3*
−47.77710
Variable


 4*
−22.51907
0.90000
1.85976
40.6


 5*
5.49697
0.96780


 6
7.89898
1.70000
2.00170
20.6


 7
21.79417
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.55112
2.50000
1.85976
40.6


10
21.65382
0.40000
2.00170
20.6


11
4.17957
0.60000


12
22.76037
1.50000
1.88300
40.8


13
−13.19010
Variable


14*
−136.73890
1.80000
1.80420
46.5


15
−15.86951
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE II-11





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.36523E−05, A6 = 9.09025E−08,



A8 = −2.14561E−09 A10 = 1.60945E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.88191E−04, A6 = −4.57427E−06,



A8 = 4.34209E−08 A10 = −2.20674E−10



Surface No. 5



K = −3.39371E+00, A4 = 2.17647E−03, A6 = −4.18815E−05,



A8 = 9.46075E−07 A10 = −1.34979E−08



Surface No. 9



K = −2.88099E−01, A4 = −2.38380E−04, A6 = −5.03439E−06,



A8 = 6.92510E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −3.29945E−05, A6 = 1.29659E−05,



A8 = −6.41813E−07 A10 = 1.26725E−08

















TABLE II-12





(Various data)


Zooming ratio 4.71468



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1453
11.1795
24.2583


F-number
3.39777
4.28927
6.21311


View angle
39.6513
18.5719
9.0119


Image height
3.8300
3.8300
3.8300


Overall length
37.7137
39.1679
46.7282


of lens system


BF
0.50696
0.48248
0.49531


d3
0.5000
6.6971
12.2770


d7
14.5410
5.6054
1.4500


d13
1.8762
5.9504
15.4550


d15
5.7217
5.8647
2.4832


Entrance pupil
9.7713
17.1562
25.9486


position


Exit pupil
−14.9074
−25.6276
−188.1820


position


Front principal
13.1991
23.5490
47.0880


points position


Back principal
32.5684
27.9884
22.4699


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−78.4663


2
2
27.0118


3
4
−5.0639


4
6
11.6547


5
9
6.2779


6
10
−5.2304


7
12
9.6459


8
14
22.1770










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.90528
3.20000
1.17728
2.70651


2
4
−9.86216
3.56780
−0.12987
1.13155


3
8
10.54809
5.00000
−0.46117
1.32934


4
14
22.17696
1.80000
1.12122
1.93013










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.32678
−0.41123
−0.53591


3
8
−0.55362
−0.96329
−1.31450


4
14
0.69528
0.68993
0.84183









Numerical Example II-5
The zoom lens system of Numerical Example II-5 corresponds to Embodiment II-5 shown in FIG. 41. Table II-13 shows the surface data of the zoom lens system of Numerical Example II-5. Table II-14 shows the aspherical data. Table II-15 shows various data.







TABLE II-13







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
29.91925
0.70000
2.00170
20.6


 2
19.98281
2.80000
1.76802
49.2


 3*
−103.25020
Variable


 4*
−22.49507
0.90000
1.85976
40.6


 5*
5.57366
0.90550


 6
7.37692
1.70000
1.94595
18.0


 7
16.02009
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.61199
2.00000
1.85976
40.6


10
−24.88350
0.75000
1.84666
23.8


11
4.01400
0.65000


12
37.05789
1.70000
1.88300
40.8


13
−13.32109
Variable


14*
−53.65745
1.75000
1.72916
54.7


15
−10.88388
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE II-14





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 8.49664E−06, A6 = 8.32166E−08,



A8 = −1.86812E−09 A10 = 1.35563E−11



Surface No. 4



K = 0.00000E+00, A4 = 3.21225E−04, A6 = −3.69715E−06,



A8 = 1.31982E−08 A10 = 7.49330E−11



Surface No. 5



K = −3.85293E+00, A4 = 2.46791E−03, A6 = −5.22942E−05,



A8 = 1.46924E−06 A10 = −2.07319E−08



Surface No. 9



K = −3.41482E−01, A4 = −2.06492E−04, A6 = −4.06797E−06,



A8 = 1.45582E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −1.53654E−04, A6 = 2.28406E−05,



A8 = −1.19750E−06 A10 = 2.33325E−08

















TABLE II-15





(Various data)


Zooming ratio 5.65218



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1467
12.2494
29.0902


F-number
3.27980
4.14117
5.61334


View angle
39.6446
17.0676
7.5838


Image height
3.8300
3.8300
3.8300


Overall length
37.3937
39.5062
47.4016


of lens system


BF
0.51662
0.48573
0.48730


d3
0.5000
6.7890
14.0599


d7
13.7902
4.9612
1.4500


d13
2.0482
6.1467
13.9872


d15
5.6833
6.2680
2.5617


Entrance pupil
10.5854
19.8135
39.4360


position


Exit pupil
−16.5628
−32.6546
1650.8359


position


Front principal
14.1812
27.5353
69.0390


points position


Back principal
32.2470
27.2568
18.3114


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−62.2622


2
2
22.0170


3
4
−5.1196


4
6
13.1930


5
9
4.6720


6
10
−4.0344


7
12
11.2755


8
14
18.4072










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
34.46402
3.50000
0.35636
1.89994


2
4
−8.71102
3.50550
0.17113
1.48371


3
8
10.59742
5.10000
−0.27952
1.44857


4
14
18.40715
1.75000
1.24804
2.00315










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.37097
−0.50667
−0.87796


3
8
−0.62790
−1.14806
−1.18357


4
14
0.64112
0.61103
0.81229









Numerical Example II-6
The zoom lens system of Numerical Example II-6 corresponds to Embodiment II-6 shown in FIG. 44. Table II-16 shows the surface data of the zoom lens system of Numerical Example II-6. Table II-17 shows the aspherical data. Table II-18 shows various data.







TABLE II-16







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
31.86466
2.50000
1.72916
54.7


 2
134.84140
Variable


 3*
−248.26680
1.20000
1.85976
40.6


 4*
5.75364
1.94000


 5
8.39253
1.70000
1.94595
18.0


 6
14.57504
Variable


 7(Diaphragm)
∞
0.00000


 8*
4.61391
2.50000
1.77377
47.2


 9
−92.73069
0.40000
1.80518
25.5


10
4.14814
0.50000


11
16.83120
1.80000
1.72916
54.7


12
−14.51842
Variable


13*
165.08590
1.80000
2.00170
20.6


14
−32.87752
Variable


15
∞
1.00000
1.51680
64.2


16
∞
(BF)


Image surface
∞
















TABLE II-17





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.34480E−04, A6 = −9.96145E−07,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 4



K = −3.36150E+00, A4 = 2.01372E−03, A6 = −3.87027E−05,



A8 = 1.15749E−06 A10 = −1.46790E−08



Surface No. 8



K = −2.95367E−01, A4 = −2.26495E−04, A6 = 2.36597E−05,



A8 = −8.11256E−06 A10 = 8.89822E−07



Surface No. 13



K = 0.00000E+00, A4 = 3.02355E−05, A6 = 2.23022E−06,



A8 = −5.36111E−08 A10 = 0.00000E+00

















TABLE II-18





(Various data)


Zooming ratio 4.70823



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1685
11.2200
24.3347


F-number
3.26820
4.15816
6.23804


View angle
38.1988
18.9234
9.0070


Image height
3.8300
3.8300
3.8300


Overall length
42.0225
44.1238
50.1723


of lens system


BF
0.51010
0.48494
0.50099


d2
0.6000
8.7177
12.8658


d6
17.4325
7.1763
1.3000


d12
2.4468
7.1761
17.7813


d14
5.6931
5.2289
2.3842


Entrance pupil
11.3010
21.9379
26.1297


position


Exit pupil
−15.2274
−25.3743
−112.2135


position


Front principal
14.7720
28.2896
45.2106


points position


Back principal
36.8540
32.9039
25.8377


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
56.6431


2
3
−6.5263


3
5
18.4496


4
8
5.7447


5
9
−4.9222


6
11
10.9553


7
13
27.4958










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
56.64310
2.50000
−0.44284
0.62602


2
3
−10.93149
4.84000
0.09096
1.50158


3
7
11.09254
5.20000
−0.43515
1.35811


4
13
27.49578
1.80000
0.75332
1.64997










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
3
−0.25336
−0.31207
−0.35399


3
7
−0.48346
−0.83216
−1.40202


4
13
0.74496
0.76276
0.86564









The following Table II-19 shows the corresponding values to the individual conditions in the zoom lens systems of each of Numerical Examples.







TABLE II-19







(Values corresponding to conditions)









Example













Condition
II-1
II-2
II-3
II-4
II-5
II-6

















(3-1)
(β2T/β2W)/(β3T/β3W)
0.49
0.51
0.69
0.84
1.26
0.48


(a-1)
ωW
38.25
42.98
39.66
39.64
39.67
38.20


(b-2)
fT/fW
4.71
4.80
4.71
4.71
5.65
4.71


(2-1)
f2/fW
−1.94
−2.03
−1.94
−1.79
−1.69
−2.12


(4-1)
M1/M3
0.68
0.87
0.84
1.11
1.14
0.68


(5)
nd2p
1.946
1.946
2.002
1.946
1.946
1.946


(6)
(r2na + r2nb)/(r2na − r2nb)
0.90
0.84
0.64
0.65
0.60
0.95


(7)
(r2nb + r2pa)/(r2nb − r2pa)
−5.06
−4.45
−5.69
−6.65
−7.18
−5.36


(8)
(r1pa + r1pb)/(r1pa − r1pb)
−1.01
−0.99
−0.13
−0.34
−0.68
−1.62


(9)
f3/fW
2.08
2.19
2.08
1.97
2.06
2.15


(10) 
f3IL/f3
1.04
0.97
1.13
1.04
1.11
1.08


(11) 
f3n/f3
−0.51
−0.50
−0.38
−0.39
−0.38
−0.44









Numerical Example III-1
The zoom lens system of Numerical Example III-1 corresponds to Embodiment III-1 shown in FIG. 48. Table III-1 shows the surface data of the zoom lens system of Numerical Example III-1. Table III-2 shows the aspherical data. Table III-3 shows various data.







TABLE III-1







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
34.17398
0.80000
1.84666
23.8


 2
23.28840
3.20000
1.72916
54.7


 3
5217.68300
Variable


 4*
−101.29280
1.20000
1.85976
40.6


 5*
5.58800
1.94000


 6
8.33970
1.70000
1.94595
18.0


 7
14.57504
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.49421
2.50000
1.77377
47.2


10
49.59507
0.40000
1.80518
25.5


11
4.00635
0.50000


12
15.55736
1.80000
1.72916
54.7


13
−14.61304
Variable


14*
33.73569
1.80000
1.58913
61.3


15
−33.83382
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE III-2





(Aspherical data)

















Surface No.4



K = 0.00000E+00, A4 = 1.31031E−04, A6 = −1.09009E−06,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 5



K = −3.29074E+00, A4 = 2.12847E−03, A6 = −4.41308E−05,



A8 = 1.38765E−06 A10 = −1.96733E−08



Surface No. 9



K = −3.35821E−01, A4 = −1.87980E−04, A6 = 2.72768E−05,



A8 = −8.64444E−06 A10 = 9.43500E−07



Surface No. 14



K = 0.00000E+00, A4 = 6.36985E−05, A6 = 2.61378E−06,



A8 = −4.23871E−08 A10 = 0.00000E+00

















TABLE III-3





(Various data)


Zooming ratio 4.70670



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1677
11.2241
24.3226


F-number
3.26552
3.95949
6.17921


View angle
38.2451
18.4933
8.9525


Image height
3.8300
3.8300
3.8300


Overall length
42.0558
44.3663
50.2027


of lens system


BF
0.49262
0.49148
0.49424


d3
0.6000
9.2713
11.8247


d7
16.3737
6.6282
1.3000


d13
2.4277
5.0960
17.3459


d15
5.3218
6.0394
2.3979


Entrance pupil
11.9231
24.8818
26.5373


position


Exit pupil
−14.8030
−20.5171
−84.7163


position


Front principal
15.3448
30.1092
43.9172


points position


Back principal
36.8881
33.1422
25.8801


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−89.3631


2
2
32.0735


3
4
−6.1279


4
6
18.1963


5
9
6.2362


6
10
−5.4342


7
12
10.6008


8
14
28.9594










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
50.88919
4.00000
−0.12750
1.59066


2
4
−10.02146
4.84000
0.08964
1.49662


3
8
10.73240
5.20000
−0.44561
1.35068


4
14
28.95942
1.80000
0.57117
1.22717










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.26534
−0.34441
−0.37754


3
8
−0.50578
−0.87494
−1.47619


4
14
0.75668
0.73194
0.85759









Numerical Example III-2
The zoom lens system of Numerical Example III-2 corresponds to Embodiment III-2 shown in FIG. 51. Table III-4 shows the surface data of the zoom lens system of Numerical Example III-2. Table III-5 shows the aspherical data. Table III-6 shows various data.







TABLE III-4







(Surface data)













Surface number
r
d
nd
vd







Object surface
∞






 1
42.20045
0.80000
1.84666
23.8



 2
24.97099
2.90000
1.72916
54.7



 3*
−75.26600
Variable



 4*
−30.93809
0.90000
1.85976
40.6



 5*
5.39301
1.48910



 6
7.94718
1.70000
1.94595
18.0



 7
16.31084
Variable



 8(Diaphragm)
∞
0.00000



 9*
4.79974
2.50000
1.85976
40.6



10
−14.66516
0.40000
1.84666
23.8



11
4.21186
0.60000



12
35.77043
1.70000
1.88300
40.8



13
−12.04398
Variable



14*
217.18110
1.80000
1.58913
61.3



15
−13.09408
Variable



16
∞
1.00000
1.51680
64.2



17
∞
(BF)



Image surface
∞

















TABLE III-5





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.11021E−05, A6 = 5.76903E−08,



A8 = −1.20097E−09 A10 = 7.11123E−12



Surface No. 4



K = 0.00000E+00, A4 = 2.30985E−04, A6 = −2.75552E−06,



A8 = 1.66601E−08 A10 = −7.35706E−11



Surface No. 5



K = −3.84341E+00, A4 = 2.62504E−03, A6 = −6.59135E−05,



A8 = 2.01477E−06 A10 = −2.90630E−08



Surface No. 9



K = −3.34609E−01, A4 = −2.42708E−04, A6 = −1.34729E−05,



A8 = 2.29294E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −7.38521E−05, A6 = 2.41783E−05,



A8 = −1.21687E−06 A10 = 2.41573E−08

















TABLE III-6





(Various data)


Zooming ratio 4.80618



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
4.5741
9.4586
21.9840


F-number
3.17859
3.86582
5.42033


View angle
42.9885
21.6541
9.9636


Image height
3.8300
3.8300
3.8300


Overall length
38.0091
39.1967
46.9950


of lens system


BF
0.50369
0.48002
0.48548


d3
0.5000
6.5541
13.4853


d7
14.2364
6.0247
1.4500


d13
2.0453
5.1834
13.2422


d15
4.9347
5.1654
2.5429


Entrance pupil
10.2416
18.5093
32.3551


position


Exit pupil
−15.2779
−24.0293
−119.2210


position


Front principal
13.4899
24.3176
50.3017


points position


Back principal
33.4350
29.7382
25.0110


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−73.8101


2
2
26.0324


3
4
−5.2811


4
6
14.9110


5
9
4.4716


6
10
−3.8275


7
12
10.3771


8
14
21.0233










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.40143
3.70000
0.74496
2.30550


2
4
−8.92286
4.08910
−0.07408
1.17904


3
8
9.99157
5.20000
0.00641
1.72344


4
14
21.02326
1.80000
1.07139
1.73540










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.30086
−0.37802
−0.53517


3
8
−0.53235
−0.88850
−1.23765


4
14
0.70689
0.69703
0.82152









Numerical Example III-3
The zoom lens system of Numerical Example III-3 corresponds to Embodiment III-3 shown in FIG. 54. Table III-7 shows the surface data of the zoom lens system of Numerical Example III-3. Table III-8 shows the aspherical data. Table III-9 shows various data.







TABLE III-7







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
77.48544
0.70000
2.14422
17.5


 2
42.37542
2.50000
1.88300
40.8


 3*
−54.64303
Variable


 4*
−24.97959
0.90000
1.85976
40.6


 5*
5.48270
0.96780


 6
7.81948
1.70000
2.00170
20.6


 7
20.38775
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.85241
2.50000
1.85976
40.6


10
−19.04782
0.40000
1.84666
23.8


11
4.26231
0.60000


12
37.18501
1.50000
1.88300
40.8


13
−13.66920
Variable


14*
−136.73890
1.80000
1.80420
46.5


15
−14.90167
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE III-8





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.47762E−05, A6 = 5.09518E−08,



A8 = −1.94970E−09 A10 = 1.59565E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.31527E−04, A6 = −2.90013E−06,



A8 = 1.68839E−08 A10 = −5.66432E−11



Surface No. 5



K = −3.52458E+00, A4 = 2.23158E−03, A6 = −4.53310E−05,



A8 = 1.14427E−06 A10 = −1.66385E−08



Surface No. 9



K = −3.07449E−01, A4 = −2.44430E−04, A6 = −4.77575E−06,



A8 = 7.41211E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −6.50732E−05, A6 = 1.34430E−05,



A8 = −7.09989E−07 A10 = 1.38939E−08

















TABLE III-9





(Various data)


Zooming ratio 4.71152



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1466
11.1810
24.2483


F-number
3.33816
4.20129
6.20279


View angle
39.6377
18.5711
9.0207


Image height
3.8300
3.8300
3.8300


Overall length
37.7216
39.2545
46.7249


of lens system


BF
0.51113
0.48442
0.49197


d3
0.5000
6.7559
11.8660


d7
14.5217
5.5731
1.4500


d13
1.9080
6.0145
15.8554


d15
5.7131
5.8587
2.4937


Entrance pupil
9.9785
17.5384
25.2778


position


Exit pupil
−15.2007
−27.1412
−894.2331


position


Front principal
13.4393
24.1941
48.8689


points position


Back principal
32.5751
28.0734
22.4766


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−82.6114


2
2
27.3598


3
4
−5.1588


4
6
11.8601


5
9
4.7266


6
10
−4.0816


7
12
11.4782


8
14
20.6601










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.76881
3.20000
1.00946
2.53622


2
4
−9.96079
3.56780
−0.07786
1.19845


3
8
10.69375
5.00000
−0.39913
1.39101


4
14
20.66011
1.80000
1.11237
1.92123










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.33513
−0.42447
−0.54264


3
8
−0.55997
−0.96877
−1.32146


4
14
0.67269
0.66693
0.82944









Numerical Example III-4
The zoom lens system of Numerical Example III-4 corresponds to Embodiment III-4 shown in FIG. 57. Table III-10 shows the surface data of the zoom lens system of Numerical Example III-4. Table III-11 shows the aspherical data. Table III-12 shows various data.







TABLE III-10







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
97.05992
0.70000
2.14422
17.5


 2
46.46025
2.50000
1.88300
40.8


 3*
−47.77710
Variable


 4*
−22.51907
0.90000
1.85976
40.6


 5*
5.49697
0.96780


 6
7.89898
1.70000
2.00170
20.6


 7
21.79417
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.55112
2.50000
1.85976
40.6


10
21.65382
0.40000
2.00170
20.6


11
4.17957
0.60000


12
22.76037
1.50000
1.88300
40.8


13
−13.19010
Variable


14*
−136.73890
1.80000
1.80420
46.5


15
−15.86951
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE III-11





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.36523E−05, A6 = 9.09025E−08,



A8 = −2.14561E−09 A10 = 1.60945E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.88191E−04, A6 = −4.57427E−06,



A8 = 4.34209E−08 A10 = −2.20674E−10



Surface No. 5



K = −3.39371E+00, A4 = 2.17647E−03, A6 = −4.18815E−05,



A8 = 9.46075E−07 A10 = −1.34979E−08



Surface No. 9



K = −2.88099E−01, A4 = −2.38380E−04, A6 = −5.03439E−06,



A8 = 6.92510E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −3.29945E−05, A6 = 1.29659E−05,



A8 = −6.41813E−07 A10 = 1.26725E−08

















TABLE III-12





(Various data)


Zooming ratio 4.71468



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1453
11.1795
24.2583


F-number
3.39777
4.28927
6.21311


View angle
39.6513
18.5719
9.0119


Image height
3.8300
3.8300
3.8300


Overall length
37.7137
39.1679
46.7282


of lens system


BF
0.50696
0.48248
0.49531


d3
0.5000
6.6971
12.2770


d7
14.5410
5.6054
1.4500


d13
1.8762
5.9504
15.4550


d15
5.7217
5.8647
2.4832


Entrance pupil
9.7713
17.1562
25.9486


position


Exit pupil
−14.9074
−25.6276
−188.1820


position


Front principal
13.1991
23.5490
47.0880


points position


Back principal
32.5684
27.9884
22.4699


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−78.4663


2
2
27.0118


3
4
−5.0639


4
6
11.6547


5
9
6.2779


6
10
−5.2304


7
12
9.6459


8
14
22.1770










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.90528
3.20000
1.17728
2.70651


2
4
−9.86216
3.56780
−0.12987
1.13155


3
8
10.54809
5.00000
−0.46117
1.32934


4
14
22.17696
1.80000
1.12122
1.93013










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.32678
−0.41123
−0.53591


3
8
−0.55362
−0.96329
−1.31450


4
14
0.69528
0.68993
0.84183









Numerical Example III-5
The zoom lens system of Numerical Example III-5 corresponds to Embodiment III-5 shown in FIG. 60. Table III-13 shows the surface data of the zoom lens system of Numerical Example III-5. Table III-14 shows the aspherical data. Table III-15 shows various data.







TABLE III-13







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
97.05992
0.70000
2.14422
17.5


 2
46.46025
2.50000
1.88300
40.8


 3*
−47.77710
Variable


 4*
−22.51907
0.90000
1.85976
40.6


 5*
5.49697
0.96780


 6
7.89898
1.70000
2.00170
20.6


 7
21.79417
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.55112
2.50000
1.85976
40.6


10
21.65382
0.40000
2.00170
20.6


11
4.17957
0.60000


12
22.76037
1.50000
1.88300
40.8


13
−13.19010
Variable


14*
−136.73890
1.80000
1.80420
46.5


15
−15.86951
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE III-14





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.36523E−05, A6 = 9.09025E−08,



A8 = −2.14561E−09 A10 = 1.60945E−11



Surface No. 4



K = 0.00000E+00, A4 = 2.88191E−04, A6 = −4.57427E−06,



A8 = 4.34209E−08 A10 = −2.20674E−10



Surface No. 5



K = −3.39371E+00, A4 = 2.17647E−03, A6 = −4.18815E−05,



A8 = 9.46075E−07 A10 = −1.34979E−08



Surface No. 9



K = −2.88099E−01, A4 = −2.38380E−04, A6 = −5.03439E−06,



A8 = 6.92510E−07 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −3.29945E−05, A6 = 1.29659E−05,



A8 = −6.41813E−07 A10 = 1.26725E−08

















TABLE III-15





(Various data)


Zooming ratio 4.71468



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1453
11.1795
24.2583


F-number
3.39777
4.28927
6.21311


View angle
39.6513
18.5719
9.0119


Image height
3.8300
3.8300
3.8300


Overall length
37.7137
39.1679
46.7282


of lens system


BF
0.50696
0.48248
0.49531


d3
0.5000
6.6971
12.2770


d7
14.5410
5.6054
1.4500


d13
1.8762
5.9504
15.4550


d15
5.7217
5.8647
2.4832


Entrance pupil
9.7713
17.1562
25.9486


position


Exit pupil
−14.9074
−25.6276
−188.1820


position


Front principal
13.1991
23.5490
47.0880


points position


Back principal
32.5684
27.9884
22.4699


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−78.4663


2
2
27.0118


3
4
−5.0639


4
6
11.6547


5
9
6.2779


6
10
−5.2304


7
12
9.6459


8
14
22.1770










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
40.90528
3.20000
1.17728
2.70651


2
4
−9.86216
3.56780
−0.12987
1.13155


3
8
10.54809
5.00000
−0.46117
1.32934


4
14
22.17696
1.80000
1.12122
1.93013










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.32678
−0.41123
−0.53591


3
8
−0.55362
−0.96329
−1.31450


4
14
0.69528
0.68993
0.84183









Numerical Example III-6
The zoom lens system of Numerical Example III-6 corresponds to Embodiment III-6 shown in FIG. 63. Table III-16 shows the surface data of the zoom lens system of Numerical Example III-6. Table III-17 shows the aspherical data. Table III-18 shows various data.







TABLE III-16







(Surface data)













Surface number
r
d
nd
vd







Object surface
∞






 1
32.95375
0.70000
2.00170
20.6



 2
22.80973
2.80000
1.72916
54.7



 3*
−69.31601
Variable



 4*
−22.01499
0.90000
1.85976
40.6



 5*
5.75371
0.86860



 6
7.34911
1.75000
1.94595
18.0



 7
15.39695
Variable



 8(Diaphragm)
∞
0.00000



 9*
4.45399
2.10000
1.85280
39.0



10
−17.72421
0.70000
1.84666
23.8



11
3.85579
0.65000



12
36.52641
1.65000
1.88300
40.8



13
−13.24632
Variable



14*
−56.84676
1.75000
1.77250
49.6



15
−11.49370
Variable



16
∞
1.00000
1.51680
64.2



17
∞
(BF)



Image surface
∞

















TABLE III-17





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.08559E−05, A6 = 4.56266E−08,



A8 = −9.75382E−10 A10 = 6.49788E−12



Surface No. 4



K = 0.00000E+00, A4 = 2.90363E−04, A6 = −3.22130E−06,



A8 = 1.76877E−08 A10 = −1.63471E−11



Surface No. 5



K = −4.05487E+00, A4 = 2.40019E−03, A6 = −5.41180E−05,



A8 = 1.54831E−06 A10 = −1.96087E−08



Surface No. 9



K = −3.25149E−01, A4 = −2.33992E−04, A6 = −6.33264E−06,



A8 = 1.49061E−06 A10 = 2.49143E−07



Surface No. 14



K = 0.00000E+00, A4 = −9.21462E−05, A6 = 1.85796E−05,



A8 = −9.58669E−07 A10 = 1.85225E−08

















TABLE III-18





(Various data)


Zooming ratio 5.65143



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1464
12.2483
29.0845


F-number
3.28775
4.20162
5.63938


View angle
39.6477
17.0627
7.5618


Image height
3.8300
3.8300
3.8300


Overall length
37.4024
39.4747
47.4053


of lens system


BF
0.51712
0.48392
0.48597


d3
0.5000
6.6381
14.1989


d7
13.9284
5.0648
1.4500


d13
2.0462
6.3703
13.8354


d15
5.5422
6.0491
2.5664


Entrance pupil
10.6398
19.3085
39.0455


position


Exit pupil
−16.3124
−33.5943
4986.8387


position


Front principal
14.2124
27.1545
68.2996


points position


Back principal
32.2561
27.2264
18.3208


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−76.6194


2
2
23.8425


3
4
−5.2273


4
6
13.4427


5
9
4.3641


6
10
−3.6856


7
12
11.1829


8
14
18.3408










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
34.88350
3.50000
0.57925
2.07992


2
4
−8.79375
3.51860
0.23102
1.58458


3
8
10.51324
5.10000
−0.43381
1.32739


4
14
18.34077
1.75000
1.21705
1.99607










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.36735
−0.49402
−0.85879


3
8
−0.62064
−1.14402
−1.19704


4
14
0.64710
0.62127
0.81105









Numerical Example III-7
The zoom lens system of Numerical Example III-7 corresponds to Embodiment III-7 shown in FIG. 66. Table III-19 shows the surface data of the zoom lens system of Numerical Example III-7. Table III-20 shows the aspherical data. Table III-21 shows various data.







TABLE III-19







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
26.24654
0.80000
1.92286
20.9


 2
19.47359
2.90000
1.77250
49.6


 3
109.68850
Variable


 4*
−124.53210
0.95000
1.85976
40.6


 5*
5.25923
1.75650


 6
8.20781
1.70000
2.14422
17.5


 7
12.83109
Variable


 8(Diaphragm)
∞
0.00000


 9*
4.65332
2.45000
1.80139
45.4


10
14.95742
0.50000
1.92286
20.9


11
4.24062
0.48000


12
13.11167
1.50000
1.80420
46.5


13
−19.34140
Variable


14*
18.34229
1.70000
1.82080
42.7


15
−317.88590
Variable


16
∞
1.00000
1.51680
64.2


17
∞
(BF)


Image surface
∞
















TABLE III-20





(Aspherical data)

















Surface No. 4



K = 0.00000E+00, A4 = 1.07024E−04, A6 = −1.68199E−06,



A8 = 1.05423E−08 A10 = 0.00000E+00



Surface No. 5



K = −2.21584E+00, A4 = 1.55616E−03, A6 = −1.26061E−05,



A8 = 2.01423E−07 A10 = −1.53348E−09



Surface No. 9



K = −4.25982E−01, A4 = −7.34038E−06, A6 = 2.29644E−05,



A8 = −6.67959E−06 A10 = 7.69046E−07



Surface No. 14



K = 0.00000E+00, A4 = 5.76025E−05, A6 = 1.05741E−06,



A8 = 0.00000E+00 A10 = 0.00000E+00

















TABLE III-21





(Various data)


Zooming ratio 5.64641



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1434
12.2384
29.0417


F-number
3.16726
3.84698
5.55779


View angle
39.9424
17.6011
7.5082


Image height
3.8300
3.8300
3.8300


Overall length
40.6659
43.5886
54.5657


of lens system


BF
0.49444
0.50779
0.49981


d3
0.5000
9.9099
17.8974


d7
15.7039
5.4929
1.4500


d13
3.8122
6.0562
16.2028


d15
4.4189
5.8852
2.7792


Entrance pupil
11.4804
26.4000
46.7566


position


Exit pupil
−16.2416
−23.5842
−223.5063


position


Front principal
15.0431
32.4214
72.0331


points position


Back principal
35.5225
31.3502
25.5239


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
−86.6861


2
2
30.2265


3
4
−5.8494


4
6
16.6426


5
9
7.6225


6
10
−6.5602


7
12
9.9213


8
14
21.1761










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
47.77654
3.70000
−0.84574
0.84735


2
4
−9.55092
4.40650
0.14386
1.58661


3
8
10.80176
4.93000
−0.72013
1.19828


4
14
21.17606
1.70000
0.05105
0.81526










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
4
−0.27501
−0.37722
−0.55107


3
8
−0.56320
−1.08618
−1.42840


4
14
0.69506
0.62519
0.77224









Numerical Example III-8
The zoom lens system of Numerical Example III-8 corresponds to Embodiment III-8 shown in FIG. 69. Table III-22 shows the surface data of the zoom lens system of Numerical Example III-8. Table III-23 shows the aspherical data. Table III-24 shows various data.







TABLE III-22







(Surface data)











Surface number
r
d
nd
vd





Object surface
∞





 1
31.86466
2.50000
1.72916
54.7


 2
134.84140
Variable


 3*
−248.26680
1.20000
1.85976
40.6


 4*
5.75364
1.94000


 5
8.39253
1.70000
1.94595
18.0


 6
14.57504
Variable


 7(Diaphragm)
∞
0.00000


 8*
4.61391
2.50000
1.77377
47.2


 9
−92.73069
0.40000
1.80518
25.5


10
4.14814
0.50000


11
16.83120
1.80000
1.72916
54.7


12
−14.51842
Variable


13*
165.08590
1.80000
2.00170
20.6


14
−32.87752
Variable


15
∞
1.00000
1.51680
64.2


16
∞
(BF)


Image surface
∞
















TABLE III-23





(Aspherical data)

















Surface No. 3



K = 0.00000E+00, A4 = 1.34480E−04, A6 = −9.96145E−07,



A8 = 0.00000E+00 A10 = 0.00000E+00



Surface No. 4



K = −3.36150E+00, A4 = 2.01372E−03, A6 = −3.87027E−05,



A8 = 1.15749E−06 A10 = −1.46790E−08



Surface No. 8



K = −2.95367E−01, A4 = −2.26495E−04, A6 = 2.36597E−05,



A8 = −8.11256E−06 A10 = 8.89822E−07



Surface No. 13



K = 0.00000E+00, A4 = 3.02355E−05, A6 = 2.23022E−06,



A8 = −5.36111E−08 A10 = 0.00000E+00

















TABLE III-24





(Various data)


Zooming ratio 4.70823



















Wide-angle
Middle
Telephoto



limit
position
limit





Focal length
5.1685
11.2200
24.3347


F-number
3.26820
4.15816
6.23804


View angle
38.1988
18.9234
9.0070


Image height
3.8300
3.8300
3.8300


Overall length
42.0225
44.1238
50.1723


of lens system


BF
0.51010
0.48494
0.50099


d2
0.6000
8.7177
12.8658


d6
17.4325
7.1763
1.3000


d12
2.4468
7.1761
17.7813


d14
5.6931
5.2289
2.3842


Entrance pupil
11.3010
21.9379
26.1297


position


Exit pupil
−15.2274
−25.3743
−112.2135


position


Front principal
14.7720
28.2896
45.2106


points position


Back principal
36.8540
32.9039
25.8377


points position










Single lens data









Lens
Initial surface
Focal


element
number
length





1
1
56.6431


2
3
−6.5263


3
5
18.4496


4
8
5.7447


5
9
−4.9222


6
11
10.9553


7
13
27.4958










Zoom lens unit data












Lens
Initial
Focal
Overall length
Front principal
Back principal


unit
surface No.
length
of lens unit
points position
points position





1
1
56.64310
2.50000
−0.44284
0.62602


2
3
−10.93149
4.84000
0.09096
1.50158


3
7
11.09254
5.20000
−0.43515
1.35811


4
13
27.49578
1.80000
0.75332
1.64997










Magnification of zoom lens unit











Lens
Initial
Wide-angle
Middle
Telephoto


unit
surface No.
limit
position
limit





1
1
0.00000
0.00000
0.00000


2
3
−0.25336
−0.31207
−0.35399


3
7
−0.48346
−0.83216
−1.40202


4
13
0.74496
0.76276
0.86564









The following Table III-25 shows the corresponding values to the individual conditions in the zoom lens systems of each of Numerical Examples.







TABLE III-25







(Values corresponding to conditions)









Example















Condition
III-1
III-2
III-3
III-4
III-5
III-6
III-7
III-8



















(4-1)
M1/M3
0.68
1.02
0.84
0.87
1.11
1.14
1.29
0.68


(a-1)
ωW
38.25
42.99
39.66
39.66
39.64
39.68
39.94
38.20


(b-2)
fT/fW
4.71
4.81
4.71
4.71
4.71
5.65
5.65
4.71


(2-1)
f2/fW
−1.94
−1.95
−1.94
−1.92
−1.79
−1.71
−1.86
−2.12


(3-1)
(β2T/β2W)/(β3T/β3W)
0.49
0.77
0.69
0.69
0.84
1.21
0.79
0.48


(5)
nd2p
1.946
1.946
2.002
2.002
1.946
1.946
2.144
1.946


(6)
(r2na + r2nb)/(r2na − r2nb)
0.90
0.70
0.64
0.61
0.65
0.59
0.92
0.95


(7)
(r2nb + r2pa)/(r2nb − r2pa)
−5.06
−5.22
−5.69
−5.58
−6.65
−8.21
−4.57
−5.36


(8)
(r1pa + r1pb)/(r1pa − r1pb)
−1.01
−0.50
−0.13
−0.01
−0.34
−0.50
−1.43
−1.62


(9)
f3/fW
2.08
2.18
2.08
2.05
1.97
2.04
2.10
2.15


(10) 
f3IL/f3
1.04
1.02
1.13
0.95
1.04
1.10
0.97
1.08


(11) 
f3n/f3
−0.51
−0.38
−0.38
−0.50
−0.39
−0.35
−0.61
−0.44









INDUSTRIAL APPLICABILITY
The zoom lens system according to the present invention is applicable to a digital input device such as a digital camera, a mobile telephone, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a Web camera or a vehicle-mounted camera. In particular, the zoom lens system according to the present invention is suitable for a photographing optical system where high image quality is required like in a digital camera.
DESCRIPTION OF THE REFERENCE CHARACTERS


    
    
        G1 first lens unit
        G2 second lens unit
        G3 third lens unit
        G4 fourth lens unit
        L1 first lens element
        L2 second lens element
        L3 third lens element
        L4 fourth lens element
        L5 fifth lens element
        L6 sixth lens element
        L7 seventh lens element
        L8 eighth lens element
        A aperture diaphragm
        P plane parallel plate
        S image surface
        1 zoom lens system
        2 image sensor
        3 liquid crystal display monitor
        4 body
        5 main barrel
        6 moving barrel
        7 cylindrical cam

## Claims

1. A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (2-1), (a-1) and (b-2) are satisfied:


−2.3<f2/fW<−1.5  (2-1)



ωW≧36  (a-1)



5.66≧fT/fW>4.5  (b-2)


where,
f2 is a composite focal length of the second lens unit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.

2. The zoom lens system as claimed in claim 1, wherein the second lens unit includes a lens element having positive optical power, and the following condition (5) is satisfied:


1.88<nd2p<2.20  (5)

where,
nd2p is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.

3. The zoom lens system as claimed in claim 1, wherein the second lens unit includes a lens element having negative optical power, and the following condition (6) is satisfied:


0.35<(r2na+r2nb)/(r2na−r2nb)<1.20  (6)

where,
r2na is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.

4. The zoom lens system as claimed in claim 1, wherein the second lens unit is composed of two lens elements, in order from the object side to the image side, including a lens element having negative optical power, and a lens element having positive optical power, and the following condition (7) is satisfied:


−8.5<(r2nb+r2pa)/(r2nb−r2pa)<−3.5  (7)

where,
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.

5. The zoom lens system as claimed in claim 1, wherein the first lens unit includes a lens element having positive optical power, and the following condition (8) is satisfied:


−1.8<(r1pa+r1pb)/(r1pa−r1pb)<0.0  (8)

where,
r1pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and
r1pb is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.

6. The zoom lens system as claimed in claim 1, wherein the following condition (9) is satisfied:


1.87<f3/fW<3.00  (9)

where,
f3 is a composite focal length of the third lens unit, and
fW is a focal length of the entire system at a wide-angle limit.

7. The zoom lens system as claimed in claim 1, wherein the following condition (10) is satisfied:


0.5<f3IL/f3<1.5  (10)

where,
f3IL is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.

8. The zoom lens system as claimed in claim 1, wherein the third lens unit includes a cemented lens element which is obtained by cementing the object side lens element having positive optical power with the lens element having negative optical power.

9. The zoom lens system as claimed in claim 1, wherein the fourth lens unit comprises solely a lens element having positive optical power.

10. The zoom lens system as claimed in claim 1, wherein the following condition (11) is satisfied:


−1.00<f3n/f3<−0.25  (11)

where,
f3n is a focal length of the lens element having negative optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.

11. An imaging device capable of outputting an optical image of an object as an electric image signal, comprising:
a zoom lens system that forms an optical image of the object; and
an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system is the zoom lens system as claimed in claim 1.

12. A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:
an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system is the zoom lens system as claimed in claim 1.

13. A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (3-1), (a-1) and (b-2) are satisfied:


0.4<(β2T/β2W)/(β3T/β3W)<1.3  (3-1)



ωW≧36  (a-1)



5.65≧fT/fW>4.5  (b-2)


where,
β2T is a lateral magnification of the second lens unit at a telephoto limit,
β2W is a lateral magnification of the second lens unit at a wide-angle limit,
β3T is a lateral magnification of the third lens unit at a telephoto limit,
β3W is a lateral magnification of the third lens unit at a wide-angle limit,
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.

14. The zoom lens system as claimed in claim 13, wherein the second lens unit includes a lens element having positive optical power, and the following condition (5) is satisfied:


1.88<nd2p<2.20  (5)

where,
nd2p is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.

15. The zoom lens system as claimed in claim 13, wherein the second lens unit includes a lens element having negative optical power, and the following condition (6) is satisfied:


0.35<(r2na+r2nb)/(r2na−r2nb)<1.20  (6)

where,
r2na is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.

16. The zoom lens system as claimed in claim 13, wherein the second lens unit is composed of two lens elements, in order from the object side to the image side, including a lens element having negative optical power, and a lens element having positive optical power, and the following condition (7) is satisfied:


−8.5<(r2nb+r2pa)/(r2nb−r2pa)<−3.5  (7)

where,
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.

17. The zoom lens system as claimed in claim 13, wherein the first lens unit includes a lens element having positive optical power, and the following condition (8) is satisfied:


−1.8<(r1pa+r1pb)/(r1pa−r1pb)<0.0  (8)

where,
r1pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and
r1pb is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.

18. The zoom lens system as claimed in claim 13, wherein the following condition (9) is satisfied:


1.87<f3/fW<3.00  (9)

where,
f3 is a composite focal length of the third lens unit, and
fW is a focal length of the entire system at a wide-angle limit.

19. The zoom lens system as claimed in claim 13, wherein the following condition (10) is satisfied:


0.5<f3IL/f3<1.5  (10)

where,
f3IL is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.

20. The zoom lens system as claimed in claim 13, wherein the third lens unit includes a cemented lens element which is obtained by cementing the object side lens element having positive optical power with the lens element having negative optical power.

21. The zoom lens system as claimed in claim 13, wherein the fourth lens unit comprises solely a lens element having positive optical power.

22. The zoom lens system as claimed in claim 13, wherein the following condition (11) is satisfied:


−1.00<f3n/f3<−0.25  (11)

where,
f3n is a focal length of the lens element having negative optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.

23. An imaging device capable of outputting an optical image of an object as an electric image signal, comprising:
a zoom lens system that forms an optical image of the object; and
an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system is the zoom lens system as claimed in claim 13.

24. A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:
an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system is the zoom lens system as claimed in claim 13.

25. A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein
the first lens unit is composed of at most two lens elements,
the second lens unit is composed of two lens elements,
the third lens unit is composed of three lens elements, in order from the object side to the image side, including an object side lens element having positive optical power, a lens element having negative optical power, and an image side lens element having positive optical power, and
the following conditions (4-1), (a-1) and (b-2) are satisfied:


0.6<M1/M3<1.5  (4-1)



ωW≧36  (a-1)



5.65≧fT/fW>4.5  (b-2)


where,
M1 is an amount of movement of the first lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
M3 is an amount of movement of the third lens unit in the direction along the optical axis during zooming from a wide-angle limit to a telephoto limit (movement from the image side to the object side is positive),
ωW is a half view angle (°) at a wide-angle limit,
fT is a focal length of the entire system at a telephoto limit, and
fW is a focal length of the entire system at a wide-angle limit.

26. The zoom lens system as claimed in claim 25, wherein the second lens unit includes a lens element having positive optical power, and the following condition (5) is satisfied:


1.88<nd2p<2.20  (5)

where,
nd2p is a refractive index to the d-line of the lens element having positive optical power, which is included in the second lens unit.

27. The zoom lens system as claimed in claim 25, wherein the second lens unit includes a lens element having negative optical power, and the following condition (6) is satisfied:


0.35<(r2na+r2nb)/(r2na−r2nb)<1.20  (6)

where,
r2na is a radius of curvature of an object side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit.

28. The zoom lens system as claimed in claim 25, wherein the second lens unit is composed of two lens elements, in order from the object side to the image side, including a lens element having negative optical power, and a lens element having positive optical power, and the following condition (7) is satisfied:


−8.5<(r2nb+r2pa)/(r2nb−r2pa)<−3.5  (7)

where,
r2nb is a radius of curvature of an image side surface of the lens element having negative optical power, which is included in the second lens unit, and
r2pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the second lens unit.

29. The zoom lens system as claimed in claim 25, wherein the first lens unit includes a lens element having positive optical power, and the following condition (8) is satisfied:


−1.8<(r1pa+r1pb)/(r1pa−r1pb)<0.0  (8)

where,
r1pa is a radius of curvature of an object side surface of the lens element having positive optical power, which is included in the first lens unit, and
r1pb is a radius of curvature of an image side surface of the lens element having positive optical power, which is included in the first lens unit.

30. The zoom lens system as claimed in claim 25, wherein the following condition (9) is satisfied:


1.87<f3/fW<3.00  (9)

where,
f3 is a composite focal length of the third lens unit, and
fW is a focal length of the entire system at a wide-angle limit.

31. The zoom lens system as claimed in claim 25, wherein the following condition (10) is satisfied:


0.5<f3IL/f3<1.5  (10)

where,
f3IL is a focal length of the image side lens element having positive optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.

32. The zoom lens system as claimed in claim 25, wherein the third lens unit includes a cemented lens element which is obtained by cementing the object side lens element having positive optical power with the lens element having negative optical power.

33. The zoom lens system as claimed in claim 25, wherein the fourth lens unit comprises solely a lens element having positive optical power.

34. The zoom lens system as claimed in claim 25, wherein the following condition (11) is satisfied:


−1.00<f3n/f3<−0.25  (11)

where,
f3n is a focal length of the lens element having negative optical power, which is included in the third lens unit, and
f3 is a composite focal length of the third lens unit.

35. An imaging device capable of outputting an optical image of an object as an electric image signal, comprising:
a zoom lens system that forms an optical image of the object; and
an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system is the zoom lens system as claimed in claim 25.

36. A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:
an imaging device including a zoom lens system that forms the optical image of the object and an image sensor that converts the optical image formed by the zoom lens system into the electric image signal, wherein
the zoom lens system is the zoom lens system as claimed in claim 25.