JP6646251B2 - Zoom lens and imaging device having the same - Google Patents

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, for example, an image pickup apparatus using an image pickup element such as a video camera, an electronic still camera, a broadcast camera, a surveillance camera, or a camera using a silver halide film. It is suitable for the device.

  2. Description of the Related Art In recent years, an imaging optical system used in an imaging apparatus has been required to be a high-performance zoom lens with a high zoom ratio while the entire system is small. In addition, it is demanded to have an auto focus (automatic focus detection) mechanism because it is easy to shoot a moving image as well as a still image. As one of zoom lenses that meet these requirements, a so-called rear focus type zoom lens that performs focusing by moving a lens group other than the first lens group on the object side is known.

  Generally, in a rear focus type zoom lens, the effective diameter of the first lens group is smaller than that of a zoom lens that performs focusing by moving the first lens group, and it is easy to reduce the size of the entire lens system. Further, since focusing can be performed by a small and lightweight lens group, the driving force of the focusing lens group can be reduced, the focus driving mechanism and the like can be simplified, and quick focusing can be performed.

  Conventionally, there have been proposed various zoom lenses using a rear focus system in which a focus lens group is small and lightweight (Patent Documents 1 to 3). Patent Documents 1 and 2 disclose a zoom system including a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a negative refractive power. In the lens, focusing is performed by the fourth lens group. Particularly, in Patent Document 1, the fourth lens group for focusing is constituted by a cemented lens (one lens component) in which a positive lens and a negative lens are cemented.

  In Patent Document 3, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fourth lens group having a positive refractive power are described. In the zoom lens composed of five lens groups, focusing is performed by the fourth lens group. Patent Literature 3 discloses a zoom lens in which the fourth lens group is formed of one lens, and quick focusing is easy.

JP 2011-247998 A JP 2012-27261A JP 2012-48199 A

  2. Description of the Related Art A zoom lens used in an imaging apparatus is required to have a compact (small) entire system, facilitate quick focusing, have a small variation in aberrations during focusing, and have high optical performance over the entire object distance. In order to achieve high optical performance over the entire object distance while minimizing the size of the entire system while minimizing aberration fluctuations during focusing, it is important to properly set the lens configuration of the zoom type and zooming and focus lens groups. It is becoming.

  In particular, it is necessary to appropriately set the refractive power of the focus lens group, the lens configuration of the lens group disposed on the image side of the focus lens group, and the like, to obtain appropriate focus sensitivity and effectively perform focusing. Becomes important.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a zoom lens having high optical performance over the entire object distance, and capable of easily performing quick focus, and an imaging apparatus having the same.

The zoom lens according to the present invention includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a negative lens unit arranged in order from the object side to the image side. A zoom lens comprising a fourth lens group having a refractive power and a fifth lens group having a positive refractive power, wherein a distance between adjacent lens groups changes during at least one of zooming and focusing,
During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the third lens group decreases . The distance between the four lens groups changes, and the fourth lens group and the fifth lens group move so that the distance between the fourth lens group and the fifth lens group does not change ;
The fourth lens group includes one negative lens,
At the time of focusing, the fourth lens group moves,
When the focal length of the fourth lens group is f4 and the focal length of the fifth lens group is f5,
7.0 <| f5 / f4 | <20.0
It is characterized by satisfying the following conditional expression.

  ADVANTAGE OF THE INVENTION According to this invention, the zoom lens which has high optical performance over the whole object distance and which is easy to focus quickly is obtained.

(A), (B), (C) Sectional view of a lens at a wide-angle end, an intermediate zoom position, and a telephoto end when focusing on infinity according to the first embodiment of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end when focusing on infinity according to the first embodiment of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end when focusing on an object distance of 1.1 m according to the first embodiment of the present invention. (A), (B), (C) Sectional view of a lens at a wide angle end, an intermediate zoom position, and a telephoto end when focusing on infinity according to a second embodiment of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end when focusing on infinity according to the second embodiment of the present invention (A), (B), (C) Aberration diagrams at a wide-angle end, an intermediate zoom position, and a telephoto end when focusing on an object distance of 1.1 m according to the second embodiment of the present invention. Schematic diagram of main parts of the imaging device of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens according to the present invention includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a negative lens unit arranged in order from the object side to the image side. The fourth lens group has a refractive power and the fifth lens group has a positive refractive power. Then, at least one of zooming and focusing changes the distance between adjacent lens groups. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the fourth lens group and the fifth lens group move. .

  FIGS. 1A, 1B, and 1C are sectional views of a zoom lens according to a first embodiment of the present invention at a wide-angle end (short focal length end), an intermediate zoom position, and a telephoto end (long focal length end). FIG. FIGS. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens according to the first embodiment, respectively, when focused on infinity.

  FIGS. 3A, 3B, and 3C are aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end, respectively, when the zoom lens according to the first embodiment is focused on the object distance of 1.1 m. Here, the object distance is a value when numerical data described later is expressed in units of mm. This is the same in the following embodiments. The first embodiment is a zoom lens having a zoom ratio of about 4.37 and an aperture ratio of about 4.16 to 5.88.

  4A, 4B, and 4C are lens cross-sectional views of the zoom lens according to the second embodiment of the present invention at the wide-angle end, at an intermediate zoom position, and at the telephoto end. FIGS. 5A, 5B, and 5C are aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens according to the second embodiment, respectively, when focused on infinity.

  6A, 6B, and 6C are aberration diagrams at the wide-angle end, an intermediate zoom position, and a telephoto end, respectively, when the zoom lens according to the second embodiment is focused on an object distance of 1.1 m. Example 2 is a zoom lens having a zoom ratio of 4.33 and an aperture ratio of about 4.16 to 5.88. FIG. 7 is a schematic diagram of a main part of a digital still camera (imaging device) including the zoom lens of the present invention.

  The zoom lens of each embodiment is an imaging optical system used for an imaging device such as a silver halide film camera, a digital still camera, a video camera, and a digital video camera. In the lens cross-sectional view, the left is the object side (front) and the right is the image side (rear). In the lens cross-sectional view, if i is the order of the lens groups from the object side, Li is the i-th lens group. SP is a stop (aperture stop).

  IP is an image plane. When used as an imaging optical system of a video camera or a digital still camera, when an imaging surface of an imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is a silver halide film camera, Corresponds to the film surface. Arrows indicate the direction of movement during zooming from the wide-angle end to the telephoto end.

  Each longitudinal aberration diagram represents, from the left, spherical aberration, astigmatism, distortion, and chromatic aberration of magnification. In the diagrams showing the spherical aberration and the chromatic aberration of magnification, the solid line d represents the d line (587.6 nm), and the broken line g represents the g line (435.8 nm). In the graph showing astigmatism, ΔS of the solid line represents a sagittal image plane of the d-line, and ΔM of a broken line represents a meridional image plane of the d-line. Further, the figure showing the distortion shows the distortion at the d-line. Fno is an F number, and ω is a half angle of view (degree).

  The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a third lens unit L3 having a positive refractive power. , A fourth lens unit L4 having a negative refractive power, and a fifth lens unit L5 having a positive refractive power. The back focus BF is relatively long at 0.7 fw to 0.8 fw with respect to the focal length fw of the entire system at the wide angle end.

  During zooming from the wide-angle end to the telephoto end, the interval between the first lens unit L1 and the second lens unit L2 increases, the interval between the second lens unit L2 and the third lens unit L3 decreases, and the fourth lens unit L4 and the fifth lens unit The group L5 moves. In at least one of zooming and focusing, the distance between adjacent lens groups changes. An aperture stop SP is arranged between the second lens unit L2 and the third lens unit L3. During zooming, the first lens unit L1, the second lens unit L2, the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 move. The second lens unit L2 is stationary.

  In the above-described lens type zoom lens, the effective lens beam diameter is likely to be small in a lens group located behind the aperture stop SP and close to the image side. Therefore, if the lens group rearward of the aperture stop and closer to the image side is used as the focusing lens group, the holding mechanism and the driving mechanism are simplified, and the size of the entire system is easily reduced. Further, when the lens configuration of the focus lens group is constituted by one lens, the weight of the focus lens group can be easily reduced.

  If the lens unit having a smaller zooming effect on the image side than the aperture stop SP is the focusing lens unit, the change in image magnification when focusing from infinity to the closest distance can be reduced. This point is optimal when capturing a moving image because the change in the angle of view can be reduced when the subject changes from infinity to close proximity.

  For this reason, in each embodiment, the fourth lens unit L4, which is located behind the aperture stop SP and close to the image side, is used as a focusing lens unit. This reduces the change in image magnification when focusing from infinity to a close position while reducing the size of the focusing lens unit. Upon focusing from infinity to a close distance, the fourth lens L4 moves to the image side. In the above-described lens type zoom lens, by appropriately setting the lens configuration of the fifth lens unit L5, an appropriate focus sensitivity is given to the fourth lens unit L4, and the overall length of the lens is reduced. .

The fourth lens unit L4 includes one negative lens G4n, and the fourth lens unit L4 moves during focusing. The focal length of the fourth lens unit L4 is f4, and the focal length of the fifth lens unit L5 is f5. At this time,
7.0 <| f5 / f4 | <20.0 (1)
The following conditional expression is satisfied.

  Conditional expression (1) is for appropriately setting the focus sensitivity at the time of focusing and reducing aberration fluctuation. When the negative refractive power of the fourth lens unit L4 is increased beyond the upper limit value of the conditional expression (1) (the absolute value of the negative refractive power is increased), the fluctuation of the optical performance during focusing is increased. Further, when the refractive power of the fifth lens unit L5 becomes weak, the overall length of the lens becomes long, and it is difficult to reduce the size of the entire system. Further, when zooming to the wide-angle end, the image plane varies greatly, making it difficult to maintain high optical performance.

  If the refractive power of the fourth lens unit L4 becomes weaker (ie, the absolute value of the negative refractive power becomes smaller) beyond the lower limit value of the conditional expression (1), the focus sensitivity of the fourth lens unit L4 becomes smaller and the focusing becomes smaller. In this case, the movement amount increases, and the overall length of the lens increases. When the positive refractive power of the fifth lens unit L5 becomes strong, the exit pupil becomes too long, and the overall length of the lens increases. Further, the effective lens diameter of the lens group behind the aperture stop SP is increased, and it is difficult to reduce the size and weight of the fourth lens unit L4.

  Further, the position sensitivity of the fourth lens unit L4 and the fifth lens unit L5 increases, and the manufacturing becomes difficult. More preferably, the numerical range of the conditional expression (1) is set as follows.

10.0 <| f5 / f4 | <16.0 (1a)
According to each embodiment, by specifying the lens configuration as described above, it is possible to obtain a zoom lens having a small and lightweight focusing lens group that is optimal for moving images. In each of the embodiments, it is preferable to satisfy at least one of the following conditional expressions in order to obtain high optical performance while having a smaller and lighter focusing.

The focal length of the entire system (zoom lens) at the wide angle end is fw, and the Abbe number of the material of the negative lens G4n is νd4n. The radii of curvature of the object-side lens surface and the image-side lens surface of the negative lens G4n are R4f and R4R, respectively. The fifth lens unit L5 includes a negative lens G5n and a positive lens G5p. The refractive index of the material of the negative lens G5n is nd5n, and the refractive index of the material of the positive lens G5p is nd5p. The focal length of the first lens unit L1 is f1. At the time of image blur correction, the second lens unit L2 moves in a direction including a component perpendicular to the optical axis, and the focal length of the second lens unit L2 is f2. At this time, it is preferable to satisfy at least one of the following conditional expressions.

1.0 <| f4 / fw | <1.5 (2)
νd4n> 50.0 (3)
1.2 <(R4f + R4R) / (R4f-R4R) <4.0 (4)
nd5n> nd5p (5)
2.0 <f1 / fw <2.8 (6)
0.35 <| f2 / fw | <0.65 (7)

  Next, the technical contents of the above-described conditional expressions will be described. Conditional expression (2) is for setting the sensitivity of the focus lens group more appropriately, similarly to conditional expression (1). If the negative refractive power of the fourth lens unit L4 is weakened beyond the upper limit value of the conditional expression (2), the focus sensitivity of the fourth lens unit L4 becomes small, which is not preferable. If the refractive power of the fourth lens unit L4 is increased beyond the lower limit value of the conditional expression (2), the fluctuation of the optical performance at the time of focusing increases.

  Conditional expression (3) is intended to reduce fluctuation of chromatic aberration during focusing. If the Abbe number of the material of the negative lens G4 constituting the fourth lens unit L4 is reduced below the lower limit value of the conditional expression (3), the chromatic aberration at the time of focusing increases, and the optical performance decreases.

  Conditional expression (4) is a shape factor indicating a meniscus shape of the negative lens G4n included in the fourth lens unit L4. If the upper limit of conditional expression (4) is exceeded, the image plane will fluctuate greatly during focusing, making it difficult to form the fourth lens unit L4 with one lens. If the lower limit of conditional expression (4) is exceeded, the fluctuation of coma during focusing will increase, and it will be difficult to configure the fourth lens unit L4 with one lens.

  Conditional expression (5) relates to the refractive indices of the material of the negative lens G5n and the material of the positive lens G5p constituting the fifth lens unit L5. When conditional expression (5) is satisfied, the Petzval sum increases. This is effective in correcting the reduced Petzval sum by increasing the refractive power of each lens surface in order to shorten the entire length of the lens. In addition, it is possible to reduce the occurrence of chromatic aberration of magnification and to maintain good image surface performance (image surface characteristics).

  Conditional expression (6) is for obtaining good optical performance while reducing the size and weight of the entire system. If the positive refractive power of the first lens unit L1 is weakened beyond the upper limit value of the conditional expression (6), the size of the entire system increases. If the positive refractive power of the first lens unit L1 is increased beyond the lower limit of conditional expression (6), chromatic aberration will increase at the telephoto end, and it will be difficult to maintain high optical performance.

  In each embodiment, at the time of image blur correction, the second lens unit L2 is moved so as to have a component in a direction perpendicular to the optical axis. That is, image stabilization is performed.

  Conditional expression (7) is for achieving downsizing of the drive mechanism for image stabilization while maintaining good optical performance during image stabilization at this time. Conditional expression (7) makes the negative refractive power of the second lens unit L2 appropriate for the focal length of the entire system at the wide-angle end. Thereby, the sensitivity of the aberration fluctuation when the second lens unit L2 is moved so as to have a component perpendicular to the optical axis during the image blur correction and the sensitivity of the image position correction are maintained in a well-balanced manner. ing.

  If the negative refractive power of the second lens unit L2 is weakened beyond the upper limit value of the conditional expression (7), the amount of driving in the direction having a vertical component with respect to vibration reduction becomes large, and the driving mechanism becomes large. .

  If the negative refractive power of the second lens unit L2 is increased beyond the lower limit value of the conditional expression (7), a large amount of eccentric aberration is generated during image stabilization, and the optical performance during image stabilization is reduced. Further, the amount of change in the image position with respect to the amount of displacement of the second lens unit L2 (hereinafter, referred to as image stabilization sensitivity) increases. For this reason, the amount of displacement of the second lens unit L2 for obtaining the necessary vibration reduction effect becomes too small, and it becomes difficult to control the amount of displacement electrically or mechanically with high accuracy. More preferably, the numerical ranges of the conditional expressions (2) to (4), (6), and (7) are set as follows.

1.0 <| f4 / fw | <1.2 (2a)
νd4n> 55.0 (3a)
1.3 <(R4f + R4R) / (R4f-R4R) <2.0 (4a)
2.05 <f1 / fw <2.60 (6a)
0.45 <| f2 / fw | <0.60 (7a)

  In each embodiment, the fourth lens unit L4 and the fifth lens unit L5 are moved integrally (with the same movement trajectory) during zooming, but may be moved independently (with different trajectories). In each embodiment, the first lens unit L1 is preferably composed of a positive lens arranged in order from the object side to the image side, and a cemented lens in which a negative lens and a positive lens are cemented. The second lens unit L2 is preferably composed of a cemented lens in which a negative lens and a positive lens are arranged in order from the object side to the image side, and a negative lens. It is preferable that the third lens unit L3 includes a positive lens, a positive lens, a negative lens, a positive lens, and a negative lens arranged in order from the object side to the image side.

  Next, an embodiment of a single-lens reflex camera system (imaging device) using the zoom lens of the present invention will be described with reference to FIG. In FIG. 7, reference numeral 10 denotes a single-lens reflex camera main body, and reference numeral 11 denotes an interchangeable lens equipped with a zoom lens according to the present invention. Reference numeral 12 denotes recording means such as a film or an image sensor for receiving a subject image obtained through the interchangeable lens 11. Reference numeral 13 denotes a finder optical system for observing a subject image from the interchangeable lens 11, and reference numeral 14 denotes a rotating quick return mirror for switching and transmitting the subject image formed by the interchangeable lens 11 to the recording means 12 and the finder optical system 13. is there.

  When observing the subject image with the viewfinder, the subject image formed on the focus plate 15 via the quick return mirror 14 is turned into an erect image by the pentaprism 16, and then enlarged and observed by the eyepiece optical system 17. At the time of photographing, the quick return mirror 14 rotates in the direction of the arrow, and the subject image is formed on the recording means 12 and recorded. Reference numeral 18 denotes a submirror, and 19 denotes a focus detection device.

  As described above, by applying the zoom lens of the present invention to an imaging device such as an interchangeable lens such as a single-lens reflex camera, an imaging device having high optical performance is obtained. Further, the image pickup apparatus of the present invention may be a mirrorless single-lens reflex camera having no quick return mirror 14 or the like, or may be applied to a non-interchangeable lens configuration.

  Hereinafter, specific numerical data corresponding to the first and second embodiments will be described. In each numerical data, i indicates the number of the surface counted from the object side. ri is the radius of curvature of the i-th optical surface (i-th surface). di is the axial distance between the i-th surface and the (i + 1) -th surface. ndi and νdi are the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line, respectively. The wide angle indicates the wide angle end, the middle indicates the middle zoom position, and the telephoto indicates the telephoto end. BF is the back focus, which represents the distance from the last lens surface to the paraxial image plane.

  The total lens length is obtained by adding the back focus BF to the distance from the lens surface closest to the object side to the final lens surface. Table 1 shows the correspondence with the above-described conditional expressions in each embodiment.

(Numerical data 1)

Unit: mm

Surface data surface number rd nd νd
1 56.117 4.61 1.48749 70.2
2 336.254 0.15
3 84.159 2.00 1.83400 37.2
4 45.033 5.44 1.49700 81.5
5 327.226 (variable)
6 -246.749 1.20 1.76200 40.1
7 17.931 4.29 1.80809 22.8
8 87.951 2.11
9 -42.910 1.00 1.80610 40.9
10 113.279 (variable)
11 (aperture) 1.00 1.00
12 64.213 4.34 1.51633 64.1
13 -32.475 0.15
14 37.791 2.66 1.59522 67.7
15 286.536 1.89
16 -38.518 1.00 1.84666 23.8
17 -195.936 0.15
18 33.287 5.16 1.58913 61.1
19 -164.075 0.10
20 18.476 1.17 1.51633 64.1
21 14.349 (variable)
22 218.373 0.80 1.59522 67.7
23 29.991 17.32
24 -41.222 0.80 1.80 100 35.0
25 35.310 5.12 1.67270 32.1
26 -29.606 (variable)
Image plane ∞

Various data zoom ratios 4.37
Wide-angle medium telephoto focal length 56.47 133.45 246.72
F-number 4.16 5.15 5.88
Half angle of view (degrees) 13.60 5.84 3.17
Image height 13.66 13.66 13.66
Total lens length 150.00 184.93 191.02
BF 41.97 57.83 68.71

Spacing at infinity
d 5 5.75 40.67 46.77
d10 33.96 19.91 2.65
d21 5.89 4.08 10.46
d26 41.97 57.83 68.71

Spacing at 1.1 m object distance
d 5 5.75 40.67 46.77
d10 33.96 19.91 2.65
d21 6.93 8.46 25.26
d23 16.28 12.94 2.51
d26 41.97 57.83 68.71

Zoom lens group data group Start surface Focal length
1 1 119.35
2 6 -27.50
3 11 28.33
4 22 -58.50
5 24 700.00

(Numerical data 2)
Unit: mm

Surface data surface number rd nd νd
1 55.713 4.84 1.48749 70.2
2 481.454 0.15
3 81.243 2.00 1.83400 37.2
4 43.632 5.26 1.49700 81.5
5 219.054 (variable)
6 -162.631 1.20 1.76200 40.1
7 19.287 4.16 1.80809 22.8
8 96.647 2.42
9 -42.859 1.00 1.80400 46.6
10 137.325 (variable)
11 (aperture) 1.00 1.00
12 85.832 5.48 1.51742 52.4
13 -33.068 0.15
14 38.853 3.25 1.59522 67.7
15 -222.885 1.24
16 -45.621 1.00 1.84666 23.8
17 638.179 0.15
18 28.610 5.21 1.51633 64.1
19 -246.941 0.81
20 18.150 1.00 1.51823 58.9
21 14.371 (variable)
22 187.777 0.80 1.60738 56.8
23 30.385 17.68
24 -43.159 0.80 1.83400 37.2
25 40.671 3.03 1.68893 31.1
26 -30.079 (variable)
Image plane ∞

Various data zoom ratio 4.33
Wide-angle medium telephoto focal length 57.03 133.45 246.73
F-number 4.16 5.14 5.88
Half angle of view (degrees) 13.47 5.84 3.17
Image height 13.66 13.66 13.66
Total lens length 150.01 184.93 191.12
BF 43.18 58.53 68.43

Spacing at infinity
d 5 5.01 39.93 46.12
d10 33.42 19.64 2.57
d21 5.77 4.20 11.36
d26 43.18 58.53 68.43

Spacing at an object distance of 1.1 m
d 5 5.01 39.93 46.12
d10 33.42 19.64 2.57
d21 6.86 8.66 26.52
d23 16.60 13.22 2.52
d26 43.18 58.53 68.43

Zoom lens group data group Start surface Focal length
1 1 120.38
2 6 -27.56
3 11 28.90
4 22 -59.80
5 24 895.00

L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group L5 Fifth lens group SP Aperture stop

Claims (10)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a negative refractive power arranged in order from the object side to the image side. A fifth lens group having a positive refractive power, wherein the distance between adjacent lens groups changes during at least one of zooming and focusing,
During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the third lens group decreases . The distance between the four lens groups changes, and the fourth lens group and the fifth lens group move so that the distance between the fourth lens group and the fifth lens group does not change ;
The fourth lens group includes one negative lens,
At the time of focusing, the fourth lens group moves,
When the focal length of the fourth lens group is f4 and the focal length of the fifth lens group is f5,
7.0 <| f5 / f4 | <20.0
A zoom lens characterized by satisfying the following conditional expression. When the focal length of the zoom lens at the wide-angle end is fw,
1.0 <| f4 / fw | <1.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the Abbe number of the material of the negative lens is νd4n,
νd4n> 50.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the radii of curvature of the object-side lens surface and the image-side lens surface of the negative lens are R4f and R4R, respectively:
1.2 <(R4f + R4R) / (R4f-R4R) <4.0
The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied. The fifth lens group includes a negative lens and a positive lens. When the refractive index of the material of the negative lens included in the fifth lens group is nd5n and the refractive index of the material of the positive lens is nd5p,
nd5n> nd5p
The zoom lens according to any one of claims 1 to 4, wherein the following conditional expression is satisfied. When the focal length of the first lens group is f1 and the focal length of the zoom lens at the wide-angle end is fw,
2.0 <f1 / fw <2.8
The zoom lens according to any one of claims 1 to 5, wherein the following conditional expression is satisfied. During image blur correction, the second lens group moves in a direction including a component perpendicular to the optical axis,
When the focal length of the second lens group is f2 and the focal length of the zoom lens at the wide-angle end is fw,
0.35 <| f2 / fw | <0.65
The zoom lens according to any one of claims 1 to 6, wherein the following conditional expression is satisfied.   During zooming from the wide-angle end to the telephoto end, the first lens group, the third lens group, the fourth lens group, and the fifth lens group move toward the object side, and the second lens group does not move. The zoom lens according to any one of claims 1 to 7, wherein:   9. The zoom lens according to claim 1, wherein upon focusing from infinity to a short distance, the fourth lens group moves to the image side. 10.   An imaging apparatus comprising: the zoom lens according to claim 1; and an imaging element that receives an image formed by the zoom lens.