阅读说明：本技术 变焦透镜及摄像装置 (Zoom lens and imaging device ) 是由 池田伸吉 田中琢也 于 2019-06-26 设计创作，主要内容包括：本发明提供一种在带有防振功能的变焦透镜中,防振时的像差变动得到抑制的高画质且高倍率的变焦透镜及具备该变焦透镜的摄像装置。该变焦透镜包括变倍时固定的正的第1透镜组、变倍时移动的负的第2透镜组、变倍时移动的正的第3透镜组、变倍时移动的正的第4透镜组及变倍时固定的正的第5透镜组,从广角端向长焦端变倍时,第4透镜组从像侧向物体侧移动,并且第2透镜组和包括第3透镜组及第4透镜组的合成组同时通过各自的横向倍率为-1倍的点,第5透镜组包括在防振时移动的负的第5A透镜组和在防振时固定的正的第5B透镜组,第5A透镜组的横向倍率为负。(The invention provides a zoom lens with a vibration prevention function, which can suppress aberration variation during vibration prevention and has high image quality and high magnification, and an imaging device provided with the zoom lens. The zoom lens includes a positive 1 st lens group fixed at the time of magnification change, a negative 2 nd lens group moving at the time of magnification change, a positive 3 rd lens group moving at the time of magnification change, a positive 4 th lens group moving at the time of magnification change, and a positive 5 th lens group fixed at the time of magnification change, the 4 th lens group moving from the image side to the object side at the time of magnification change from the wide angle end to the telephoto end, and the 2 nd lens group and a combined group including the 3 rd lens group and the 4 th lens group simultaneously pass through points at which respective lateral magnifications are-1 times, the 5 th lens group includes a negative 5A lens group moving at the time of vibration prevention and a positive 5B lens group fixed at the time of vibration prevention, and the lateral magnifications of the 5A lens group are negative.)

1. A zoom lens comprising, in order from an object side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, a 3 rd lens group having positive refractive power, a 4 th lens group having positive refractive power, and a 5 th lens group having positive refractive power,

in the zooming, the 1 st lens group and the 5 th lens group are fixed with respect to an image surface, and the 2 nd lens group, the 3 rd lens group, and the 4 th lens group are moved while changing the interval therebetween,

the 4 th lens group is moved from an image side to an object side upon varying magnification from a wide angle end to a telephoto end, and the 2 nd lens group and a combined group including the 3 rd lens group and the 4 th lens group simultaneously pass points at which respective lateral magnifications are-1 times,

the 5 th lens group includes, in order from the object side, a 5A lens group having negative refractive power which moves in a direction having a component in a direction perpendicular to the optical axis during vibration isolation to perform image shake correction, and a 5B lens group having positive refractive power which is fixed during vibration isolation,

the lateral magnification of the 5A lens group is negative.

2. The variable focus lens according to claim 1,

when the lateral magnification of the 5A lens group is beta 5A, the following conditional expression (1) is satisfied,

-0.3＜1/β5A＜0 (1)。

3. zoom lens according to claim 1 or 2,

when the lateral magnification of the 5A lens group is beta 35A and the lateral magnification of the 5B lens group is beta 5B, the following conditional expression (2) is satisfied,

-1.3＜(1-β5A)×β5B＜-1 (2)。

4. zoom lens according to claim 1 or 2,

when the lateral magnification of the 5 th lens group is beta 5, the following conditional expression (3) is satisfied,

0.9＜1/β5＜1.1 (3)。

5. zoom lens according to claim 1 or 2,

when the lateral magnification of the 5A lens group is beta 5A, the lateral magnification of the 5B lens group is beta 5B, and the lateral magnification of the 5 th lens group is beta 5, a conditional expression (4) shown below is satisfied,

-1.4＜(1-β5A)×β5B/β5＜-1 (4)。

6. zoom lens according to claim 1 or 2,

when the focal length of the 5A lens group is f5A and the focal length of the 5 th lens group is f5, the following conditional expression (5) is satisfied,

-1.2＜f5A/f5＜-0.5 (5)。

7. zoom lens according to claim 1 or 2,

when the focal length of the 5A lens group is f5A and the focal length of the 5B lens group is f5B, the following conditional expression (6) is satisfied,

-1＜f5A/f5B＜-0.6 (6)。

8. zoom lens according to claim 1 or 2,

the 5A lens group includes 2 negative lenses and 1 positive lens.

9. Zoom lens according to claim 1 or 2,

the 5B lens group includes, in order from the object side, a 5B1N lens group having positive refractive power and a 5B2 lens group having positive refractive power,

the 5B1N lens group can be replaced with a 5B1E lens group of magnified imaging power,

when the lateral magnification of the 5B2 lens group is represented by β 5B2, the position at which the 5B1N lens group and the 5B2 lens group are divided is a portion where the air space on the optical axis is the widest when the following conditional expression (7) is satisfied,

-1＜β5B2＜1 (7)，

when the focal length of the 5B2 th lens group is f5B2 and the focal length of the 5B1N th lens group is f5B1N, the following conditional expression (8) is satisfied,

f5B2/f5B1N＜0.5 (8)。

10. the zoom lens of claim 9,

when the focal length of the 5A lens group is f5A and the focal length of the 5B1N lens group is f5B1N, conditional expression (9) shown below is satisfied,

-0.5＜f5A/f5B1N (9)。

11. the zoom lens of claim 9,

the 5B1N lens group includes, in order from the object side, at least two consecutive cemented lenses and a positive lens having a convex object-side surface.

12. The variable focus lens according to claim 2,

satisfies the conditional expression (1-1) shown below,

-0.2＜1/β5A＜0 (1-1)。

13. zoom lens according to claim 3,

satisfies the conditional expression (2-1) shown below,

-1.2＜(1-β5A)×β5B＜-1.1 (2-1)。

14. zoom lens according to claim 4,

satisfies the conditional expression (3-1) shown below,

0.91＜1/β5＜1 (3-1)。

15. zoom lens according to claim 5,

satisfies the conditional expression (4-1) shown below,

-1.3＜(1-β5A)×β5B/β5＜-1 (4-1)。

16. the variable focus lens according to claim 6,

satisfies the conditional expression (5-1) shown below,

-1.1＜f5A/f5＜-0.5 (5-1)。

17. the zoom lens of claim 7,

satisfies the conditional expression (6-1) shown below,

-0.9＜f5A/f5B＜-0.7 (6-1)。

18. the zoom lens of claim 9,

satisfies the conditional expression (8-1) shown below,

0.1＜f5B2/f5B1N＜0.4 (8-1)。

19. the variable focus lens according to claim 10,

satisfies the conditional expression (9-1) shown below,

-0.4＜f5A/f5B1N＜-0.1 (9-1)。

20. an imaging device comprising the zoom lens according to any one of claims 1 to 19.

Technical Field

The present disclosure relates to a zoom lens and an image pickup apparatus.

Background

In recent years, the image quality of images has been improved, and a lens system having a resolution performance of 4K or more, which can be used in an imaging device such as a broadcasting camera, is required. Further, as a lens system for a broadcasting camera, it is preferable to have a zoom function so as to be able to cope with various scenes, and therefore a zoom lens with a high magnification is required. Further, the magnification of the zoom lens is increased to increase the focal length on the telephoto side, and the zoom lens is more susceptible to vibrations and hand trembling, and therefore, a vibration isolation function is required at the time of shooting. As a zoom lens with such a vibration-proof function, the zoom lens of patent document 1 or 2 is proposed.

Patent document 1: japanese patent laid-open publication No. 2016-

Patent document 2: japanese patent No. 5836654

However, the zoom lens described in patent document 1 or 2 has a problem that suppression of aberration variation during vibration isolation is insufficient.

Disclosure of Invention

In view of the above circumstances, an object of the present disclosure is to provide a zoom lens with a vibration prevention function, which suppresses aberration variation during vibration prevention and has high image quality and high magnification, and an imaging apparatus including the zoom lens.

Specific means for solving the above problems include the following means.

<1> a zoom lens comprising, in order from the object side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, a 3 rd lens group having positive refractive power, a 4 th lens group having positive refractive power, and a 5 th lens group having positive refractive power, wherein the 1 st lens group and the 5 th lens group are fixed with respect to an image plane at the time of magnification change, the 2 nd lens group, the 3 rd lens group, and the 4 th lens group are moved while changing mutual intervals, and when magnification is changed from the wide angle end to the telephoto end, the 4 th lens group is moved from the image side to the object side and the 2 nd lens group and a combined group comprising the 3 rd lens group and the 4 th lens group pass through respective points having a lateral magnification of-1, and the 5 th lens group comprises, in order from the object side, a 5A lens group having negative refractive power which is moved in a direction having a component in a direction perpendicular to the optical axis at the time of vibration prevention to perform image shake correction, the lateral magnification of the 5A lens group is negative.

<2> the zoom lens according to <1>, which satisfies conditional expression (1) when the lateral magnification of the 5A lens group is β 5A.

-0.3＜1/β5A＜0 (1)

<3> A zoom lens according to <1> or <2>, which satisfies conditional expression (2) when the lateral magnification of the 5A lens group is β 5A and the lateral magnification of the 5B lens group is β 5B.

-1.3＜(1-β5A)×β5B＜-1 (2)

<4> the zoom lens according to any one of <1> to <3>, which satisfies conditional expression (3) when a lateral magnification of the 5 th lens group is β 5.

0.9＜1/β5＜1.1 (3)

<5> the zoom lens according to any one of <1> to <4>, which satisfies conditional expression (4) when the lateral magnification of the 5A lens group is β 5A, the lateral magnification of the 5B lens group is β 5B, and the lateral magnification of the 5 th lens group is β 5.

-1.4＜(1-β5A)×β5B/β5＜-1 (4)

<6> the zoom lens according to any one of <1> to <5>, which satisfies conditional expression (5) when a focal length of the 5 th A lens group is set to f5A and a focal length of the 5 th lens group is set to f 5.

-1.2＜f5A/f5＜-0.5 (5)

<7> the zoom lens according to any one of <1> to <6>, which satisfies conditional expression (6) when a focal length of the 5A lens group is set to f5A and a focal length of the 5B lens group is set to f 5B.

-1＜f5A/f5B＜-0.6 (6)

<8> the zoom lens according to any one of <1> to <7>, wherein the 5 th a lens group includes 2 negative lenses and 1 positive lens.

<9> a zoom lens according to any one of <1> to <8>, wherein the 5B lens group comprises, in order from the object side, a 5B1N lens group having a positive refractive power and a 5B2 lens group having a positive refractive power, the 5B1N lens group is replaceable with the 5B1E lens group having a magnification, and when the lateral power of the 5B2 lens group is β 5B2, the positions at which the 5B1N lens group and the 5B2 lens group are divided are the portions where the air space on the optical axis is widest when conditional expression (7) is satisfied, and when the focal length of the 5B2 lens group is f5B2 and the focal length of the 5B1N lens group is f5B1N, conditional expression (8) is satisfied.

-1＜β5B2＜1 (7)

f5B2/f5B1N＜0.5 (8)

<10> the zoom lens according to <9>, which satisfies conditional expression (9) when a focal length of the 5 th A lens group is set to f5A and a focal length of the 5B1N lens group is set to f5B 1N.

-0.5＜f5A/f5B1N (9)

<11> the zoom lens according to <9> or <10>, wherein the 5B1N th lens group includes, in order from the object side, at least two consecutive cemented lenses and a positive lens having a convex surface on the object side.

<12> the zoom lens according to <2>, which satisfies conditional expression (1-1).

-0.2＜1/β5A＜0 (1-1)

<13> the zoom lens according to <3>, which satisfies conditional expression (2-1).

-1.2＜(1-β5A)×β5B＜-1.1 (2-1)

<14> the zoom lens according to <4>, which satisfies conditional expression (3-1).

0.91＜1/β5＜1 (3-1)

<15> the zoom lens according to <5>, which satisfies conditional expression (4-1).

-1.3＜(1-β5A)×β5B/β5＜-1 (4-1)

<16> the zoom lens according to <6>, which satisfies conditional expression (5-1).

-1.1＜f5A/f5＜-0.5 (5-1)

<17> the zoom lens according to <7>, which satisfies conditional expression (6-1).

-0.9＜f5A/f5B＜-0.7 (6-1)

<18> the zoom lens according to <9>, which satisfies conditional expression (8-1).

0.1＜f5B2/f5B1N＜0.4 (8-1)

<19> the zoom lens according to <10>, which satisfies conditional expression (9-1).

-0.4＜f5A/f5B1N＜-0.1 (9-1)

<20> an image pickup apparatus comprising the zoom lens according to any one of <1> to <19 >.

In addition, the terms "include" and "include" in the present specification mean that, in addition to the components listed above, the components may include: a lens having substantially no optical power; optical elements other than lenses such as an aperture, a filter, and cover glass; and mechanism parts such as lens flanges, lens barrels, imaging elements, and hand shake correction mechanisms.

In the present specification, "group having positive refractive power" means that the group as a whole has positive refractive power. Similarly, "group having negative refractive power" means that the group as a whole has negative refractive power. "a lens having positive refractive power" means the same as "a positive lens". The "lens having negative refractive power" has the same meaning as the "negative lens". The "lens group" is not limited to a structure including a plurality of lenses, and may be a structure including only 1 lens.

The value used in the conditional expression is a value based on the d-line in a state of focusing on an object at infinity. When the refractive indices of a lens with respect to g, F and C lines are Ng, NF and NC, respectively, the partial dispersion ratio θ gF between the g and F lines of the lens is defined as (Ng-NF)/(NF-NC). The "d line", "C line", "F line" and "g line" described in the present specification are open lines, the wavelength of the d line is 587.56nm (nm), the wavelength of the C line is 656.27nm (nm), the wavelength of the F line is 486.13nm (nm), and the wavelength of the g line is 435.84nm (nm).

Effects of the invention

According to the present disclosure, it is possible to provide a zoom lens with a vibration prevention function, which suppresses aberration variation during vibration prevention and has high image quality and high magnification, and an imaging apparatus including the zoom lens.

Drawings

Fig. 1 is a sectional view showing a configuration of a zoom lens according to embodiment 1 of the present invention.

Fig. 2 is a sectional view showing the structure of a zoom lens according to embodiment 2 of the present invention.

Fig. 3 is a sectional view showing a configuration of a zoom lens according to embodiment 3 of the present invention.

Fig. 4 is a sectional view showing the structure of a zoom lens according to embodiment 4 of the present invention.

Fig. 5 is a sectional view showing the structure of a zoom lens according to embodiment 5 of the present invention.

Fig. 6 is each aberration diagram of a zoom lens according to embodiment 1 of the present invention.

Fig. 7 is each aberration diagram of a zoom lens according to embodiment 2 of the present invention.

Fig. 8 is each aberration diagram of a zoom lens according to embodiment 3 of the present invention.

Fig. 9 is each aberration diagram of a zoom lens according to embodiment 4 of the present invention.

Fig. 10 is each aberration diagram of a zoom lens according to embodiment 5 of the present invention.

Fig. 11 is a schematic configuration diagram of an imaging apparatus according to an embodiment of the present invention.

Detailed Description

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a cross-sectional view showing a configuration of a zoom lens according to an embodiment of the present invention at a wide-angle end. The configuration example shown in fig. 1 corresponds to a zoom lens according to embodiment 1 of the present invention, which will be described later. In fig. 1, the left side is the object side and the right side is the image side. Fig. 1 shows a state of focusing on an object at infinity, and the on-axis light flux Wa and the maximum angle of view light flux Wb are also shown. In fig. 1, the movement trajectories of the 2 nd lens group G2, the 3 rd lens group G3, and the 4 th lens group G4 at the time of magnification change are also shown. In fig. 1, the 2 nd lens group G2 and the combined group including the 3 rd lens group G3 and the 4 th lens group G4 are also shown together at a position where the lateral magnification is-1 times.

The zoom lens shown in fig. 1 includes, in order from the object side to the image side along the optical axis Z, a 1 st lens group G1 having positive refractive power, a 2 nd lens group G2 having negative refractive power, a 3 rd lens group G3 having positive refractive power, a 4 th lens group G4 having positive refractive power, and a 5 th lens group G5 having positive refractive power, and when zooming, the 1 st lens group G1 and the 5 th lens group G5 are fixed to the image plane Sim, and the 2 nd lens group G2, the 3 rd lens group G3, and the 4 th lens group G4 move with their mutual intervals changed.

With this configuration, it is possible to suppress the on-axis chromatic aberration, particularly on the telephoto side, which is easy to expand, while suppressing the aberration variation during magnification change, and thus it is possible to realize a zoom lens having a magnification ratio of 30 times or more.

In the example of fig. 1, an optical member PP having an incident surface and an exit surface perpendicular to the optical axis Z is disposed between the 5 th lens group G5 and the image plane Sim. The optical member PP is a member assumed to be various filters, prisms, cover glasses, and the like. In the present invention, the optical member PP may be disposed at a position different from the example of fig. 1, and the optical member PP can also be omitted. The aperture stop St shown in fig. 1 indicates a position on the optical axis Z, and does not necessarily indicate a size or a shape.

Further, when zooming from the wide angle end to the telephoto end, the 4 th lens group G4 is configured to move from the image side to the object side, and the combined group including the 2 nd lens group G2 and the 3 rd lens group G3 and the 4 th lens group G4 is configured to pass through respective lateral magnifications at the same time at a point of-1 magnification. With this configuration, a zoom lens having a zoom ratio of 30 times or more can be realized while maintaining high image quality in the entire zoom region.

The 5 th lens group G5 is composed of, in order from the object side, a 5A lens group G5A having negative refractive power which moves in a direction having a component in a direction perpendicular to the optical axis Z during vibration isolation to correct image blur, and a 5B lens group G5B having positive refractive power which is fixed during vibration isolation.

With such a configuration, the zoom lens can be provided with a vibration-proof function. Further, in the zoom lens of the present embodiment, since the light flux is incident on the 5 th lens group G5 in a convergent manner from the 4 th lens group G4, by arranging the 5A lens group G5A having a negative refractive power and the 5B lens group G5B having a positive refractive power in this order from the object side as described above, the back focal length is easily lengthened, which is advantageous in suppressing spherical aberration in the entire zoom region.

The 5A lens group G5A is configured to have negative lateral magnification. In the zoom lens of the present embodiment, since the light flux is converged from the 4 th lens group G4 to enter the 5 th lens group G5, the lateral magnification of the 5A lens group G5A is negative, and the symmetry between the incident side and the outgoing side of the axial marginal ray with respect to the 5A lens group G5A becomes better than that in the case of being positive, and therefore, the aberration variation during vibration isolation can be reduced.

In the zoom lens according to the present embodiment, it is preferable that conditional expression (1) is satisfied where β 5A is a lateral magnification of the 5A lens group G5A. By not being equal to or more than the upper limit of conditional expression (1), the symmetry between the incident side and the emission side of the light beam with respect to the axial upper edge of the 5A lens group G5A becomes good, and thus aberration variation during vibration isolation can be reduced. By not being equal to or less than the lower limit of conditional expression (1), the height of the edge ray incident on the axis of the 5B lens group G5B can be reduced, which is advantageous in suppressing the occurrence of spherical aberration. Further, satisfying the conditional expression (1-1) can provide more favorable characteristics.

-0.3＜1/β5A＜0 (1)

-0.2＜1/β5A＜0 (1-1)

When the lateral magnification of the 5A lens group G5A is β 5A and the lateral magnification of the 5B lens group G5B is β 5B, it is preferable that conditional expression (2) is satisfied. By not being equal to or more than the upper limit of the conditional expression (2), the movement amount of the 5A lens group G5A in the vibration-proof can be suppressed, and hence the follow-up property of the vibration-proof lens group (5A lens group G5A) can be improved.

By not being equal to or less than the lower limit of conditional expression (2), the sensitivity of the anti-vibration lens group (the 5A lens group G5A) can be prevented from becoming excessively high, and thus the image position at the time of anti-vibration can be easily controlled. Further, satisfying the conditional expression (2-1) can provide more favorable characteristics.

-1.3＜(1-β5A)×β5B＜-1 (2)

-1.2＜(1-β5A)×β5B＜-1.1 (2-1)

When the lateral magnification of the 5 th lens group G5 is β 5, it is preferable that conditional expression (3) is satisfied. By not being equal to or more than the upper limit of conditional expression (3), the combined focal length from the 1 st lens group G1 to the 4 th lens group G4 can be suppressed to be short, and the entire length of the magnification-varying unit (the 2 nd lens group G2 to the 4 th lens group G4) can be suppressed, which is advantageous for downsizing the lens system. By not being equal to or less than the lower limit of conditional expression (3), the back focal length becomes easy to be elongated, which is advantageous in suppressing spherical aberration in the entire zoom region. Further, satisfying the conditional expression (3-1) can provide more favorable characteristics.

0.9＜1/β5＜1.1 (3)

0.91＜1/β5＜1 (3-1)

Further, it is preferable that conditional expression (4) is satisfied where β 5A is a lateral magnification of the 5A lens group G5A, β 5B is a lateral magnification of the 5B lens group G5B, and β 5 is a lateral magnification of the 5d lens group G5. By not being equal to or more than the upper limit of conditional expression (4), it is advantageous to miniaturize the lens system while suppressing the moving amount of the vibration-proof lens group (5A lens group G5A). By not being equal to or less than the lower limit of conditional expression (4), it is advantageous to suppress spherical aberration in the entire zoom region while preventing sensitivity of the vibration-proof lens group (5A lens group G5A) from becoming high. Further, satisfying the conditional expression (4-1) can provide more favorable characteristics.

-1.4＜(1-β5A)×β5B/β5＜-1 (4)

-1.3＜(1-β5A)×β5B/β5＜-1 (4-1)

It is preferable that the conditional expression (5) is satisfied where f5A is a focal length of the 5A lens group G5A and f5 is a focal length of the 5 th lens group G5. The length of the 5 th lens group G5 can be advantageously reduced by not being equal to or more than the upper limit of conditional expression (5). By not being equal to or less than the lower limit of conditional expression (5), the sensitivity of the vibration-proof lens group (5A lens group G5A) can be easily increased. Further, satisfying the conditional expression (5-1) can provide more favorable characteristics.

-1.2＜f5A/f5＜-0.5 (5)

-1.1＜f5A/f5＜-0.5 (5-1)

It is preferable that conditional expression (6) be satisfied where f5A denotes a focal length of the 5A lens group G5A and f5B denotes a focal length of the 5B lens group G5B. The length of the 5 th lens group G5 can be advantageously reduced by not being equal to or more than the upper limit of conditional expression (6). By not being equal to or less than the lower limit of conditional expression (6), the sensitivity of the vibration-proof lens group (the 5A-th lens group G5A) can be easily increased. Further, satisfying conditional expression (6-1) can provide more favorable characteristics.

-1＜f5A/f5B＜-0.6 (6)

-0.9＜f5A/f5B＜-0.7 (6-1)

Also, the 5 th a lens group G5A preferably includes 2 negative lenses and 1 positive lens. With this configuration, the occurrence of spherical aberration during vibration isolation can be suppressed.

Preferably, the 5B lens group G5B includes, in order from the object side, a 5B1N lens group G5B1N having a positive refractive power and a 5B2 lens group G5B2 having a positive refractive power, and the 5B1N lens group G5B1N is replaceable with a 5B1E lens group having a magnification, and when the lateral magnification of the 5B2 lens group G5B2 is 5B2, the positions of the 5B1N lens group G5B1N and the 5B2 lens group G5B2 are divided into a portion where the air space on the optical axis is the widest when conditional expression (7) is satisfied, and when the focal length of the 5B 2G 5B2 is f5B2 and the focal length of the 5B1N lens group G5B1N is f5B1N, conditional expression (8) is satisfied.

-1＜β5B2＜1 (7)

f5B2/f5B1N＜0.5 (8)

0.1＜f5B2/f5B1N＜0.4 (8-1)

When a beam expanding lens (5B 1E th lens group) that is replaced with a part of lens groups so that the imaging magnification of the entire system after replacement is larger than that of the entire system before replacement is used, by disposing the 5B1N th lens group G5B1N that is replaced with a beam expanding lens (5B 1E th lens group) on the image side of the 5A lens group G5A, it is not necessary to change the control amount of the anti-vibration lens group for the anti-vibration angle even in the case of switching the imaging magnification.

Further, the position of the split 5B1N lens group G5B1N and the 5B2 lens group G5B2 satisfies the condition (7), and the paraxial light incident on the 5B2 lens group G5B2 is close to being parallel to the optical axis, and the change of the spherical aberration due to the position error on the optical axis of the 5B1N lens group G5B1N can be suppressed, and therefore, the split position is optimal.

Further, it is advantageous to ensure the back focus by not being equal to or more than the upper limit of conditional expression (8). Further, satisfying conditional expression (8-1) can provide more favorable characteristics. By not being lower than the lower limit of conditional expression (8), positive refractive power can be appropriately dispersed by the 5B1N th lens group G5B1N and the 5B2 th lens group G5B2, thereby contributing to correction of spherical aberration.

Further, it is preferable that the conditional expression (9) is satisfied where f5A is a focal length of the 5A lens group G5A and f5B1N is a focal length of the 5B1N lens group G5B 1N. By not being equal to or less than the lower limit of conditional expression (9), the height of the edge ray incident on the axis of the 5B-th lens group G5B can be reduced, which is advantageous for correcting spherical aberration. Further, satisfying conditional expression (9-1) can provide more favorable characteristics. By not being equal to or more than the upper limit of conditional expression (9), it is advantageous to secure the back focus.

-0.5＜f5A/f5B1N (9)

-0.4＜f5A/f5B1N＜-0.1 (9-1)

Preferably, the 5B1N th lens group G5B1N includes, in order from the object side, at least two consecutive cemented lenses and a positive lens having a convex object-side surface. By thus continuously arranging the cemented lenses, it is possible to correct the on-axis chromatic aberration while suppressing the generation of a difference in spherical aberration depending on the wavelength. Further, since the object-side surface of the next positive lens has a convex shape, the angle at which the axial edge light enters the object-side surface can be reduced, and thus positive power can be applied while suppressing the occurrence of spherical aberration.

The above-described preferred configurations and realizable configurations can be arbitrarily combined and preferably selectively employed as appropriate in accordance with the required specifications.

Next, a numerical example of the zoom lens of the present invention will be described.

Example 1 (reference state)

Fig. 1 shows a structure of a zoom lens according to example 1. Since the method shown in fig. 1 is as described above, a part of the description thereof will be omitted.