# Patent

## Title
Zoom lens

## Abstract

A zoom lens includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and fifth lens group. The zoom lens further satisfies given conditions.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zoom lens suitable for an imaging apparatus equipped with a solid state image sensor such as a charge-coupled device (CCD) and a complementary metal-oxide-semiconductor (CMOS).
2. Description of the Related Art
An abundance of zoom lenses have been proposed that can be mounted to an imaging apparatus equipped with a solid state image sensor such as a CCD and a CMOS. Recently, rapid advances in achieving high pixel counts of solid state image sensors have enabled finer features of a subject to be seen and many zoom lenses for megapixel counts have emerged (for example, refer to Japanese Patent Laid-Open Publication Nos. 2011-154390 and 2006-3589).
In addition to advances in achieving high pixel counts, there is a rising need for high resolution zoom lenses having a long focal length and capable of handling megapixel counts under the visible light range to the near-infrared light range to enable reliable high-image recording for the collection of evidence by a surveillance camera during a crime as well as during normal times. Further, consequent to strong demand for reductions in the size of imaging apparatuses, a zoom lens that is simple and compact is desirable.
Although the zoom lens recited in Japanese Patent Laid-Open Publication No. 2011-154390 realizes a high zoom ratio lens having a simple structure, with respect to near-infrared light, axial chromatic aberration and chromatic difference of magnification at the telephoto edge is prominent and optical performance markedly deteriorates. Further, with the zoom lens recited in Japanese Patent Laid-Open Publication No. 2006-3589, although aberration at high zoom ratios and up to the near-infrared light range is corrected, the light output from a third group has a tendency to diverge and therefore, aberration variations consequent to focusing become large and high optical performance cannot be maintained. Furthermore, differences in optical performance arise among manufactured products.
SUMMARY OF THE INVENTION
It is an object of the present invention to at least solve the above problems in the conventional technologies.
A zoom lens according to one aspect of the invention includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and fifth lens group. The second lens group is moved along an optical axis, from the object side toward an image side, to zoom from a wide angle edge to a telephoto edge. The fourth lens group is moved along the optical axis to correct image plane variation accompanying zooming. The third lens group includes sequentially from the object side, a positive lens having at least one aspheric surface, a cemented lens formed by a positive lens and a negative lens, and a positive lens group. The fourth lens group includes sequentially from the object side, a positive lens group, and a cemented lens formed by a positive lens and a negative lens. The fifth lens group includes sequentially from the object side, at least one negative lens and at least one positive lens.
The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram depicting a state where incident light at the maximum angle of view is incident on a lens surface farthest on the object side of a fourth lens group;
FIG. 2 is a cross sectional view (along the optical axis) of a zoom lens according to a first embodiment;
FIG. 3 is a diagram of various types of aberration occurring in the zoom lens according to the first embodiment;
FIG. 4 is a cross sectional view (along the optical axis) of the zoom lens according to a second embodiment;
FIG. 5 is a diagram of various types of aberration occurring in the zoom lens according to the second embodiment;
FIG. 6 is a cross sectional view (along the optical axis) of the zoom lens according to a third embodiment;
FIG. 7 is a diagram of various types of aberration occurring in the zoom lens according to the third embodiment;
FIG. 8 is a cross sectional view (along the optical axis) of the zoom lens according to a fourth embodiment;
FIG. 9 is a diagram of various types of aberration occurring in the zoom lens according to the fourth embodiment;
FIG. 10 is a cross sectional view (along the optical axis) of the zoom lens according to a fifth embodiment;
FIG. 11 is a diagram of various types of aberration occurring in the zoom lens according to the fifth embodiment;
FIG. 12 is a cross sectional view (along the optical axis) of the zoom lens according to a sixth embodiment;
FIG. 13 is a diagram of various types of aberration occurring in the zoom lens according to the sixth embodiment;
FIG. 14 is a cross sectional view (along the optical axis) of the zoom lens according to a seventh embodiment; and
FIG. 15 is a diagram of various types of aberration occurring in the zoom lens according to the seventh embodiment.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of a zoom lens according to the present invention are explained in detail below with reference to the accompanying drawings.
The zoom lens according to the present invention includes sequentially from a side nearest an object (object side), a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group. The second lens group is moved along an optical axis, whereby zooming is performed from a wide angle edge to a telephoto edge. Further, the fourth lens group is moved along the optical axis, whereby image plane variation accompanying zooming is corrected and focusing is performed.
The third lens group includes sequentially from the object side, a positive lens having at least one aspheric surface; a cemented lens formed by a positive lens and a negative lens; and a positive lens group. By disposing the positive aspheric lens farthest on the object side of the third lens group, spherical aberration can be corrected favorably. By including the cemented lens formed by a positive lens and a negative lens, axial chromatic aberration and chromatic difference of magnification can be corrected favorably. By disposing the positive lens group farthest on an image side (side nearest the image) of the third lens group, the light incident on the fourth lens group can be converged. As a result, aberration variations at the time of focusing and arising when the light incident on the fourth lens group diverges can be suppressed. The positive lens group includes at least one positive lens. Configuring the positive lens group by one positive lens enables manufacturing costs to be reduced and the length of the optical system to be shortened.
The fourth lens group includes sequentially from the object side, a positive lens group, and a cemented lens formed by a positive lens and a negative lens. The positive lens group disposed farthest on the object side of the fourth lens group further converges the light converged by the positive lens group of the third lens group. The positive lens group of the fourth lens group also includes at least one positive lens and by configuring the positive lens group by one positive lens, manufacturing costs and the length of the optical system can be reduced. Although the fourth lens group also includes a cemented lens formed by a positive lens and a negative lens, disposal of the cemented lens in the fourth lens group enables favorable correction of the chromatic difference of magnification that could not be corrected by the cemented lens in the third lens group.
The fifth lens group includes sequentially from the object side, at least one negative lens and at least one positive lens. By including the fifth lens group, field curvature can be corrected favorably.
Consequent to having the configuration above, the zoom lens according to the present invention can favorably correct various types of aberration occurring over the entire zoom range with respect to light from the visible light range to the near-infrared light range, and is applicable to imaging apparatuses equipped with solid state image sensors for which megapixel counts are progressing.
To realize a long focal length while facilitating size reductions of the optical system and further achieving preferable optical performance, in the present invention, various conditions are set as indicated below, in addition to the configuration above.
The zoom lens according to the present invention preferably satisfies the following conditional expressions, where f3 is the focal length of the third lens group; fT is the focal length of the entire optical system at the telephoto edge; ΔD4 is the difference of the interval between the third lens group and the fourth lens group at the wide angle edge and the interval between the third lens group and the fourth lens group at the telephoto edge; β3T is the zoom ratio of the third lens group at the telephoto edge; β4T is the zoom ratio of the fourth lens group at the telephoto edge; and υ3p is the Abbe number with respect to the d-line of the positive lens of the cemented lens in the third lens group.

0.50≦f3/fT≦0.80  (1)

0.08≦ΔD4/fT≦0.20  (2)

−300≦β3T/β4T≦−20  (3)

90≦υ3p≦100  (4)

Conditional expression (1) prescribes a range of a proper ratio of the focal length f3 of the third lens group and the focal length fT of the entire optical system at the telephoto edge. By satisfying conditional expression (1), the zoom lens in addition to realizing a long focal length and facilitating a compact optical system, favorably corrects visible light range aberration and near-infrared light range aberration by a proper amount, using the same lens arrangement.
Below the lower limit of conditional expression (1), the positive refractive index of the third lens group becomes too strong, whereby spherical aberration of the visible light range becomes over corrected and thus, favorable correction of visible light range aberration and near-infrared light range aberration by a proper amount becomes impossible. Meanwhile, above the upper limit of conditional expression (1), the positive refractive index of the third lens group becomes too weak, increasing the overall length of the optical system and making size reductions of the optical system difficult.
More favorable results can be expected if the zoom lens satisfies conditional expression (1) within the range indicated below.

0.55≦f3/fT≦0.75  (1a)

By satisfying conditional expression (1) within the range prescribed by conditional expression (1a), the zoom lens can favorably correct spherical aberration of the visible light range and field curvature of the near-infrared light range by a proper amount and can further correct spherical aberration of the visible light range more favorably.

Conditional expression (2) prescribes a range of a proper ratio of the difference ΔD4 (the difference of the interval between the third lens group and the fourth lens group at the wide angle edge and the interval between the third lens group and the fourth lens group at the telephoto edge) and the focal length fT (the focal length of the entire optical system at the telephoto edge). By satisfying conditional expression (2), the zoom lens can favorably correct field curvature over the entire zoom range, on top of facilitating size reductions of the optical system.
Below the lower limit of conditional expression (2), when image plane variation accompanying zooming is corrected, the fourth lens group cannot be moved a sufficient distance, making field curvature occurring near an intermediate focal position particularly difficult to correct. Meanwhile, above the upper limit of conditional expression (2), when image plane variation accompanying zooming is corrected, the fourth lens group is moved excessively, increasing the overall length of the optical system and making size reductions of the optical system difficult.
More favorable results can be expected if the zoom lens satisfies conditional expression (2) within the range indicated below.

0.08≦ΔD4/fT≦0.15  (2a)

By satisfying conditional expression (2) within the range prescribed by conditional expression (2a), the zoom lens more favorably corrects field curvature at the telephoto edge.

Conditional expression (3) prescribes a range of a proper ratio of the zoom ratio β3T of the third lens group at the telephoto edge and the zoom ratio β4T of the fourth lens group at the telephoto edge. By satisfying conditional expression (3), the zoom lens can improve optical performance at the telephoto edge.
Below the lower limit of conditional expression (3), the positive refractive power of the fourth lens group becomes too strong and at the telephoto edge, aberration variations consequent to focusing become large. Further, manufacturing of the optical system becomes difficult and differences in optical performance arise among manufactured products. Meanwhile, above the upper limit of conditional expression (3), the positive refractive power of the third lens group becomes too strong and at the telephoto edge, the correction of visible light range aberration and of near-infrared light range aberration by a proper amount becomes difficult.
Conditional expression (4) prescribes a proper range of the Abbe number υ3p with respect to the d-line of the positive lens of the cemented lens in the third lens group. By satisfying conditional expression (4), the zoom lens can favorably correct axial chromatic aberration and chromatic difference of magnification of the near-infrared light range; and can favorably correct field curvature at the wide angle edge.
Below the lower limit of conditional expression (4), the correction of axial chromatic aberration/chromatic difference of magnification of near-infrared light at the wide angle edge and at the telephoto edge becomes difficult. Meanwhile, above the upper limit of conditional expression (4), the refractive index of the positive lens of the cemented lens in the third lens group becomes low with respect to the d-line, making the correction of field curvature at the wide angle edge difficult, if the positive lens is formed of a glass material.
To favorably correct visible light range aberration and near-infrared light range aberration by a proper amount, the zoom lens according to the present invention preferably satisfies the following conditional expressions, where Δυ3BA is the difference of the Abbe numbers (with respect to the d-line) of the positive lens and the negative lens forming the cemented lens in the third lens group; and Δυ4BA is the difference of the Abbe numbers (with respect to the d-line) of the positive lens and the negative lens of the cemented lens in the fourth lens group.

30≦|Δυ3BA|≦78  (5)

50≦|Δυ4BA|≦78  (6)

Conditional expression (5) prescribes a proper range of the absolute value of the difference Δυ3BA of the Abbe numbers of the positive lens and the negative lens of the cemented lens in the third lens group. By satisfying conditional expression (5), the zoom lens can favorably correct visible light range aberration and near-infrared aberration at the wide angle edge, by a proper amount.
Below the lower limit of conditional expression (5), the correction of axial chromatic aberration and chromatic difference of magnification of near-infrared light at the wide angle edge becomes difficult. Meanwhile, above the upper limit of conditional expression (5), favorable correction of visible light range aberration and near-infrared light range aberration at the wide angle edge, by a proper amount becomes difficult.
More favorable results can be expected if the zoom lens satisfies condition expression (5) within the range indicated below.

30≦|Δυ3BA|≦60  (5a)

By satisfying conditional expression (5) within the range prescribed by conditional expression (5a), the zoom lens can more effectively correct chromatic difference of magnification and field curvature at the wide angle edge.

Conditional expression (6) prescribes a proper range of the absolute value of the difference Δυ4BA of the Abbe number of the positive lens and of the negative lens of the cemented lens of the fourth lens group. By satisfying conditional expression (6), the zoom lens can favorably correct visible light range aberration and near-infrared light range aberration at the telephoto edge, by a proper amount.
Below the lower limit of conditional expression (6), the correction of axial chromatic aberration and chromatic difference of magnification of near-infrared light at the telephoto edge becomes difficult. Meanwhile, above the upper limit of conditional expression (6), favorable correction of visible light range aberration and near-infrared light range aberration at the telephoto edge, by a proper amount, becomes difficult.
More favorable results can be expected if the zoom lens satisfies conditional expression (6) within the range indicated below.

50≦|Δυ4BA|≦70  (6a)

By satisfying conditional expression (6) within the range prescribed by conditional expression (6a), the zoom lens can more effectively correct chromatic difference of magnification and field curvature at the telephoto edge.

To achieve more favorable optical performance without sacrificing size reductions of the optical system, the zoom lens according to the present invention preferably satisfies the following conditional expressions, where f3 is the focal length of the third lens group, f4 is the focal length of the fourth lens group, and f5 is the focal length of the fifth lens group.

0.10≦|f3/f5|≦0.70  (7)

0.10≦|f4/f5|≦0.70  (8)

Conditional expression (7) prescribes a proper range of the absolute value of the ratio of the focal length f3 of the third lens group and the focal length f4 of the fourth lens group. By satisfying conditional expression (7), the zoom lens can favorably correct field curvature at the wide angle edge without sacrificing size reductions of the optical system.
Below the lower limit of conditional expression (7), the refractive power of the fifth lens group becomes too weak, making correction of field curvature at the wide angle edge difficult. Meanwhile, above the upper limit of conditional expression (7), the positive refractive index of the third lens group becomes too weak, increasing the overall length of the optical system and making size reductions of the optical system difficult.
Conditional expression (8) prescribes a proper range of the absolute value of the ratio of the focal length f4 of the fourth lens group and the focal length f5 of the fifth lens group. By satisfying conditional expression (8), the zoom lens can suppress aberration variations consequent to focusing, without sacrificing size reductions of the optical system.
Below the lower limit of conditional expression (8), the refractive power of the fourth lens group becomes too strong, making aberration variations consequent to focusing large. Further, manufacturing of the optical system becomes difficult and differences in optical performance arise among the manufactured products. Meanwhile, above the upper limit of conditional expression (8), the positive refractive power of the fourth lens group becomes too weak, increasing the distance that the fourth lens group is moved when image plane variation accompanying zooming is corrected and thereby increasing the overall length of the optical system and making size reductions of the optical system difficult.
To secure more favorable optical performance, in the zoom lens according to the present invention, the maximum angle of incidence has to be set for the marginal ray of the light incident on the lens surface farthest on the object side of the fourth lens group, at the maximum angle of view for the wide angle edge and for the telephoto edge. FIG. 1 is a diagram depicting a state where incident light at the maximum angle of view is incident on the lens surface farthest on the object side of the fourth lens group. In the drawing, θ1 represents the angle of incidence of the marginal ray of the incident light at the maximum angle of view, to the lens surface farthest on the object side of the fourth lens group. θ1 is suitably set for the wide angle edge and the telephoto edge, and the refractive index of the positive lens disposed farthest on the object side of the fourth lens group is suitable set with respect to the d-line, thereby enabling a zoom lens having more favorable optical performance to be realized.
The zoom lens according to the present invention preferably satisfies the following conditional expressions, where N4ob is the refractive index (with respect to the d-line) of the positive lens disposed farthest on the object side of the fourth lens group; θ1(W) is the maximum angle of incidence of the marginal ray at the maximum angle of view for the wide angle edge, to the lens surface farthest on the object side of the fourth lens group; ωw is the half-angle of the optical system at the wide angle edge; θ1(T) is the maximum angle of incidence of the marginal ray at the maximum angle of view for the telephoto edge, to the lens surface farthest on the object side of the fourth lens group; and ωT is the half-angle of the optical system at the telephoto edge.

1.85≦N4ob≦1.95  (9)

0.30≦θ1(W)/ωW≦0.60  (10)

2.5≦θ1(T)/ωT≦5.0  (11)

Conditional expression (9) prescribes a proper range of the refractive index N4ob (with respect to the d-line) of the positive lens disposed farthest on the object side of the fourth lens group. By satisfying conditional expression (9), the zoom lens can favorably correct spherical aberration and axial chromatic aberration at the wide angle edge and the telephoto edge.
Below the lower limit of conditional expression (9), favorable correction of spherical aberration at the wide angle edge and at the telephoto edge becomes difficult. Meanwhile, above the upper limit of conditional expression (9), if the positive lens disposed farthest on the object side of the fourth lens group is formed of a glass material, the lens becomes a high dispersion lens, making the correction of axial chromatic aberration at the wide angle edge and at the telephoto edge difficult.
Conditional expression (10) prescribes a proper range of the ratio of the maximum angle of incidence θ1(W) of the marginal ray at the maximum angle of view for the wide angle edge, to the lens surface farthest on the object side of the fourth lens group and the half-angle ωw of the optical system at the wide angle edge. By satisfying conditional expression (10), the zoom lens can further improve the optical performance of the optical system at the wide angle edge.
Below the lower limit of conditional expression (10), the exit pupil position at the wide angle edge becomes too close to the image plane. Typically, micro-lenses for effectively making light enter are provided on a surface of the solid state image sensor. Nonetheless, if the exit pupil position is too close to the image plane, off-axis light output from the optical system enters the image plane at an angle causing shading to occur. In this case, the collection of light by the micro-lens becomes insufficient and an undesirable state occurs where the image brightness at a central portion and at the periphery drastically change. Meanwhile, above the upper limit of conditional expression (10), aberration variations at the wide angle edge and consequent to focusing are large. Furthermore, manufacturing of the optical system becomes difficult and differences in optical performance among the manufactured products arise.
Conditional expression (11) prescribes a proper range of the ratio of the maximum angle of incidence θ1(T) of the marginal ray at the maximum angle of view for the telephoto edge, to the lens surface farthest on the object side of the fourth lens group and the half-angle ωT of the optical system at the telephoto edge. By satisfying conditional expression (11), the zoom lens can further improve the optical performance of the optical system at the telephoto edge.
Below the lower limit of conditional expression (11), the exit pupil position at the telephoto edge becomes to close to the image plane. In this case as well, the same problems described above arise and an undesirable state occurs where the image brightness at a central portion and at the periphery drastically change. Meanwhile, above the upper limit of conditional expression (11), aberration variations at the telephoto edge and consequent to focusing are large. Furthermore, manufacturing of the optical system becomes difficult and differences in optical performance among the manufactured products arise.
To further improve near-infrared light resolution at the telephoto edge, the zoom lens according to the present invention preferably satisfies the following conditional expression, where υ3a is the Abbe number (with respect to the d-line) of the positive lens disposed farthest on the object side of the third lens group.

65.0≦υ3a≦85.0  (12)

Conditional expression (12) prescribes a proper range of the Abbe number υ3a (with respect to the d-line) of the positive lens disposed farthest on the object side of the third lens group. By satisfying conditional expression (12), the zoom lens can particularly improve resolution of near-infrared light at the telephoto edge.
Below the lower limit of conditional expression (12), the correction of axial chromatic aberration of near-infrared light at the wide angle edge and at the telephoto edge becomes difficult. Meanwhile, above the upper limit of conditional expression (12), if the positive lens disposed farthest on the object side of the third lens group is formed of a glass material, the refractive index of the positive lens becomes low with respect to the d-line and the correction of spherical aberration at the wide angle edge becomes difficult.
As described, the zoom lens according to the present invention has the above configuration, enabling the realization of a long focal length by a simple and compact structure and further enabling the realization of a high-resolution optical system that can favorably correct various types of aberration occurring over the entire zoom range with respect to light from the visible light range to the near-infrared light range and that can handle megapixel counts. In particular, by satisfying the conditional expressions above, the zoom lens can achieve more favorable optical performance without sacrificing size reductions of the optical system.
With reference to the accompanying drawings, embodiments of the zoom lens according to the present invention will be described in detail. Nonetheless, the present invention is not limited by the embodiments below.
FIG. 2 is a cross sectional view (along the optical axis) of the zoom lens according to a first embodiment. The zoom lens includes sequentially from a side nearest a non-depicted object (the object side), a first lens group G11 having a positive refractive power, a second lens group G12 having a negative refractive power, an aperture stop STOP, a third lens group G13 having a positive refractive power, a fourth lens group G14 having a positive refractive power, and a fifth lens group G15 having a positive refractive power.
A cover glass CG is disposed between the fifth lens group G15 and an imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G11 includes sequentially from the object side, a cemented lens L111 formed by a negative lens L111A, and a positive lens L111B, and a positive lens L112.
The second lens group G12 includes sequentially from the object side, a negative lens L121, a negative lens L122, and a cemented lens L123 formed by a positive lens L123A and a negative lens L123B.
The third lens group G13 includes sequentially from the object side, a positive lens L131, a cemented lens L132 formed by a positive lens L132A and a negative lens L132B, and a positive lens group L133 configured by a positive lens L133A. Both surfaces of the positive lens L131 are aspheric.
The fourth lens group G14 includes sequentially from the object side, a positive lens group L141 configured by a positive lens L141A, and a cemented lens L142 formed by a positive lens L142A and a negative lens L142B.
The fifth lens group G15 includes sequentially from the object side, a negative lens L151 and a positive lens L152.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G12 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G14 along the optical axis.
Here, various values related to the zoom lens according to the first embodiment are given.










Focal length of entire zoom lens = 8.20 (wide angle edge) to


48.55 (fT: telephoto edge)


F number = 1.63 (wide angle edge) to 2.00 (telephoto edge)


Half-angle (ω) = 23.91 (ωW: wide angle edge) to


3.90 (ωT: telephoto edge)







(Lens data)









r1 = 45.2246











d1 = 1.50
nd1 = 1.80809
νd1 = 22.76









r2 = 31.1449











d2 = 6.03
nd2 = 1.49700
νd2 = 81.61









r3 = −184.9157











d3 = 0.15











r4 = 36.2379











d4 = 3.19
nd3 = 1.61800
νd3 = 63.39









r5 = 101.1640










d5 = D(5) (variable)










r6 = 261.4406











d6 = 0.60
nd4 = 1.83400
νd4 = 37.34









r7 = 14.0964











d7 = 2.32











r8 = −17.0702











d8 = 0.60
nd5 = 1.91082
νd5 = 35.25









r9 = 44.2380











d9 = 0.80











r10 = 41.9829











d10 = 2.32
nd6 = 1.95906
νd6 = 17.47









r11 = −27.4098











d11 = 0.60
nd7 = 1.91082
νd7 = 35.25









r12 = −90.5502










d12 = D(12) (variable)










r13 = ∞(aperture stop)











d13 = 0.70











r14 = 118.3906 (aspheric surface)











d14 = 1.54
nd8 = 1.59201
νd8 = 67.02









r15 = −179.2841 (aspheric surface)











d15 = 0.15











r16 = 24.4339











d16 = 4.03
nd9 = 1.43700
νd9 = 95.10









r17 = −15.0000











d17 = 0.60
nd10 = 1.51680
νd10 = 64.20









r18 = 22.6483











d18 = 0.22











r19 = 26.6482











d19 = 3.37
nd11 = 1.43700
νd11 = 95.10









r20 = −23.4654










d20 = D(20) (variable)










r21 = 37.6075











d21 = 2.35
nd12 = 1.88300
νd12 = 40.80









r22 = −51.9172











d22 = 0.10











r23 = 12.0000











d23 = 3.17
nd13 = 1.49700
νd13 = 81.61









r24 = −120.8492











d24 = 0.60
nd14 = 1.69895
νd14 = 30.05









r25 = 11.8722










d25 = D(25) (variable)










r26 = 16.8887











d26 = 1.22
nd15 = 1.75211
νd15 = 25.05









r27 = 9.5626











d27 = 4.18











r28 = 25.0505











d28 = 1.94
nd16 = 1.80420
νd16 = 46.50









r29 = −83.8603











d29 = 1.10











r30 = ∞











d30 = 1.50
nd17 = 1.51633
νd17 = 64.14









r31 = ∞










d31 = D(31) (variable)










r32 = ∞ (imaging plane)













Constants of the cone (k) and aspheric



coefficients (A, B, C, D, E)



(Fourteenth plane)



k = 1.0000,



A = 0,



B = −2.12928 × 10−6, C = −7.77748 × 10−7,



D = 8.75138 × 10−9, E = −1.01012 × 10−10



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 3.39892 × 10−5, C = −6.87094 × 10−7,



D = 8.15498 × 10−9, E = −9.25682 × 10−11











(Zoom data)












wide angle edge
telephoto edge







D(5)
0.7523
23.3292



D(12)
24.0094
1.4324



D(20)
6.9065
2.5431



D(25)
1.4293
5.7927



D(31)
7.0025
6.9989







(Values related to conditional expression (1))



f3 (focal length of third lens group G13) = 31.618



f3/fT = 0.65



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G13 and fourth lens group G14 at wide angle edge and interval between third lens group G13 and fourth lens group G14 at telephoto edge) = 4.363



ΔD4/fT = 0.09



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G13 at telephoto edge) = −7.046



β4T (zoom ratio of fourth lens group G14 at telephoto edge) = 0.106



β3T/β4T = −66.38



(Values related to conditional expression (4))



ν3p (Abbe number of positive lens L132A with respect to d-line) = 95.10



(Values related to conditional expression (5))



|Δν3BA (difference of Abbe numbers of positive lens L132A and negative lens L132B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δν4BA (difference of Abbe numbers of positive lens L142A and negative lens L142B with respect to d-line)| = 51.56



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G15) = 70.382



|f3/f5| = 0.45



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G14) = 29.950



|f4/f5| = 0.43



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L141A with respect to d-line) = 1.88300



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at maximum angle of view for wide angle edge, to lens surface farthest on object side of fourth lens group G14) = 12.746



θ1(W)/ωW = 0.53



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at maximum angle of view for telephoto edge, to lens surface farthest on object side of fourth lens group G14) = 12.914



θ1(T)/ωT = 3.31



(Values related to conditional expression (12))



ν3a (Abbe number of positive lens L131 with respect to d-line) = 67.02






FIG. 3 is a diagram of various types of aberration occurring in the zoom lens according to the first embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
FIG. 4 is a cross sectional view (along the optical axis) of the zoom lens according to a second embodiment. The zoom lens includes sequentially from the object side, a first lens group G21 having a positive refractive power, a second lens group G22 having a negative refractive power, the aperture stop STOP, a third lens group G23 having a positive refractive power, a fourth lens group G24 having a positive refractive power, and a fifth lens group G25 having a positive refractive power.
The cover glass CG is disposed between the fifth lens group G25 and the imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G21 includes sequentially from the object side, a cemented lens L211 formed by a negative lens L211A and a positive lens L211B, and a positive lens L212.
The second lens group G22 includes sequentially from the object side, a negative lens L221, a negative lens L222, and a cemented lens L223 formed by a positive lens L223A and a negative lens L223B.
The third lens group G23 includes sequentially from the object side, a positive lens L231, a cemented lens L232 formed by a positive lens L232A and a negative lens L232B, and a positive lens group L233 configured by a positive lens L233A. Both surfaces of the positive lens L231 are aspheric.
The fourth lens group G24 includes sequentially from the object side, a positive lens group L241 configured by a positive lens L241A, and a cemented lens L242 formed by a positive lens L242A and a negative lens L242B.
The fifth lens group G25 includes sequentially from the object side, a negative lens L251 and a positive lens L252.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G22 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G24 along the optical axis.
Here, various values related to the zoom lens according to the second embodiment are given.










Focal length of entire zoom lens = 5.15 (wide angle edge) to


48.55 (fT: telephoto edge)


F number = 1.64 (wide angle edge) to 2.08 (telephoto edge)


Half-angle (ω) = 35.75 (ωW: wide angle edge) to


3.83(ωT: telephoto edge)







(Lens data)









r1 = 61.0042











d1 = 1.00
nd1 = 1.92286
νd1 = 20.88









r2 = 37.7545











d2 = 6.64
nd2 = 1.49700
νd2 = 81.61









r3 = −241.1020











d3 = 0.10











r4 = 34.3380











d4 = 4.52
nd3 = 1.77250
νd3 = 49.62









r5 = 114.3887










d5 = D(5) (variable)










r6 = −918.2205











d6 = 0.60
nd4 = 1.90366
νd4 = 31.31









r7 = 9.4778











d7 = 3.58











r8 = −20.3807











d8 = 0.60
nd5 = 1.91082
νd5 = 35.25









r9 = −204.1198











d9 = 0.10











r10 = 18.7741











d10 = 2.89
nd6 = 1.95906
νd6 = 17.47









r11 = −42.5551











d11 = 0.50
nd7 = 1.91082
νd7 = 35.25









r12 = 31.7503










d12 = D(12) (variable)










r13 = ∞ (aperture stop)











d13 = 0.60











r14 = 38.5266 (aspheric surface)











d14 = 1.73
nd8 = 1.59201
νd8 = 67.02









r15 = −210.6287 (aspheric surface)











d15 = 0.10











r16 = 28.3543











d16 = 3.30
nd9 = 1.43700
νd9 = 95.10









r17 = −11.6401











d17 = 0.60
nd10 = 1.51680
νd10 = 64.20









r18 = 19.5588











d18 = 0.30











r19 = 25.0000











d19 = 2.54
nd11 = 1.43700
νd11 = 95.10









r20 = −27.3642










d20 = D(20) (variable)










r21 = 24.5852











d21 = 2.27
nd12 = 1.88300
νd12 = 40.80









r22 = −40.8401











d22 = 0.71











r23 = 14.2305











d23 = 2.51
nd13 = 1.49700
νd13 = 81.61









r24 = −30.0524











d24 = 0.60
nd14 = 1.75520
νd14 = 27.53









r25 = 15.3708










d25 = D(25) (variable)










r26 = 12.3841











d26 = 0.60
nd15 = 1.80809
νd15 = 22.76









r27 = 7.4242











d27 = 0.84











r28 = 19.0999











d28 = 1.78
nd16 = 1.77250
νd16 = 49.62









r29 = −129.1950











d29 = 1.10











r30 = ∞











d30 = 1.50
nd17 = 1.51633
νd17 = 64.14









r31 = ∞










d31 = D(31) (variable)










r32 = ∞ (imaging plane)













Constants of the cone (k) and aspheric



coefficients (A, B, C, D, E)



(Fourteenth plane)



k = 1.0000,



A = 0,



B = −3.59592 × 10−5, C = −3.16856 × 10−7,



D = 1.98370 × 10−9, E = −6.42721 × 10−12



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 1.02798 × 10−5, C = −3.44988 × 10−7,



D = 4.11310 × 10−9, E = −4.57401 × 10−11











(Zoom data)












wide angle edge
telephoto edge







D(5)
0.9881
26.0839



D(12)
26.8957
1.8000



D(20)
8.1129
2.5476



D(25)
0.8770
6.4423



D(31)
6.4852
6.4880







(Values related to conditional expression (1))



f3 (focal length of third lens group G23) = 30.520



3/fT = 0.63



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G23 and fourth lens group G24 at wide angle edge and interval between third lens group G23 and fourth lens group G24 at telephoto edge) = 5.565



ΔD4/fT = 0.11



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G23 at telephoto edge) = 14.816



β4T (zoom ratio of fourth lens group G24 at telephoto edge) = −0.054



β3T/β4T = −273.26



(Values related to conditional expression (4))



ν3p (Abbe number of positive lens L232A with respect to d-line) = 95.10



(Values related to conditional expression (5))



|Δν3BA (difference of Abbe numbers of positive lens L232A and negative lens L232B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δν4BA (difference of Abbe numbers of positive lens L242A and negative lens L242B with respect to d-line)| = 54.08



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G25) = 172.657



|f3/f5| = 0.18



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G24) = 21.902



|f4/f5| = 0.13



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L241A with respect to d-line) = 1.88300



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at maximum angle of view for wide angle edge, to lens surface farthest on object side of fourth lens group G24) = 18.324



θ1(W)/ωW = 0.51



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at maximum angle of view for telephoto edge, to lens surface farthest on object side of fourth lens group G24) = 19.088



θ1(T)/ωT = 4.98



(Values related to conditional expression (12))



ν3a (Abbe number of positive lens L231 with respect to d-line) = 67.02






FIG. 5 is a diagram of various types of aberration occurring in the zoom lens according to the second embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
FIG. 6 is a cross sectional view (along the optical axis) of the zoom lens according to a third embodiment. The zoom lens includes sequentially from the object side, a first lens group G31 having a positive refractive power, a second lens group G32 having a negative refractive power, the aperture stop STOP, a third lens group G33 having a positive refractive power, a fourth lens group G34 having a positive refractive power, and a fifth lens group G35 having a positive refractive power.
The cover glass CG is disposed between the fifth lens group G35 and the imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G31 includes sequentially from the object side, a cemented lens L311 formed by a negative lens L311A and a positive lens L311B, and a positive lens L312.
The second lens group G32 includes sequentially from the object side, a negative lens L321, a negative lens L322, and a cemented lens L323 formed by a positive lens L323A and a negative lens L323B.
The third lens group G33 includes sequentially from the object side, a positive lens L331, a cemented lens L332 formed by a positive lens L332A and a negative lens L332B, and a positive lens group L333 configured by a positive lens L333A. Both surfaces of the positive lens L331 are aspheric.
The fourth lens group G34 includes sequentially from the object side, a positive lens group L341 configured by a positive lens L341A, and a cemented lens L342 formed by a positive lens L342A and a negative lens L342B.
The fifth lens group G35 includes sequentially from the object side, a negative lens L351 and a positive lens L352.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G32 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G34 along the optical axis.
Here, various values related to the zoom lens according to the third embodiment are given.










Focal length of entire zoom lens = 8.20 (wide angle edge) to


48.54 (fT: telephoto edge)


F number = 1.63 (wide angle edge) to 2.00 (telephoto edge)


Half-angle (ω) = 23.86 (ωW: wide angle edge) to


3.90 (ωT: telephoto edge)







(Lens data)









r1 = 47.1899











d1 = 1.50
nd1 = 1.80809
νd1 = 22.76









r2 = 32.0220











d2 = 5.95
nd2 = 1.49700
νd2 = 81.61









r3 = −187.3214











d3 = 0.15











r4 = 35.6965











d4 = 3.36
nd3 = 1.61800
νd3 = 63.39









r5 = 110.1448










d5 = D(5) (variable)










r6 = 337.0936











d6 = 0.60
nd4 = 1.83400
νd4 = 37.34









r7 = 13.7198











d7 = 2.33











r8 = −16.8276











d8 = 0.60
nd5 = 1.91082
νd5 = 35.25









r9 = 53.7401











d9 = 0.88











r10 = 46.2473











d10 = 2.30
nd6 = 1.95906
νd6 = 17.47









r11 = −26.4043











d11 = 0.60
nd7 = 1.91082
νd7 = 35.25









r12 = −85.3324










d12 = D(12) (variable)










r13 = ∞ (aperture stop)











d13 = 0.70











r14 = 118.9072 (aspheric surface)











d14 = 1.54
nd8 = 1.59201
νd8 = 67.02









r15 = −182.9621 (aspheric surface)











d15 = 0.15











r16 = 23.8562











d16 = 4.09
nd9 = 1.43700
νd9 = 95.10









r17 = −15.0000











d17 = 0.60
nd10 = 1.51680
νd10 = 64.20









r18 = 22.6762











d18 = 0.22











r19 = 26.6763











d19 = 3.37
nd11 = 1.43700
νd11 = 95.10









r20 = −23.9158










d20 = D(20) (variable)










r21 = 35.6233











d21 = 2.40
nd12 = 1.88100
νd12 = 40.14









r22 = −51.9680











d22 = 0.10











r23 = 12.0000











d23 = 3.23
nd13 = 1.49700
νd13 = 81. 61









r24 = −73.8380











d24 = 0.60
nd14 = 1.69895
νd14 = 30.05









r25 = 11.7130










d25 = D(25) (variable)










r26 = 16.6317











d26 = 0.98
nd15 = 1.78472
νd15 = 25.72









r27 = 9.6558











d27 = 4.33











r28 = 25.2826











d28 = 2.01
nd16 = 1.80420
νd16 = 46.50









r29 = −79.5754











d29 = 1.10











r30 = ∞











d30 = 1.50
nd17 = 1.51633
νd17 = 64.14









r31 = ∞










d31 = D(31) (variable)










r32 = ∞ (imaging plane)













Constants of the cone (k) and aspheric



coefficients (A, B, C, D, E)



(Fourteenth plane)



k = 1.0000,



A = 0,



B = −2.00106 × 10−6, C = −7.82793 × 10−7,



D = 8.89401 × 10−9, E = −1.01643 × 10−10



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 3.34679 × 10−5, C = −6.78233 × 10−7,



D = 7.94663 × 10−9, E = −8.90983 × 10−11











(Zoom data)












wide angle edge
telephoto edge







D(5)
0.7484
23.1722



D(12)
23.8412
1.4173



D(20)
6.8128
2.5912



D(25)
1.4233
5.6449



D(31)
7.0053
6.9981







(Values related to conditional expression (1))



f3 (focal length of third lens group G33) = 31.604



f3/fT = 0.65



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G33 and fourth lens group G34 at wide angle edge and interval between third lens group G33 and fourth lens group G34 at telephoto edge) = 4.222



ΔD4/fT = 0.09



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G33 at telephoto edge) = −6.817



β4T (zoom ratio of fourth lens group G34 at telephoto edge) = 0.109



β3T/β4T = −62.74



(Values related to conditional expression (4))



ν3p (Abbe number of positive lens L332A with respect to d-line) = 95.10



(Values related to conditional expression (5))



|Δν3BA (difference of Abbe numbers of positive lens L332A and negative lens L332B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δν4BA (difference of Abbe numbers of positive lens L342A and negative lens L342B with respect to d-line)| = 51.56



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G35) = 68.467



|f3/f5| = 0.46



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G34) = 29.863



|f4/f5| = 0.44



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L341A with respect to d-line) = 1.88100



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at maximum angle of view for wide angle edge, to lens surface farthest on object side of fourth lens group G34) = 13.040



θ1(W)/ωW = 0.55



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at maximum angle of view for telephoto edge, to lens surface farthest on object side of fourth lens group G34) = 13.236



θ1(T)/ωT = 3.39



(Values related to conditional expression (12))



ν3a (Abbe number of positive lens L331 with respect to d-line) = 67.02






FIG. 7 is a diagram of various types of aberration occurring in the zoom lens according to the third embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
FIG. 8 is a cross sectional view (along the optical axis) of the zoom lens according to a fourth embodiment. The zoom lens includes sequentially from the object side, a first lens group G41 having a positive refractive power, a second lens group G42 having a negative refractive power, the aperture stop STOP, a third lens group G43 having a positive refractive power, a fourth lens group G44 having a positive refractive power, and a fifth lens group G45 having a positive refractive power.
The cover glass CG is disposed between the fifth lens group G45 and the imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G41 includes sequentially from the object side, a cemented lens L411 formed by a negative lens L411A and a positive lens L411B, and a positive lens L412.
The second lens group G42 includes sequentially from the object side, a negative lens L421, a negative lens L422, and a cemented lens L423 formed by a positive lens L423A and a negative lens L423B.
The third lens group G43 includes sequentially from the object side, a positive lens L431, a cemented lens L432 formed by a positive lens L432A and a negative lens L432B, and a positive lens group L433 configured by a positive lens L433A. Both surfaces of the positive lens L431 as aspheric.
The fourth lens group G44 includes sequentially from the object side, a positive lens group L441 configured by a positive lens L441A, and a cemented lens L442 formed by a positive lens L442A and a negative lens L442B.
The fifth lens group G45 includes sequentially from the object side, a negative lens L451 and a positive lens L452.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G42 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G44 along the optical axis.
Here, various values related to the zoom lens according to the fourth embodiment are given.










Focal length of entire zoom lens = 8.20 (wide angle edge) to


48.55 (fT: telephoto edge)


F number = 1.63 (wide angle edge) to 2.00 (telephoto edge)


Half-angle (ω) = 23.89 (ωW: wide angle edge) to 3.90 (ωT:


telephoto edge)







(Lens data)













r1 = 44.7887
d1 = 1.50
nd1 = 1.80809
υd1 = 22.76


r2 = 30.9280
d2 = 6.10
nd2 = 1.49700
υd2 = 81.61


r3 = −191.6351
d3 = 0.15




r4 = 35.8816
d4 = 3.26
nd3 = 1.61800
υd3 = 63.39


r5 = 102.7000
d5 = D(5)





(variable)




r6 = 286.7781
d6 = 0.60
nd4 = 1.83400
υd4 = 37.34


r7 = 14.0223
d7 = 2.29




r8 = −17.0784
d8 = 0.60
nd5 = 1.91082
υd5 = 35.25


r9 = 50.3221
d9 = 0.98




r10 = 46.1600
d10 = 2.31
nd6 = 1.95906
υd6 = 17.47


r11 = −25.8017
d11 = 0.60
nd7 = 1.91082
υd7 = 35.25


r12 = −105.9951
d12 = D(12)





(variable)




r13 = ∞
d13 = 0.70




(aperture stop)





r14 = 97.5331
d14 = 1.59
nd8 = 1.49710
υd8 = 81.56


(aspheric surface)





r15 = −148.7928
d15 = 0.15




(aspheric surface)





r16 = 23.9275
d16 = 4.10
nd9 = 1.43700
υd9 = 95.10


r17 = −15.0000
d17 = 0.60
nd10 = 1.51680
υd10 = 64.20


r18 = 24.4354
d18 = 0.22




r19 = 29.7966
d19 = 3.33
nd11 = 1.43700
υd11 = 95.10


r20 = −22.7200
d20 = D(20)





(variable)




r21 = 37.4362
d21 = 2.33
nd12 = 1.88100
υd12 = 40.14


r22 = −54.2128
d22 = 0.10




r23 = 12.0000
d23 = 3.21
nd13 = 1.49700
υd13 = 81.61


r24 = −91.7837
d24 = 0.60
nd14 = 1.69895
υd14 = 30.05


r25 = 11.7513
d25 = D(25)





(variable)




r26 = 16.9215
d26 = 1.45
nd15 = 1.78472
υd15 = 25.72


r27 = 9.5749
d27 = 3.64




r28 = 25.4027
d28 = 1.93
nd16 = 1.80420
υd16 = 46.50


r29 = −74.6561
d29 = 1.10




r30 = ∞
d30 = 1.50
nd17 = 1.51633
υd17 = 64.14


r31 = ∞
d31 = D(31)





(variable)




r32 = ∞





(imaging plane)










Constants of the cone (k) and aspheric coefficients (A, B, C, D, E)












(Fourteenth plane)



k = 1.0000,



A = 0,



B = −6.47823 × 10−6, C = −7.91552 × 10−7,



D = 8.80330 × 10−9, E = −1.06765 × 10−10



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 3.71329 × 10−5, C = −6.68736 × 10−7,



D = 7.62957 × 10−9, E = −9.12856 × 10−11










(Zoom data)












wide angle edge
telephoto edge






D(5)
0.7535
23.0015



D(12)
23.7008
1.4529



D(20)
7.1592
2.5765



D(25)
1.4398
6.0225



D(31)
7.0046
7.0012












(Values related to conditional expression (1))



f3 (focal length of third lens group G43) = 30.724



f3/fT = 0.63



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G43



and fourth lens group G44 at wide angle edge and interval



between third lens group G43 and fourth lens group G44 at



telephoto edge) = 4.583



ΔD4/fT = 0.09



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G43 at telephoto



edge) = −5.896



β4T (zoom ratio of fourth lens group G44 at telephoto



edge) = 0.130



β3T/β4T = −45.32



(Values related to conditional expression (4))



υ3p (Abbe number of positive lens L432A with respect to d-



line) = 95.10



(Values related to conditional expression (5))



|Δυ3BA (difference of Abbe numbers of positive lens L432A



and negative lens L432B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δυ4BA (difference of Abbe numbers of positive lens L442A



and negative lens L442B with respect to d-line)| = 51.56



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G45) = 74.971



|f3/f5| = 0.41



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G44) = 31.416



|f4/f5| = 0.42



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L441A with respect



to d-line) = 1.88100



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at



maximum angle of view for wide angle edge, to lens surface



farthest on object side of fourth lens group G44) = 12.576



θ1(W)/ωW = 0.53



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at



maximum angle of view for telephoto edge, to lens surface



farthest on object side of fourth lens group G44) = 12.716



θ1(T)/ωT = 3.26



(Values related to conditional expression (12))



υ3a (Abbe number of positive lens L431 with respect to



d-line) = 81.56









FIG. 9 is a diagram of various types of aberration occurring in the zoom lens according to the fourth embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
FIG. 10 is a cross sectional view (along the optical axis) of the zoom lens according to a fifth embodiment. The zoom lens includes sequentially from the object side, a first lens group G51 having a positive refractive power, a second lens group G52 having a negative refractive power, the aperture stop STOP, a third lens group G53 having a positive refractive power, a fourth lens group G54 having a positive refractive power, and a fifth lens group G55 having a negative refractive power.
The cover glass CG is disposed between the fifth lens group G55 and the imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G51 includes sequentially from the object side, a cemented lens L511 formed by a negative lens L511A and a positive lens L511B, and a positive lens L512.
The second lens group G52 includes sequentially from the object side, a negative lens L521, a negative lens L522, and a cemented lens L523 formed by a positive lens L523A and a negative lens L523B.
The third lens group G53 includes sequentially from the object side, a positive lens L531, a cemented lens L532 formed by a positive lens L532A and a negative lens L532B, and a positive lens group L533 configured by a positive lens L533A. Both surfaces of the positive lens L531 are aspheric.
The fourth lens group G54 includes sequentially from the object side, a positive lens group L541 configured by a positive lens L541A, and a cemented lens L542 formed by a positive lens L542A and a negative lens L542B.
The fifth lens group G55 includes sequentially from the object side, a negative lens L551 and a positive lens L552.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G52 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G54 along the optical axis.
Here, various values related to the zoom lens according to the fifth embodiment are given.










Focal length of entire zoom lens = 8.20 (wide angle edge) to


48.55 (fT: telephoto edge)


F number = 1.63 (wide angle edge) to 1.95 (telephoto edge)


Half-angle (ω) = 21.22 (ωW: wide angle edge) to 3.49 (ωT:


telephoto edge)







(Lens data)













r1 = 75.0780
d1 = 1.50
nd1 = 1.80809
υd1 = 22.76


r2 = 41.9370
d2 = 5.31
nd2 = 1.49700
υd2 = 81.61


r3 = −172.4947
d3 = 0.15




r4 = 27.0291
d4 = 4.28
nd3 = 1.61800
υd3 = 63.39


r5 = 70.4905
d5 = D(5)





(variable)




r6 = −183.3764
d6 = 0.60
nd4 = 1.83400
υd4 = 37.34


r7 = 14.0306
d7 = 2.11




r8 = −19.9714
d8 = 0.60
nd5 = 1.91082
υd5 = 35.25


r9 = 27.2898
d9 = 1.45




r10 = 37.6827
d10 = 2.14
nd6 = 1.95906
υd6 = 17.47


r11 = −46.3339
d11 = 0.60
nd7 = 1.91082
υd7 = 35.25


r12 = −51.6529
d12 = D(12)





(variable)




r13 = ∞
d13 = 0.70




(aperture stop)





r14 = 104.9292
d14 = 1.57
nd8 = 1.59201
υd8 = 67.02


(aspheric surface)





r15 = −183.3560
d15 = 0.15




(aspheric surface)





r16 = 21.5309
d16 = 4.60
nd9 = 1.43700
υd9 = 95.10


r17 = −15.0000
d17 = 0.60
nd10 = 1.51680
υd10 = 64.20


r18 = 22.6000
d18 = 0.20




r19 = 26.7000
d19 = 3.44
nd11 = 1.43700
υd11 = 95.10


r20 = −26.7055
d20 = D(20)





(variable)




r21 = 76.7163
d21 = 2.45
nd12 = 1.88300
υd12 = 40.80


r22 = −30.7570
d22 = 0.10




r23 = 12.0000
d23 = 3.54
nd13 = 1.49700
υd13 = 81.61


r24 = −31.0371
d24 = 0.60
nd14 = 1.69895
υd14 = 30.05


r25 = 12.8063
d25 = D(25)





(variable)




r26 = 14.1108
d26 = 2.90
nd15 = 1.75211
υd15 = 25.05


r27 = 7.8563
d27 = 0.65




r28 = 13.4850
d28 = 1.57
nd16 = 1.80420
υd16 = 46.50


r29 = 20.5566
d29 = 1.10




r30 = ∞
d30 = 1.50
nd17 = 1.51633
υd17 = 64.14


r31 = ∞
d31 = D(31)





(variable)




r32 = ∞





(imaging plane)










Constants of the cone (k) and aspheric coefficients (A, B, C, D, E)












(Fourteenth plane)



k = 1.0000,



A = 0,



B = −7.12299 × 10−6, C = −7.59779 × 10−7,



D = 8.48959 × 10−9, E = −6.53913 × 10−11



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 2.94243 × 10−5, C = −6.10954 × 10−7,



D = 8.19549 × 10−9, E = −6.19786 × 10−11










(Zoom data)












wide angle edge
telephoto edge






D(5)
1.0191
24.9183



D(12)
25.1642
1.2649



D(20)
6.2311
2.3323



D(25)
1.1651
5.0639



D(31)
6.9688
6.9268












(Values related to conditional expression (1))



f3 (focal length of third lens group G53) = 31.000



f3/fT = 0.64



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G53



and fourth lens group G54 at wide angle edge and interval



between third lens group G53 and fourth lens group G54 at



telephoto edge) = 3.898



ΔD4/fT = 0.08



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G53 at telephoto



edge) = −4.290



β4T (zoom ratio of fourth lens group G54 at telephoto



edge) = 0.156



β3T/β4T = −27.47



(Values related to conditional expression (4))



υ3p (Abbe number of positive lens L532A with respect to d-



line) = 95.10



(Values related to conditional expression (5))



|Δυ3BA (difference of Abbe numbers of positive lens L532A



and negative lens L532B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δυ4BA (difference of Abbe numbers of positive lens L542A



and negative lens L542B with respect to d-line)| = 51.56



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G55) = −71.005



|f3/f5| = 0.44



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G54) = 29.800



|f4/f5| = 0.42



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L541A with respect



to d-line) = 1.88300



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at



maximum angle of view for wide angle edge, to lens surface



farthest on object side of fourth lens group G54) = 8.111



θ1(W)/ωW = 0.38



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at



maximum angle of view for telephoto edge, to lens surface



farthest on object side of fourth lens group G54) = 9.929



θ1(T)/ωT = 2.85



(Values related to conditional expression (12))



υ3a (Abbe number of positive lens L531 with respect to



d-line) = 67.02









FIG. 11 is a diagram of various types of aberration occurring in the zoom lens according to the fifth embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
FIG. 12 is a cross sectional view (along the optical axis) of the zoom lens according to a sixth embodiment. The zoom lens includes sequentially from the object side, a first lens group G61 having a positive refractive power, a second lens group G62 having a negative refractive power, the aperture stop STOP, a third lens group G63 having a positive refractive power, a fourth lens group G64 having a positive refractive power, and a fifth lens group G65 having a positive refractive power.
The cover glass CG is disposed between the fifth lens group G65 and the imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G61 includes sequentially from the object side, a cemented lens L611 formed by a negative lens L611A and a positive lens L611B, and a positive lens L612.
The second lens group G62 includes sequentially from the object side, a negative lens L621, a negative lens L622, and a cemented lens L623 formed by a positive lens L623A and a negative lens L623B.
The third lens group G63 includes sequentially from the object side, a positive lens L631, a cemented lens L632 formed by a positive lens L632A and a negative lens L63213, and a positive lens group L633 configured by a positive lens L633A and a positive lens L633B. Both surfaces of the positive lens L631 are aspheric.
The fourth lens group G64 includes sequentially from the object side, a positive lens group L641 configured by a positive lens L641A, and a cemented lens L642 formed by a positive lens L642A and negative lens L642B.
The fifth lens group G65 includes sequentially from the object side, a negative lens L651 and a positive lens L652.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G62 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G64 along the optical axis.
Here, various values related to the zoom lens according to the sixth embodiment are given.










Focal length of entire zoom lens = 8.21 (wide angle edge) to


48.61 (fT: telephoto edge)


F number = 1.62 (wide angle edge) to 1.77 (telephoto edge)


Half-angle (ω) = 24.18 (ωW: wide angle edge) to 3.90


(ωT: telephoto edge)







(Lens data)













r1 = 42.2486
d1 = 1.50
nd1 = 1.80809
υd1 = 22.76


r2 = 30.0207
d2 = 7.27
nd2 = 1.49700
υd2 = 81.61


r3 = −193.8119
d3 = 0.18




r4 = 36.6647
d4 = 3.34
nd3 = 1.61800
υd3 = 63.39


r5 = 86.8993
d5 = D(5)





(variable)




r6 = 668.6868
d6 = 0.61
nd4 = 1.83400
υd4 = 37.34


r7 = 17.0948
d7 = 2.16




r8 = −20.1399
d8 = 0.60
nd5 = 1.91082
υd5 = 35.25


r9 = 37.3828
d9 = 0.70




r10 = 34.3546
d10 = 2.46
nd6 = 1.95906
υd6 = 17.47


r11 = −27.5232
d11 = 0.59
nd7 = 1.91082
υd7 = 35.25


r12 = 155.9044
d12 = D(12)





(variable)




r13 = ∞
d13 = 0.70




(aperture stop)





r14 = 112.4884
d14 = 1.62
nd8 = 1.59201
υd8 = 67.02


(aspheric surface)





r15 = −115.4826
d15 = 0.15




(aspheric surface)





r16 = 25.7271
d16 = 3.80
nd9 = 1.43700
υd9 = 95.10


r17 = −14.9982
d17 = 0.59
nd10 = 1.51680
υd10 = 64.20


r18 = 18.8302
d18 = 1.28




r19 = 100.0134
d19 = 1.59
nd11 = 1.43700
υd11 = 95.10


r20 = −488.7620
d20 = 0.10




r21 = 25.0010
d21 = 3.45
nd12 = 1.43700
υd12 = 95.10


r22 = −26.8748
d22 = D(22)





(variable)




r23 = 41.6247
d23 = 2.49
nd13 = 1.88300
υd13 = 40.80


r24 = −48.0201
d24 = 0.10




r25 = 16.0088
d25 = 3.31
nd14 = 1.49700
υd14 = 81.61


r26 = −31.3121
d26 = 0.60
nd15 = 1.69895
υd15 = 30.05


r27 = 17.5888
d27 = D(27)





(variable)




r28 = 16.6456
d28 = 1.77
nd16 = 1.75211
υd16 = 25.05


r29 = 9.4367
d29 = 2.80




r30 = 34.8157
d30 = 3.95
nd17 = 1.80420
υd17 = 46.50


r31 = −66.2378
d31 = 1.10




r32 = ∞
d32 = 1.50
nd18 = 1.51633
υd18 = 64.14


r33 = ∞
d33 = D(33)





(variable)




r34 = ∞





(imaging plane)










Constants of the cone (k) and aspheric coefficients (A, B, C, D, E)












(Fourteenth plane)



k = 1.0000,



A = 0,



B = 1.72586 × 10−6, C = −6.66653 × 10−7,



D = 9.36800 × 10−9, E = −1.37530 × 10−10



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 3.34464 × 10−5, C = −5.94406 × 10−7,



D = 8.11846 × 10−9, E = −1.21767 × 10−10










(Zoom data)












wide angle edge
telephoto edge






D(5)
1.0103
23.5418



D(12)
24.1323
1.6906



D(22)
6.4253
2.4590



D(27)
1.0048
4.9397



D(33)
7.0137
6.9892












(Values related to conditional expression (1))



f3 (focal length of third lens group G63) = 31.011



f3/fT = 0.64



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G63



and fourth lens group G64 at wide angle edge and interval



between third lens group G63 and fourth lens group G64 at



telephoto edge) = 3.935



ΔD4/fT = 0.08



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G63 at telephoto



edge) = −4.788



β4T (zoom ratio of fourth lens group G64 at telephoto



edge) = 0.146



β3T/β4T = −32.90



(Values related to conditional expression (4))



υ3p (Abbe number of positive lens L632A with respect to d-



line) = 95.10



(Values related to conditional expression (5))



|Δυ3BA (difference of Abbe numbers of positive lens L632A



and negative lens L632B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δυ4BA (difference of Abbe numbers of positive lens L642A



and negative lens L642B with respect to d-line)| = 51.56



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G65) = 167.056



|f3/f5| = 0.19



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G64) = 29.987



|f4/f5| = 0.18



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L641A with respect



to d-line) = 1.88300



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at



maximum angle of view for wide angle edge, to lens surface



farthest on object side of fourth lens group G64) = 12.373



θ1(W)/ωW = 0.51



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at



maximum angle of view for telephoto edge, to lens surface



farthest on object side of fourth lens group G64) = 13.408



θ1(T)/ωT = 3.43



(Values related to conditional expression (12))



υ3a (Abbe number of positive lens L631 with respect to



d-line) = 67.02









FIG. 13 is a diagram of various types of aberration occurring in the zoom lens according to the sixth embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
FIG. 14 is a cross sectional view (along the optical axis) of the zoom lens according to a seventh embodiment. The zoom lens includes sequentially from the object side, a first lens group G71 having a positive refractive power, a second lens group G72 having a negative refractive power, the aperture stop STOP, a third lens group G73 having a positive refractive power, a fourth lens group G74 having a positive refractive power, and a fifth lens group G75 having a positive refractive power.
The cover glass CG is disposed between the fifth lens group G75 and the imaging plane IMG. The cover glass CG is disposed as necessary and may be omitted accordingly. At the image plane IMG, the light receiving surface of a solid state image sensor, such as a CCD and CMOS, is disposed.
The first lens group G71 includes sequentially from the object side, a cemented lens L711 formed by a negative lens L711A and a positive lens L711B, and a positive lens L712.
The second lens group G72 includes sequentially from the object side, a negative lens L721, a negative lens L722, and a cemented lens L723 formed by a positive lens L723A and a negative lens L723B.
The third lens group G73 includes sequentially from the object side, a positive lens L731, a cemented lens L732 formed by a positive lens L732A and a negative lens L732B, and a positive lens group L733 configured by a positive lens L733A. Both surfaces of the positive lens L731 are aspheric.
The fourth lens group G74 includes sequentially from the object side, a positive lens group L741 configured by a positive lens L741A and a positive lens L741B, and a cemented lens L742 formed by a positive lens L742A and negative lens L742B.
The fifth lens group G75 includes sequentially from the object side, a negative lens L751 and a positive lens L752.
The zoom lens zooms from the wide angle edge to the telephoto edge by moving the second lens group G72 along the optical axis, from the object side to the imaging plane IMG side. Further, the zoom lens corrects image plane variations accompanying zooming and performs focusing by moving the fourth lens group G74 along the optical axis.
Here, various values related to the zoom lens according to the seventh embodiment are given.










Focal length of entire zoom lens = 8.20 (wide angle edge) to


48.55 (fT: telephoto edge)


F number = 1.63 (wide angle edge) to 1.98 (telephoto edge)


Half-angle (ω) = 23.83 (ωW: wide angle edge) to 3.91 (ωT:


telephoto edge)







(Lens data)













r1 = 44.6737
d1 = 1.50
nd1 = 1.80809
υd1 = 22.76


r2 = 30.7811
d2 = 6.40
nd2 = 1.49700
υd2 = 81.61


r3 = −154.8520
d3 = 0.15




r4 = 32.9952
d4 = 3.27
nd3 = 1.61800
υd3 = 63.39


r5 = 79.0541
d5 = D(5)





(variable)




r6 = 113.0517
d6 = 0.60
nd4 = 1.83400
υd4 = 37.34


r7 = 13.5063
d7 = 2.80




r8 = −16.7218
d8 = 0.60
nd5 = 1.91082
υd5 = 35.25


r9 = 36.7313
d9 = 0.78




r10 = 36.9640
d10 = 2.30
nd6 = 1.95906
υd6 = 17.47


r11 = −28.9425
d11 = 0.60
nd7 = 1.91082
υd7 = 35.25


r12 = −108.2819
d12 = D(12)





(variable)




r13 = ∞
d13 = 0.70




(aperture stop)





r14 = 122.0734
d14 = 1.53
nd8 = 1.59201
υd8 = 67.02


(aspheric surface)





r15 = −178.2336
d15 = 0.15




(aspheric surface)





r16 = 21.2654
d16 = 4.10
nd9 = 1.43700
υd9 = 95.10


r17 = −15.0000
d17 = 0.60
nd10 = 1.51680
υd10 = 64.20


r18 = 21.0000
d18 = 0.22




r19 = 25.0000
d19 = 3.22
nd11 = 1.43700
υd11 = 95.10


r20 = −26.1079
d20 = D(20)





(variable)




r21 = 40.2911
d21 = 2.21
nd12 = 1.88300
υd12 = 40.80


r22 = −62.2904
d22 = 0.10




r23 = 500.0000
d23 = 1.17
nd13 = 1.88300
υd13 = 40.80


r24 = −160.3827
d24 = 0.10




r25 = 12.2830
d25 = 3.08
nd14 = 1.49700
υd14 = 81.61


r26 = −73.4161
d26 = 0.60
nd15 = 1.69895
υd15 = 30.05


r27 = 12.0235
d27 = D(27)





(variable)




r28 = 19.3772
d28 = 0.60
nd16 = 1.75211
υd16 = 25.05


r29 = 10.2034
d29 = 3.72




r30 = 19.8644
d30 = 2.30
nd17 = 1.80420
υd17 = 46.50


r31 = −255.6251
d31 = 1.10




r32 = ∞
d32 = 1.50
nd18 = 1.51633
υd18 = 64.14


r33 = ∞
d33 = D(33)





(variable)




r34 = ∞





(imaging plane)










Constants of the cone (k) and aspheric coefficients (A, B, C, D, E)












(Fourteenth plane)



k = 1.0000,



A = 0,



B = −2.39367 × 10−6, C = −7.52715 × 10−7,



D = 8.53601 × 10−9, E = −9.34460 × 10−11



(Fifteenth plane)



k = 1.0000,



A = 0,



B = 3.32622 × 10−5, C = −6.81784 × 10−7,



D = 8.78755 × 10−9, E = −9.67011 × 10−11










(Zoom data)












wide angle edge
telephoto edge






D(5)
0.7701
22.3651



D(12)
23.0585
1.4635



D(20)
6.6765
2.7439



D(27)
1.4833
5.4159



D(33)
6.9999
6.9896












(Values related to conditional expression (1))



f3 (focal length of third lens group G73) = 31.498



f3/fT = 0.65



(Values related to conditional expression (2))



ΔD4 (difference of interval between third lens group G73



and fourth lens group G74 at wide angle edge and interval



between third lens group G73 and fourth lens group G74 at



telephoto edge) = 3.933



ΔD4/fT = 0.08



(Values related to conditional expression (3))



β3T (zoom ratio of third lens group G73 at telephoto



edge) = −8.156



β4T (zoom ratio of fourth lens group G74 at telephoto



edge) = 0.091



β3T/β4T = −89.92



(Values related to conditional expression (4))



υ3p (Abbe number of positive lens L732A with respect to d-



line) = 95.10



(Values related to conditional expression (5))



|Δυ3BA (difference of Abbe numbers of positive lens L732A



and negative lens L732B with respect to d-line)| = 30.90



(Values related to conditional expression (6))



|Δυ4BA (difference of Abbe numbers of positive lens L742A



and negative lens L742B with respect to d-line)| = 51.56



(Values related to conditional expression (7))



f5 (focal length of fifth lens group G75) = 68.501



|f3/f5| = 0.46



(Values related to conditional expression (8))



f4 (focal length of fourth lens group G74) = 28.467



|f4/f5| = 0.42



(Values related to conditional expression (9))



N4ob (refractive index of positive lens L741A with respect



to d-line) = 1.88300



(Values related to conditional expression (10))



θ1(W) (maximum angle of incidence of marginal ray at maximum



angle of view for wide angle edge, to lens surface farthest



on object side of fourth lens group G74) = 12.677



θ1(W)/ωW = 0.53



(Values related to conditional expression (11))



θ1(T) (maximum angle of incidence of marginal ray at



maximum angle of view for telephoto edge, to lens surface



farthest on object side of fourth lens group G74) = 12.793



θ1(T)/ωT = 3.27



(Values related to conditional expression (12))



υ3a (Abbe number of positive lens L731 with respect to



d-line) = 67.02









FIG. 15 is a diagram of various types of aberration occurring in the zoom lens according to the seventh embodiment. In the diagram, g indicates the wavelength aberration corresponding to g-line (λ=435.83 nm), d indicates the wavelength aberration corresponding to d-line (λ=587.56 nm), and C indicates the wavelength aberration corresponding to C-line (λ=656.27 nm). S and M shown with respect to astigmatism, respectively indicate aberration at the sagittal image plane and at the meridonal image plane.
Among the values for each of the embodiments, r1, r2, . . . indicate radii of curvature for each lens, aperture stop surface, etc.; d1, d2, . . . indicate the thickness of the lenses, aperture stop, etc. or the distance between surfaces thereof; nd1, nd2, . . . indicate the refraction index of each lens with respect to the d-line (λ=587.56 nm); and υd1, υd2, . . . indicate the Abbe number with respect to the d-line (λ=587.56 nm) of each lens. Lengths are indicated in units of [mm] and angles are indicated in [degrees].
Each aspheric shape above is expressed by equation [1], where H is a height orthogonal to the optical axis; X(H) is displacement (in a direction along the optical axis) at a height H when the apex of the lens surface is regarded as the origin; R is paraxial radius of curvature; k is the constant of the cone; and A, B, C, D, and E are the fourth, sixth, eighth, and tenth order aspheric coefficients, respectively.




  
    
      
        
          X
          ⁡
          
            (
            H
            )
          
        
        =
        
          
            
              
                H
                2
              
              /
              R
            
            
              1
              +
              
                
                  1
                  -
                  
                    (
                    
                      
                        kH
                        2
                      
                      /
                      
                        R
                        2
                      
                    
                    )
                  
                
              
            
          
          +
          
            AH
            2
          
          +
          
            BH
            4
          
          +
          
            CH
            6
          
          +
          
            DH
            8
          
          +
          
            EH
            10
          
        
      
    
    
      
        [
        1
        ]
      
    
  




As described, the zoom lens of each of the embodiments achieves a long focal length by a simple and compact structure, favorably corrects various types of aberration occurring over the entire zoom range with respect to light from the visible light range to the near-infrared light range, and can realize a high-resolution optical system capable of handling megapixel counts. In particular, by satisfying the conditional expressions above, the zoom lens achieves more favorable optical performance with sacrificing size reductions of the optical system.
As described, the zoom lens according to the present invention is useful in a small imaging apparatus equipped with a solid state image sensor such as digital still camera and a digital video camera. In particular, the zoom lens is optimal for a surveillance camera equipped with a solid state image sensor of a high pixel count.
Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.
The present document incorporates by reference the entire contents of Japanese priority document, 2012-035639 filed in Japan on Feb. 21, 2012.

## Claims

1. A zoom lens comprises sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an aperture stop, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and fifth lens group, wherein
the second lens group is moved along an optical axis, from the object side toward an image side, to zoom from a wide angle edge to a telephoto edge,
the fourth lens group is moved along the optical axis to correct image plane variation accompanying zooming,
the third lens group includes sequentially from the object side, a positive lens having at least one aspheric surface, a cemented lens formed by a positive lens and a negative lens, and a positive lens group,
the fourth lens group includes sequentially from the object side, a positive lens group, and a cemented lens formed by a positive lens and a negative lens, and
the fifth lens group includes sequentially from the object side, at least one negative lens and at least one positive lens.

2. The zoom lens according to claim 1, wherein the zoom lens satisfies:
a conditional expression (1) 0.50≦f3/fT≦0.80,
a conditional expression (2) 0.08≦ΔD4/fT≦0.20,
a conditional expression (3) −300≦β3T/β4T≦−20, and
a conditional expression (4) 90≦υ3p≦100,
where, f3 represents a focal length of the third lens group; fT represents an optical system focal length at the telephoto edge; ΔD4 represents a difference of an interval between the third lens group and the fourth lens group at the wide angle edge and an interval between the third lens group and the fourth lens group at the telephoto edge; β3T represents a zoom ratio of the third lens group at the telephoto edge; β4T represents a zoom ratio of the fourth lens group at the telephoto edge; and υ3p represents, with respect to d-line, an Abbe number of the positive lens forming the cemented lens in the third lens group.

3. The zoom lens according to claim 1, wherein the zoom lens satisfies:
a conditional expression (5) 30≦|Δυ3BA|≦78, and
a conditional expression (6) 50≦|Δυ4BA|≦78,
where, Δυ3BA represents, with respect to d-line, a difference of Abbe numbers of the positive lens and the negative forming the cemented lens in the third lens group; and Δυ4BA represents, with respect to the d-line, a difference of Abbe numbers of the positive lens and the negative lens forming the cemented lens in the fourth lens group.

4. The zoom lens according to claim 1, wherein the zoom lens satisfies:
a conditional expression (7) 0.10≦|f3/f5|≦0.70, and
a conditional expression (8) 0.10≦|f4/f5|≦0.70,
where, f3 represents a focal length of the third lens group; f4 represents a focal length of the fourth lens group; and f5 represents a focal length of the fifth lens group.

5. The zoom lens according to claim 1, wherein the zoom lens satisfies:
a conditional expression (9) 1.85≦N4ob≦1.95,
a conditional expression (10) 0.30≦θ1(W)/ωW≦60, and
a conditional expression (11) 2.5≦θ1(T)/ωT≦5.0,
where, N4ob represents, with respect to d-line, a refractive index of a positive lens disposed farthest on the object side of the fourth lens group; θ1(W) represents a maximum angle of incidence of a marginal ray at a maximum angle of view for the wide angle edge, to a lens surface farthest on the object side of the fourth lens group; ωw represents a half-angle of the optical system at the wide angle edge; θ1(T) represents a maximum angle of incidence of a marginal ray at a maximum angle of view for the telephoto edge, to the lens surface farthest on the object side of the fourth lens group; and ωT represents a half-angle of the optical system at the telephoto edge.

6. The zoom lens according to claim 1, wherein the zoom lens satisfies a conditional expression (12) 65.0≦υ3a≦85.0, where, υ3a represents, with respect to d-line, an Abbe number of the positive lens farthest on the object side of the third lens group.