# Patent

## Title
Zoom lens and image pickup apparatus including the same

## Abstract

A zoom lens includes, in order from an object side: a first positive lens unit not moving for zooming; a second negative lens unit moving during zooming; a third positive lens unit moving during zooming; a fourth positive lens unit moving during zooming; and a fifth positive lens unit not moving for zooming. Each of the lens units includes positive and negative lenses, and satisfies 10<νp−νn<54, −1<β2w<−0.05, −5<β2t<−1, and −1<β34z2<−0.3, where νp is average Abbe constant of the positive lens of the fourth unit, νn an average Abbe constant of the negative lens of the fourth unit, β2w a magnification of the second unit at wide angle end, β2t a magnification of the second unit at telephoto end, and β34z2 a magnification of a combined lens unit including the third and fourth unit at a zoom position where the magnification of the second unit is −1.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus including the zoom lens, which are suitable for use in a broadcasting television camera, a video camera, a digital still camera, a monitoring camera, and a silver-halide film camera.
2. Description of the Related Art
In recent years, there have been demanded a zoom lens having a wide angle of field, a high zoom ratio, and high optical performance for image pickup apparatus such as a television camera, a silver-halide film camera, a digital camera, and a video camera. As the zoom lens having the wide angle of field and the high zoom ratio, there has been known a positive-lead type five-unit zoom lens including five lens units in which a lens unit having a positive refractive power is arranged at the end on an object side.
As the positive-lead type zoom lens, there has been known a five-unit zoom lens in which three movable lens units including a second lens unit having a negative refractive power, a third lens unit having the positive refractive power, and a fourth lens unit having the positive refractive power vary magnification and correct an image plane variation accompanying zooming (Japanese Patent Application Laid-Open Nos. H07-248449, 2009-128491, and 2009-128492).
Japanese Patent Application Laid-Open No. H07-248449 discloses a zoom lens having a zoom ratio of about 17 and a photographing angle of field at a wide angle end of about 70°. Japanese Patent Application Laid-Open Nos. 2009-128491 and 2009-128492 each disclose a zoom lens having a zoom ratio of about 54 and a photographing angle of field at a wide angle end of about 60°.
In the five-unit zoom lens, in order to obtain high optical performance while maintaining an increased angle of field and an increased zoom ratio, it is important to appropriately set a refractive power arrangement, configuration, and the like of each lens unit. It is especially important to appropriately set a refractive power, a moving condition during zooming, and the like of each of the second, third, and fourth lens units as zooming lens units. Additionally, it is important to select glass materials and shapes of the fourth lens unit and appropriately set a combined refractive power of the third and fourth lens units, loci of movement of the third and fourth lens units from the wide angle end to a telephoto end, and the like. Unless the configurations are appropriately set, it becomes difficult to obtain the zoom lens having the high optical performance over the entire zoom range with the wide angle of field and the high zoom ratio.
In the zoom lens disclosed in each of Japanese Patent Application Laid-Open Nos. H07-248449, 2009-128491, and 2009-128492, the refractive powers and the loci of movement of the zooming lens units are defined so that an imaging magnification of a combined lens unit including the third and fourth lens units is always −1 when an imaging magnification of the second lens unit is −1 at a predetermined middle zoom position. Moreover, one of the third and fourth lens units includes only positive lenses, and when the loci of movement during zooming are set in order to suppress an increase in effective diameter accompanying further increases in angle of field and zoom ratio, variations in aberrations accompanying the zooming have tended to increase.
The high zoom ratio is a zoom ratio of about 20 to 35 when the angle of field at the wide angle end is about 75° to 85°, or a zoom ratio of about 80 to 130 when the angle of field at the wide angle end is 60° to 67°.
SUMMARY OF THE INVENTION
The present invention provides a zoom lens having a wide angle of field and a high zoom ratio as well as high optical performance over the entire zoom range and providing a fine zoom operation, and an image pickup apparatus including the zoom lens.
A zoom lens according to one embodiment of the present invention includes, in order from an object side to an image side: a first lens unit having a positive refractive power which does not move for zooming; a second lens unit having a negative refractive power which moves during zooming; a third lens unit having the positive refractive power which moves during zooming; a fourth lens unit having the positive refractive power which moves during zooming; and a fifth lens unit having the positive refractive power which does not move for zooming, in which each of the first lens unit to the fifth lens unit includes at least one positive lens and at least one negative lens, and in which the following conditional expressions are satisfied:

−10<νp−νn<54;

−1<β2w<−0.05;

−5<β2t<−1;

and

−1<β34z2<−0.3,

where νp is an average Abbe constant of the at least one positive lens of the fourth lens unit, νn is an average Abbe constant of the at least one negative lens of the fourth lens unit, β2w is an imaging magnification of the second lens unit at a wide angle end, β2t is an imaging magnification of the second lens unit at a telephoto end, and β34z2 is an imaging magnification of a combined lens unit including the third lens unit and the fourth lens unit at a zoom position z2 where the imaging magnification of the second lens unit is −1.

According to the present invention, it is possible to provide the zoom lens having a wide angle of view, a high zoom ratio, and high optical performance over the entire zoom range, and the image pickup apparatus including the zoom lens.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a paraxial refractive power arrangement of a zoom lens according to Embodiment 1 of the present invention.
FIGS. 2A, 2B, 2C and 2D are optical path diagrams at a wide angle end, a zoom position z1, a zoom position z2, and a telephoto end.
FIG. 3 is a schematic diagram of a paraxial refractive power arrangement of a transition type zoom lens.
FIG. 4 is a schematic diagram of a paraxial refractive power of a four-unit zoom lens.
FIG. 5 is a diagram of two-color achromatism and a remaining secondary spectrum of a positive lens unit.
FIG. 6 is a graph of a distribution of Abbe constants ν and partial dispersion ratios θ of optical materials.
FIG. 7 is a lens cross-sectional view when focused on an object at infinity at the wide angle end according to Numerical Embodiment 1.
FIG. 8A is an aberration diagram when focused on the object at infinity at the wide angle end according to Numerical Embodiment 1.
FIG. 8B is an aberration diagram when focused on the object at infinity at the zoom position z1 according to Numerical Embodiment 1.
FIG. 8C is an aberration diagram when focused on the object at infinity at the zoom position z2 according to Numerical Embodiment 1.
FIG. 8D is an aberration diagram when focused on the object at infinity at the telephoto end according to Numerical Embodiment 1.
FIG. 9 is a lens cross-sectional view when focused on the object at infinity at the wide angle end according to Numerical Embodiment 2.
FIG. 10A is an aberration diagram when focused on the object at infinity at the wide angle end according to Numerical Embodiment 2.
FIG. 10B is an aberration diagram when focused on the object at infinity at the zoom position z1 according to Numerical Embodiment 2.
FIG. 10C is an aberration diagram when focused on the object at infinity at the zoom position z2 according to Numerical Embodiment 2.
FIG. 10D is an aberration diagram when focused on the object at infinity at the telephoto end according to Numerical Embodiment 2.
FIG. 11 is a lens cross-sectional view when focused on the object at infinity at the wide angle end according to Numerical Embodiment 3.
FIG. 12A is an aberration diagram when focused on the object at infinity at the wide angle end according to Numerical Embodiment 3.
FIG. 12B is an aberration diagram when focused on the object at infinity at the zoom position z1 according to Numerical Embodiment 3.
FIG. 12C is an aberration diagram when focused on the object at infinity at the zoom position z2 according to Numerical Embodiment 3.
FIG. 12D is an aberration diagram when focused on the object at infinity at the telephoto end according to Numerical Embodiment 3.
FIG. 13 is a lens cross-sectional view when focused on the object at infinity at the wide angle end according to Numerical Embodiment 4.
FIG. 14A is an aberration diagram when focused on the object at infinity at the wide angle end according to Numerical Embodiment 4.
FIG. 14B is an aberration diagram when focused on the object at infinity at the zoom position z1 according to Numerical Embodiment 4.
FIG. 14C is an aberration diagram when focused on the object at infinity at the zoom position z2 according to Numerical Embodiment 4.
FIG. 14D is an aberration diagram when focused on the object at infinity at the telephoto end according to Numerical Embodiment 4.
FIG. 15 is a lens cross-sectional view when focused on the object at infinity at the wide angle end according to Numerical Embodiment 5.
FIG. 16A is an aberration diagram when focused on the object at infinity at the wide angle end according to Numerical Embodiment 5.
FIG. 16B is an aberration diagram when focused on the object at infinity at the zoom position z1 according to Numerical Embodiment 5.
FIG. 16C is an aberration diagram when focused on the object at infinity at the zoom position z2 according to Numerical Embodiment 5.
FIG. 16D is an aberration diagram when focused on the object at infinity at the telephoto end according to Numerical Embodiment 5.
FIG. 17 is a lens cross-sectional view when focused on the object at infinity at the wide angle end according to Numerical Embodiment 6.
FIG. 18A is an aberration diagram when focused on the object at infinity at the wide angle end according to Numerical Embodiment 6.
FIG. 18B is an aberration diagram when focused on the object at infinity at the zoom position z1 according to Numerical Embodiment 6.
FIG. 18C is an aberration diagram when focused on the object at infinity at the zoom position z2 according to Numerical Embodiment 6.
FIG. 18D is an aberration diagram when focused on the object at infinity at the telephoto end according to Numerical Embodiment 6.
FIG. 19 is a schematic diagram of a main part of an image pickup apparatus according to the present invention.



DESCRIPTION OF THE EMBODIMENTS
In the following, an embodiment of the present invention is described in detail with reference to the attached drawings. A zoom lens according to the present invention includes, in order from an object side to an image side, a first lens unit (front lens unit) U1 having a positive refractive power which does not move for zooming, a second lens unit U2 having a negative refractive power which moves during zooming, a third lens unit U3 having a positive refractive power which moves during zooming, a fourth lens unit U4 which moves during zooming, and a fifth lens unit (relay lens unit) U5 having a positive refractive power which does not move for zooming.
The expression that “a lens unit does not move for zooming” means herein that the lens unit is not driven for a purpose of zooming, but the lens unit may move for focusing if zooming and focusing are performed simultaneously.
FIG. 1 is a schematic diagram of a paraxial refractive power arrangement of a zoom lens according to Embodiment 1 (Numerical Embodiment 1) of the present invention, which is to be described later, and illustrates loci of movement of second to fourth lens units U2 to U4 during zooming. In the figure, the upper part is a wide angle end (WIDE) and the lower part is a telephoto end (TELE). The solid lines connecting from the upper part to the lower part represent the loci of the lens units which move during zooming. In FIG. 1, the third lens unit U3 and the fourth lens unit U4 move so that an interval L34 is large near a zoom position z1 and the interval L34 is small near a zoom position z2 where an imaging magnification of the second lens unit U2 becomes −1.
FIGS. 2A to 2D are optical path diagrams from the wide angle end to the telephoto end according to the present invention, and are optical path diagrams at the wide angle end, the zoom position z1, the zoom position z2, and the telephoto end, respectively. As light beams, two light beams including an axial light beam and an off-axial light beam, which corresponds to the most periphery of the screen, are illustrated. As illustrated in FIG. 2B, the most-peripheral off-axial marginal ray passes through a position higher than that at the wide angle end with respect to the first lens unit U1, and passes through the highest position near z1. Further, as illustrated in FIG. 2C, the axial marginal ray passes through the highest position near z2 with respect to the third lens unit U3 and the fourth lens unit U4.
In other words, a lens diameter of the first lens unit U1 is determined near z1, and lens diameters of the third lens unit U3 and the fourth lens unit U4 are determined near z2.
In addition, FIG. 3 illustrates a paraxial schematic diagram of a four-unit zoom lens generally called a transition type that is a zoom lens advantageous for increasing a zoom ratio. The transition type zoom lens includes a first lens unit U1 having a positive refractive power, a second lens unit U2 having a negative refractive power which moves during zooming, a third lens unit U3 having a positive refractive power which moves during zooming, and a fourth lens unit U4 having a positive refractive power for imaging. In FIG. 3, the upper part is the wide angle end (WIDE), and the lower part is the telephoto end (TELE). The solid lines connecting from the upper part to the lower part represent loci of the second lens unit U2 and the third lens unit U3 when the second lens unit U2 and the third lens unit U3 move during zooming. The transition type zoom lens satisfies a condition that when the lateral magnification β2 of the second lens unit U2 is −1, the lateral magnification β3 of the third lens unit U3 becomes −1. Thus, the third lens unit U3 can continue to move in one way from the image side (the right side) to the object side (the left side) during zooming. As a result, a variation of β3 during zooming can be increased, which is advantageous for increasing a zoom ratio.
Note that, FIG. 4 illustrates a paraxial schematic diagram of an ordinary four-unit zoom lens that does not satisfy this condition. As illustrated in FIG. 4, in the four-unit zoom lens, the third lens unit U3 that generally corrects the image point can move along two loci of movement represented by a dashed double-dotted line and a broken line. The transition type zoom lens illustrated in FIG. 3 is a special case of FIG. 4. When the above-mentioned condition is satisfied, the two loci of movement intersect each other at one point so that it is possible to transfer from one of the two loci of movement to the other locus of movement at the intersection.
In the zoom lens according to the present invention, each of the first lens unit to the fifth lens unit U1 to U5 includes at least one positive lens and at least one negative lens. In this case, the following conditional expressions are satisfied:

10<νp−νn<54  (1);

−1<β2w<−0.05  (2);

−5<β2t<−1  (3);

and

−1<β34z2<−0.3  (4),

where νp is an average Abbe constant of the positive lens of the fourth lens unit, νn is an average Abbe constant of the negative lens of the fourth lens unit, β2w is an imaging magnification of the second lens unit at the wide angle end, β2t is an imaging magnification of the second lens unit at the telephoto end, and β34z2 is an imaging magnification of a combined lens unit including the third lens unit and the fourth lens unit at the zoom position z2 where the imaging magnification of the second lens unit is −1.

Conditional Expression (1) is a condition for appropriately correcting variations in axial chromatic aberration and lateral chromatic aberration caused by zooming at a middle zoom position. In the zoom lens according to the present invention, a lens configuration and dispersion characteristics of lens materials of the fourth lens unit U4 are important factors in correcting the variations in axial chromatic aberration and lateral chromatic aberration caused by the zooming at the middle zoom position satisfactorily. Conditional Expression (1) is satisfied so that the interval between the third lens unit U3 and the fourth lens unit U4 at the middle zoom position is large, and so that the variations in axial chromatic aberration and lateral chromatic aberration caused by the zooming may be corrected satisfactorily even when the interval is small.
When the upper limit condition of Conditional Expression (1) is not satisfied, chromatic aberrations within the fourth lens unit U4 are overcorrected, which makes it difficult to correct the axial chromatic aberration and the lateral chromatic aberration at the middle zoom position. When the lower limit condition of Conditional Expression (1) is not satisfied, the chromatic aberrations within the fourth lens unit U4 are undercorrected, which makes it difficult to correct the axial chromatic aberration and the lateral chromatic aberration at the middle zoom position and to correct a secondary spectrum of an axial chromatic aberration at the telephoto end.
FIG. 5 is a schematic diagram of two-color achromatism and a remaining secondary spectrum of a lens unit LP having a positive refractive power. FIG. 6 is a graph of a distribution of Abbe constants ν and partial dispersion ratios θ of existing optical materials. Here, the Abbe constants ν and the partial dispersion ratios θ are respectively expressed by the following expressions:

ν=(Nd−1)/(NF−NC)  (i)

θ=(Ng−NF)/(NF−NC)  (ii)

where Ng is a refractive index at the g-line, NF is a refractive index at the F-line, Nd is a refractive index at the d-line, and NC is a refractive index at the C-line. As shown in FIG. 6, the existing optical materials are distributed in the region having a narrow partial dispersion ratio θ with respect to the Abbe constant ν, and there is a tendency that the partial dispersion ratio θ increases as the Abbe constant ν decreases.

A correction condition of chromatic aberrations of a thin lens system including two lenses G1 and G2 having refractive powers φ1 and φ2 and Abbe constants of materials ν1 and ν2, respectively (combined refractive power φ) is expressed by the following expression.

φ1/ν1+φ2/ν2=E  (iii)

Here, φ is expressed as follows.

φ=φ1+φ2  (iv)

If E=0 is satisfied in the expression (iii), an imaging position is identical between the C-line and the F-line. In a middle zoom range in which a focal length is short and the secondary spectrum is not large, the chromatic aberrations may be corrected when E=0 is satisfied.
In order to correct the variations in chromatic aberrations at the middle zoom position, it is preferred to set glass materials used for the fourth lens unit U4 so as to satisfy Conditional Expression (1), and it is more preferred to set the glass materials as follows:

20<νp−νn<49  (1a).

Conditional Expression (2) defines a lateral magnification of the second lens unit U2 at the wide angle end. When the upper limit condition of Conditional Expression (2) is not satisfied, an interval between the first lens unit U1 and the second lens unit U2 becomes too large, which increases the entire length of the lens. Alternatively, a refractive power of the second lens unit U2 becomes too large, which increases the variations in aberrations accompanying the zooming. When the lower limit condition of Conditional Expression (2) is not satisfied, it becomes difficult to secure intervals among the second to fourth lens units U2 to U4 at the telephoto end, which is unsuitable for a high zoom ratio.
Conditional Expression (3) defines a lateral magnification of the second lens unit U2 at the telephoto end. When the upper limit condition of Conditional Expression (3) is not satisfied, in order to increase the zoom ratio, an amount of movement of the second lens unit U2 needs to be increased, which increases the entire length of the lens. When the lower limit condition of Conditional Expression (3) is not satisfied, it becomes difficult to secure the intervals among the second to fourth lens units U2 to U4 at the telephoto end, which is unsuitable for the high zoom ratio.
In order to attain the increase in zoom ratio, it is preferred to satisfy Conditional Expressions (2) and (3) and set the imaging magnification of the second lens unit U2 so as to pass a point of −1 during zooming.
Conditional Expression (4) defines the imaging magnification of the combined lens unit including the third and fourth lens units U3 and U4 at the zoom position z2 where the imaging magnification of the second lens unit U2 is −1. Conditional Expression (4) is satisfied so that the lens diameters of the third and fourth lens units U3 and U4 may be reduced as compared to those of the transition type zoom lens illustrated in FIG. 3.
When the upper limit condition of Conditional Expression (4) is not satisfied, the imaging magnification of the combined lens unit is too large, which is unsuitable for increasing the zoom ratio. When the lower limit condition of Conditional Expression (4) is not satisfied, the imaging magnification of the combined lens unit is too small, which results in increased lens diameters of the third and fourth lens units U3 and U4 than those of the transition type zoom lens.
It is more preferred to set numerical ranges of Conditional Expressions (2) to (4) as follows:

−0.2<βw<−0.05  (2a);

−4.5<β2t<−1.5  (3a);

and

−0.96<β34z2<−0.5  (4a).

By satisfying the above conditions, the present invention provides a small and lightweight zoom lens in which the aberrations are corrected satisfactorily over the entire zoom range.
It is further preferred that the third lens unit U3 pass through the point where the imaging magnification is −1 during zooming from the wide angle end to the telephoto end. With this configuration, a change in lateral magnification of the third lens unit U3 becomes large to facilitate the increase in zoom ratio.
It is further preferred to satisfy the following condition:

0.1<f3/f4<1.0  (5),

where f3 is a focal length of the third lens unit, and f4 is a focal length of the fourth lens unit.

Conditional Expression (5) defines a ratio of the focal lengths of the third lens unit U3 and the fourth lens unit U4. When the upper limit condition of Conditional Expression (5) is not satisfied, the focal length of the third lens unit U3 becomes too short, which makes efficient zooming difficult and increases the entire length of the lens. When the lower limit condition of Conditional Expression (5) is not satisfied, the focal length of the fourth lens unit U4 becomes relatively too short, which makes it difficult to reduce the lens diameter.
It is further preferred to satisfy the following condition:

0.5<(R41+R42)/(R41−R42)<10  (6),

where R41 is a radius of curvature of a surface on the object side and R42 is a radius of curvature of a surface on the image side of a negative lens at the end on the object side of the fourth lens unit U4.

Conditional Expression (6) is an expression generally called a shape factor, and defines a shape of the negative lens at the end on the object side of the fourth lens unit U4. When the upper limit condition of Conditional Expression (6) is not satisfied, a refractive power of the negative lens becomes too small to reduce the effect of correcting the aberrations. Workability is also poor. When the lower limit condition of Conditional Expression (6) is not satisfied, an angle is formed with a light beam that enters the negative lens, which causes the aberrations and leads to an increase in number of constituent lenses of the lens unit.
It is further preferred to satisfy the following condition:

−5.5×10−3<(θ2p−θ2n)/(ν2p−ν2n)<−2.0×10−3  (7),

where ν2p and θ2p are average values of an Abbe constant ν and a partial dispersion ratio θ of the at least one positive lens of the second lens unit U2, respectively, and ν2n and θ2n are average values of an Abbe constant ν and a partial dispersion ratio θ of the at least one negative lens of the second lens unit U2, respectively.

Conditional Expression (7) is a condition for appropriately correcting the secondary spectrum of the axial chromatic aberration especially at the telephoto end. When the upper limit condition of Conditional Expression (7) is not satisfied, the effect of correcting the secondary spectrum of the axial chromatic aberration at the telephoto end is small to cause undercorrection. When the lower limit condition of Conditional Expression (7) is not satisfied, the secondary spectrum of the lateral chromatic aberration at the wide angle end is increased.
In FIG. 5, for achromatism of the lens unit LP having the positive refractive power, the material having the large Abbe constant ν1 is used as the positive lens G1, and the material having the small Abbe constant ν2 is used as the negative lens G2. Therefore, as can be seen from FIG. 6, the positive lens G1 has a small partial dispersion ratio θ1 and the negative lens has a large partial dispersion ratio θ2, and when the chromatic aberrations are corrected for the F-line and the C-line, an imaging point of the g-line is shifted to the image side. This amount of shift when defined as a secondary spectrum amount Δ is expressed as:

Δ=−(1/φ)·(θ1−θ2)/(ν1−ν2)  (v).

In the case of the positive lens, the g-line remains closer to the image plane side as illustrated in FIG. 5, and in the case of the negative lens, the g-line remains on the object side. Therefore, through selection of a glass material that reduces A for the positive lens and a glass material that increases A for the negative lens, the secondary spectrum may be corrected.
It is further preferred to satisfy at least one of the following conditions:

−2.5×10−3<(θ3p−θ3n)/(ν3p−ν3n)<−2.0×10−4  (8),

−3.5×10−3<(θ4p−θ4n)/(ν4p−ν4n)<−5.0×10−4  (9),

where ν3p and θ3p are average values of an Abbe constant ν and a partial dispersion ratio θ of the at least one positive lens of the third lens unit U3, respectively, and ν3n and θ3n are average values of an Abbe constant ν and a partial dispersion ratio θ of the at least one negative lens of the third lens unit U3, respectively. Similarly, ν4p and θ4p are average values of an Abbe constant ν and a partial dispersion ratio θ of the at least one positive lens of the fourth lens unit U4, respectively, and ν4n and θ4n are average values of an Abbe constant ν and a partial dispersion ratio θ of the at least one negative lens of the fourth lens unit U4, respectively.

Conditional Expressions (8) and (9) are conditions for appropriately correcting the secondary spectrum of the axial chromatic aberration especially at the telephoto end.
When the upper limit condition of Conditional Expression (8) is not satisfied, it becomes difficult to suppress the variation in lateral chromatic aberration on the wide angle side. When the lower limit condition of Conditional Expression (8) is not satisfied, the secondary spectrum of the axial chromatic aberration at the telephoto end is increased.
When the upper limit condition of Conditional Expression (9) is not satisfied, a glass material having a small refractivity needs to be selected for the positive lens, which makes the correction of the aberrations difficult. When the lower limit condition of Conditional Expression (9) is not satisfied, the secondary spectrum of the axial chromatic aberration at the telephoto end is increased.
It is further preferred to satisfy the following condition:

0.5<f34w/f34z1<1.06  (10),

where f34w is a combined focal length of the third lens unit U3 and the fourth lens unit U4 at the wide angle end, and f34z1 is a combined focal length of the third lens unit U3 and the fourth lens unit U4 at a zoom position z1, provided that z is a zoom ratio, and z1 is the zoom position having the zoom ratio of z0.25.

Conditional Expression (10) defines a ratio of the focal lengths at the wide angle end and the zoom position z1 of the combined lens unit including the third lens unit U3 and the fourth lens unit U4.
When the upper limit condition of Conditional Expression (10) is not satisfied, a lens interval between the third lens unit U3 and the fourth lens unit U4 at the zoom position z1 becomes too large, which makes it difficult to reduce the entire length of the lens. When the lower limit condition of Conditional Expression (10) is not satisfied, the lens interval between the third lens unit U3 and the fourth lens unit U4 at the zoom position z1 is smaller than that at the wide angle end, which leads to an increased lens diameter of the first lens unit U1.
When a focal length of one of two lens units is represented by fa, a focal length of the other is represented by fb, and a principal point interval between the two lens units is represented by e, a combined focal length F of the two lens units may generally be expressed by the following expression:

1/F=1/fa+1/fb−e/(fa×fb)  (vi).

Therefore, through an increase or decrease of the principal point interval e between the two lens units, the focal length of the combined lens unit may be changed arbitrarily. Both the third and fourth lens units U3 and U4 of the present invention are positive lenses so that when the interval is increased, the focal length of the combined lens unit is increased, and when the interval is reduced, the focal length of the combined lens unit is reduced.
It is further preferred to satisfy at least one of the following conditions:

1.5<|ft/f1|<5.0  (11);

and

3.0<|f1/f2|<15.0  (12),

where f1 is a focal length of the first lens unit U1, f2 is a focal length of the second lens unit U2, and ft is a focal length at the telephoto end.

Conditional Expression (11) defines a ratio of the focal length at the telephoto end and the focal length of the first lens unit U1. When the upper limit condition of Conditional Expression (11) is not satisfied, a magnification of the first lens unit U1 at the telephoto end becomes too large, which makes it difficult to correct a variation in spherical aberration and the axial chromatic aberration on the telephoto side. When the lower limit condition of Conditional Expression (11) is not satisfied, the focal lengths of the second to fourth lens units U2 to U4 tend to be reduced, which makes it difficult to suppress the variations in aberrations caused by the zooming.
Conditional Expression (12) defines a ratio of the focal length f1 of the first lens unit U1 and the focal length f2 of the second lens unit U2. When the upper limit condition of Conditional Expression (12) is not satisfied, the focal length of the first lens unit U1 becomes relatively long, which increases the lens diameter of the first lens unit U1 and makes it difficult to increase the angle of field. When the lower limit condition of Conditional Expression (12) is not satisfied, the focal length of the first lens unit U1 becomes relatively short, which makes it difficult to correct the variation in spherical aberration and the axial chromatic aberration on the telephoto side.
It is further preferred to satisfy the following condition:

2.0<β2wt/β34wt<7.0  (13),

where β2wt is a ratio of the lateral magnifications at the wide angle end and the telephoto end of the second lens unit U2, and β34wt is a ratio of lateral magnifications at the wide angle end and the telephoto end of the combined lens unit including the third lens unit U3 and the fourth lens unit U4.

Conditional Expression (13) defines a ratio of the ratio of the lateral magnifications at the wide angle end and the telephoto end of the second lens unit U2 and the ratio of combined lateral magnifications at the wide angle end and the telephoto end of the combined lens unit including the third lens unit U3 and the fourth lens unit U4. A product of β2wt and β34wt represents the zoom ratio of the entire lens system, and it can be rephrased that Conditional Expression (13) defines a proportion contributing to the zoom ratio.
When the upper limit condition of Conditional Expression (13) is not satisfied, a proportion in which a combined lens unit U34 contributes to the correction of the aberrations on the telephoto side is small, which makes it difficult to correct the axial chromatic aberration on the telephoto side. When the lower limit condition of Conditional Expression (13) is not satisfied, a share of zooming of the second lens unit U2 becomes small, which makes it difficult to reduce the entire length of the lens and the lens diameters of the third lens unit U3 and the fourth lens unit U4.
It is preferred that at least one surface of the fourth lens unit U4 have an aspherical shape. When applied to a surface having the positive refractive power, it is preferred that the aspherical shape be a shape in which the positive refractive power is reduced from an optical axis to the periphery. When applied to a surface having a negative refractive power, it is preferred that the aspherical shape be a shape in which the negative refractive power is increased from the optical axis to the periphery.
With this configuration, the correction of the variations in aberrations during zooming, especially a spherical aberration, a field curvature, and a coma on the wide angle side is facilitated, which is advantageous in increasing the angle of field.
It is further preferred to set numerical ranges of Conditional Expressions (5) to (13) as follows:

0.2<f3/f4<0.7  (5a);

1.0<(R41+R42)/(R41−R42)<7.5  (6a);

−5.0×10−3<(θ2p−θ2n)/(ν2p−ν2n)<−3.5×103  (7a);

−2.0×10−3<(θ3p−θ3n)/(ν3p−ν3n)<−1.0×10−3  (8a);

−2.5×10−3<(θ4p−θ4n)/(ν4p−ν4n)<−1.2×103  (9a);

0.8<f34w/f34z1<1.0  (10a);

3.0<|ft/f1|<4.5  (11a);

9.3<|f1/f2|<13.0  (12a);

and

3.0<β2wt/β34wt<6.0  (13a).

Features of the lens configuration of the zoom lens of each embodiment of the present invention are now described.
Embodiment 1
A zoom lens according to Embodiment 1 of the present invention includes, in order from the object side, the first lens unit U1 having the positive refractive power which does not move for zooming, the second lens unit U2 having the negative refractive power which moves during zooming, the third lens unit U3 having the positive refractive power which moves during zooming, the fourth lens unit U4 having the positive refractive power which moves during zooming, and the fifth lens unit U5 having the positive refractive power and an imaging action which does not move for zooming. In lens cross-sectional views, the left side represents the subject (object) side (front side), and the right side represents the image side (back side).
The first lens unit U1 includes a focus lens unit U1b, and fixed lens units U1a and U1c which do not move for focusing. The focus lens unit U1b moves toward the object side during focusing from an object at infinity to an object at close distance.
In the zoom lens of each embodiment, the second lens unit U2 to the fourth lens unit U4 move on the optical axis while changing lens intervals thereamong to perform zooming and correct an image plane variation accompanying the zooming. Those three lens units (second lens unit U2 to fourth lens unit U4) constitute a zoom system (zoom unit).
FIG. 7 is a lens cross-sectional view of the zoom lens when focused on the object at infinity at the wide angle end (focal length f=8.8 mm) according to Embodiment 1 (Numerical Embodiment 1) of the present invention. The lens cross-sectional views illustrate, on the image side of the fifth lens unit U5, in order from the object side, a stop (aperture stop) SP, a glass block P representing a color separation prism, an optical filter, and the like, and an image plane I. In the figure, the glass block P includes the color separation prism, the optical filter, and the like. The image plane I corresponds to an image plane of a solid-state image pickup element (photoelectric transducer) or the like for receiving an image formed by the zoom lens and performing photoelectric conversion.
In the zoom lens of Embodiment 1, the first lens unit U1 corresponds to the 1st to 10th lens surfaces. The second lens unit U2 corresponds to the 11th to 17th lens surfaces. The third lens unit U3 corresponds to the 18th to 24th lens surfaces. The fourth lens unit U4 corresponds to the 25th to 28th lens surfaces.
During zooming from the wide angle end to the telephoto end, when the second lens unit U2 moves linearly to the image side, the third lens unit U3 and the fourth lens unit U4 substantially move from the image side to the object side on uncurved loci at the middle zoom position. The fourth lens unit U4 moves once to the image side in order to correct the variations in aberrations near the zoom position z1 on the wide angle side, and then substantially moves from the image side to the object side on a non-linear locus. Further, the interval between the third lens unit U3 and the fourth lens unit U4 is decreased near the zoom position z2, and the combined lens unit including the third and fourth lens units U3 and U4 is positioned on the image side. In this manner, an increase in lens diameter of the combined lens unit is suppressed. Further, the interval between the third lens unit U3 and the fourth lens unit U4 is increased at the telephoto end, and the combined lens unit including the third and fourth lens units U3 and U4 is positioned on the image side. In this manner, the amount of movement of the second lens unit U2 may be increased on the locus that is advantageous for the increase in zoom ratio.
The second of the four zoom positions is the zoom position z1 (f=28.50 mm), and the lens diameter of the first lens unit U1 is determined near the focal length. The third is the zoom position z2 (f=275.82 mm), and the imaging magnification β2 of the second lens unit is −1. Near the focal length, the lens diameters of the third lens unit U3 and the fourth lens unit U4 are determined.
The 11th, 19th, and 25th lens surfaces have aspherical shapes. The 11th lens surface mainly corrects a distortion on the wide angle side, and the 19th and 25th lens surfaces correct off-axial aberrations such as a coma on the wide angle side and the spherical aberration on the telephoto side.
FIGS. 8A to 8D are aberration diagrams when focused on the object at infinity at the wide angle end, the zoom position (focal length) z1 (f=28.50 mm), the zoom position (focal length) z2 (f=275.82 mm), and the telephoto end at which f=968.00 mm according to Numerical Embodiment 1, respectively. Note that, the focal lengths are values when values of numerical embodiments are expressed in mm. The same also applies to the embodiments below.
In the aberration diagrams, a straight line, a one-dot dashed line, and a dotted line of the spherical aberration represent an e-line, a g-line, and a C-line, respectively. A dotted line and a solid line in the astigmatism represent a meridional image plane and a sagittal image plane, respectively, and a one-dot dashed line and a dotted line in a lateral chromatic aberration represent the g-line and the C-line, respectively. A half angle of field is represented by ω, and an F-number is represented by Fno. Note that, in the following embodiments, a case where a lens unit for zooming is located at a shortest focal length side is referred to as the wide angle end, and a case where a lens unit for zooming is located at a longest focal length side is referred to as the telephoto end.
As shown in Table 1 to be described later, Numerical Embodiment 1 satisfies all of Conditional Expressions (1) to (13), and attains the high zoom ratio of 110 and an increase in angle of field with a photographing angle of field (angle of field) at the wide angle end of 64.01°. Moreover, high optical performance is provided with the aberrations being corrected satisfactorily over the entire zoom range.
Next, Numerical Embodiment 1 corresponding to Embodiment 1 of the present invention is shown below. In the numerical embodiment, “i” represents the order of a surface from the object side, “ri” represents a radius of curvature of an i-th surface from the object side, “di” represents an interval between the i-th surface and the (i+1)th surface from the object side, and “ndi” and “νdi” respectively represent a refractive index and an Abbe constant of the i-th optical material. The lens surfaces having the aspherical surfaces are marked with asterisks (*) on the left side of surface numbers. The final three surfaces correspond to a glass block such as a filter. Table 1 shows correspondences between each embodiment and the conditional expressions described above.
Note that, the aspherical shape is expressed by the following expression:




  X
  =
  
    
      
        
          H
          2
        
        /
        R
      
      
        1
        +
        
          
            1
            -
            
              
                (
                
                  1
                  +
                  k
                
                )
              
              ⁢
              
                
                  (
                  
                    H
                    /
                    R
                  
                  )
                
                2
              
            
          
        
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      4
      ⁢
      
        
      
      ⁢
      
        H
        4
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      6
      ⁢
      
        
      
      ⁢
      
        H
        6
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      8
      ⁢
      
        
      
      ⁢
      
        H
        8
      
    
  




where X is a coordinate in the optical axis direction; H is a coordinate in a direction perpendicular to the optical axis; a traveling direction of light corresponds to a positive direction; R is a paraxial radius of curvature; k is a conic constant; and A4, A6, and A8 are aspherical coefficients. “e-Z” means “×10−z”. Note that, the same also applies to the numerical embodiments below.

Numerical Embodiment 1












Unit: mm


Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
6797.00000
6.00000
1.834000
37.16
0.5775
192.593
−425.783


 2
339.38183
1.55392



185.954


 3
328.64687
25.64875
1.433870
95.10
0.5373
185.578
464.151


 4
−511.04586
25.85381



184.366


 5
342.57109
15.01615
1.433870
95.10
0.5373
175.902
765.287


 6
−11597.47237
0.25000



175.463


 7
244.16605
16.15023
1.433870
95.10
0.5373
172.153
681.145


 8
1360.51151
1.20000



170.995


 9
206.55243
14.00000
1.496999
81.54
0.5374
163.686
837.878


10
399.44933
(Variable)



160.544


11*
1146.47021
2.00000
1.882997
40.76
0.5667
45.268
−53.384


12
45.49218
8.19436



39.674


13
−82.28400
1.90000
1.816000
46.62
0.5568
38.566
−63.967


14
146.27271
3.84668



37.579


15
−87.95320
1.90000
1.834807
42.71
0.5642
37.505
45.356


16
67.79927
6.01825
1.959060
17.47
0.6599
38.399
52.078


17
−190.94156
(Variable)



39.233


18
199.43346
9.10556
1.603001
65.44
0.5402
76.508
185.102


19*
−251.19110
0.50000



77.133


20
199.55740
12.04291
1.438750
94.93
0.5343
78.655
193.044


21
−145.07467
0.20000



78.727


22
111.42583
2.50000
1.846660
23.78
0.6205
76.086
−188.165


23
65.15178
14.80454
1.496999
81.54
0.5374
72.978
129.535


24
−6654.57563
(Variable)



72.104


25*
127.25822
3.50000
1.749505
35.33
0.5818
69.463
−166.119


26
62.39948
0.19784



65.771


27
62.40201
11.59414
1.620411
60.29
0.5426
65.792
99.349


28
−6882.21077
(Variable)



64.935


29 (Stop)
∞
3.18904



32.296


30
−93.00692
1.80000
1.816000
46.62
0.5568
31.013
−28.150


31
30.97861
5.48005
1.808095
22.76
0.6307
29.679
42.758


32
253.25269
6.96512



29.272


33
−30.76052
1.49977
1.816000
46.62
0.5568
28.497
−24.225


34
57.34289
9.60444
1.548141
45.79
0.5685
30.824
35.080


35
−27.42176
24.91827



31.994


36
−215.30071
9.39368
1.487490
70.23
0.5300
32.739
85.333


37
−35.46337
1.35680



33.135


38
−94.43561
3.73535
1.834000
37.16
0.5775
31.246
−39.040


39
51.08404
8.39043
1.487490
70.23
0.5300
30.631
55.876


40
−55.61116
0.19999



30.803


41
1485.67954
5.91933
1.517417
52.43
0.5564
30.263
55.867


42
−29.57610
3.99459
1.882997
40.76
0.5667
29.996
−58.704


43
−72.68917
5.39164



30.699


44
72.70044
4.12142
1.517417
52.43
0.5564
29.174
79.531


45
−93.96287
10.00000



28.848


46
∞
33.00000
1.608590
46.44
0.5664
60.000
0.000


47
∞
13.20000
1.516330
64.15
0.5352
60.000
0.000


48
∞
10.01262



60.000


Image
∞


plane










Aspherical surface data










Eleventh surface










K = 6.40406e+002
A4 = 1.93315e−007
A6 = −2.69890e−010
A8 = 1.42143e−013







Nineteenth surface










K = −4.79134e+001
A4 = −1.81299e−007
A6 = 1.06331e−010
A8 = −1.59896e−014







Twenty-fifth surface










K = 1.96569e+000
A4 = −1.32891e−007
A6 = −1.24824e−011
A8 = −3.22804e−015










Various data


Zoom ratio 110.00
















Focal length
8.80
28.50
275.82
968.00



F-number
1.80
1.80
1.80
5.60



Half angle of field
32.01
10.92
1.14
0.33



Image height
5.50
5.50
5.50
5.50



Total lens length
636.28
636.28
636.28
636.28



d10
2.77
98.55
183.89
199.17



d17
282.68
170.18
57.68
2.00



d24
1.18
14.74
1.56
29.89



d28
3.50
6.66
47.00
59.07



Incident pupil position
121.88
392.78
2558.13
12283.52



Exit pupil position
183.88
183.88
183.88
183.88



Front principal point
131.12
425.96
3271.49
18640.71



position



Rear principal point
1.21
−18.49
−265.80
−957.98



position











Zoom lens unit data















First
Focal
Lens structure
Front principal
Rear principal



Unit
surface
length
length
point position
point position







1
1
257.97
105.67
60.47
−18.29



2
11
−25.58
23.86
4.66
−13.30



3
18
79.74
39.15
7.84
−18.50



4
25
253.64
15.29
−0.34
−9.68



5
29
42.43
152.16
56.91
17.17










Embodiment 2
The zoom lens according to Embodiment 2 also has a configuration similar to that of the zoom lens according to Embodiment 1.
FIG. 9 is a lens cross-sectional view of the zoom lens when focused on the object at infinity at the wide angle end (focal length f=9.00 mm) according to Embodiment 2 (Numerical Embodiment 2) of the present invention.
In Embodiment 2, the first lens unit U1 corresponds to the 1st to 10th lens surfaces. The second lens unit U2 corresponds to the 11th to 17th lens surfaces. The third lens unit U3 corresponds to the 18th to 24th lens surfaces. The fourth lens unit U4 corresponds to the 25th to 27th lens surfaces.
During zooming from the wide angle end to the telephoto end, when the second lens unit U2 moves linearly to the image side, the third lens unit U3 substantially moves from the image side to the object side along a non-linear locus at the middle zoom position. Compared to Embodiment 1, the interval between the third lens unit U3 and the fourth lens unit U4 is increased especially at the wide angle end so as to provide a greater effect of reducing the lens diameters of the third and fourth lens units U3 and U4.
The second of the four zoom positions is the zoom position z1 (f=28.46 mm), and the lens diameter of the first lens unit U1 is determined near the focal length. The third is the zoom position z2 (f=249.84 mm), and the imaging magnification β2 of the second lens unit is −1. Near the focal length, the lens diameters of the third and fourth lens units U3 and U4 are determined.
The 11th, 19th, and 27th lens surfaces have aspherical shapes. The 11th lens surface mainly corrects a distortion on the wide angle side, and the 19th and 27th lens surfaces correct off-axial aberrations such as a coma on the wide angle side and the spherical aberration on the telephoto side.
FIGS. 10A to 10D are aberration diagrams when focused on the object at infinity at the wide angle end, the zoom position (focal length) z1 (f=28.46 mm), the zoom position (focal length) z2 (f=249.84 mm), and the telephoto end at which f=899.98 mm according to Numerical Embodiment 2, respectively.
As shown in Table 1 to be described later, Numerical Embodiment 2 satisfies all of Conditional Expressions (1) to (13). Embodiment 2 attains the high zoom ratio of 100 and the increase in angle of field with a photographing angle of field (angle of field) at the wide angle end of 62.86°. Moreover, the high optical performance is provided with the aberrations being corrected satisfactorily over the entire zoom range.
Numerical Embodiment 2












Unit: mm


Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
5434.02380
6.00000
1.834000
37.16
0.5775
210.014
−455.000


 2
356.63625
2.13509



202.496


 3
360.44201
27.02044
1.433870
95.10
0.5373
202.125
515.715


 4
−580.45663
28.08162



201.296


 5
339.84204
20.27987
1.433870
95.10
0.5373
204.280
718.034


 6
−3786.15639
0.25000



203.799


 7
253.96136
20.82550
1.433870
95.10
0.5373
198.551
666.314


 8
2001.56949
1.20000



197.274


 9
216.57139
12.48564
1.496999
81.54
0.5374
186.080
1010.879


10
372.53916
(Variable)



183.997


11*
−73071.60959
2.20000
2.003300
28.27
0.5980
46.735
−55.496


12
56.18822
8.59820



41.636


13
−63.32560
1.40000
1.834000
37.16
0.5775
40.462
−37.351


14
62.71093
8.69492
1.959060
17.47
0.6599
39.566
34.417


15
−66.78678
1.51820



39.183


16
−51.49036
1.60000
1.882997
40.76
0.5667
38.358
−47.100


17
226.27163
(Variable)



37.865


18
211.69445
7.52775
1.595220
67.74
0.5442
61.514
190.610


19*
−243.06787
0.50000



62.181


20
273.48577
8.73422
1.595220
67.74
0.5442
62.939
161.635


21
−147.44671
0.20000



63.043


22
778.09768
2.50000
1.846660
23.78
0.6205
62.121
−166.709


23
120.29490
6.00935
1.438750
94.93
0.5343
61.221
308.402


24
1046.36475
(Variable)



61.101


25
104.79879
2.50000
1.846660
23.78
0.6205
60.833
−349.121


26
76.71439
11.01805
1.595220
67.74
0.5442
59.628
89.918


27*
−169.48400
(Variable)



59.081


28 (Stop)
∞
2.36822



29.373


29
−89.03149
2.00000
1.816000
46.62
0.5568
28.698
−20.703


30
21.19400
11.91473
1.846660
23.78
0.6205
27.513
24.270


31
−737.35131
7.78511



26.359


32
−31.36783
2.00000
1.882997
40.76
0.5667
24.441
−17.675


33
32.36570
8.63520
1.620411
60.29
0.5426
26.003
46.225


34
−234.07138
6.76154



28.279


35
−130.69482
6.66518
1.589130
61.14
0.5406
32.060
58.965


36
−28.04978
9.16258



33.116


37
319.52271
2.00000
1.882997
40.76
0.5667
32.000
−32.330


38
26.26833
8.58866
1.518229
58.90
0.5456
31.410
33.381


39
45.53131
2.02791



31.559


40
126.09468
8.60709
1.487490
70.23
0.5300
31.722
46.804


41
−27.34549
2.00000
1.882997
40.76
0.5667
31.555
−36.180


42
−189.85376
0.19963



33.064


43
218.32118
9.40095
1.531717
48.84
0.5630
33.531
50.688


44
−30.45438
10.00000



34.228


45
∞
33.00000
1.608590
46.44
0.5664
60.000
0.000


46
∞
13.20000
1.516330
64.15
0.5352
60.000
0.000


47
∞
15.07578



60.000


Image
∞


plane










Aspherical surface data










Eleventh surface










K = 1.69407e+006
A4 = 7.95307e−007
A6 = −9.70819e−011
A8 = 2.85357e−013







Nineteenth surface










K = −1.45313e+001
A4 = 1.51572e−007
A6 = 2.29624e−011
A8 = −3.73351e−015







Twenty-seventh surface










K = 7.92880e+000
A4 = 4.02021e−007
A6 = 2.13607e−011
A8 = 1.56802e−014










Various data


Zoom ratio 100.00
















Focal length
9.00
28.46
249.84
899.98



F-number
1.80
1.80
1.86
4.50



Half angle of field
31.43
10.94
1.26
0.35



Image height
5.50
5.50
5.50
5.50



Total lens length
649.62
649.62
649.62
649.62



d10
2.78
102.78
191.99
206.13



d17
263.53
152.41
59.76
2.12



d24
37.64
32.13
0.75
9.46



d27
3.00
19.64
54.45
89.25



Incident pupil position
133.88
423.37
2798.46
13226.17



Exit pupil position
162.00
162.00
162.00
162.00



Front principal point
143.43
457.35
3473.15
19639.08



position



Rear principal point
6.08
−13.39
−234.77
−884.91



position











Zoom lens unit data















First
Focal
Lens structure
Front principal
Rear principal



Unit
surface
length
length
point position
point position







1
1
268.44
118.28
68.00
−19.95



2
11
−24.98
24.01
6.61
−9.08



3
18
115.10
25.47
3.39
−13.00



4
25
121.89
13.52
3.00
−5.41



5
28
39.60
146.32
54.10
14.31










Embodiment 3
The zoom lens according to Embodiment 3 also has a configuration similar to that of the zoom lens according to Embodiment 1.
FIG. 11 is a lens cross-sectional view of the zoom lens when focused on the object at infinity at the wide angle end (focal length f=8.9 mm) according to Embodiment 3 (Numerical Embodiment 3) of the present invention.
In Embodiment 3, the first lens unit U1 corresponds to the 1st to 10th lens surfaces. The second lens unit U2 corresponds to the 11th to 17th lens surfaces. The third lens unit U3 corresponds to the 18th to 24th lens surfaces. The fourth lens unit U4 corresponds to the 25th to 27th lens surfaces.
During zooming from the wide angle end to the telephoto end, when the second lens unit U2 moves linearly to the image side, the third lens unit U3 substantially moves from the image side to the object side along a non-linear locus at the middle zoom position. Compared to Embodiment 1, the interval between the third lens unit U3 and the fourth lens unit U4 is increased especially at the telephoto end so as to provide a locus advantageous for increasing the zoom ratio.
The second of the four zoom positions is the zoom position z1 (f=29.15 mm), and the lens diameter of the first lens unit U1 is determined near the focal length. The third is the zoom position z2 (f=239.84 mm), and the imaging magnification β2 of the second lens unit is −1. Near the focal length, the lens diameters of the third and fourth lens units U3 and U4 are determined.
The 11th, 19th, and 25th lens surfaces have aspherical shapes. The 11th lens surface mainly corrects a distortion on the wide angle side, and the 19th and 25th lens surfaces correct off-axial aberrations such as a coma on the wide angle side and the spherical aberration on the telephoto side.
FIGS. 12A to 12D are aberration diagrams when focused on the object at infinity at the wide angle end, the zoom position (focal length) z1 (f=29.15 mm), the zoom position (focal length) z2 (f=239.84 mm), and the telephoto end at which f=1,023.50 mm according to Numerical Embodiment 3, respectively.
As shown in Table 1 to be described later, Numerical Embodiment 3 satisfies all of Conditional Expressions (1) to (13). Embodiment 3 attains the high zoom ratio of 115 and the increase in angle of field with a photographing angle of field (angle of field) at the wide angle end of 63.43°. Moreover, the high optical performance is provided with the aberrations being corrected satisfactorily over the entire zoom range.
Numerical Embodiment 3












Unit: mm


Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
5793.01429
6.00000
1.834000
37.16
0.5775
208.891
−433.304


 2
342.03734
2.31956



199.751


 3
349.17389
26.51749
1.433870
95.10
0.5373
199.455
513.399


 4
−605.23335
26.73333



198.379


 5
325.51120
20.05077
1.433870
95.10
0.5373
198.447
687.627


 6
−3616.03833
0.25000



197.997


 7
256.83401
19.77079
1.433870
95.10
0.5373
193.358
670.178


 8
2109.25001
1.20000



192.135


 9
212.14116
14.00000
1.496999
81.54
0.5374
181.652
887.023


10
398.85802
(Variable)



179.132


11*
16798.45555
2.20000
2.003300
28.27
0.5980
53.086
−68.567


12
69.07870
8.46954



47.566


13
−91.37436
1.40000
1.882997
40.76
0.5667
46.070
−37.966


14
53.82530
10.47934
1.959060
17.47
0.6599
43.782
33.222


15
−72.94882
1.93558



43.060


16
−52.81839
1.60000
1.903660
31.32
0.5946
41.501
−41.775


17
137.85390
(Variable)



40.315


18
140.80509
9.33322
1.592820
68.63
0.5446
69.730
182.507


19*
−462.54928
0.50000



70.270


20
161.16576
10.79574
1.592820
68.63
0.5446
71.263
146.256


21
−184.35912
0.20000



71.080


22
113.12109
2.50000
1.805181
25.42
0.6161
68.138
−142.208


23
56.59845
14.31731
1.438750
94.93
0.5343
64.707
124.475


24
−1547.77025
(Variable)



63.772


25*
159.86250
3.50000
1.666800
33.05
0.5957
60.822
−320.019


26
90.86623
8.06085
1.639999
60.08
0.5370
58.755
136.070


27
−2232.09151
(Variable)



57.643


28 (Stop)
∞
2.90925



31.311


29
−106.27972
1.40000
1.816000
46.62
0.5568
30.117
−31.760


30
34.71034
0.20000



28.961


31
31.64649
6.15981
1.808095
22.76
0.6307
29.202
40.347


32
734.91671
5.53173



28.501


33
−72.89730
1.40000
1.882997
40.76
0.5667
26.663
−53.865


34
140.43195
22.71861



26.504


35
−90.86857
1.80000
1.639999
60.08
0.5370
28.109
−96.116


36
194.27351
2.92242
1.846660
23.78
0.6205
28.686
−1100.236


37
159.90459
3.03000



29.089


38
1087.63312
6.23090
1.487490
70.23
0.5300
30.107
93.109


39
−47.44488
0.20000



31.035


40
−169.19629
1.60000
1.882997
40.76
0.5667
31.160
−46.159


41
54.34597
9.62001
1.496999
81.54
0.5374
31.715
47.323


42
−39.22444
0.20000



32.874


43
1288.47832
7.47811
1.548141
45.79
0.5685
32.981
66.762


44
−37.78760
1.60000
1.882997
40.76
0.5667
33.012
−72.972


45
−92.43419
0.20000



33.695


46
54.60772
9.79868
1.487490
70.23
0.5300
33.726
64.306


47
−69.81636
14.00000



32.678


48
∞
33.00000
1.608590
46.44
0.5664
60.000
0.000


49
∞
13.20000
1.516330
64.15
0.5352
60.000
0.000


50
∞
11.99775



60.000


Image
∞


plane










Aspherical surface data










Eleventh surface










K = −4.15562e+006
A4 = 9.64938e−007
A6 = −2.11065e−010
A8 = 4.00855e−013







Nineteenth surface










K = −7.63858e+001
A4 = 1.91972e−007
A6 = 2.39994e−011
A8 = 3.29461e−016







Twenty-fifth surface










K = 2.26047e+000
A4 = −9.56035e−008
A6 = −2.25528e−011
A8 = 1.13017e−014










Various data


Zoom ratio 115.00
















Focal length
8.90
29.15
239.84
1023.50



F-number
1.80
1.80
1.80
5.30



Half angle of field
31.71
10.69
1.31
0.31



Image height
5.50
5.50
5.50
5.50



Total lens length
636.89
636.89
636.89
636.89



d10
2.74
100.13
180.34
199.14



d17
280.68
169.66
66.02
2.00



d24
1.15
8.92
1.97
83.44



d27
3.00
8.85
39.23
2.98



Incident pupil position
136.55
430.01
2366.06
15446.07



Exit pupil position
151.11
151.11
151.11
151.11



Front principal point
146.02
465.26
3019.42
23999.92



position



Rear principal point
3.10
−17.15
−227.85
−1011.50



position











Zoom lens unit data















First
Focal
Lens structure
Front principal
Rear principal



Unit
surface
length
length
point position
point position







1
1
260.74
116.84
67.49
−18.81



2
11
−26.63
26.08
8.33
−8.15



3
18
77.31
37.65
6.15
−18.81



4
25
240.15
11.56
0.32
−6.69



5
28
39.14
145.20
55.23
16.79










Embodiment 4
The zoom lens according to Embodiment 4 also has a configuration similar to that of the zoom lens according to Embodiment 1.
FIG. 13 is a lens cross-sectional view of the zoom lens when focused on the object at infinity at the wide angle end (focal length f=8.9 mm) according to Embodiment 4 (Numerical Embodiment 4) of the present invention.
In Embodiment 4, the first lens unit U1 corresponds to the 1st to 10th lens surfaces. The second lens unit U2 corresponds to the 11th to 17th lens surfaces. The third lens unit U3 corresponds to the 18th to 24th lens surfaces. The fourth lens unit U4 corresponds to the 25th to 28th lens surfaces.
During zooming from the wide angle end to the telephoto end, when the second lens unit U2 moves linearly to the image side, the third lens unit U3 substantially moves from the image side to the object side along a non-linear locus at the middle zoom position.
The second of the four zoom positions is the zoom position z1 (f=29.46 mm), and the lens diameter of the first lens unit U1 is determined near the focal length. The third is the zoom position z2 (f=251.97 mm), and the imaging magnification β2 of the second lens unit is −1. Near the focal length, the lens diameters of the third and fourth lens units U3 and U4 are determined.
The 11th, 19th, and 25th lens surfaces have aspherical shapes. The 11th lens surface mainly corrects a distortion on the wide angle side, and the 19th and 25th lens surfaces correct off-axial aberrations such as a coma on the wide angle side and the spherical aberration on the telephoto side.
FIGS. 14A to 14D are aberration diagrams when focused on the object at infinity at the wide angle end, the zoom position (focal length) z1 (f=29.46 mm), the zoom position (focal length) z2 (f=251.97 mm), and the telephoto end at which f=1,068.00 mm according to Numerical Embodiment 4, respectively.
As shown in Table 1 to be described later, Numerical Embodiment 4 satisfies all of Conditional Expressions (1) to (13). Thus, Embodiment 4 attains the high zoom ratio of 120 and an increase in angle of field with a photographing angle of field (angle of field) at the wide angle end of 63.43°. Moreover, high optical performance is provided with the aberrations being corrected satisfactorily over the entire zoom range.
Numerical Embodiment 4












Unit: mm


Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
6797.00000
6.00000
1.834000
37.16
0.5775
201.250
−427.333


 2
340.55544
2.16846



194.288


 3
344.60560
27.02980
1.433870
95.10
0.5373
195.026
483.368


 4
−526.41708
25.44604



195.609


 5
317.11504
18.90832
1.433870
95.10
0.5373
198.517
739.359


 6
22370.55003
0.25000



198.012


 7
252.02981
19.58207
1.433870
95.10
0.5373
193.671
681.551


 8
1642.44953
1.20000



192.440


 9
210.80230
14.00000
1.496999
81.54
0.5374
182.269
793.425


10
441.44413
(Variable)



180.524


11*
−7064.01182
2.20000
2.003300
28.27
0.5980
46.419
−52.950


12
53.98674
8.05582



41.271


13
−77.05757
1.40000
1.834807
42.71
0.5642
40.179
−36.203


14
50.59902
7.75585
1.959060
17.47
0.6597
38.937
35.987


15
−104.71398
1.71806



38.522


16
−65.38717
1.60000
1.882997
40.76
0.5667
37.931
−53.580


17
176.81880
(Variable)



37.365


18
211.53009
8.67340
1.618000
63.33
0.5441
73.576
170.014


19*
−207.02964
0.50000



74.108


20
182.48621
9.64438
1.592010
67.02
0.5357
75.372
164.013


21
−204.97727
0.20000



75.260


22
183.20446
2.50000
1.805181
25.42
0.6161
72.978
−133.668


23
67.77481
12.64284
1.438750
94.93
0.5343
69.956
154.085


24
∞
(Variable)



69.529


25*
146.28125
3.50000
1.737999
32.26
0.5899
68.244
−325.200


26
90.20692
0.18229



66.362


27
89.84076
9.06852
1.651597
58.55
0.5426
66.363
116.192


28
474.37141
(Variable)



65.886


29 (Stop)
∞
2.58913



29.588


30
−78.87459
1.80000
1.816000
46.62
0.5568
28.804
−25.127


31
28.18412
5.33716
1.808095
22.76
0.6307
27.782
36.015


32
621.40708
5.00436



27.510


33
−30.07184
3.99834
1.816000
46.62
0.5568
27.130
−22.704


34
51.83074
14.30965
1.548141
45.79
0.5685
30.187
35.877


35
−28.82109
29.22478



33.552


36
−340.35564
13.14140
1.487490
70.23
0.5300
34.787
89.125


37
−39.13525
0.19997



35.329


38
−93.01765
3.79997
1.834000
37.16
0.5775
34.073
−36.976


39
47.44248
7.03399
1.487490
70.23
0.5300
33.564
53.123


40
−54.65398
4.36774



33.700


41
−3347.51559
9.43058
1.517417
52.43
0.5564
32.558
60.172


42
−31.01546
1.54305
1.882997
40.76
0.5667
32.036
−58.211


43
−79.33522
0.94307



32.682


44
68.15021
5.01899
1.517417
52.43
0.5564
33.029
72.477


45
−82.10984
15.00000



32.882


46
∞
33.00000
1.608590
46.44
0.5664
60.000
0.000


47
∞
13.20000
1.516330
64.15
0.5352
60.000
0.000


48
∞
9.99980



60.000


Image
∞


plane










Aspherical surface data










Eleventh surface










K = −2.36774e+005
A4 = 5.62251e−007
A6 = 1.21054e−010
A8 = −1.11890e−013







Nineteenth surface










K = −2.02204e+001
A4 = −4.61496e−008
A6 = 4.15741e−011
A8 = −2.11496e−015







Twenty-fifth surface










K = 3.71110e+000
A4 = −1.10320e−007
A6 = −4.77366e−011
A8 = 5.697400−015










Various data


Zoom ratio 120.00
















Focal length
8.90
29.46
251.97
1068.00



F-number
1.80
1.80
1.80
5.50



Half angle of field
31.72
10.58
1.25
0.30



Image height
5.50
5.50
5.50
5.50



Total lens length
669.52
669.52
669.52
669.52



d10
2.77
102.87
181.18
197.68



d17
280.86
169.52
69.26
2.00



d24
19.22
16.15
1.09
38.20



d28
3.50
17.82
54.83
68.47



Incident pupil position
129.67
436.82
2659.43
17257.92



Exit pupil position
133.28
133.28
133.28
133.28



Front principal point
139.21
473.31
3426.38
27578.10



position



Rear principal point
1.10
−19.46
−241.97
−1058.00



position











Zoom lens unit data















First
Focal
Lens structure
Front principal
Rear principal



Unit
surface
length
length
point position
point position







1
1
255.48
114.58
65.47
−19.09



2
11
−24.37
22.73
6.48
−8.41



3
18
91.75
34.16
4.55
−17.75



4
25
182.76
12.75
1.83
−5.91



5
29
37.03
168.94
53.49
12.97










Embodiment 5
The zoom lens according to Embodiment 5 also has a configuration similar to that of the zoom lens according to Embodiment 1.
FIG. 15 is a lens cross-sectional view of the zoom lens when focused on the object at infinity at the wide angle end (focal length f=6.75 mm) according to Embodiment 5 (Numerical Embodiment 5) of the present invention.
In Embodiment 5, the first lens unit U1 corresponds to the 1st to 19th lens surfaces. The second lens unit U2 corresponds to the 20th to 26th lens surfaces. The third lens unit U3 corresponds to the 27th to 33rd lens surfaces. The fourth lens unit U4 corresponds to the 34th to 37th lens surfaces.
During zooming from the wide angle end to the telephoto end, when the second lens unit U2 moves linearly to the image side, the third lens unit U3 substantially moves from the image side to the object side along a non-linear locus at the middle zoom position.
The second of the four zoom positions is the zoom position z1 (f=15.53 mm), and the lens diameter of the first lens unit U1 is determined near the focal length. The third is the zoom position z2 (f=66.57 mm), and the imaging magnification β2 of the second lens unit is −1. Near the focal length, the lens diameters of the third and fourth lens units U3 and U4 are determined.
The 20th, 28th, and 36th lens surfaces have aspherical shapes. The 20th lens surface mainly corrects a distortion on the wide angle side, and the 28th and 36th lens surfaces correct off-axial aberrations such as a coma on the wide angle side and the spherical aberration on the telephoto side.
FIGS. 16A to 16D are aberration diagrams when focused on the object at infinity at the wide angle end, the zoom position (focal length) z1 (f=15.53 mm), the zoom position (focal length) z2 (f=66.57 mm), and the telephoto end at which f=189.00 mm according to Numerical Embodiment 5, respectively.
As shown in Table 1 to be described later, Numerical Embodiment 5 satisfies all of Conditional Expressions (1) to (13). Thus, Embodiment 5 attains the high zoom ratio of 28 and an increase in angle of field with a photographing angle of field (angle of field) at the wide angle end of 78.35°. Moreover, high optical performance is provided with the aberrations being corrected satisfactorily over the entire zoom range.
Numerical Embodiment 5












Unit: mm


Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
378.48165
5.35000
1.772499
49.60
0.5521
173.904
−187.094


 2
104.30474
48.15487



146.481


 3
−173.47322
4.40000
1.696797
55.53
0.5433
145.316
−196.555


 4
671.08887
0.09299



147.557


 5
254.55301
10.80583
1.805181
25.42
0.6161
149.871
408.755


 6
1068.64458
6.57913



149.641


 7
7885.69945
19.25204
1.433870
95.10
0.5373
149.297
410.445


 8
−182.52731
0.09864



149.114


 9
−3663.98983
4.20000
1.720467
34.70
0.5834
141.093
−319.066


10
247.17073
18.69132
1.496999
81.54
0.5374
137.025
298.379


11
−364.03637
26.28305



136.423


12
690.30071
19.68226
1.433870
95.10
0.5373
144.884
378.469


13
−214.30176
1.59065



145.526


14
167.28801
4.30000
1.755199
27.51
0.6103
145.009
−491.750


15
114.35424
0.83582



140.142


16
117.62468
28.01647
1.496999
81.54
0.5374
140.143
227.201


17
−2803.18358
0.08859



139.297


18
151.65937
14.73531
1.620411
60.29
0.5426
133.613
308.708


19
691.06916
(Variable)



132.224


20*
556.45781
2.50000
1.772499
49.60
0.5521
53.422
−61.232


21
43.70280
4.28305



45.834


22
64.47126
9.75889
1.808095
22.76
0.6307
44.558
41.845


23
−67.72978
1.50000
1.754998
52.32
0.5476
42.877
−39.310


24
53.76655
7.53861



36.839


25
42.51256
1.50000
1.882997
40.76
0.5667
36.830
−68.641


26
−142.79643
(Variable)



38.522


27
112.99500
7.64436
1.592400
68.30
0.5456
50.691
93.408


28*
−106.42637
0.09674



50.932


29
125.97027
8.85939
1.438750
94.93
0.5343
50.737
110.391


30
−77.31383
0.49461



50.430


31
−91.08900
1.90000
1.755199
27.51
0.6103
49.719
−104.213


32
622.86364
5.76098
1.438750
94.93
0.5343
49.425
187.668


33
−94.88868
(Variable)



49.337


34
1955.31277
2.00000
1.654115
39.70
0.5737
43.890
−302.260


35
180.45807
0.49332



43.272


36*
135.06046
5.25584
1.696797
55.53
0.5433
43.129
119.699


37
−217.01028
(Variable)



42.570


38 (Stop)
∞
2.67000



27.734


39
−54.86213
1.50000
1.696797
55.53
0.5433
27.224
−25.352


40
26.51461
6.24999
1.808095
22.76
0.6307
26.657
53.806


41
59.79807
13.14691



26.041


42
−70.48387
1.50000
1.772499
49.60
0.5521
26.976
−32.407


43
39.47781
10.23452
1.603420
38.03
0.5835
28.165
29.651


44
−29.85502
0.19890



29.415


45
−32.28082
1.60000
1.816000
46.62
0.5568
29.339
−29.985


46
105.56305
13.27575
1.595509
39.24
0.5804
31.701
54.566


47
45.12427
2.99970



35.694


48
−913.51893
5.46540
1.531717
48.84
0.5630
37.355
148.782


49
−73.28323
0.19985



37.925


50
203.90821
2.00000
1.882997
40.76
0.5667
37.900
−56.460


51
40.06134
9.17680
1.496999
81.54
0.5374
37.374
60.000


52
−109.00000
0.81000



37.843


53
93.58960
8.76092
1.496999
81.54
0.5374
38.141
71.946


54
−56.32992
2.00000
1.761821
26.52
0.6135
37.812
−87.076


55
−361.27717
0.20000



37.957


56
96.88656
8.64470
1.487490
70.23
0.5300
37.887
71.246


57
−52.83203
10.00000



37.389


58
∞
33.00000
1.608590
46.44
0.5664
50.000
0.000


59
∞
13.20000
1.516330
64.15
0.5352
50.000
0.000


60
∞
15.10183



50.000


Image
∞


plane










Aspherical surface data










Twentieth surface










K = −2.04859e+002
A4 = 6.64887e−007
A6 = −2.22325e−011
A8 = −1.47253e−013







Twenty-eighth surface










K = −1.67902e+000
A4 = 6.35831e−007
A6 = 1.31051e−011
A8 = 3.96102e−014







Thirty-sixth surface










K = 8.78418e+000
A4 = −5.94570e−007
A6 = −3.43946e−010
A8 = 7.66112e−014










Various data


Zoom ratio 28.00
















Focal length
6.75
15.53
66.57
189.00



F-number
1.60
1.60
1.60
2.30



Half angle of field
39.17
19.51
4.72
1.67



Image height
5.50
5.50
5.50
5.50



Total lens length
600.15
600.15
600.15
600.15



d19
2.01
43.76
93.00
108.06



d26
160.80
106.77
46.17
1.24



d33
0.66
8.84
0.67
29.79



d37
2.00
6.10
25.63
26.38



Incident pupil position
109.63
153.36
356.35
938.18



Exit pupil position
127.41
127.41
127.41
127.41



Front principal point
116.79
171.03
462.38
1445.26



position



Rear principal point
8.35
−0.43
−51.46
−173.90



position











Zoom lens unit data















First
Focal
Lens structure
Front principal
Rear principal



Unit
surface
length
length
point position
point position







1
1
103.29
213.16
126.42
58.54



2
20
−28.75
27.08
11.34
−7.13



3
27
65.94
24.76
5.30
−11.92



4
34
196.50
7.75
3.90
−0.90



5
38
33.61
146.83
47.00
9.38










Embodiment 6
The zoom lens according to Embodiment 6 also has a configuration similar to that of the zoom lens according to Embodiment 1.
FIG. 17 is a lens cross-sectional view of the zoom lens when focused on the object at infinity at the wide angle end (focal length f=8.9 mm) according to Embodiment 6 (Numerical Embodiment 6) of the present invention.
In Embodiment 6, the first lens unit U1 corresponds to the 1st to 12th lens surfaces. The second lens unit U2 corresponds to the 13th to 19th lens surfaces. The third lens unit U3 corresponds to the 20th to 23rd lens surfaces. The fourth lens unit U4 corresponds to the 24th to 30th lens surfaces.
During zooming from the wide angle end to the telephoto end, when the second lens unit U2 moves linearly to the image side, the third lens unit U3 substantially moves from the image side to the object side along a non-linear locus at the middle zoom position.
The second of the four zoom positions is the zoom position z1 (f=27.41 mm), and the lens diameter of the first lens unit U1 is determined near the focal length. The third is the zoom position z2 (f=243.05 mm), and the imaging magnification β2 of the second lens unit is −1. Near the focal length, the lens diameters of the third and fourth lens units U3 and U4 are determined.
FIGS. 18A to 18D are aberration diagrams when focused on the object at infinity at the wide angle end, the zoom position (focal length) z1 (f=27.41 mm), the zoom position (focal length) z2 (f=243.05 mm), and the telephoto end at which f=801.00 mm according to Numerical Embodiment 6, respectively.
As shown in Table 1 to be described later, Numerical Embodiment 6 satisfies Conditional Expressions (1) to (4) and Conditional Expressions (6) to (13). Thus, Embodiment 6 attains the high zoom ratio of 90 and an increase in angle of field with a photographing angle of field (angle of field) at the wide angle end of 63.43°. Moreover, high optical performance is provided with the aberrations being corrected satisfactorily over the entire zoom range.
Numerical Embodiment 6












Unit: mm


Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
−3840.48133
6.00000
1.834000
37.16
0.5775
214.230
−434.925


 2
403.67229
9.89821



207.669


 3
415.24185
19.09246
1.433870
95.10
0.5373
206.456
789.235


 4
−1953.41578
0.25000



205.637


 5
1333.41693
17.19550
1.433870
95.10
0.5373
203.102
877.388


 6
−532.55646
23.59261



202.314


 7
336.79425
17.31671
1.433870
95.10
0.5373
189.759
740.645


 8
−7293.94593
0.25000



188.139


 9
321.37720
13.61893
1.433870
95.10
0.5373
179.391
889.214


10
1876.33483
1.20000



178.277


11
168.02303
13.65906
1.438750
94.93
0.5343
167.502
814.332


12
308.62327
(Variable)



165.693


13
352.11125
2.00000
1.882997
40.76
0.5667
44.881
−50.578


14
39.73153
8.41426



39.029


15
−83.78395
1.90000
1.816000
46.62
0.5568
38.233
−86.579


16
470.48958
4.68482



37.542


17
−87.16000
1.90000
1.882997
40.76
0.5667
37.042
−40.491


18
61.84980
6.11891
1.959060
17.47
0.6597
37.671
52.367


19
−273.32589
(Variable)



37.825


20
−537.16487
11.28035
1.496999
81.54
0.5374
68.709
171.597


21
−74.29980
2.08138



70.208


22
−64.63738
4.00000
1.772499
49.60
0.5521
70.267
−503.872


23
−79.52886
(Variable)



73.508


24
118.20775
12.96189
1.595220
67.74
0.5442
78.604
143.680


25
−300.41148
0.30000



78.274


26
97.31622
2.50000
1.805181
25.42
0.6161
75.086
−153.673


27
54.06450
14.25979
1.438750
94.93
0.5343
70.718
153.419


28
250.00000
1.37579



69.772


29
140.17903
6.88080
1.595220
67.74
0.5442
68.929
234.681


30
∞
(Variable)



68.022


31
∞
3.96569



36.558


32
−173.66465
1.80000
1.816000
46.62
0.5568
34.777
−46.072


33
48.52009
6.62831
1.808095
22.76
0.6307
33.578
66.615


34
422.18953
15.12736



32.747


35
−30.24187
4.00000
1.816000
46.62
0.5568
29.207
−26.240


36
79.08126
15.65493
1.548141
45.79
0.5685
32.229
41.506


37
−29.91087
27.64508



35.913


38
−90.58133
7.38653
1.487490
70.23
0.5300
33.561
221.927


39
−50.70117
6.06918



34.010


40
208.40845
4.00000
1.834000
37.16
0.5775
31.669
−43.820


41
30.98826
6.02036
1.487490
70.23
0.5300
30.191
55.067


42
−192.83598
0.66686



30.202


43
462.30374
6.74306
1.517417
52.43
0.5564
30.103
46.175


44
−25.18820
4.00000
1.882997
40.76
0.5667
30.001
−43.018


45
−79.44703
0.39662



31.685


46
123.45357
5.90802
1.517417
52.43
0.5564
31.905
59.284


47
−40.39048
15.00000



31.839


48
∞
33.00000
1.608590
46.44
0.5664
60.000
0.000


49
∞
13.20000
1.516330
64.15
0.5352
60.000
0.000


50
∞
9.97627



60.000


Image
∞


plane










Various data


Zoom ratio 90.00
















Focal length
8.90
27.41
243.05
801.00



F-number
1.85
1.85
1.85
4.50



Half angle of field
31.72
11.35
1.30
0.39



Image height
5.50
5.50
5.50
5.50



Total lens length
684.45
684.45
684.45
684.45



d12
2.63
103.91
178.71
192.28



d19
269.77
174.75
63.25
4.80



d23
19.12
2.13
1.54
9.31



d30
3.00
13.73
51.02
88.14



Incident pupil position
131.20
432.17
2288.20
8438.66



Exit pupil position
129.62
129.62
129.62
129.62



Front principal point
140.76
465.86
3025.03
14602.36



position



Rear principal point
1.08
−17.43
−233.08
−791.02



position











Zoom lens unit data















First
Focal
Lens structure
Front principal
Rear principal



Unit
surface
length
length
point position
point position







1
1
248.81
122.07
74.99
−14.54



2
13
−25.22
25.02
5.10
−13.60



3
20
268.45
17.36
14.10
2.32



4
24
94.47
38.28
7.00
−19.18



5
31
43.17
177.21
67.98
11.30

















TABLE 1





Table 1: Values corresponding to the conditional expressions in Numerical Embodiments 1 to 6

















Numerical Embodiment
















1
2
3
4
5
6





Focal
Wide angle end
8.80
9.00
8.90
8.90
6.75
8.90


length
fz1
28.50
28.46
29.15
29.46
15.53
27.41



fz2
275.82
249.84
239.84
251.97
66.57
243.05



Telephoto end
968.0
899.98
1023.50
1068.00
189.00
801.00













Zoom
110.00
100.00
115.00
120.00
28.00
90.00


magnification


Z{circumflex over ( )}0.25
3.24
3.16
3.27
3.31
2.30
3.08


f1
257.97
268.44
260.74
255.48
103.29
248.81


f2
−25.58
−24.98
−26.63
−24.37
−28.75
−25.22


f3
79.74
115.10
77.31
91.75
65.94
268.45


f4
253.64
121.89
240.15
182.76
196.50
94.47


β2w
−0.12
−0.12
−0.13
−0.12
−0.24
−0.13


β2z2
−1.00
−1.00
−1.00
−1.00
−1.00
−1.00


β2t
−2.49
−2.32
−3.40
−3.10
−2.10
−2.16


β3w
−0.32
−0.61
−0.31
−0.40
−0.46
−4.68


β3z2
−1.59
−16.15
−1.37
−2.34
−1.31
2.11


β3t
−2.44
6.50
−1.38
−3.95
−1.79
1.72


β4w
0.75
0.48
0.75
0.67
0.71
0.06


β4z2
0.58
0.06
0.60
0.39
0.59
−0.45


β4t
0.53
−0.23
0.75
0.32
0.59
−0.84


β2wt
20.12
19.86
26.07
25.83
8.75
17.24


β34wt
5.47
5.04
4.41
4.65
3.20
5.22


f34w
64.40
76.52
62.47
71.14
52.68
74.78


f34z1
67.31
74.29
64.15
70.23
54.49
71.22











Conditional
Numerical Embodiment













Expression
1
2
3
4
5
6

















(1)
vp − vn
24.96
43.96
27.03
26.29
15.83
51.38


(2)
β2w
−0.12
−0.12
−0.13
−0.12
−0.24
−0.13


(3)
β2t
−2.49
−2.32
−3.40
−3.10
−2.10
−2.16


(4)
β34z2
−0.91
−0.95
−0.82
−0.91
−0.78
−0.95


(5)
f3/f4
0.31
0.94
0.32
0.50
0.34
2.84


(6)
(R41 + R42)/
2.92
6.46
3.63
4.22
1.20
3.50



(R41 − R42)


(7)
(θ2p − θ2n)/
−3.76E−03
−4.41E−03
−4.60E−03
−4.22E−03
−3.03E−03
−3.82E−03



(v2p − v2n)


(8)
(θ3p − θ3n)/
−1.46E−03
−1.50E−03
−1.44E−03
−1.57E−03
−1.23E−03
−4.58E−04



(v3p − v3n)


(9)
(θ4p − θ4n)/
−1.57E−03
−1.73E−03
−2.17E−03
−1.80E−03
−1.92E−03
−1.46E−03



(v4p − v4n)


(10) 
f34w/f34z1
0.96
1.03
0.97
1.01
0.97
1.05


(11) 
|ft/f1|
3.75
3.35
3.93
4.18
1.83
3.22


(12) 
|f1/f2|
10.08
10.75
9.79
10.48
3.59
9.87


(13) 
β2wt/β24wt
3.68
3.94
5.91
5.56
2.73
3.30





“E-Z” means “×10−Z”.






As described above, according to the zoom lens of the present invention, the refractive power arrangement of each lens unit, the loci of movement of the moving lens units for zooming, and the like are appropriately defined. This allows both the increase in zoom ratio and the increase in angle of field to be attained, and allows the zoom lens in which the aberrations are corrected satisfactorily to be provided.
Embodiment 7
FIG. 19 is a schematic diagram of a main part of an image pickup apparatus (television camera system) using the zoom lens according to each of Embodiments 1 to 6 of the present invention as a photographing optical system. In FIG. 19, an image pickup apparatus 125 includes a zoom lens 101 according to any one of Embodiments 1 to 6, and a camera 124. The zoom lens 101 is removably attached to the camera 124. The camera 124 attached with the zoom lens 101 constitutes the image pickup apparatus 125. The zoom lens 101 includes a first lens unit U1F, a zooming portion LZ, and a fourth lens unit U4R for imaging. The first lens unit U1F includes a lens unit for focusing.
The zooming portion LZ includes the second lens unit U2 which moves on the optical axis for zooming, and the third lens unit U3 and the fourth lens unit U4 which move on the optical axis for correcting the image plane variation accompanying the zooming. The aperture stop is denoted by SP. The fourth lens unit U4R includes lens units IE′ and IE which can be inserted into and removed from an optical path. The lens units IE and IE′ are switched to displace the focal length range of the entire system of the zoom lens 101. Drive mechanisms 114 and 115, such as a helicoid and a cam, drive the first lens unit U1F and the zooming portion LZ in an optical axis direction, respectively.
Motors (drive units) 116 to 118 electrically drive the drive mechanisms 114 and 115 and the aperture stop SP. Detectors 119 to 121, such as an encoder, a potentiometer, or a photo-sensor, are configured to detect the positions of the first lens unit U1F and the zooming portion LZ on the optical axis, and the aperture diameter of the aperture stop SP. The camera 124 includes a glass block 109, which corresponds to an optical filter or a color separation optical system provided within the camera 124. Further, the camera 124 includes a solid-state image pickup element (photoelectric transducer) 110, such as a charge-coupled device (CCD) sensor or a complementary metal-oxide semiconductor (CMOS) sensor. The solid-state image pickup element 110 is configured to receive a subject image formed by the zoom lens 101.
Further, central processing units (CPUs) 111 and 122 control the driving of the camera 124 and the zoom lens 101. By applying the zoom lens according to the present invention to a television camera as described above, an image pickup apparatus having a high optical performance may be realized.
The exemplary embodiments of the present invention are described above. However, it goes without saying that the present invention is not limited to these embodiments and can be modified and changed variously within the scope of the gist thereof.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2012-180899, filed Aug. 17, 2012, which is hereby incorporated by reference herein in its entirety.

## Claims

1. A zoom lens comprising, in order from an object side to an image side:
a first lens unit having a positive refractive power which does not move for zooming;
a second lens unit having a negative refractive power which moves during zooming;
a third lens unit having the positive refractive power which moves during zooming;
a fourth lens unit having the positive refractive power which moves during zooming; and
a fifth lens unit having the positive refractive power which does not move for zooming,
wherein each of the first lens unit to the fifth lens unit includes at least one positive lens and at least one negative lens, and
wherein the following conditional expressions are satisfied:


−10<νp−νn<54;



−1<β2w<−0.05;



−5<β2t<−1;



and



−1<β34z2<−0.3,


where νp is an average Abbe constant of the at least one positive lens of the fourth lens unit, νn is an average Abbe constant of the at least one negative lens of the fourth lens unit, β2w is an imaging magnification of the second lens unit at a wide angle end, β2t is an imaging magnification of the second lens unit at a telephoto end, and β34z2 is an imaging magnification of a combined lens unit including the third lens unit and the fourth lens unit at a zoom position z2 where the imaging magnification of the second lens unit is −1.

2. The zoom lens according to claim 1, wherein:
the third lens unit passes through a point where the imaging magnification is −1 during zooming from the wide angle end to the telephoto end, and
the following conditional expression is satisfied:


0.1<f3/f4<1.0,


where f3 is a focal length of the third lens unit, and f4 is a focal length of the fourth lens unit.

3. The zoom lens according to claim 1, wherein the following conditional expression is satisfied:


0.5<(R41+R42)/(R41−R42)<10,

where R41 is a radius of curvature of a surface on the object side of a negative lens at an end on the object side of the fourth lens unit, and R42 is a radius of curvature of a surface on the image side of the negative lens at the end on the object side of the fourth lens unit.

4. The zoom lens according to of claim 1, wherein the following conditional expression is satisfied:


−5.5×10−3<(θ2p−θ2n)/(ν2p−ν2n)<−2.0×10−3,

where ν2p is an average value of an Abbe constant of the at least one positive lens of the second lens unit, θ2p is an average value of a partial dispersion value of the at least one positive lens of the second lens unit, ν2n is an average value of an Abbe constant of the at least one negative lens of the second lens unit, and θ2n is an average value of a partial dispersion ratio of the at least one negative lens of the second lens unit.

5. The zoom lens according to of claim 1, wherein the following conditional expressions are satisfied:


−2.5×10−3<(θ3p−θ3n)/(ν3p−ν3n)<−2.0×10−4,



and



−3.5×10−3<(θ4p−θ4n)/(ν4p−ν4n)<−5.0×10−4,

where ν3p is an average value of an Abbe constant of the at least one positive lens of the third lens unit, θ3p is an average value of a partial dispersion value of the at least one positive lens of the third lens unit, ν3n is an average value of an Abbe constant of the at least one negative lens of the third lens unit, θ3n is an average value of a partial dispersion ratio of the at least one negative lens of the third lens unit, ν4p is an average value of an Abbe constant of the at least one positive lens of the fourth lens unit, θ4p is an average value of a partial dispersion ratio of the at least one positive lens of the fourth lens unit, ν4n is an average value of an Abbe constant of the at least one negative lens of the fourth lens unit, and θ4n is an average value of a partial dispersion ratio of the at least one negative lens of the fourth lens unit.

6. The zoom lens according to of claim 1, wherein the following conditional expression is satisfied:


0.5<f34w/f34z1<1.06,

where f34w is a combined focal length of the third lens unit and the fourth lens unit at the wide angle end, and f34z1 is a combined focal length of the third lens unit and the fourth lens unit at a zoom position z1 having a zoom ratio of z0.25, z being a zoom ratio of the zoom lens.

7. The zoom lens according to of claim 1, wherein the following conditional expressions are satisfied:


1.5<|ft/f1|<5.0;



and



3.0<|f1/f2|<15.0,

where f1 is a focal length of the first lens unit, f2 is a focal length of the second lens unit, and ft is a focal length of an entire system at the telephoto end.

8. The zoom lens according to of claim 1, wherein the following conditional expression is satisfied:


2.0<β2wt/β34wt<7.0,

where β2wt is a ratio of lateral magnifications at the wide angle end and the telephoto end of the second lens unit, and β34wt is a ratio of lateral magnifications at the wide angle end and the telephoto end of the combined lens unit including the third lens unit and the fourth lens unit.

9. The zoom lens according to claim 1, wherein:
at least one surface of the fourth lens unit is an aspherical surface,
when a surface having the positive refractive power is the aspherical surface, the surface has a shape in which the positive refractive power is reduced from an optical axis to a periphery, and
when a surface having the negative refractive power is the aspherical surface, the surface has a shape in which the negative refractive power is increased from the optical axis to the periphery.

10. An image pickup apparatus comprising:
a zoom lens comprising, in order from an object side to an image side:
a first lens unit having a positive refractive power which does not move for zooming;
a second lens unit having a negative refractive power which moves during zooming;
a third lens unit having the positive refractive power which moves during zooming;
a fourth lens unit having the positive refractive power which moves during zooming; and
a fifth lens unit having the positive refractive power which does not move for zooming,
wherein each of the first lens unit to the fifth lens unit includes at least one positive lens and at least one negative lens, and
wherein the following conditional expressions are satisfied:


10<νp−νn<54;



−1<β2w<−0.05;



−5<β2t<−1;



and



−1<β34z2<−0.3,


where νp is an average Abbe constant of the at least one positive lens of the fourth lens unit, νn is an average Abbe constant of the at least one negative lens of the fourth lens unit, β2w is an imaging magnification of the second lens unit at a wide angle end, β2t is an imaging magnification of the second lens unit at a telephoto end, and β34z2 is an imaging magnification of a combined lens unit including the third lens unit and the fourth lens unit at a zoom position z2 where the imaging magnification of the second lens unit is −1; and

a solid-state image pickup element for receiving an image formed by the zoom lens.