JP7467082B2 - Zoom lens and imaging device having the same - Google Patents

Description

The present invention relates to a zoom lens that is suitable for digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, surveillance cameras, etc.

A positive-lead zoom lens, in which a lens group with positive refractive power is positioned closest to the object, is known as a telephoto zoom lens used in an imaging device.

Patent document 1 discloses a zoom lens that is composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a rear group that includes one or more subsequent lens groups.

JP 2013-101316 A

In a positive-lead zoom lens, if you try to increase the focal length while shortening the overall lens length, various aberrations, including chromatic aberration, increase, and the optical performance tends to deteriorate. In addition, as the focal length is increased, the entire lens system becomes larger and its mass increases.

Therefore, in order to realize a zoom lens that is small and lightweight yet has high optical performance, it is important to appropriately set the number of lens groups that make up the zoom lens and the sign of the refractive power.

The zoom lens described in Patent Document 1 was insufficient in achieving both high performance and compactness and weight reduction.

Therefore, the present invention aims to provide a zoom lens that is small, lightweight, and has excellent optical performance.

A zoom lens of the present invention has, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, and the distance between adjacent lens groups changes during zooming. During zooming from the wide-angle end to the telephoto end, the second lens group does not move, and the first lens group is composed of a negative lens G1 and a positive lens G2, arranged in order from the object side to the image side, and the second lens group has a negative lens G3 arranged closest to the object side. When the Abbe number at the d-line of the positive lens G2 is νdG2, the focal length of the first lens group is f1, the focal length of the zoom lens at the telephoto end is ft, the radius of curvature of the object-side lens surface of the negative lens G3 is G3R1, and the radius of curvature of the image-side lens surface of the negative lens G3 is G3R2,
65<νdG2<100
0.40<f1/ft< 0.60
-1.00<(G3R2+G3R1)/(G3R2-G3R1)<-0.40
The present invention is characterized in that the following conditional expression is satisfied:

The present invention makes it possible to realize a zoom lens that is small, lightweight, and has excellent optical performance.

1 is a cross-sectional view of a zoom lens according to a first embodiment. 4A to 4C are aberration diagrams of the zoom lens of Example 1. FIG. 11 is a cross-sectional view of a zoom lens according to a second embodiment. 11A to 11C are aberration diagrams of the zoom lens of Example 2. FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment. 11A to 11C are aberration diagrams of the zoom lens of Example 3. FIG. 1 is a schematic diagram of an imaging device.

The following describes an embodiment of the zoom lens of the present invention and an imaging device having the same, with reference to the attached drawings.

Figures 1, 3, and 5 are cross-sectional views of zoom lenses according to the first to third embodiments of the present invention. In each cross-sectional view, (A) is a cross-sectional view at the wide-angle end, and (C) is a cross-sectional view at the telephoto end. (B) is a cross-sectional view at a focal length intermediate between the wide-angle end and the telephoto end (intermediate zoom position).

The zoom lens L0 in each embodiment is used in imaging devices such as digital still cameras, video cameras, silver halide film cameras, and broadcast cameras, and in projection devices such as projectors. In each lens cross-sectional view, the left side is the object side (enlargement side) and the right side is the image side (reduction side).

In addition, in each lens cross-sectional view, "Li" (i is a natural number) represents the "i-th lens group" when counting the lens groups constituting the zoom lens L0 from the object side to the image side. Note that in this specification, a lens group is a component of the zoom lens L0 that is composed of one or more lenses. During zooming, each lens group moves or remains stationary as a unit, and the distance between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end.

SP is an aperture stop that determines (limits) the light flux of the maximum F-number (Fno). IP is an image plane, on which the imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed when the zoom lens L0 of each embodiment is used as the photographing optical system of a video camera or digital still camera. When the zoom lens L0 of each embodiment is used as the photographing optical system of a silver halide camera, the photosensitive surface of the film is placed on the image plane IP.

The arrows shown in each lens cross-sectional diagram are simplified representations of the movement trajectory of each lens group when zooming from the wide-angle end to the telephoto end. Note that in this specification, the wide-angle end and telephoto end refer to the zoom positions when each lens group is located at either end of the mechanically movable range.

The zoom lens L0 of each embodiment has, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power. As shown in Examples 2 and 3, the effect of the present invention can be effectively obtained even if there is a further lens group on the image side of the fifth lens group L5.

In addition, in the zoom lens L0 of each embodiment, the first lens group L1 is composed of a negative lens G1 and a positive lens G2 arranged in this order from the object side to the image side.

In addition, in the zoom lens L0 of each embodiment, the second lens group L2 has a negative lens G3 arranged closest to the object.

The zoom lens L0 of the first embodiment is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fourth lens group L4, and the fifth lens group L5 move monotonically toward the object side. The second lens group L2 does not move during zooming (the relative position between the second lens group L2 and the image plane IP does not change during zooming). In addition, the fifth lens group L5 moves along the optical axis during focusing.

The zoom lens of Example 2 is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with negative refractive power, and a sixth lens group L6 with negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fourth lens group L4, the fifth lens group L5, and the sixth lens group L6 move monotonically toward the object side. The second lens group L2 does not move during zooming. In the zoom lens of Example 2, the fourth lens group L4 and the sixth lens group L6 move together (on the same trajectory) during zooming. Also, the fifth lens group L5 moves along the optical axis during focusing.

The zoom lens of Example 3 is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with negative refractive power, a sixth lens group L6 with positive refractive power, and a seventh lens group L7 with negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, the fourth lens group L4, the fifth lens group L5, the sixth lens group L6, and the seventh lens group L7 move monotonically toward the object side. The second lens group L2 does not move during zooming. Furthermore, the fifth lens group L5 moves along the optical axis during focusing.

In the zoom lens L0 of each embodiment, one or more lenses may be decentered so as to include a component perpendicular to the optical axis during image blur correction, thereby allowing it to function as an anti-vibration optical system. In addition, a parallel plate with virtually no refractive power, such as a low-pass filter or an infrared cut filter, may be placed between the lens located closest to the image side and the imaging surface.

Figures 2, 4, and 6 are aberration diagrams of the zoom lens L0 of Examples 1 to 3, respectively. In each aberration diagram, (A) is the aberration diagram at the wide-angle end, (B) is the aberration diagram at the intermediate zoom position, and (C) is the aberration diagram at the telephoto end in the infinity focused state.

In the aberration diagram, Fno is the F-number, ω is the half angle of view (degrees), which is the angle of view calculated by paraxial calculation. In the spherical aberration diagram, d indicates the d-line (wavelength 587.56 nm), and g indicates the g-line (wavelength 435.835 nm).

In the astigmatism diagram, S indicates the d-line on the sagittal image plane, and M indicates the d-line on the meridional image plane. The distortion diagram shows the d-line. The chromatic aberration diagram shows the amount of chromatic aberration of magnification for the g-line relative to the d-line.

Next, we will explain the characteristics of the zoom lens L0 in each embodiment.

The zoom lens L0 in each embodiment is a so-called positive lead type zoom lens.

In the zoom lens L0 of each embodiment, the first lens group L1 is composed of a negative lens G1 and a positive lens G2, and the focal length of the first lens group L1 and the Abbe number of the positive lens G2 are optimized. Also, the shape of the negative lens G3 arranged closest to the object in the second lens group L2 is optimized. Specifically, the zoom lens L0 of each embodiment satisfies the following conditional expression.
65<νdG2<100 (1)
0.40<f1/ft<0.65 (2)
-1.00 < (G3R2 + G3R1) / (G3R2 - G3R1) < -0.40 (3)

where νdG2 is the Abbe number at the d-line of the positive lens G2. f1 is the focal length of the first lens group L1. ft is the focal length of the zoom lens L0 at the telephoto end. G3R1 and G3R2 are the radii of curvature of the object-side and image-side lens surfaces of the negative lens G3, respectively.

Conditional expression (1) relates to the Abbe number of the positive lens G2. If the upper limit of conditional expression (1) is exceeded, the correction of lateral chromatic aberration and axial chromatic aberration will be excessive, which is undesirable. On the other hand, if the lower limit is exceeded, the correction of lateral chromatic aberration and axial chromatic aberration will be insufficient, which is undesirable.

Conditional expression (2) relates to the ratio of the focal length of the first lens group L1 to the focal length of the zoom lens at the telephoto end. If the lower limit of conditional expression (2) is not satisfied, the refractive power of the first lens group L1 becomes too strong, increasing the spherical aberration at the telephoto end that occurs in the first lens group L1, making it difficult to sufficiently correct this with the entire zoom lens. On the other hand, if the upper limit of conditional expression (2) is exceeded, the refractive power of the first lens group L1 becomes too weak, making it difficult to shorten the overall lens length at the telephoto end. Alternatively, the lens diameter of the second lens group becomes large, making it difficult to miniaturize the optical system.

Conditional expression (3) relates to the shape of the negative lens G3. Satisfying conditional expression (3) means that the negative lens G3 has a biconcave shape with a curvature of the image-side surface greater than the curvature of the object-side surface. By satisfying conditional expression (3), off-axis aberrations such as astigmatism and distortion at the wide-angle end can be effectively corrected.

The zoom lens of each embodiment has the above configuration, which allows it to achieve excellent optical performance while being small and lightweight.

It is more preferable to set the numerical ranges of the above-mentioned conditional expressions (1) to (3) as specified by the following conditional expressions (1a) to (3a).
65<νdG2<90 (1a)
0.45<f1/ft<0.65 (2a)
−0.90<(G3R2+G3R1)/(G3R2−G3R1)<−0.45 (3a)

It is more preferable to set the numerical ranges of the conditional expressions (1) to (3) as specified by the following conditional expressions (1b) to (3b).
66<νdG2<85 (1b)
0.48<f1/ft<0.60 (2b)
−0.80<(G3R2+G3R1)/(G3R2−G3R1)<−0.48 (3b)

Next, we will describe the conditions that are preferably satisfied in the zoom lens L0 of each embodiment.

It is preferable that the zoom lens L0 of each embodiment satisfies one or more of the following conditional expressions (4) to (9).
−0.40<f2/f1<−0.20 (4)
-0.20<f2/ft<-0.10 (5)
-1.00<f5/fw<-0.40 (6)
0.65<TLt/ft<0.85 (7)
-0.60<fw/f12air<-0.20 (8)
0.30<(βrt/βrw)/(ft/fw)<1.50 (9)

Here, f2 is the focal length of the second lens group L2. f5 is the focal length of the fifth lens group L5. fw is the focal length of the zoom lens at the wide-angle end. TLt is the total lens length at the telephoto end (the distance from the lens surface closest to the object to the image surface). f12air is the focal length of the air lens formed between the lens closest to the image side of the first lens group L1 at the wide-angle end and the lens closest to the object side of the second lens group L2 at the wide-angle end. βrt is the composite lateral magnification from the fourth lens group L4 to the lens group arranged closest to the image side at the telephoto end. βrw is the composite lateral magnification from the fourth lens group L4 to the lens group arranged closest to the image side at the wide-angle end.

Conditional expression (4) relates to the ratio of the focal length of the second lens group L2 to the focal length of the first lens group L1. If the lower limit of conditional expression (4) is not satisfied, the refractive power of the first lens group L1 becomes too strong, making it difficult to sufficiently correct spherical aberration. Alternatively, the refractive power of the second lens group L2 becomes too weak, making it difficult to sufficiently shorten the overall lens length. On the other hand, if the upper limit of conditional expression (4) is exceeded, the refractive power of the first lens group L1 becomes too weak, making it difficult to sufficiently shorten the overall lens length. Alternatively, the refractive power of the second lens group becomes too strong, making it difficult to sufficiently correct various aberrations including spherical aberration.

Conditional expression (5) relates to the ratio of the focal length of the second lens group L2 to the focal length of the zoom lens at the telephoto end. If the lower limit of conditional expression (5) is not reached, the refractive power of the second lens group L2 will be weak, making it difficult to sufficiently shorten the overall lens length at the telephoto end. On the other hand, if the upper limit of conditional expression (5) is exceeded, it will be difficult to sufficiently correct various aberrations, such as spherical aberration, particularly at the telephoto end.

Conditional expression (6) relates to the ratio of the focal length of the fifth lens group L5 to the focal length of the zoom lens at the wide-angle end. If the lower limit of conditional expression (6) is not reached, the refractive power of the fifth lens group L5 becomes weak, making it difficult to sufficiently shorten the overall lens length at the wide-angle end. On the other hand, if the upper limit of conditional expression (6) is exceeded, it is advantageous for shortening the overall lens length, but it becomes difficult to sufficiently correct off-axis aberrations such as astigmatism and distortion at the wide-angle end.

Conditional expression (7) relates to the ratio between the total lens length at the telephoto end and the focal length of the zoom lens at the telephoto end. If the lower limit of conditional expression (7) is exceeded, the total lens length at the telephoto end becomes too short, making it difficult to sufficiently correct spherical aberration and other aberrations across the entire zoom range. On the other hand, if the upper limit of conditional expression (7) is exceeded, the total lens length at the telephoto end becomes too long.

Conditional expression (8) relates to the ratio of the focal length of the zoom lens at the wide-angle end to the focal length of the air lens formed between the lens closest to the image in the first lens group L1 at the wide-angle end and the lens closest to the object in the second lens group L2. If the lower limit of conditional expression (8) is exceeded and the negative refractive power of the air lens becomes strong, the field curvature at the wide-angle end becomes over, making correction difficult. In addition, it becomes difficult to correct barrel distortion. If the upper limit of conditional expression (8) is exceeded and the negative refractive power of the air lens becomes weak, the field curvature at the wide-angle end becomes under, making correction difficult.

Conditional formula (9) relates to the ratio of the composite zoom ratio from the fourth lens group L4 to the lens group closest to the image side to the zoom ratio. Here, the composite zoom ratio from the fourth lens group L4 to the lens group closest to the image side is the ratio of the composite lateral magnification at the telephoto end from the fourth lens group L4 to the lens group closest to the image side to the composite lateral magnification at the wide-angle end. If the lower limit of conditional formula (9) is exceeded, the zoom ratio of the lens group closer to the object side than the fourth lens group L4 becomes large, and the amount of movement of each lens group closer to the object side than the fourth lens group increases. As a result, it becomes difficult to sufficiently shorten the overall lens length. Or, the refractive power of each lens group closer to the object side than the fourth lens group becomes strong, making it difficult to sufficiently correct various aberrations. On the other hand, if the upper limit of conditional formula (9) is exceeded, the zoom ratio of the lens group from the fourth lens group L4 to the lens group closest to the image side becomes too large, and the amount of movement of each lens group from the fourth lens group L4 to the lens group closest to the image side becomes too large. As a result, it becomes difficult to sufficiently shorten the overall lens length. Alternatively, the refractive power of each lens group from the fourth lens group L4 to the lens group closest to the image side becomes strong, making it difficult to sufficiently correct various aberrations.

It is more preferable to set the numerical ranges of the above-mentioned conditional expressions (4) to (9) as specified by the following conditional expressions (4a) to (9a).
−0.35<f2/f1<−0.25 (4a)
−0.20<f2/ft<−0.11 (5a)
−0.80<f5/fw<−0.45 (6a)
0.70<TLt/ft<0.82 (7a)
-0.55<fw/f12air<-0.20 (8a)
0.40<(βrt/βrw)/(ft/fw)<1.30 (9a)

It is more preferable to set the numerical ranges of the conditional expressions (4) to (9) as specified by the following conditional expressions (4b) to (9b).
−0.32<f2/f1<−0.26 (4b)
−0.17<f2/ft<−0.13 (5b)
−0.70<f5/fw<−0.50 (6b)
0.75<TLt/ft<0.80 (7b)
-0.50<fw/f12air<-0.25 (8b)
0.45<(βrt/βrw)/(ft/fw)<1.10 (9b)

When focusing from infinity to a close distance, it is preferable to move the fifth lens unit L5 toward the object side. This makes it easier to suppress fluctuations in field curvature and spherical aberration when the object distance changes.

It is also preferable that the second lens group L2 does not move during zooming. By minimizing the number of groups that move during zooming, it becomes easier to simplify and downsize the mechanism.

It is also preferable that the aperture stop SP is disposed between the third lens unit L3 and the fourth lens unit L4. This makes it easier to reduce the diameter of the stop, and therefore the overall lens system.

Next, we present numerical examples 1 to 3 corresponding to examples 1 to 3, respectively.

In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial distance (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incidence side. In addition, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. Note that the Abbe number νd of a certain material is given by Nd, NF, NC, and Ng, respectively, as the refractive indexes at the d-line (587.56 nm), F-line (486.1 nm), C-line (656.3 nm), and g-line (wavelength 435.835 nm) of the Fraunhofer lines.
νd=(Nd−1)/(NF-NC)
It is expressed as:

In each numerical example, the focal length (mm), F-number, and half angle of view (°) are all values when the zoom lens of each example is focused on an object at infinity. The back focus BF is the air-equivalent distance from the final lens surface to the image surface. The total lens length is the distance on the optical axis from the first lens surface to the final lens surface plus the back focus BF.

The entrance pupil position is the distance from the lens surface closest to the object (first surface) to the entrance pupil. The exit pupil position is the distance from the lens surface closest to the image (last lens surface) to the exit pupil. The front principal point position is the distance from the first lens surface to the front principal point. The rear principal point position is the distance from the last lens surface to the rear principal point. Each of these numerical values is a paraxial quantity, and the signs are positive in the direction from the object side to the image side.

[Numerical Example 1]
Unit: mm

Surface data Surface number rd nd νd Effective diameter
1 65.681 2.00 1.91082 35.3 41.88
2 47.259 7.20 1.49700 81.5 40.86
3 -278.957 (variable) 40.60
4 -71.676 1.10 1.66672 48.3 21.20
5 24.148 2.80 1.80810 22.8 20.97
6 56.703 1.80 20.80
7 -85.157 1.10 1.80100 35.0 20.81
8 -250.180 (variable) 21.04
9 56.979 3.10 1.83481 42.7 21.72
10 -90.950 0.15 21.63
11 32.843 4.85 1.48749 70.2 20.82
12 -55.908 1.10 1.95375 32.3 19.83
13 62.107 7.75 19.19
14 (Aperture) ∞ (Variable) 18.12
15 87.040 1.00 1.85883 30.0 16.97
16 25.173 4.25 1.48749 70.2 16.63
17 -36.261 0.15 16.55
18 28.581 1.70 1.91082 35.3 16.29
19 53.742 (variable) 16.12
20 -178.159 2.45 1.85478 24.8 15.93
21 -25.827 1.00 1.74320 49.3 15.98
22 24.096 (variable) 15.96
Image plane ∞

Various data Zoom ratio 4.34

Wide Angle Mid Telephoto Focal Length 56.50 135.00 245.00
F-number 4.12 5.17 5.85
Half angle of view (°) 13.59 5.78 3.19
Image height 13.66 13.66 13.66
Lens length 138.50 174.37 193.50
BF 21.90 53.63 70.32

d 3 10.70 46.57 65.70
d 8 27.60 16.92 2.03
d14 21.00 6.66 8.16
d19 13.80 7.09 3.80
d22 21.90 53.63 70.32

Entrance pupil position 57.84 154.98 233.15
Exit pupil position -22.59 -13.53 -13.34
Front principal point position 42.58 18.61 -239.35
Rear principal point position -34.60 -81.37 -174.68

Zoom lens group data group Starting surface Focal length Lens length Front principal point position Rear principal point position
1 1 143.91 9.20 0.19 -5.71
2 4 -41.24 6.80 2.09 -2.49
3 9 54.93 16.95 -4.58 -17.07
4 15 41.00 7.10 3.21 -1.20
5 20 -31.75 3.45 1.67 -0.21

Single lens data lens Starting surface Focal length
1 1 -195.09
2 2 81.91
3 4 -26.97
4 5 50.12
5 7 -161.65
6 9 42.37
7 11 43.21
8 12 -30.71
9 15 -41.55
10 16 31.19
11 18 64.93
12 20 35.08
13 21 -16.63

[Numerical Example 2]
Unit: mm

Surface data Surface number rd nd νd Effective diameter
1 65.654 2.00 1.90366 31.3 41.88
2 43.645 7.35 1.59522 67.7 40.74
3 -374.999 (variable) 40.43
4 -76.313 1.10 1.76200 40.1 20.16
5 19.557 3.65 1.84666 23.8 19.80
6 77.938 1.00 19.59
7 -187.813 1.10 1.72916 54.7 19.59
8 90.891 (variable) 19.65
9 253.579 2.25 1.76200 40.1 20.57
10 -65.392 0.15 20.68
11 36.906 4.10 1.48749 70.2 20.50
12 -52.029 1.10 1.95375 32.3 20.11
13 228.904 13.15 19.94
14 (Aperture) ∞ (Variable) 19.28
15 51.018 1.00 1.85883 30.0 18.75
16 25.420 4.55 1.49700 81.5 18.38
17 -43.980 0.15 18.26
18 27.946 1.90 1.69680 55.5 17.48
19 70.677 (variable) 17.13
20 108.502 2.20 1.85478 24.8 16.12
21 -45.828 1.00 1.83481 42.7 15.81
22 22.067 (variable) 15.00
23 -33.287 3.90 1.61340 44.3 16.51
24 -14.172 1.00 1.59522 67.7 17.05
25 -56.978 (variable) 18.21
Image plane ∞

Various data Zoom ratio 4.45

Wide Angle Mid Telephoto Focal Length 55.03 135.00 245.00
F-number 4.12 5.17 5.85
Half angle of view (°) 13.94 5.78 3.19
Image height 13.66 13.66 13.66
Lens total length 140.00 175.51 194.32
BF 20.65 42.09 46.74

d 3 2.80 38.31 57.12
d 8 21.65 15.57 3.58
d14 22.65 7.29 14.64
d19 13.20 6.59 3.05
d22 6.40 13.01 16.55
d25 20.65 42.09 46.74

Entrance pupil position 42.09 143.85 252.81
Exit pupil position -32.07 -27.99 -34.04
Front principal point position 39.67 18.82 -245.24
Rear principal point position -34.38 -92.91 -198.26

Zoom lens group data group Starting surface Focal length Lens length Front principal point position Rear principal point position
1 1 120.28 9.35 0.19 -5.51
2 4 -34.37 6.85 2.54 -1.62
3 9 63.52 20.75 -1.42 -19.09
4 15 34.44 7.60 2.75 -2.15
5 20 -34.49 3.20 2.24 0.48
6 23 -164.90 4.90 -5.75 -9.11

Single lens data lens Starting surface Focal length
1 1 -150.57
2 2 66.11
3 4 -20.33
4 5 29.98
5 7 -83.86
6 9 68.43
7 11 44.97
8 12 -44.36
9 15 -60.08
10 16 33.13
11 18 65.15
12 20 37.94
13 21 -17.72
14 23 37.34
15 24 -31.97

[Numerical Example 3]
Unit: mm

Surface data Surface number rd nd νd Effective diameter
1 63.162 2.00 1.91082 35.3 41.88
2 44.340 7.30 1.53775 74.7 40.76
3 -396.180 (variable) 40.46
4 -118.440 1.10 1.76200 40.1 21.20
5 20.090 3.55 1.80810 22.8 20.76
6 59.403 2.00 20.56
7 -60.203 1.10 1.72916 54.7 20.57
8 -126.590 (variable) 20.85
9 98.559 2.45 1.83481 42.7 21.47
10 -96.069 0.15 21.47
11 33.399 4.50 1.48749 70.2 21.01
12 -52.095 1.10 1.95375 32.3 20.40
13 107.985 4.05 19.99
14 (Aperture) ∞ (Variable) 19.53
15 72.351 1.00 1.85883 30.0 18.37
16 28.425 4.20 1.48749 70.2 18.04
17 -43.760 0.15 17.93
18 47.742 1.65 1.91082 35.3 17.49
19 143.646 (variable) 17.27
20 -68.057 1.55 1.85478 24.8 16.43
21 -45.062 1.65 16.39
22 -75.249 1.00 1.77250 49.6 15.64
23 31.156 (variable) 15.74
24 43.085 2.55 1.80400 46.6 18.28
25 -176.278 (variable) 18.14
26 -65.464 2.35 1.78472 25.7 18.47
27 -25.771 1.00 1.81600 46.6 18.66
28 56.610 (variable) 19.25
Image plane ∞

Various data Zoom ratio 4.34

Wide Angle Mid Telephoto Focal Length 56.50 135.00 244.99
F-number 4.12 5.17 5.85
Half angle of view (°) 13.59 5.78 3.19
Image height 13.66 13.66 13.66
Lens length 134.97 171.67 189.98
BF 14.02 32.29 45.60

d 3 5.80 42.49 60.81
d 8 24.90 14.66 2.28
d14 19.20 11.18 10.25
d19 12.75 6.62 3.75
d23 4.60 11.75 17.99
d25 7.30 6.28 2.92
d28 14.02 32.29 45.60

Entrance pupil position 45.63 136.34 202.55
Exit pupil position -25.92 -26.79 -29.92
Front principal point position 22.19 -37.14 -347.27
Rear principal point position -42.48 -102.71 -199.40

Zoom lens group data group Starting surface Focal length Lens length Front principal point position Rear principal point position
1 1 134.57 9.30 -0.12 -5.95
2 4 -40.91 7.75 2.43 -2.76
3 9 63.58 12.25 -3.19 -11.82
4 15 43.80 7.00 3.09 -1.30
5 20 -35.10 4.20 2.97 -0.06
6 24 43.29 2.55 0.28 -1.14
7 26 -35.76 3.35 1.02 -0.82

Single lens data lens Starting surface Focal length
1 1 -172.08
2 2 74.59
3 4 -22.46
4 5 36.11
5 7 -158.55
6 9 58.61
7 11 42.48
8 12 -36.72
9 15 -55.10
10 16 36.04
11 18 77.87
12 20 151.32
13 22 -28.41
14 24 43.29
15 26 52.79
16 27 -21.58

The various values for each numerical example are summarized in Table 1 below.

[Imaging device]
Next, an embodiment of a digital still camera (imaging device) 10 using the zoom lens of the present invention as an imaging optical system will be described with reference to Fig. 7. In Fig. 7, 13 denotes a camera body, and 11 denotes an imaging optical system constituted by any one of the zoom lenses L0 described in the first to third embodiments. 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that is built into the camera body and receives an optical image formed by the imaging optical system 11 and photoelectrically converts it. The camera body 13 may be a so-called single-lens reflex camera having a quick-turn mirror, or a so-called mirrorless camera having no quick-turn mirror.

In this way, by applying the zoom lens of the present invention to an imaging device such as a digital still camera, it is possible to obtain an imaging device that is small and lightweight yet has excellent optical performance.

The zoom lenses of the above-mentioned embodiments can be applied not only to imaging devices such as digital still cameras, but also to various optical instruments such as telescopes.

The above describes preferred embodiments and examples of the present invention, but the present invention is not limited to these embodiments and examples, and various combinations, modifications, and variations are possible within the scope of the gist of the invention.

L0 Zoom lens L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group L5 Fifth lens group G1 Negative lens G1
G2 positive lens G2
G3 Negative Lens G3

Claims (16)

A zoom lens having, in order from an object side to an image side, 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 positive refractive power, and a fifth lens group having a negative refractive power, wherein the distance between adjacent lens groups changes during zooming,
During zooming from the wide-angle end to the telephoto end, the second lens group does not move,
The first lens group is composed of a negative lens G1 and a positive lens G2, which are arranged in this order from the object side to the image side.
the second lens group has a negative lens G3 disposed closest to the object;
Let vdG2 be the Abbe number at the d-line of the positive lens G2, f1 be the focal length of the first lens group, ft be the focal length of the zoom lens at the telephoto end, G3R1 be the radius of curvature of the lens surface on the object side of the negative lens G3, and G3R2 be the radius of curvature of the lens surface on the image side of the negative lens G3.
65<νdG2<100
0.40<f1/ft< 0.60
-1.00<(G3R2+G3R1)/(G3R2-G3R1)<-0.40
A zoom lens characterized by satisfying the following conditional expressions: When the focal length of the second lens group is f2,
-0.40<f2/f1<-0.20
2. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of the second lens group is f2,
-0.20<f2/ft<-0.10
3. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of the fifth lens group is f5 and the focal length of the zoom lens at the wide-angle end is fw,
-1.00<f5/fw<-0.40
4. The zoom lens according to claim 1, wherein the following condition is satisfied: When the total lens length at the telephoto end is TLt,
0.65<TLt/ft<0.85
5. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of an air lens formed between the lens closest to the image side in the first lens group and the lens closest to the object side in the second lens group at the wide-angle end is f12air and the focal length of the zoom lens at the wide-angle end is fw,
-0.60<fw/f12air<-0.20
6. The zoom lens according to claim 1, wherein the following condition is satisfied: A zoom lens having, in order from an object side to an image side, 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 positive refractive power, and a fifth lens group having a negative refractive power, wherein the distance between adjacent lens groups changes during zooming,
The first lens group is composed of a negative lens G1 and a positive lens G2, which are arranged in this order from the object side to the image side.
the second lens group has a negative lens G3 disposed closest to the object;
Let vdG2 be the Abbe number at the d-line of the positive lens G2, f1 be the focal length of the first lens group, ft be the focal length of the zoom lens at the telephoto end, G3R1 be the radius of curvature of the object-side lens surface of the negative lens G3, G3R2 be the radius of curvature of the image-side lens surface of the negative lens G3, f12air be the focal length at the wide-angle end of an air lens formed between the lens closest to the image side of the first lens group and the lens closest to the object side of the second lens group, and fw be the focal length of the zoom lens at the wide-angle end.
65<νdG2<100
0.40<f1/ft<0.65
-1.00<(G3R2+G3R1)/(G3R2-G3R1)<-0.40
-0.60<fw/f12air<-0.20
A zoom lens characterized by satisfying the following conditional expressions: Let βrt be the composite lateral magnification from the fourth lens group to the lens group arranged closest to the image side at the telephoto end, βrw be the composite lateral magnification from the fourth lens group to the lens group arranged closest to the image side at the wide-angle end, and fw be the focal length of the zoom lens at the wide-angle end.
0.30<(βrt/βrw)/(ft/fw)<1.50
8. The zoom lens according to claim 1, wherein the following condition is satisfied: The zoom lens according to any one of claims 1 to 8, characterized in that the fifth lens group moves during focusing. The zoom lens according to any one of claims 1 to 9, characterized in that it has an aperture stop between the third lens group and the fourth lens group. The zoom lens according to any one of claims 1 to 10, characterized in that the zoom lens is composed of the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group, arranged in this order from the object side to the image side. A zoom lens comprising, arranged in order from an object side to an image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, wherein the distance between adjacent lens groups changes during zooming,
During zooming from the wide-angle end to the telephoto end, the second lens group does not move,
The first lens group is composed of a negative lens G1 and a positive lens G2, which are arranged in this order from the object side to the image side.
the second lens group has a negative lens G3 disposed closest to the object;
Let vdG2 be the Abbe number at the d-line of the positive lens G2, f1 be the focal length of the first lens group, ft be the focal length of the zoom lens at the telephoto end, G3R1 be the radius of curvature of the lens surface on the object side of the negative lens G3, and G3R2 be the radius of curvature of the lens surface on the image side of the negative lens G3.
65<νdG2<100
0.40<f1/ft<0.65
-1.00<(G3R2+G3R1)/(G3R2-G3R1)<-0.40
A zoom lens characterized by satisfying the following conditional expressions: The zoom lens according to any one of claims 1 to 10, characterized in that the zoom lens is composed of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and a sixth lens group having negative refractive power, arranged in this order from the object side to the image side. A zoom lens comprising, arranged in order from an object side to an image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having negative refractive power, wherein the distance between adjacent lens groups changes during zooming,
The first lens group is composed of a negative lens G1 and a positive lens G2, which are arranged in this order from the object side to the image side.
the second lens group has a negative lens G3 disposed closest to the object;
Let vdG2 be the Abbe number at the d-line of the positive lens G2, f1 be the focal length of the first lens group, ft be the focal length of the zoom lens at the telephoto end, G3R1 be the radius of curvature of the lens surface on the object side of the negative lens G3, and G3R2 be the radius of curvature of the lens surface on the image side of the negative lens G3.
65<νdG2<100
0.40<f1/ft<0.65
-1.00<(G3R2+G3R1)/(G3R2-G3R1)<-0.40
A zoom lens characterized by satisfying the following conditional expressions: The zoom lens according to any one of claims 1 to 10, characterized in that the zoom lens is composed of, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, a sixth lens group with positive refractive power, and a seventh lens group with negative refractive power. An imaging device comprising the zoom lens according to any one of claims 1 to 15 and an imaging element that photoelectrically converts an optical image formed by the zoom lens.

Images