JP2021015195A - Zoom lens and image capturing device having the same - Google Patents

Abstract

To provide a zoom lens which offers both correction for imaging field variation caused by focusing on the wide-angle side and reduced size, and to provide an image capturing device having the same.SOLUTION: A zoom lens having a first lens group configured to be stationary for zooming and disposed on the most object side is provided, the zoom lens having a first focusing group configured to move for focusing and disposed within the first lens group, and a second focusing group configured to move for focusing and disposed within a lens group located on the image side of the first lens group. At least the second focusing lens group is moved for focusing when a zoom position of the zoom lens is on the wide-angle side of a given focal length f, and at least the first focusing group is moved for focusing when the zoom position is on the telephoto side of the given focal length f.SELECTED DRAWING: Figure 1

Description

The present invention relates to a zoom lens and an image pickup device having the same, and is particularly suitable for a television camera for broadcasting, a movie camera, a video camera, a digital still camera, a camera for silver halide photography, and the like.

In recent years, there has been a demand for a zoom lens having a wide angle of view, a high zoom ratio, and high optical performance for an imaging device such as a TV camera, a movie camera, a photographic camera, and a video camera. In particular, in a television / movie lens as a professional movie shooting system, it is required that the shooting image world does not change due to focusing. In addition, as a zoom lens with a wide angle of view and a high zoom ratio, a positive lead in which a first lens group with a positive refractive power for focusing and a second lens group with a negative refractive power for scaling are arranged in order from the object side. Type zoom lenses are known.

As a method of correcting a change in the shooting image field due to focusing, a zoom lens is known that drives the focus unit and the zoom unit in conjunction with each other and cancels the change in the shooting image field due to focusing by the change in the shooting image field due to scaling. ing.

In Patent Document 1, the positions of the focus unit and the zoom unit are acquired in advance before focusing, and the change in the shooting image field due to focusing is corrected by performing scaling in conjunction with focusing based on a data table. doing.

Further, in Patent Document 2, the second lens group moves to the space where all or a part of the lenses of the first lens group move due to focusing at the wide-angle end, and the change in the photographing image field due to focusing is corrected. ..

Japanese Unexamined Patent Publication No. 10-282396 Japanese Unexamined Patent Publication No. 6-235862

In the above-mentioned positive lead type zoom lens, when the amount of movement of the lens group that moves during focusing increases in order to shoot a subject at a closer distance, the change in the shooting image field due to focusing becomes remarkable. In particular, since the depth of field is deep on the wide-angle side, if the change in the shooting image field due to focusing remains, it will be as if the magnification is changed.

However, in the zoom lens disclosed in Patent Document 1 described above, the scaling is linked at the time of focusing, and in the focal length range in which the zoom portion can be moved, the change in the photographing image field due to focusing is caused. It is possible to correct. On the other hand, since the zoom portion cannot be moved in the focal length range on the wide-angle side, it is not possible to correct the change in the shooting image field due to focusing.

Further, in the zoom lens disclosed in Patent Document 2 above, since the second lens group moves to the space where all or a part of the lenses of the first lens group move due to focusing, the second lens group moves. The length of the cam tube is lengthened, which leads to an increase in the total length of the lens.

Therefore, an object of the present invention is to provide a zoom lens having both correction of changes in the photographic image field due to focusing on the wide-angle side and miniaturization, and an imaging device having the same.

In order to achieve the above object, the zoom lens according to the present invention and the imaging device having the same are used.
In a zoom lens in which a first lens group that does not move for scaling is arranged on the most object side, a first focus group that moves for focusing is provided in the first lens group, and the first lens group If the lens group on the image side has a second focus group that moves for focusing, and the zoom position of the zoom lens is on the wider angle side than the predetermined focal distance f, at least the second focus group is moved. By doing so, when the zoom position is on the telephoto side of the predetermined focal distance, at least the first focus group is moved to focus, and the focal distances at the wide-angle end and the telescopic end are set to fw and ft, respectively. When
1.0 ≦ f / fw <(ft / fw) ^ 0.5
It is characterized by satisfying.

According to the present invention, it is possible to provide a zoom lens that achieves both correction of changes in the shooting image field due to focusing on the wide-angle side and miniaturization, and an imaging device having the same.

Operation flowchart in the first embodiment Numerical value Cross-sectional view of the lens at infinity focusing at the wide-angle end of Example 1 Operation flowchart in the second embodiment (A) Cross-sectional view of the lens at infinity focusing at the wide-angle end where the focal length range of Numerical Example 2 is the reference state, and (b) Infinity focusing at the wide-angle end when switching to the built-in extender of Numerical Example 2. Lens cross section of time Schematic diagram of the image pickup apparatus of the present invention

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an operation flow of a zoom lens according to a first embodiment (numerical value embodiment 1) of the present invention, and FIG. 2 shows a cross-sectional view of a zoom lens according to a first embodiment of the present invention.

The zoom lens of the present invention is a zoom lens in which a first lens group that does not move for magnification change is arranged on the object side most, and has a first focus group that moves for focusing in the first lens group. When the lens group has a second focus group that moves to the image side lens group from the first lens group for focusing, and the zoom position of the zoom lens is wider than the predetermined focal distance f, at least the said Focusing is performed by moving the second focus group, and when the zoom position is on the telephoto side of the predetermined focal distance, at least the first focus group is moved to focus, and the focal distances at the wide-angle end and the telephoto end are performed. When is fw and ft, respectively,
1.0 ≤ f / fw <(ft / fw) ^ 0.5 ... (1)
Meet. Next, the operation of the first embodiment will be described with reference to the flowchart of FIG. First, the zoom position f (focal length) of the zoom lens is acquired in S101. Next, in S102, it is determined whether or not the zoom position f acquired in S101 satisfies fw ≦ f <(ft / fw) ^ 0.5. If it is satisfied, the process proceeds to S103 and the second focus group is focused. If the condition is not satisfied, the process proceeds to S104 and the first focus group is used for focusing.

As shown in FIG. 2, the zoom lens of the first embodiment has a first lens group U1 having a positive refractive power for focusing in order from the object side. Further, it has a second group U2 of negative refractive power for scaling that moves to the image side when scaling from the wide-angle end to the telephoto end. Further, it has a third lens group U3 having a positive refractive power that moves non-linearly on the optical axis in conjunction with the movement of the second lens group U2 and corrects image plane fluctuations due to scaling. Further, it has a fourth lens group U4 having a positive refractive power that performs a fixed imaging action at the time of scaling. The second lens group U2 and the third lens group U3 form a variable magnification system.

The SP is an aperture diaphragm and is arranged on the object side of the fourth lens group U4. The fourth lens group U4 is composed of a 41st lens group U41 having a negative refractive power, a 42nd lens group U42, and a 43rd lens group U43 having a positive refractive power. P is a color separation optical system or an optical filter, and is shown as a glass block. The IP is an image plane and corresponds to an image pickup surface of a solid-state image sensor.

In each of the following embodiments, the wide-angle end and the telephoto end refer to the zoom positions when the second group U2 for scaling is located at both ends of the movable range on the optical axis with respect to the mechanism. In addition, it has a first focus group U12 that moves for focusing in the first lens group. Further, it has a second focus group U43 that moves for focusing on a part of the lens group U4 on the most image side.

In the present invention, when the zoom position is on the wide-angle side of the predetermined focal length f, the focus on the wide-angle side is achieved by adopting the second focus group in which the change in the shooting image field due to focusing is small as the main focus group. It suppresses changes in the shooting image world. Further, the above-mentioned equation (1) defines a zoom position for switching between the first focus group and the second focus group. If the upper limit of Eq. (1) is not satisfied, the second focus group is the main focus group up to the range on the telephoto side, so the amount of movement for focusing of the second focus group becomes large, and the zoom lens is compact. It becomes difficult to change. More preferably, the equation (1) is set as follows.

1.0 ≤ f / fw <(ft / fw) ^ 0.3 ... (1a)
A further aspect of the zoom lens of the present invention is that it has a final lens group that does not move due to magnification change on the image side, and the second focus group is a part of the final lens group. For example, with respect to the zoom lens of the first embodiment, it is possible to set the second lens group and the third lens group that move at the time of scaling as the second focus group. However, setting a part of the final lens group that does not move at the time of scaling to the second focus group makes it possible to simplify the drive system for moving the focus group.

As a further aspect of the zoom lens of the present invention, when the extension amount of the second focus group is x2w, the extension amount of the first focus group at the telephoto end is x1t, and the extension amount of the second focus group is x2t.
0 ≦ | x2w / x1t | <0.05 ... (2)
0 ≦ | x2t / x1t | <1.0 ... (3)
Meet. Equations (2) and (3) define the ratio of the feeding amount of the first focus group and the second focus group. By satisfying the equations (2) and (3), the zoom lens is downsized while suppressing the change in the shooting image field due to the focusing on the wide-angle side. If the upper limit of the equation (2) is not satisfied, the amount of movement of the second focus lens group, which has a small shooting image field due to focusing, becomes small, and it becomes difficult to suppress the change in the shooting image field due to focusing on the wide-angle side. If the upper limit of the equation (3) is not satisfied, the amount of movement of the second focus lens group at the telephoto end becomes large, which makes it difficult to reduce the size of the zoom lens. More preferably, the equations (2) and (3) are set as follows.

0 ≦ | x2w / x1t | <0.03 ... (2a)
0 ≦ | x2t / x1t | <0.5 ... (3a)
Numerical value Example 1 corresponding to the said Example 1 will be described. In each numerical example, i indicates the order of the surfaces (optical surfaces) from the object side, ri is the radius of curvature of the i-th surface from the object side, and di is the i-th surface and the th-th from the object side. The distance between the i + 1th planes (on the optical axis) is shown. Further, ndi, νdi, and θgFi represent the refractive index, Abbe number, and partial dispersion ratio of the medium (optical member) between the i-th plane and the i + 1-th plane, and BF represents the back focus in terms of air. ing. The aspherical shape has an X-axis in the optical axis direction, an H-axis in the direction perpendicular to the optical axis, a positive light traveling direction, R is the radius of curvature of the near axis, k is a conical constant, A4, A6, A8, A10, A12, When A14 and A16 are the aspherical coefficients, they are expressed by the following equations. Further, "e-Z" means " ^x10 -Z".

Table 1 shows the values corresponding to each conditional expression in this embodiment. In addition, the values when the change in the shooting field at the wide-angle end of this embodiment is defined as the ratio of the change in the focal length of the entire system at the closest distance to the focal length of the entire system at the object distance infinity at the wide-angle end are shown in the table. Shown in 2. Further, Table 2 compares the change in the photographic image field of this embodiment and the change in the photographic image field when the focus is set in the first focus group at the wide-angle end. In this embodiment, a zoom lens that achieves both correction of changes in the shooting image field due to focusing on the wide-angle side and miniaturization is achieved. However, although it is essential that the zoom lens of the present invention satisfies the equation (1), the zoom lenses (2) and (3) may not be satisfied. However, even better effects can be achieved if at least one of the equations (2) and (3) is satisfied. This also applies to other embodiments.

FIG. 3 shows an operation flow of the zoom lens according to the second embodiment (numerical value embodiment 2) of the present invention, and FIG. 4 shows a cross-sectional view of the zoom lens according to the second embodiment of the present invention.

The zoom lens of the present invention switches to the built-in extender in a zoom lens having a built-in extender that shifts the focal length range of the entire system to the long focal length side by inserting and removing a partial lens group of the final lens group from the optical path. At that time, if the zoom position of the zoom lens is on the wider angle side than the predetermined focal length nex, focusing is performed by moving at least the second focus group, and the zoom position is on the telescopic side of the predetermined focal length nex. In this case, when at least the first focus group is moved to focus and the focal lengths at the wide-angle end and the telephoto end when switching to the built-in extender are set to fwex and ftex, respectively.
1.0 ≤ fex / fwex <(ftex / fwex) ^ 0.35 ... (4)
Meet.

Next, the operation of the second embodiment will be described with reference to the flowchart of FIG.

First, it is determined whether or not the built-in extender is switched in S201. If it is determined that the extender has been switched, the process proceeds to S201, and if it is not determined, the process proceeds to S101 of the first embodiment. Next, in S202, the zoom position nex (focal length when switching the built-in extender) of the zoom lens is acquired. In S203, it is determined whether or not the zoom position fex acquired in S202 satisfies fwex ≦ f <(ftex / fwex) ^ 0.35. If it is satisfied, the process proceeds to S204, and the second focus group is focused. If not, the process proceeds to S205, and the first focus group is used for focusing.

As shown in FIG. 4, the zoom lens of the second embodiment is the same as that of the first embodiment from the first lens group U1 to the third lens group U3. The fourth lens group U4 is composed of a 41st lens group U41 having a negative refractive power, a 42nd lens group U42, and a 43rd lens group U43 having a positive refractive power. The 42nd group U42 is configured to be removable from the extender lens 44th lens group U44. By replacing the 42nd group U42 with the 44th group U44, the focal length range of the entire system is displaced twice to the long focal length side.

In the present invention, when the zoom position is on the wide-angle side of the predetermined focal length flex, the focus on the wide-angle side is achieved by adopting the second focus group in which the change in the shooting image field due to focusing is small as the main focus group. It suppresses changes in the shooting image world.

Further, the above-mentioned equation (4) defines a zoom position for switching between the first focus group and the second focus group. When the focal length range of the entire system is on the long focal length side, if the lens group on the image side of the extender lens is set to the second focus group, the second focus group will be compared with the case where the focal length range of the entire system is in the reference state. The amount of feeding increases. Therefore, in this embodiment, the zoom position for switching between the first focus group and the second focus group is set to the wide-angle side as compared with the case where the focal length range of the entire system is in the reference state. If the upper limit of Eq. (4) is not satisfied, the second focus group is the main focus group up to the range on the telephoto side, so the amount of movement for focusing of the second focus group becomes large, and the zoom lens is compact. It becomes difficult to change. More preferably, the equation (4) is set as follows.

1.0 ≤ fex / fwex <(ftex / fwex) ^ 0.25 ... (4a)
FIG. 5 is a schematic view of an image pickup apparatus (television camera system) using the zoom lens of each embodiment as a photographing optical system.

In FIG. 5, 101 is a zoom lens according to any one of Examples 1 and 2. 124 is a camera. The zoom lens 101 is removable from the camera 124. Reference numeral 125 denotes an imaging device configured by attaching a zoom lens 101 to a camera 124. The zoom lens 101 has a first lens group F, a variable magnification portion LZ, and a fourth lens group R for imaging. The first lens group F includes a first focus group. The scaling unit LZ includes a second lens group that moves on the optical axis for scaling, and a third lens group that moves on the optical axis to correct image plane fluctuations due to scaling. SP is an aperture stop. The fourth lens group R has lens units IE and IE'that can be inserted and removed from the optical path. By switching the lens units IE and IE', the focal length range of the entire system of the zoom lens 101 is displaced.

114 and 115 are drive mechanisms such as a helicoid and a cam that drive the first lens group F and the variable magnification portion LZ in the optical axis direction, respectively. Reference numerals 116 to 118 are motors (driving means) for electrically driving the drive mechanisms 114, 115 and the aperture stop SP. Reference numerals 119 to 121 are detectors such as an encoder, a potentiometer, or a photo sensor for detecting the position of the first lens group F or the variable magnification portion LZ on the optical axis and the aperture diameter of the aperture aperture SP. In the camera 124, 109 is a glass block corresponding to an optical filter and a color separation optical system in the camera 124, and 110 is a solid-state image sensor (photoelectric conversion) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the zoom lens 101. Element). Further, 111 and 122 are CPUs that control various drives of the camera 124 and the zoom lens 101.

As described above, by applying the zoom lens of the present invention to a television camera, an imaging device that achieves both correction of changes in the shooting image field due to focusing on the wide-angle side and miniaturization has been realized.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

<Numerical Example 1>
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 7000.000 6.00 1.83400 37.2 195.69
2 345.379 2.00 189.57
3 345.379 25.91 1.43387 95.1 190.61
4-527.375 20.74 191.16
5 331.921 18.73 1.43387 95.1 193.34
6 -4082.422 0.25 192.86
7 264.903 19.29 1.43387 95.1 188.46
8 3887.712 0.25 187.25
9 171.964 16.12 1.43875 94.9 174.67
10 367.798 (variable) 172.80
11 1547.347 2.00 2.00330 28.3 42.77
12 43.466 8.24 37.79
13 -55.129 2.00 1.88300 40.8 37.77
14 63.246 9.63 1.92286 18.9 41.36
15 -66.171 1.02 42.37
16 -59.413 2.00 1.77250 49.6 42.43
17 * 2736.384 (variable) 44.72
18 108.766 12.13 1.56907 71.3 81.41
19 * -3543.181 0.20 81.81
20 100.674 13.34 1.49700 81.5 83.34
21 -613.181 0.20 82.78
22 103.700 2.50 1.84666 23.8 79.37
23 60.132 20.33 1.43875 94.9 74.98
24 -268.844 0.20 73.52
25 * 201.189 5.73 1.43875 94.9 71.02
26 -889.802 (variable) 69.63
27 (Aperture) ∞ 4.50 32.62
28 -218.375 1.00 1.81600 46.6 32.95
29 34.790 0.20 31.73
30 30.180 4.33 1.84666 23.8 31.95
31 82.724 4.91 31.30
32 -60.480 1.00 1.88300 40.8 30.55
33 -307.193 6.38 30.64
34 -67.453 1.80 1.75500 52.3 27.78
35 62.254 4.41 1.80518 25.4 28.64
36 693.124 3.03 29.08
37 ∞ 11.21 1.62041 60.3 30.00
38 -104.615 6.53 31.93
39 94.562 8.62 1.48749 70.2 33.07
40 -48.439 0.20 32.92
41 -68.383 1.60 1.88300 40.8 32.43
42 49.733 9.12 1.48749 70.2 32.51
43 -36.756 0.20 33.02
44 310.864 7.63 1.56732 42.8 32.19
45 -28.174 1.60 1.88300 40.8 31.83
46 -140.085 0.20 32.41
47 53.439 7.71 1.48749 70.2 32.37
48 -74.444 14.00 31.63
49 ∞ 33.00 1.60859 46.4 60.00
50 ∞ 13.20 1.51633 64.2 60.00
51 ∞ 12.03 60.00
Image plane ∞

17th surface of aspherical data
K = -2.53234e + 004 A 4 = -4.13015e-007 A 6 = -2.16427e-010 A 8 = 2.26588e-013

Page 19
K = 5.22565e + 003 A 4 = 8.81676e-008 A 6 = 1.58180e-012 A 8 = 6.14872e-015

25th page
K =-9.48244e + 000 A 4 = -7.57187e-007 A 6 = -1.54476e-010 A 8 = 2.42122e-014

Various data Zoom ratio 100.00
Wide-angle telephoto focal length 9.30 929.98
F number 1.85 4.90
Angle of view 30.60 0.34
Image height 5.50 5.50
Lens overall length 619.37 619.37
BF 12.03 12.03

d10 3.07 176.64
d17 266.10 1.96
d26 3.00 93.57
d51 12.03 12.03

Entrance pupil position 124.58 11114.47
Exit pupil position 341.49 341.49
Front principal point position 134.14 14669.48
Rear principal point position 2.73 -917.96

Zoom lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 238.05 109.29 59.18 -20.74
2 11 -25.00 24.89 4.19 -12.46
3 18 66.50 54.63 13.57 -26.05
4 27 50.37 146.37 59.63 17.29

Amount of movement of the first focus group and the second focus group during focusing
(The direction from the object side to the image side is positive)
Wide-angle end group Infinity closest (3.5m)
1st focus group 0.00 0.00
2nd focus group 0.00 -0.025

Telephoto end group Infinity closest (3.5m)
1st focus group 0.00 -17.32
2nd focus group 0.00 0.00


<Numerical Example 2>
(Focal length range in reference state)
Unit mm

Surface data Surface number rd nd vd Effective diameter
1 7000.000 6.00 1.83400 37.2 195.69
2 345.379 2.00 189.57
3 345.379 25.91 1.43387 95.1 190.61
4-527.375 20.74 191.16
5 331.921 18.73 1.43387 95.1 193.34
6 -4082.422 0.25 192.86
7 264.903 19.29 1.43387 95.1 188.46
8 3887.712 0.25 187.25
9 171.964 16.12 1.43875 94.9 174.67
10 367.798 (variable) 172.80
11 1547.347 2.00 2.00330 28.3 42.77
12 43.466 8.24 37.79
13 -55.129 2.00 1.88300 40.8 37.77
14 63.246 9.63 1.92286 18.9 41.36
15 -66.171 1.02 42.37
16 -59.413 2.00 1.77250 49.6 42.43
17 * 2736.384 (variable) 44.72
18 108.766 12.13 1.56907 71.3 81.41
19 * -3543.181 0.20 81.81
20 100.674 13.34 1.49700 81.5 83.34
21 -613.181 0.20 82.78
22 103.700 2.50 1.84666 23.8 79.37
23 60.132 20.33 1.43875 94.9 74.98
24 -268.844 0.20 73.52
25 * 201.189 5.73 1.43875 94.9 71.02
26 -889.802 (variable) 69.63
27 (Aperture) ∞ 5.19 32.62
28 186.208 1.40 1.81600 46.6 29.05
29 25.515 5.51 1.84666 23.8 27.14
30 65.304 4.72 25.92
31 -74.674 1.40 1.88300 40.8 24.90
32 -336.961 7.27 24.76
33 -23.629 1.80 1.77250 49.6 24.00
34 72.693 2.47 1.84666 23.8 26.53
35 304.414 3.03 27.10
36 ∞ 9.60 1.62041 60.3 29.30
37 -33.451 5.48 31.93
38 968.789 6.61 1.48749 70.2 33.07
39 -42.681 0.20 33.28
40 -147.760 1.60 1.88300 40.8 32.40
41 38.666 10.22 1.49700 81.5 32.01
42 -52.689 0.20 32.65
43 168.155 8.81 1.56732 42.8 32.33
44 -28.418 1.60 1.88300 40.8 31.93
45 -157.717 0.20 32.63
46 106.332 7.51 1.48749 70.2 32.74
47 -42.361 14.00 32.52
48 ∞ 33.00 1.60859 46.4 60.00
49 ∞ 13.20 1.51633 64.2 60.00
50 ∞ 11.99 60.00
Image plane ∞

17th surface of aspherical data
K = -2.53234e + 004 A 4 = -4.13015e-007 A 6 = -2.16427e-010 A 8 = 2.26588e-013

Page 19
K = 5.22565e + 003 A 4 = 8.81676e-008 A 6 = 1.58180e-012 A 8 = 6.14872e-015

25th page
K =-9.48244e + 000 A 4 = -7.57187e-007 A 6 = -1.54476e-010 A 8 = 2.42122e-014

Various data Zoom ratio 100.00
Wide-angle telephoto focal length 9.30 929.98
F number 1.85 4.90
Angle of view 30.60 0.34
Image height 5.50 5.50
Lens overall length 617.99 617.99
BF 11.99 11.99

d10 3.07 176.64
d17 266.10 1.96
d26 3.00 93.57
d50 11.99 11.99

Entrance pupil position 124.58 11114.47
Exit pupil position 227.25 227.25
Front principal point position 134.28 16062.25
Rear principal point position 2.69 -917.99

Zoom lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 238.05 109.29 59.18 -20.74
2 11 -25.00 24.89 4.19 -12.46
3 18 66.50 54.63 13.57 -26.05
4 27 46.22 145.02 59.24 16.83


(Extender lens)

32 -336.961 3.50 24.76
33 65.994 2.75 1.48749 70.2 23.90
34 -449.738 0.40 23.53
35 17.296 5.07 1.64000 60.1 21.81
36 197.534 0.90 1.84666 23.8 20.59
37 18.033 5.51 18.30
38 182.659 0.80 1.78800 47.4 17.05
39 11.672 3.59 1.80809 22.8 16.07
40 35.812 1.13 15.72
41 97.623 1.00 1.88300 40.8 15.64
42 43.673 5.00 15.44

Various data Zoom ratio 100.00
Wide-angle telephoto focal length 18.60 1859.96
F number 3.70 9.80
Angle of view 16.47 0.17
Image height 5.50 5.50
Lens overall length 617.99 617.99
BF 12.00 12.00

d10 3.07 176.64
d17 266.10 1.96
d26 3.00 93.57
d55 12.00 12.00

Entrance pupil position 124.58 996.17 11114.21
Exit pupil position -234.78 -234.78 -234.78
Front principal point position 141.77 1040.49 -1044.22
Rear principal point position -6.60 -176.88 -1847.95

Zoom lens group Data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 238.05 109.29 59.18 -20.74
2 11 -25.00 24.89 4.19 -12.46
3 18 66.50 54.63 13.57 -26.05
4 27 -1426.27 145.01 -725.80 -1712.61

Amount of movement of the first focus group and the second focus group during focusing
(The direction from the object side to the image side is positive)
Wide-angle end group Infinity closest (3.5m)
1st focus group 0.00 -6.33
2nd focus group 0.00 -0.063

Telephoto end group Infinity closest (3.5m)
1st focus group 0.00 -17.24
2nd focus group 0.00 -5.17

U1 1st lens group, U2 2nd lens group, U3 3rd lens group,
U4 4th lens group, SP aperture stop, I image plane

Claims (5)

In a zoom lens in which a first lens group that does not move for scaling is arranged on the most object side, a first focus group that moves for focusing is provided in the first lens group, and the first lens group When the lens group on the image side has a second focus group that moves for focusing, and the zoom position of the zoom lens is on the wider angle side than the predetermined focal distance f, at least the second focus group is moved. When the zoom position is on the telephoto side of the predetermined focal distance f, the first focus group is moved at least to focus, and the focal distances at the wide-angle end and the telephoto end are set to fw and ft, respectively. A zoom lens characterized by satisfying the following equations.
1.0 ≦ f / fw <(ft / fw) ^ 0.5 The zoom lens according to claim 1, wherein the zoom lens has a final lens group that does not move due to magnification change on the image side, and the second focus group is a part of the final lens group. When the extension amount of the second focus group is x2w, the extension amount of the first focus group at the telephoto end is x1t, and the extension amount of the second focus group is x2t, the following equation is satisfied. The zoom lens according to claim 1 or 2.
0 ≦ | x2w / x1t | <0.05
0 ≦ | x2t / x1t | <1.0 In a zoom lens having a built-in extender that shifts the focal distance range of the entire system to the long focal length side by inserting and removing a partial lens group of the final lens group from the optical path, when the zoom lens is switched to the built-in extender, the zoom When the zoom position of the lens is on the wider angle side than the predetermined focal distance nex, focusing is performed by moving at least the second focus group, and when the zoom position is on the telescope side of the predetermined focal distance nex, at least the second focus group is performed. 1. The following equations are satisfied when the focal distances at the wide-angle end and the telephoto end when the focus group is moved to focus and the built-in extender is switched to fwex and ftex, respectively. The zoom lens according to any one of claim 3.
1.0 ≤ fex / fwex <(ftex / fwex) ^ 0.35 An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 4 and a solid-state image pickup device that receives an image formed by the zoom lens.