CN114326064A - Zoom lens and image pickup apparatus - Google Patents

Abstract

The subject is to provide a compact zoom lens and an imaging device with small variation of the center of gravity position. The zoom lens includes, in order from an object side: the zoom lens includes a 1 st lens group (G1) having positive power, a 2 nd lens group (G2) having negative power, a 3 rd lens group (G3) having positive power, a 4 th lens group (G4) having negative power, and a 5 th lens group (G5), wherein an interval between adjacent lens groups changes when magnification is changed, the 1 st lens group (G1) is fixed with respect to an image surface, the 3 rd lens group (G3) and the 5 th lens group (G5) move in a direction different from that of the 2 nd lens group (G2), and the zoom lens satisfies a predetermined mathematical formula.

Description

Zoom lens and image pickup apparatus

Technical Field

The present invention relates to a zoom lens and an imaging device.

Background

With the demand for high image quality of digital cameras, image pickup devices are becoming larger in size, and with mirrorless cameras and the like, the flange pitch is becoming shorter, and there is an increasing demand for downsizing of optical systems. Cameras mounted on moving bodies such as unmanned aerial vehicles are also becoming popular, and zoom lenses with less fluctuation in the center of gravity position during zooming are required to achieve stable shooting even when moving.

As a zoom lens for achieving downsizing, a positive-lead type zoom lens including a lens group having positive power on the most object side is known (for example, see patent documents 1 to 3).

Prior art documents

Patent document

[ patent document 1] International publication No. 2016/157340

[ patent document 2] Japanese patent laid-open No. 2012 and 113182

[ patent document 3] Japanese patent laid-open No. 2014-215434

Disclosure of Invention

Problems to be solved by the invention

In the zoom lens described in patent document 1, since the 1 st lens group moves during zooming, the position of the center of gravity of the zoom lens greatly fluctuates during zooming. When the zoom lens is used as a zoom lens for a camera mounted on a mobile body such as an unmanned aerial vehicle, it is difficult to suppress the fluctuation of the center of gravity position of the mobile body.

In the zoom lenses described in patent documents 2 and 3, the 1 st lens group is fixed at the time of magnification change. However, the moving amount of the 3 rd lens group with respect to the 2 nd lens group or the moving amount of the 5 th lens group with respect to the 2 nd lens group at the time of magnification change is not appropriate, and therefore the barycentric position of the zoom lens fluctuates greatly with the movement of these lens groups. Even when these zoom lenses are used as zoom lenses for cameras mounted on a mobile body such as an unmanned aerial vehicle, it is difficult to suppress fluctuations in the position of the center of gravity of the mobile body.

Accordingly, an object of the present invention is to provide a compact zoom lens and an imaging device with small fluctuation in the center of gravity position at the time of magnification change.

Means for solving the problems

In order to solve the above problem, a zoom lens according to the present invention includes, in order from an object side: a 1 st lens group having positive power, a 2 nd lens group having negative power, a 3 rd lens group having positive power, a 4 th lens group having negative power, and a 5 th lens group,

in the zooming, the interval between adjacent lens groups is changed, the 1 st lens group is fixed relative to the image surface, and the 3 rd lens group and the 5 th lens group move in a direction different from the 2 nd lens group,

the zoom lens satisfies the following formula:

0.01＜|M3/M2|＜1.34·····(1)

0.61＜|M5/M2|＜1.81·····(2)

wherein the content of the first and second substances,

m2: a moving amount of the 2 nd lens group from a wide angle end to a telephoto end

M3: a moving amount of the 3 rd lens group from a wide angle end to a telephoto end

M5: a moving amount of the 5 th lens group from a wide-angle end to a telephoto end.

In order to solve the above problem, an imaging device according to the present invention includes the zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electric signal.

Effects of the invention

According to the present invention, a compact zoom lens and an imaging device with small fluctuation in the center of gravity position at the time of magnification change can be provided.

Drawings

Fig. 1 is a sectional view of a zoom lens of embodiment 1.

Fig. 2 is an aberration diagram of the zoom lens of embodiment 1 at the wide-angle end.

Fig. 3 is an aberration diagram at an intermediate focal length position of the zoom lens of embodiment 1.

Fig. 4 is an aberration diagram at the telephoto end of the zoom lens of embodiment 1.

Fig. 5 is a sectional view of the zoom lens of embodiment 2.

Fig. 6 is an aberration diagram of the zoom lens of embodiment 2 at the wide-angle end.

Fig. 7 is an aberration diagram of the zoom lens of embodiment 2 at an intermediate focal length position.

Fig. 8 is an aberration diagram at the telephoto end of the zoom lens of embodiment 2.

Fig. 9 is a sectional view of the zoom lens of embodiment 3.

Fig. 10 is an aberration diagram at the wide angle end of the zoom lens of embodiment 3.

Fig. 11 is an aberration diagram at an intermediate focal length position of the zoom lens of embodiment 3.

Fig. 12 is an aberration diagram at the telephoto end of the zoom lens of embodiment 3.

Fig. 13 is a sectional view of a zoom lens of embodiment 4.

Fig. 14 is an aberration diagram at the wide angle end of the zoom lens of embodiment 4.

Fig. 15 is an aberration diagram at an intermediate focal length position of the zoom lens of embodiment 4.

Fig. 16 is an aberration diagram at the telephoto end of the zoom lens of embodiment 4.

Fig. 17 is a diagram schematically showing an example of the configuration of an imaging device according to an embodiment of the present invention.

Description of the reference numerals

S.Aperture diaphragm

CG protective glass

IP image plane

G1. group 1

G2. group 2

G3. group 3

G4. group 4

G5. group 5

G6. group 6

1. camera device

2. camera

3. lens

21. image pickup element

Detailed Description

Embodiments of a zoom lens and an imaging device according to the present invention are described below. However, the zoom lens and the imaging device described below are one embodiment of the zoom lens and the imaging device according to the present invention, and the zoom lens and the imaging device according to the present invention are not limited to the following embodiment.

1. Zoom lens

1-1. optical construction

The zoom lens includes: a 1 st lens group having positive power, a 2 nd lens group having negative power, a 3 rd lens group having positive power, a 4 th lens group having negative power, and a 5 th lens group. By adopting this power arrangement, an axial light flux close to the effective diameter is incident on the 3 rd lens group, and therefore spherical aberration can be corrected in the 3 rd lens group. Further, when the zoom lens is divided into the object side group and the image side group, the object side group has positive power and the image side group has negative power, and the zoom lens can be a telescopic zoom lens. With this configuration, the total optical length of the zoom lens can be shortened. In this case, the zoom lens preferably includes an object side group including the 1 st to 3 rd lens groups and an image side group including the 4 th and subsequent lens groups.

(1) Group 1 lens

The 1 st lens group is a lens group disposed most to the object side in the zoom lens, and has positive power. The 1 st lens group is preferably composed of a lens having negative refractive power (hereinafter referred to as a negative lens) and a lens having positive refractive power (hereinafter referred to as a positive lens) in this order from the object side, whereby chromatic aberration can be corrected well. In addition, it is more preferable that these 2 lenses are joined in terms of shortening the total optical length.

(2) Group 2 lens

The 2 nd lens group is a lens group disposed on the image side of the 1 st lens group, and has negative power. It is preferable that the 2 nd lens group has a negative lens, a positive lens, and a negative lens in this order from the object side, since each aberration is easily corrected. Further, it is preferable that the lens disposed most to the image side in the 2 nd lens group is a negative meniscus lens having a concave object side in order to correct each aberration in the 2 nd lens group.

(3) Group 3 lens

The 3 rd lens group is a lens group disposed on the image side of the 2 nd lens group, and has positive power. Further, it is preferable that the 3 rd lens group has at least 1 aspherical surface, since the weight reduction of the lens is easy. In addition, 4 or less lens groups of the 3 rd lens group are preferable in terms of suppressing the lens diameter of the 3 rd lens group and correcting various aberrations.

(4) Group 4 lens

The 4 th lens group is a lens group disposed on the image side of the 3 rd lens group, and has negative power. Further, a negative meniscus lens having a concave image side disposed on the most image side of the 4 th lens group is preferable in correcting curvature of field of the zoom lens.

(5) After the 5 th lens group

The 5 th lens group is a lens group disposed on the image side of the 4 th lens group. In addition, a negative lens having a concave object side disposed on the most object side of the 5 th lens group is preferable because curvature of field of the zoom lens can be easily corrected. The zoom lens may include 1 or more lens groups on the image side of the 5 th lens group. Further, the total number of lenses arranged between the 5 th lens group and the image plane is preferably 3 or less in order to simplify the control of the fluctuation of the center of gravity position. In addition, it is preferable to include at least 1 positive lens and at least 1 negative lens in terms of easy correction of chromatic aberration.

(6) Aperture diaphragm

In the zoom lens, the position of the aperture stop is not particularly limited. Here, the aperture stop means an aperture stop for defining a beam diameter of the zoom lens, that is, an aperture stop for defining an F value of the zoom lens. The aperture stop is preferably disposed on the image side of the 2 nd lens group. Further, an aperture stop is preferably disposed on the object side of the 3 rd lens group or within the 3 rd lens group.

1-2. actions

(1) Variable magnification

The zoom lens has a variable interval between adjacent lens groups when zooming. Further, whether or not each lens group is moved, the direction of movement, and the amount of movement are not particularly limited, and all the lens groups may be moved along the optical axis at the time of magnification change, or any one or more lens groups among all the lens groups may be fixed with respect to the image plane at the time of magnification change. Preferably, the following are provided: at the time of magnification variation, the interval of the 1 st lens group and the 2 nd lens group is made to vary in a manner larger at the telephoto end than at the wide-angle end. According to this configuration, it is possible to easily suppress the fluctuation of the center of gravity position and to realize a sufficient magnification ratio. Preferably, the 2 nd lens group is moved so that the distance between the 1 st lens group and the 2 nd lens group becomes maximum at the telephoto end, whereby the fluctuation of the gravity center position is easily suppressed. In addition, it is preferable that the 1 st lens group is fixed to suppress variation in the position of the center of gravity in magnification variation. The 3 rd lens group and the 5 th lens group are preferably moved in a direction different from the direction of the 2 nd lens group, because the variation in the position of the center of gravity is easily suppressed. Further, it is preferable that the 2 nd lens group is moved to the image side at the time of varying magnification from the wide-angle end to the telephoto end. In addition, regarding the lens groups after the 3 rd lens group, the 3 rd lens group and the 5 th lens group are preferably moved to the object side, but the moving direction of the other lens groups is not particularly limited. For example, the 4 th lens group may be moved to the image side. However, from the viewpoint of suppressing the fluctuation of the position of the center of gravity, it is more preferable that all the lens groups after the 3 rd lens group are moved toward the object side.

(2) Focusing

In the zoom lens, the focus group moves on the optical axis when focusing from infinity to a close object. The focus group is not particularly limited, and the direction of movement of the focus group in focusing is not particularly limited, but the 4 th lens group is preferably used as the focus group. In this configuration, the 4 th lens group can be formed of a lens having a small diameter, and therefore, the focus control group can be reduced in size and weight. Therefore, the actuator for moving the focus group and the like can be downsized, and the zoom lens can be made compact. In the zoom lens, the 4 th lens group is constituted by only 1 lens component, and thus the actuator and the like can be downsized by reducing the weight of the focus group. In addition, the zoom lens is more preferably a 4 th lens group composed of only 1 lens.

In the present specification, the lens component includes a lens and a cemented lens in which a plurality of lenses are integrated without an air gap therebetween. The lens includes 1 single lens and a compound lens in which 1 single lens is integrated with a resin without an air gap. The single lens is composed of 1 material. Specifically, 1 cemented lens obtained by cementing 2 single lenses was counted as 1 lens component and 2 lenses were counted. The lenses (single lens and compound lens) were counted as 1 lens component, and also as 1 lens. Here, the single lens means a spherical lens and an aspherical lens (including a compound aspherical lens).

1-3, mathematical formula

The zoom lens preferably has the above-described configuration and satisfies at least 1 or more of the following expressions.

1-3-1, formula (1)

0.01＜|M3/M2|＜1.34·····(1)

Wherein the content of the first and second substances,

m2: moving amount of the 2 nd lens group from wide-angle end to telephoto end

M3: moving amount of the 3 rd lens group from wide-angle end to telephoto end

The above expression (1) is a mathematical expression which defines an absolute value of a ratio of a moving amount of the 3 rd lens group from the wide-angle end to the telephoto end to a moving amount of the 2 nd lens group from the wide-angle end to the telephoto end. Satisfying equation (1) makes it easier to reduce the variation in the position of the center of gravity of the zoom lens. Here, the moving amount of the lens group refers to a difference between a position on the optical axis of the lens group at the wide-angle end and a position on the optical axis of the lens group at the telephoto end.

On the other hand, if the value of expression (1) is lower than the lower limit value, the moving amount of the 2 nd lens group relative to the moving amount of the 3 rd lens group becomes large, and the variation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the variation in the center of gravity position of the zoom lens. On the other hand, if the value of expression (1) is equal to or greater than the upper limit value, the amount of movement of the 3 rd lens group relative to the amount of movement of the 2 nd lens group becomes large, and therefore the variation in the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the variation in the center of gravity position of the zoom lens.

In order to obtain the above-described effects, the lower limit value of formula (1) is preferably 0.20, and more preferably 0.40. The upper limit of formula (1) is preferably 1.32, more preferably 1.30. When these preferable lower limit values or upper limit values are used, the inequality numbers (<) may be replaced with inequality numbers (≦) having an equal sign in the formula (1). The same applies to other mathematical expressions as a principle.

1-3-2, formula (2)

0.61＜|M5/M2|＜1.81·····(2)

Wherein the content of the first and second substances,

m2: moving amount of the 2 nd lens group from wide-angle end to telephoto end

M5: moving amount of the 5 th lens group from wide-angle end to telephoto end

The above expression (2) is a mathematical expression which defines an absolute value of a ratio of a moving amount of the 5 th lens group from the wide-angle end to the telephoto end to a moving amount of the 2 nd lens group from the wide-angle end to the telephoto end. Satisfying equation (2) makes it easier to reduce the variation in the position of the center of gravity of the zoom lens.

On the other hand, if the value of expression (2) is lower than the lower limit value, the shift amount of the 2 nd lens group relative to the 5 th lens group becomes large, and therefore the variation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the variation in the center of gravity position of the zoom lens. On the other hand, if the value of expression (2) is equal to or greater than the upper limit value, the shift amount of the 5 th lens group relative to the 2 nd lens group becomes large, and therefore the variation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the variation in the center of gravity position of the zoom lens.

In order to obtain the above-described effects, the lower limit value of formula (2) is preferably 0.65, more preferably 0.70. The upper limit of the formula (2) is preferably 1.70, more preferably 1.60.

1-3-3. formula (3)

0.90＜β3t/β3w/(β2t/β2w)＜1.75·····(3)

Wherein the content of the first and second substances,

β 2 w: transverse magnification of 2 nd lens group at infinity focusing at wide-angle end

β 2 t: transverse power of 2 nd lens group at infinity focusing at telephoto end

β 3 w: lateral magnification of the 3 rd lens group at infinity focusing at wide-angle end

β 3 t: lateral power of 3 rd lens group at infinity focusing at telephoto end

The above expression (3) is a mathematical expression which defines a ratio of lateral power ratios of the 2 nd lens group and the 3 rd lens group in the zoom lens when the zoom lens is zoomed from the wide-angle end to the telephoto end. Satisfying equation (3) can make each lateral magnification of the 2 nd lens group and the 3 rd lens group appropriate, define a movement amount while securing a zoom ratio of the zoom lens, and reduce variation in the center of gravity position of the zoom lens.

On the other hand, if the value of expression (3) is equal to or less than the lower limit value, the lateral magnification ratio of the 2 nd lens group is too large relative to the lateral magnification ratio of the 3 rd lens group, so that the moving amount of the 2 nd lens group becomes large, and the fluctuation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens. On the other hand, if the value of expression (3) is equal to or greater than the upper limit value, the lateral magnification ratio of the 3 rd lens group is too large relative to the lateral magnification ratio of the 2 nd lens group, and therefore the amount of movement of the 3 rd lens group becomes large, and the fluctuation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens.

In order to obtain the above-described effects, the lower limit value of formula (3) is preferably 1.00, more preferably 1.10. The upper limit of formula (3) is preferably 1.65, more preferably 1.60.

1-3-4. formula (4)

0.75＜β4t/β4w/(β2t/β2w)＜1.30·····(4)

Wherein the content of the first and second substances,

β 2 w: transverse magnification of 2 nd lens group at infinity focusing at wide-angle end

β 2 t: transverse power of 2 nd lens group at infinity focusing at telephoto end

β 4 w: transverse magnification of the 4 th lens group at infinity focusing at wide-angle end

β 4 t: lateral power of 4 th lens group at infinity focusing at telephoto end

The above expression (4) is a mathematical expression which defines a ratio of lateral power ratios of the 2 nd lens group and the 4 th lens group in the zoom lens when the zoom lens is zoomed from the wide-angle end to the telephoto end. Satisfying equation (4) makes it possible to adjust the respective lateral magnifications of the 2 nd lens group and the 4 th lens group, to define the movement amount while securing the zoom ratio of the zoom lens, and to reduce the variation in the center of gravity position of the zoom lens.

On the other hand, if the value of expression (4) is equal to or less than the lower limit value, the lateral magnification ratio of the 2 nd lens group is too large relative to the lateral magnification ratio of the 4 th lens group, so that the moving amount of the 2 nd lens group becomes large, and the fluctuation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens. On the other hand, if the value of expression (4) is equal to or greater than the upper limit value, the lateral magnification ratio of the 4 th lens group is too large relative to the lateral magnification ratio of the 2 nd lens group, and therefore the amount of movement of the 4 th lens group becomes large, and the fluctuation of the barycentric position at the time of magnification change becomes large. Therefore, it is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens.

In order to obtain the above-described effects, the lower limit value of formula (4) is preferably 0.76, more preferably 0.77. The upper limit of formula (4) is preferably 1.20, more preferably 1.00.

1-3-5, formula (5)

Nd2n＜1.80·····(5)

Wherein the content of the first and second substances,

nd2 n: refractive index of negative lens disposed closest to object side among at least 1 negative lens included in the 2 nd lens group at d-line

The above expression (5) is a mathematical expression for specifying the refractive index at the d-line of the most object-side negative lens among at least 1 negative lens included in the 2 nd lens group. The specific gravity of the lens has the following tendency: the higher the refractive index of the glass material, the greater the specific gravity of the lens. Satisfying equation (5) can reduce the weight of the 2 nd lens group and reduce the variation in the position of the center of gravity of the zoom lens.

On the other hand, if the value of expression (5) is equal to or greater than the upper limit value, it is difficult to reduce the weight of the 2 nd lens group, and the variation in the position of the center of gravity of the zoom lens becomes large. In order to obtain the above-described effects, the upper limit value of formula (5) is preferably 1.78, and more preferably 1.76.

In terms of well correcting the curvature of field, the lower limit value of the formula (5) is preferably 1.40, more preferably 1.50, and further preferably 1.55.

1-3-6, formula (6)

0.10＜|f2|/f1＜0.40·····(6)

Wherein the content of the first and second substances,

f 1: focal length of the 1 st lens group

f 2: focal length of the 2 nd lens group

The above expression (6) is a mathematical expression for specifying the ratio of the focal length of the 2 nd lens group to the focal length of the 1 st lens group. By satisfying the formula (6), it is possible to achieve both correction of each aberration and shortening of the total optical length, and the zoom lens can be miniaturized.

On the other hand, if the value of the expression (6) is equal to or less than the lower limit, the refractive power of the 1 st lens group is weak with respect to the refractive power of the 2 nd lens group, and the telephoto range is weak, so that it is difficult to shorten the total optical length. Therefore, this zoom lens is not preferable from the viewpoint of downsizing. On the other hand, if the value of expression (6) is equal to or greater than the upper limit value, the optical power of the 1 st lens group is too strong with respect to the optical power of the 2 nd lens group, and distortion aberration at the wide-angle end, spherical aberration at the telephoto end, and axial chromatic aberration are not easily corrected, which is not preferable.

In order to obtain the above-described effects, the lower limit value of formula (6) is preferably 0.15, and more preferably 0.20. The upper limit of the formula (6) is preferably 0.35, more preferably 0.30.

1-3-7, formula (7)

1.50＜β3t/β3w＜2.50·····(7)

Wherein the content of the first and second substances,

β 3 w: lateral magnification of the 3 rd lens group at infinity focusing at wide-angle end

β 3 t: lateral power of 3 rd lens group at infinity focusing at telephoto end

The above expression (7) is a mathematical expression for specifying the lateral power ratio of the 3 rd lens group when the zoom lens is zoomed from the wide-angle end to the telephoto end. Satisfying equation (7) can achieve both sufficient zoom action and shortening of the total optical length, and can achieve miniaturization of the zoom lens.

On the other hand, if the value of expression (7) is equal to or less than the lower limit value, the lateral power ratio of the 3 rd lens group becomes small, and it is difficult to secure a sufficient power ratio. On the other hand, if the value of expression (7) is the upper limit value or more, the lateral magnification ratio of the 3 rd lens group becomes large and thus the moving amount of the 3 rd lens group increases. Therefore, the total optical length is long, which is not preferable from the viewpoint of downsizing the zoom lens.

In order to obtain the above-described effects, the lower limit value of formula (7) is preferably 1.60, more preferably 1.70. The upper limit of the formula (7) is preferably 2.40, more preferably 2.30.

1-3-8, formula (8)

0.30＜|f2|/fw＜1.00·····(8)

Wherein the content of the first and second substances,

f 2: focal length of the 2 nd lens group

fw: a focal length of the zoom lens at infinity focusing at a wide-angle end

The above expression (8) is a mathematical expression which specifies a ratio of the focal length of the 2 nd lens group to the focal length of the zoom lens at the time of infinity focusing at the wide-angle end. By satisfying equation (8), it is possible to achieve both correction of each aberration and downsizing of the zoom lens.

On the other hand, if the value of expression (8) is equal to or less than the lower limit, the optical power of the 2 nd lens group becomes too strong, and it becomes difficult to correct curvature of field and distortion aberration at the wide-angle end, which is not preferable. On the other hand, if the value of expression (8) is equal to or greater than the upper limit value, the optical focus of the 2 nd lens group is too weak, and the amount of movement of the 2 nd lens group at the time of magnification change needs to be increased in order to achieve a predetermined magnification change ratio, so the total optical length becomes longer. Therefore, this zoom lens is not preferable from the viewpoint of downsizing.

In order to obtain the above-described effects, the lower limit value of formula (8) is preferably 0.40, and more preferably 0.50. The upper limit of formula (8) is preferably 0.90, more preferably 0.80.

1-3-9, formula (9)

0.50＜f1/ft＜2.00·····(9)

Wherein the content of the first and second substances,

f 1: focal length of the 1 st lens group

ft: focal length of the zoom lens at infinity focusing at telephoto end

The above expression (9) is a mathematical expression which specifies the ratio of the focal length of the 1 st lens group to the focal length of the zoom lens at the time of infinity focusing at the telephoto end. By satisfying equation (9), it is possible to achieve both correction of various aberrations and downsizing of the zoom lens.

On the other hand, if the value of expression (9) is equal to or less than the lower limit, the optical power of the 1 st lens group becomes too strong, and it becomes difficult to correct spherical aberration and axial chromatic aberration at the telephoto end, which is not preferable. On the other hand, if the value of the formula (9) is not less than the upper limit value, the optical focus of the 1 st lens group is too weak, and it is difficult to shorten the total optical length at the telephoto end, which is not preferable.

In order to obtain the above-described effects, the lower limit value of formula (9) is preferably 0.70, and more preferably 0.90. The upper limit of formula (9) is preferably 1.70, more preferably 1.40.

1-3-10, formula (10)

0.50＜f4/f2＜3.50·····(10)

Wherein the content of the first and second substances,

f 2: focal length of the 2 nd lens group

f 4: focal length of the 4 th lens group

The above expression (10) is a mathematical expression for specifying the ratio of the focal length of the 4 th lens group to the focal length of the 2 nd lens group. By satisfying the formula (10), it is possible to achieve both correction of each aberration and downsizing of the zoom lens.

On the other hand, if the value of the formula (10) is less than or equal to the lower limit, the optical power of the 4 th lens group is too strong with respect to the 2 nd lens group, and it is difficult to correct spherical aberration, astigmatism, and curvature of field, which is not preferable. On the other hand, if the value of expression (10) is equal to or greater than the upper limit value, the optical focus of the 4 th lens group is too weak with respect to the 2 nd lens group, the 4 th lens group becomes large, and the diameter of the lens barrel becomes large, which is not preferable. Further, when the 4 th lens group is set as the focus adjustment group, the moving amount of the 4 th lens group at the time of focusing becomes large, and therefore it is difficult to shorten the total optical length.

In order to obtain the above-described effects, the lower limit value of formula (10) is preferably 1.00, more preferably 1.50. The upper limit of the formula (10) is preferably 3.00, more preferably 2.50.

1-3-11, formula (11)

4.55＜|f5|/f3＜7.10·····(11)

Wherein the content of the first and second substances,

f 3: focal length of the 3 rd lens group

f 5: focal length of the 5 th lens group

The above expression (11) is a mathematical expression for specifying a ratio of the focal length of the 5 th lens group to the focal length of the 3 rd lens group. By satisfying equation (11), it is possible to achieve both correction of each aberration and downsizing of the zoom lens.

On the other hand, if the value of the formula (11) is equal to or less than the lower limit value, the optical power of the 5 th lens group is too strong with respect to the 3 rd lens group, and it is difficult to correct spherical aberration, astigmatism, and curvature of field, which is not preferable. On the other hand, if the value of expression (11) is equal to or greater than the upper limit value, the optical power of the 3 rd lens group is too strong with respect to the 5 th lens group, making it difficult to correct spherical aberration and to achieve both correction of various aberrations and downsizing of the zoom lens.

In order to obtain the above-described effects, the lower limit value of formula (11) is preferably 4.70, more preferably 4.85. The upper limit of formula (11) is preferably 7.00, more preferably 6.90.

2. Image pickup apparatus

Next, an imaging device according to the present invention will be described. An imaging device according to the present invention includes the zoom lens according to the present invention and an imaging element that converts an optical image formed by the zoom lens into an electric signal. Further, the image pickup element is preferably disposed on the image side of the zoom lens.

Here, the imaging element and the like are not particularly limited, and a solid-state imaging element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal oxide semiconductor) sensor may be used. The imaging device according to the present invention is suitable for imaging devices using these solid-state imaging elements, such as digital cameras and video cameras. The imaging device can be applied to various imaging devices such as a single lens reflex camera, a mirrorless single lens camera, a digital camera, a monitoring camera, a vehicle-mounted camera, and a drone-mounted camera. Further, these image pickup apparatuses may be interchangeable lens type image pickup apparatuses, or may be fixed lens type image pickup apparatuses in which a lens is fixed to a housing. The zoom lens according to the present invention is particularly suitable as a zoom lens of an image pickup apparatus equipped with an image pickup device having a large size such as a full size. The zoom lens is small and lightweight as a whole, and has high optical performance, and therefore, when used as a zoom lens for such an imaging device, a high-quality captured image can be obtained.

Fig. 17 is a diagram schematically showing an example of the configuration of the imaging apparatus 1. The camera 2 includes a detachable zoom lens 3, an image pickup device 21(CCD sensor or CMOS sensor) disposed on an image plane IP of the zoom lens 3, and a cover glass CG disposed on the object side of the image pickup device 21. The zoom lens 3 has an aperture stop 31.

Next, examples are shown and the present invention is specifically explained. However, the present invention is not limited to the following examples.

[ example 1]

(1) Optical construction

Fig. 1 is a sectional view of a zoom lens according to embodiment 1 of the present invention in infinity focusing at a wide angle end, an intermediate focal length, and a telephoto end. The zoom lens is composed of, in order from an object side, a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, a 3 rd lens group G3 having positive power, a 4 th lens group G4 having negative power, and a 5 th lens group G5 having positive power.

Upon zooming from the wide-angle end to the telephoto end, the 1 st lens group G1 is fixed with respect to the image plane without moving, the 2 nd lens group G2 is moved toward the image side, the 3 rd lens group G3 is moved toward the object side, the 4 th lens group G4 is first moved toward the object side and then moved toward the image side, and the 5 th lens group G5 is moved toward the object side. In addition, upon zooming, the 3 rd lens group G3 and the 5 th lens group G5 move in a different direction from the 2 nd lens group G2 with the same trajectory.

Upon focusing from an infinity object to a close object, the 4 th lens group G4 moves along the optical axis.

The aperture stop S is disposed adjacent to the object side of the 3 rd lens group G3.

The structure of each lens group will be described below.

The 1 st lens group G1 is composed of a cemented lens in which a negative meniscus lens having a convex shape on the object side and a positive meniscus lens are cemented in this order from the object side.

The 2 nd lens group G2 is composed of, in order from the object side, a negative meniscus lens, a biconcave lens, a biconvex lens, and a negative meniscus lens having a concave shape on the object side.

The 3 rd lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, and a cemented lens in which a negative meniscus lens having a convex shape on the object side and a biconvex lens are cemented.

The 4 th lens group G4 is formed of a negative meniscus lens having a convex object side.

The 5 th lens group G5 is composed of a biconcave lens and a biconvex lens in order from the object side.

In fig. 1, "IP" denotes an image plane, specifically, an imaging plane of a solid-state imaging device such as a CCD sensor or a CMOS sensor, or a thin film plane of a silver halide thin film. On the object side of the image plane IP, a parallel flat plate having no substantial optical power, such as a protective glass CG, is provided. In fig. 1, the lenses constituting each lens group are not given any reference numerals. These points are the same in the cross-sectional views of the lenses shown in the other embodiments, and therefore, the description thereof will be omitted.

(2) Numerical example

Next, a numerical example of the zoom lens to which specific numerical values are applied will be described. Hereinafter, "lens data", "various specification tables", "variable intervals", "aspherical surface coefficients", and "lens group data" are shown. The values of the respective formulae (table 1) are shown in a summary manner after example 4.

In (lens data), "surface number" indicates the number of lens surfaces counted from the object side, "R" indicates the radius of curvature of the lens surface, "D" indicates the lens wall thickness or air space on the optical axis, "Nd" indicates the refractive index at the D-line (wavelength λ 587.6nm), and "ABV" indicates the abbe number at the D-line. In the column of "surface number", ASPH "added after the surface number indicates that the lens surface is an aspherical surface, and STOP" indicates that the surface is an aperture STOP. In the column of "D", the terms "D (3)", "D (12)", and the like mean that the interval on the optical axis of the lens surface is a variable interval that changes when the magnification is changed. In addition, the column of the curvature radius "0.0000" means infinity, meaning that the lens surface is a plane.

In (various specification tables), "F" denotes a focal length of the zoom lens, "Fno" denotes an F value, "ω" denotes a half angle of view, "Y" denotes an image height, and "TL" denotes an optical total length. Values at the wide-angle end, the intermediate focal length, and the telephoto end are respectively indicated.

In (variable interval), values at the time of infinity focusing at the wide-angle end, the intermediate focal length, and the telephoto end are indicated, respectively.

The (aspherical surface coefficient) represents an aspherical surface coefficient when an aspherical surface shape is defined as follows. Where x is a displacement amount with respect to the reference surface in the optical axis direction, r is a paraxial radius of curvature, H is a height with respect to the optical axis in a direction perpendicular to the optical axis, k is a conic coefficient, and An is An aspheric coefficient of n-th order. In addition, in the table of "aspherical surface coefficients", the "E ± XX" is expressed by an index notation, which means "× 10^±XX”。

[ numerical formula 1]

The matters in the tables are the same in the tables shown in the other embodiments, and therefore, the description thereof will be omitted below.

Fig. 2, 3, and 4 show longitudinal aberration diagrams of the zoom lens at infinity focusing at the wide angle end, the intermediate focal length, and the telephoto end. The longitudinal aberration diagrams shown in the respective diagrams are spherical aberration (mm), astigmatism (mm), and distortion aberration (%) in this order from the left side of the diagram. In the spherical aberration diagram, the solid line represents the spherical aberration at the d-line (wavelength 587.6nm), the broken line represents the spherical aberration at the F-line (wavelength 486.1nm), and the dotted line represents the spherical aberration at the C-line (wavelength 656.3 nm). In the astigmatism diagram, the vertical axis represents the image height (Y), the horizontal axis represents defocus, the solid line represents the sagittal image plane (S) of the d-line, and the broken line represents the meridional image plane (T) of the d-line. In the distortion aberration diagram, the vertical axis represents the image height (Y), and the horizontal axis represents the distortion aberration. These matters are the same for each aberration diagram shown in other embodiments, and therefore, the explanation thereof is omitted below.

(lens data)

(various specification tables)

	Wide angle end	Intermediate (II)	Telephoto end
				f	28.8419	44.3139	72.7392
Fno	4.1128	4.1402	4.1053
				ω	37.8908	26.1810	15.9258
Y	20.2060	21.4087	21.6330
				TL	130.000	130.000	130.000

(variable Interval)

	Wide angle end	Intermediate (II)	Telephoto end
				D(3)	0.9000	7.8954	15.2490
D(12)	27.4467	14.6673	2.2598
				D(20)	1.8078	4.2359	9.9958
D(22)	16.5562	14.1281	8.3682
				D(26)	24.5619	30.3458	35.3998

(aspherical surface coefficient)

(lens group data)

Group of	Focal length
		G1	84.44
G2	-20.02
		G3	23.78
G4	-43.35
		G5	150.55

[ example 2]

(1) Optical construction

Fig. 5 is a sectional view of a zoom lens according to embodiment 2 of the present invention in infinity focusing at the wide-angle end, intermediate focal length, and telephoto end. The zoom lens is composed of, in order from an object side, a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, a 3 rd lens group G3 having positive power, a 4 th lens group G4 having negative power, and a 5 th lens group G5 having positive power.

Upon zooming from the wide-angle end to the telephoto end, the 1 st lens group G1 is fixed with respect to the image plane without moving, the 2 nd lens group G2 is moved toward the image side, the 3 rd lens group G3 is moved toward the object side, the 4 th lens group G4 is first moved toward the object side and then moved toward the image side, and the 5 th lens group G5 is moved toward the object side.

Upon focusing from an infinity object to a close object, the 4 th lens group G4 moves along the optical axis.

The aperture stop S is disposed adjacent to the object side of the 3 rd lens group G3.

The structure of each lens group will be described below.

The 1 st lens group G1 is composed of a cemented lens in which a negative meniscus lens having a convex shape on the object side and a positive meniscus lens are cemented in this order from the object side.

The 2 nd lens group G2 is composed of, in order from the object side, a negative meniscus lens, a biconcave lens, a biconvex lens, and a negative meniscus lens having a concave shape on the object side.

The 3 rd lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, and a cemented lens in which a negative meniscus lens having a convex shape on the object side and a biconvex lens are cemented.

The 4 th lens group G4 is formed of a negative meniscus lens having a convex object side.

The 5 th lens group G5 is composed of a biconcave lens and a biconvex lens in order from the object side.

(2) Numerical example

Next, as numerical examples to which specific numerical values are applied in the zoom lens, there are shown "lens data", "various specification tables", "variable intervals", "aspherical coefficients", and "lens group data". Fig. 6, 7, and 8 show longitudinal aberration diagrams of the zoom lens at infinity focusing at the wide angle end, the intermediate focal length, and the telephoto end.

(lens data)

Noodle numbering	R	D	Nd	ABV
						1	43.6206	1.5000	1.84666	23.78
2	29.1642	9.7000	1.72916	54.67
					3	211.9514	D(3)
4ASPH	338.8778	0.2000	1.53610	41.21
					5	140.3579	1.1000	1.72916	54.67
6	16.8372	8.2077
					7	-56.6957	1.0000	1.79952	42.22
8	47.3109	0.1000
					9	34.9299	6.2583	1.85025	30.06
10	-45.5169	1.3323
					11	-25.7327	1.1000	1.53996	59.46
12	-260.9036	D(12)
					13Stop	0.0000	1.0000
14ASPH	23.5767	4.1015	1.59201	67.02
					15ASPH	-148.5272	3.1447
16	59.2940	1.8766	1.48749	70.44
					17	208.4901	0.1993
18	40.9023	1.0000	1.80610	40.73
					19	14.1474	8.3877	1.49700	81.61
20	-31.5958	D(20)
					21ASPH	120.4655	1.1000	1.59201	67.02
22ASPH	21.3635	D(22)
					23	-41.6645	1.2000	1.66680	33.05
24	265.6613	1.8599
					25	71.8601	5.6514	1.65160	58.55
26	-46.2660	D(26)
					27	0.0000	2.5000	1.51680	64.20
28	0.0000	1.0000
					29	0.0000

(various specification tables)

	Wide angle end	Intermediate (II)	Telephoto end
				f	28.8361	44.3099	72.7320
Fno	4.0833	4.2061	4.1269
				ω	37.8973	26.2598	15.9475
Y	20.2060	21.4087	21.6330
				TL	130.000	130.000	130.000

(variable Interval)

	Wide angle end	Intermediate (II)	Telephoto end
				D(3)	0.9000	6.3702	13.8327
D(12)	27.4863	14.4033	1.6217
				D(20)	2.2215	4.1491	9.5833
D(22)	12.9683	13.4442	7.4664
				D(26)	22.9045	28.1138	33.9765

(aspherical surface coefficient)

Noodle numbering	K	A4	A6	A8	A10
						4	1.00000E+00	5.98733E-06	-2.42232E-09	-5.90416E-12	2.53587E-14
14	3.09547E-01	-7.15932E-06	-5.93023E-08	9.23203E-10	-5.81614E-12
						15	0.00000E+00	1.38775E-05	-5.39596E-08	9.99946E-10	-6.34338E-12
21	-2.02913E+01	-2.53852E-05	6.78813E-08	2.47336E-10	7.35212E-13
						22	1.14267E-02	-1.65687E-05	4.22860E-08	1.03838E-10	2.85655E-13

(lens group data)

Group of	Focal length
		G1	80.93
G2	-20.22
		G3	23.83
G4	-44.05
		G5	163.66

[ example 3]

(1) Optical construction

Fig. 9 is a sectional view of a zoom lens according to embodiment 3 of the present invention in infinity focusing at the wide-angle end, intermediate focal length, and telephoto end. The zoom lens is composed of, in order from an object side, a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, a 3 rd lens group G3 having positive power, a 4 th lens group G4 having negative power, a 5 th lens group G5 having negative power, and a 6 th lens group G6 having positive power.

Upon zooming from the wide-angle end to the telephoto end, the 1 st lens group G1 is fixed with respect to the image plane without moving, the 2 nd lens group G2 is moved toward the image side, the 3 rd lens group G3 is moved toward the object side, the 4 th lens group G4 is moved toward the object side, the 5 th lens group G5 is moved toward the object side, and the 6 th lens group G6 is moved toward the object side.

Upon focusing from an infinity object to a close object, the 4 th lens group G4 moves along the optical axis.

The aperture stop S is disposed adjacent to the object side of the 3 rd lens group G3.

The structure of each lens group will be described below.

The 1 st lens group G1 is composed of a cemented lens in which a negative meniscus lens having a convex shape on the object side and a positive meniscus lens are cemented in this order from the object side.

The 2 nd lens group G2 is composed of, in order from the object side, a negative meniscus lens, a biconcave lens, a biconvex lens, and a negative meniscus lens having a concave shape on the object side.

The 3 rd lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a convex positive meniscus lens on the object side, and a cemented lens in which a convex negative meniscus lens and a biconvex lens on the object side are cemented.

The 4 th lens group G4 is composed of a biconcave lens.

The 5 th lens group G5 is formed of a negative meniscus lens having a concave object side.

The 6 th lens group G6 is composed of a biconvex lens.

(2) Numerical example

Next, as numerical examples to which specific numerical values are applied in the zoom lens, there are shown "lens data", "various specification tables", "variable intervals", "aspherical coefficients", and "lens group data". Fig. 10, 11, and 12 show longitudinal aberration diagrams of the zoom lens at infinity focusing at the wide angle end, the intermediate focal length, and the telephoto end.

(lens data)

(various specification tables)

	Wide angle end	Intermediate (II)	Telephoto end
				f	28.8400	44.3100	77.2417
Fno	4.4078	4.3636	4.5054
				ω	37.8977	26.4518	15.2674
Y	20.2060	21.4087	21.6330
				TL	140.170	140.170	140.170

(variable Interval)

	Wide angle end	Intermediate (II)	Telephoto end
				D(3)	0.9000	8.4515	14.0365
D(12)	30.6905	16.6590	1.1333
				D(20)	2.3398	3.6644	9.4586
D(22)	13.3101	14.3464	3.4960
				D(24)	10.8331	5.7620	6.2517
D(26)	17.5000	26.6901	41.1974

(aspherical surface coefficient)

Noodle numbering	K	A4	A6	A8	A10
						4	10.00000E-01	5.13382E-06	-7.00902E-10	-8.03582E-12	2.14741E-14
14	4.65713E-01	-4.77138E-06	-5.97403E-08	7.25836E-10	-3.26740E-12
						15	0.00000E+00	8.81851E-06	-5.28576E-08	8.45021E-10	-3.73875E-12
21	-1.11036E+05	-2.23784E-05	6.39109E-08	-1.06215E-09	1.11899E-11
						22	5.18849E-01	-9.84438E-06	2.71436E-08	-8.81225E-10	7.85457E-12

(lens group data)

Group of	Focal length
		G1	84.19
G2	-20.07
		G3	24.12
G4	-41.82
		G5	-120.58
G6	63.64

[ example 4]

(1) Optical construction

Fig. 13 is a cross-sectional view of a zoom lens system according to embodiment 4 of the present invention in infinity focusing at the wide-angle end and the telephoto end. The zoom lens is composed of, in order from an object side, a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, a 3 rd lens group G3 having positive power, a 4 th lens group G4 having negative power, and a 5 th lens group G5 having positive power.

Upon zooming from the wide-angle end to the telephoto end, the 1 st lens group G1 is fixed with respect to the image plane without moving, the 2 nd lens group G2 is moved toward the image side, the 3 rd lens group G3 is moved toward the object side, the 4 th lens group G4 is first moved toward the object side and then moved toward the image side, and the 5 th lens group G5 is moved toward the object side.

Upon focusing from an infinity object to a close object, the 4 th lens group G4 moves along the optical axis.

The aperture stop S is disposed adjacent to the object side of the 3 rd lens group G3.

The structure of each lens group will be described below.

The 1 st lens group G1 is composed of a cemented lens in which a negative meniscus lens having a convex shape on the object side and a positive meniscus lens are cemented in this order from the object side.

The 2 nd lens group G2 is composed of, in order from the object side, a negative meniscus lens, a biconcave lens, a biconvex lens, and a negative meniscus lens having a concave shape on the object side.

The 3 rd lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a positive meniscus lens, and a cemented lens in which a negative meniscus lens and a biconvex lens having a convex shape on the object side are cemented.

The 4 th lens group G4 is formed of a negative meniscus lens having a convex object side.

The 5 th lens group G5 is composed of a biconcave lens and a biconvex lens in order from the object side.

(2) Numerical example

Next, as numerical examples to which specific numerical values are applied in the zoom lens, there are shown "lens data", "various specification tables", "variable intervals", "aspherical coefficients", and "lens group data". Fig. 14, 15, and 16 show longitudinal aberration diagrams of the zoom lens at infinity focusing at the wide angle end, the intermediate focal length, and the telephoto end.

(lens data)

(various specification tables)

	Wide angle end	Intermediate (II)	Telephoto end
				f	28.8359	44.3130	72.7244
Fno	4.0939	4.0016	3.9376
				ω	37.9013	26.3367	15.9533
Y	20.2060	21.4087	21.6330
				TL	130.000	130.000	130.000

(variable Interval)

	Wide angle end	Intermediate (II)	Telephoto end
				D(3)	0.9000	10.1487	18.3918
D(12)	28.0453	14.6530	1.8027
				D(20)	1.9434	3.9552	8.1997
D(22)	16.9047	11.0041	3.8517
				D(26)	21.4551	29.4876	37.0026

(aspherical surface coefficient)

Noodle numbering	K	A4	A6	A8	A10
						4	1.00000E+00	7.65705E-06	-5.39614E-10	-1.56730E-11	4.65804E-14
14	3.39394E-01	-6.86626E-06	-5.42233E-08	9.15665E-10	-7.68331E-12
						15	0.00000E+00	1.70457E-05	-4.71781E-08	9.32692E-10	-8.15032E-12
21	2.77018E+00	-2.40136E-05	6.17240E-08	6.37727E-11	3.27147E-12
						22	-1.12409E-01	-1.84230E-05	1.33924E-08	-9.77149E-11	1.99878E-12

(lens group data)

Group of	Focal length
		G1	91.18
G2	-21.14
		G3	23.26
G4	-39.73
		G5	130.36

[ Table 1]

Formula (II)		Example 1	Example 2	Example 3	Example 4
						Formula (1)	|M3/M2|	0.76	1.00	1.25	0.50
Formula (2)	|M5/M2|	0.76	0.86	1.46	0.89
						Formula (3)	β3t/β3w/(β2t/β2w)	1.34	1.35	1.54	1.25
Formula (4)	β4t/β4w/(β2t/β2w)	0.79	0.81	0.97	0.79
						Formula (5)	Nd2n	1.73	1.73	1.73	1.73
Formula (6)	|f2|/f1	0.24	0.25	0.24	0.23
						Formula (7)	β3t/β3w	1.84	1.83	2.06	1.80
Formula (8)	|f2|/fw	0.69	0.70	0.70	0.73
						Formula (9)	f1/ft	1.16	1.11	1.09	1.25
Formula (10)	f4/f2	2.17	2.18	2.08	1.88
						Formula (11)	|f5|/f3	6.33	6.87	5.00	5.61

Industrial applicability

The zoom lens according to the present invention can be suitably used as an imaging optical system of an imaging device such as a film camera, a digital camera, and a digital video camera.

Claims (12)

1. A zoom lens is provided, which has a zoom lens with a lens unit,

the zoom lens includes, in order from an object side: a 1 st lens group having positive power, a 2 nd lens group having negative power, a 3 rd lens group having positive power, a 4 th lens group having negative power, and a 5 th lens group,

in the zooming, the interval between adjacent lens groups is changed, the 1 st lens group is fixed relative to the image surface, and the 3 rd lens group and the 5 th lens group move in a direction different from the 2 nd lens group,

the zoom lens satisfies the following formula:

0.01＜|M3/M2|＜1.34·····(1)

0.61＜|M5/M2|＜1.81·····(2)

wherein the content of the first and second substances,

m2: a moving amount of the 2 nd lens group from a wide angle end to a telephoto end

M3: a moving amount of the 3 rd lens group from a wide angle end to a telephoto end

M5: a moving amount of the 5 th lens group from a wide-angle end to a telephoto end.

2. The zoom lens according to claim 1, wherein,

satisfies the following formula:

0.90＜β3t/β3w/(β2t/β2w)＜1.75·····(3)

0.75＜β4t/β4w/(β2t/β2w)＜1.30·····(4)

wherein the content of the first and second substances,

β 2 w: lateral magnification of the 2 nd lens group at infinity focusing at wide-angle end

β 2 t: lateral power of the 2 nd lens group at infinity focusing at telephoto end

β 3 w: lateral magnification of the 3 rd lens group at infinity focusing at wide-angle end

β 3 t: lateral power of the 3 rd lens group at infinity focusing at telephoto end

β 4 w: lateral magnification of the 4 th lens group at infinity focusing at wide-angle end

β 4 t: a lateral power of the 4 th lens group at the time of infinity focusing at a telephoto end.

3. The zoom lens according to claim 1 or claim 2,

satisfies the following formula:

Nd2n＜1.80·····(5)

wherein the content of the first and second substances,

nd2 n: a refractive index of a negative lens disposed closest to the object side among at least 1 negative lens included in the 2 nd lens group at a d-line.

4. The zoom lens according to any one of claim 1 to claim 3,

satisfies the following formula:

0.10＜|f2|/f1＜0.40·····(6)

wherein the content of the first and second substances,

f 1: focal length of the 1 st lens group

f 2: focal length of the 2 nd lens group.

5. The zoom lens according to any one of claim 1 to claim 4,

satisfies the following formula:

1.50＜β3t/β3w＜2.50·····(7)

wherein the content of the first and second substances,

β 3 w: lateral magnification of the 3 rd lens group at infinity focusing at wide-angle end

β 3 t: lateral power of the 3 rd lens group at the time of infinity focusing at the telephoto end.

6. The zoom lens according to any one of claim 1 to claim 5,

satisfies the following formula:

0.30＜|f2|/fw＜1.00·····(8)

wherein the content of the first and second substances,

f 2: focal length of the 2 nd lens group

fw: a focal length of the zoom lens at infinity focusing at the wide-angle end.

7. The zoom lens according to any one of claim 1 to claim 6,

satisfies the following formula:

0.50＜f1/ft＜2.00·····(9)

wherein the content of the first and second substances,

f 1: focal length of the 1 st lens group

ft: the focal length of the zoom lens at the time of infinity focusing at the telephoto end.

8. The zoom lens according to any one of claim 1 to claim 7,

satisfies the following formula:

0.50＜f4/f2＜3.50·····(10)

wherein the content of the first and second substances,

f 2: focal length of the 2 nd lens group

f 4: focal length of the 4 th lens group.

9. The zoom lens according to any one of claim 1 to claim 8,

the 3 rd lens group has a positive lens at least 1 side of which is aspherical.

10. The zoom lens according to any one of claim 1 to claim 9,

the 4 th lens group moves along the optical axis upon focusing.

11. The zoom lens according to any one of claim 1 to claim 10,

the 4 th lens group is composed of only 1 lens component.

12. An imaging device is characterized by comprising:

a zoom lens according to any one of claims 1 to 11; and

and an image pickup element that converts an optical image formed by the zoom lens into an electric signal on an image side of the zoom lens.

Images