JP7703732B2 - Zoom lens and imaging device having the same - Google Patents

Description

The present invention relates to a zoom lens and an imaging device having the same, and is particularly suitable for imaging devices such as digital still cameras, video cameras, surveillance cameras, and vehicle-mounted cameras.

In recent years, there has been a demand for zoom lenses with a compact overall system and high resolution (high optical performance) for digital still cameras and video cameras.

There is also a demand for zoom lenses to be equipped with a mechanism (anti-vibration mechanism) that compensates for image blurring (image shake) that occurs when accidental vibrations such as camera shake are transmitted to the zoom lens. A known zoom lens that meets these demands is a negative-lead type zoom lens in which a lens group with negative refractive power is positioned closest to the object. Among these negative-lead type zoom lenses, there is known a zoom lens that has an anti-vibration mechanism that compensates for image blurring by moving some of the lens groups (anti-vibration group, image shake correction group) so that they have a component perpendicular to the optical axis (Patent Document 1, Patent Document 2).

Patent Document 1 discloses a three-group or four-group zoom lens having, in order from the object side to the image side, a first lens group with negative refractive power, a second lens group with positive refractive power, and a subsequent group with negative or positive refractive power. The zoom lens in Patent Document 1 discloses a zoom lens that performs image blur correction by moving some of the lens parts in the second lens group in a direction perpendicular to the optical axis.

Patent Document 2 discloses a four-group zoom lens consisting of, in order from the object side to the image side, a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with positive refractive power, and a fourth lens group with negative refractive power. The zoom lens in Patent Document 2 discloses a zoom lens in which image blur correction is performed by a lens portion in the second lens group, and focusing is performed by moving the third lens group in the optical axis direction.

JP 2018-025572 A JP 2019-008235 A

In recent years, when image blur correction is performed by moving the image blur correction group in a direction perpendicular to the optical axis, there is a demand for the image blur correction group to be small and lightweight in order to reduce the size of the moving mechanism (anti-vibration mechanism) and to save power. There is also a demand for there to be little aberration fluctuation during image blur correction, particularly chromatic aberration fluctuation, and for good optical performance to be maintained even during image blur correction.

In general, some of the lens groups in a zoom lens are used as image blur correction groups, and image blur correction can be performed by moving them in a direction perpendicular to the optical axis. However, if the lens configuration of the zoom lens and the lens configuration of the image blur correction group that is moved for image blur correction are not appropriate, the amount of movement of the image blur correction group will be large in order to obtain the desired amount of image blur correction. Alternatively, the optical performance during image blur correction will be significantly reduced, or the lens diameter of the image blur correction group will become large. For this reason, in a zoom lens with an anti-shake mechanism, it is important to appropriately set the overall zoom configuration and the lens configuration of the image blur correction group. In particular, it is necessary to appropriately set the number of lens groups that make up the zoom lens, the refractive power of each lens group, the configuration of the image blur correction group, etc.

The present invention provides a compact zoom lens that effectively corrects aberration fluctuations during image shake correction and provides high optical performance during image shake correction across the entire zoom range.

A zoom lens according to one aspect of the present invention is a zoom lens comprising, arranged in order from the object side to the image side, a front group having negative refractive power and a rear group having positive refractive power overall, the rear group comprising, arranged in order from the object side to the image side, a first subgroup having positive refractive power , a second subgroup having positive refractive power , a third subgroup having negative refractive power , a fourth subgroup having negative refractive power, and a fifth subgroup having negative refractive power , the front group has a positive meniscus lens with a convex surface facing the object side, the distance between the front group and the rear group changes during zooming, the distance between the third subgroup and the fourth subgroup changes during at least one of zooming and focusing, the first subgroup, the third subgroup, and the fourth subgroup are stationary during image shake correction, and the second subgroup moves so as to have a component perpendicular to the optical axis during the image shake correction.

Other objects and features of the present invention are described in the following examples.

According to the present invention, it is possible to realize a compact zoom lens that effectively corrects aberration fluctuations during image shake correction and has high optical performance during image shake correction across the entire zoom range.

1 is a lens cross-sectional view of a zoom lens of Example 1 at a wide-angle end. 5A and 5B are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at a middle zoom position, and at the telephoto end. 4A to 4C are diagrams illustrating lateral aberration after an image position is displaced by 0.3 degrees at the telephoto end of the zoom lens of Example 1. FIG. 11 is a lens cross-sectional view of a zoom lens according to a second embodiment at a wide-angle end. 10A and 10B are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at a middle zoom position, and at the telephoto end. 11A and 11B are diagrams illustrating lateral aberration after an image position is displaced by 0.3 degrees at the telephoto end of the zoom lens according to the second embodiment. FIG. 11 is a lens cross-sectional view of a zoom lens according to a third embodiment at a wide-angle end. 11A and 11B are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, at a middle zoom position, and at the telephoto end. 11A to 11C are diagrams illustrating lateral aberration after an image position is displaced by 0.3 degrees at the telephoto end of the zoom lens of Example 3. FIG. 11 is a lens cross-sectional view of a zoom lens according to a fourth embodiment at a wide-angle end. 11A and 11B are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, at a middle zoom position, and at the telephoto end. 13A to 13C are diagrams illustrating lateral aberration after an image position is displaced by 0.3 degrees at the telephoto end of the zoom lens according to Example 4. FIG. 13 is a lens cross-sectional view of a zoom lens of Example 5 at the wide-angle end. 13A and 13B are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, at a middle zoom position, and at the telephoto end. 13A to 13C are lateral aberration diagrams of the zoom lens of Example 5 at the telephoto end after an image position is displaced by 0.3 degrees. 1 is a schematic diagram of a main part of an imaging device according to the present invention;

Below, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a lens cross-sectional view of a zoom lens of Example 1 of the present invention at the wide-angle end (short focal length end). Figures 2 (A), (B), and (C) are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens of Example 1 is a zoom lens with a zoom ratio of 2.74 and an aperture ratio of approximately 4.1 to 7.3. Figure 3 is a lateral aberration diagram of the zoom lens of Example 1 at the telephoto end after an image position displacement of 0.3 degrees.

Figure 4 is a lens cross-sectional view of the zoom lens of Example 2 of the present invention at the wide-angle end. Figures 5 (A), (B), and (C) are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens of Example 2 is a zoom lens with a zoom ratio of 2.77 and an aperture ratio of approximately 4.1 to 7.3. Figure 6 is a lateral aberration diagram of the zoom lens of Example 2 at the telephoto end after the image position is displaced by 0.3 degrees.

Figure 7 is a lens cross-sectional view of the zoom lens of Example 3 of the present invention at the wide-angle end. Figures 8 (A), (B), and (C) are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens of Example 3 is a zoom lens with a zoom ratio of 2.35 and an aperture ratio of approximately 4.1 to 7.2. Figure 9 is a lateral aberration diagram of the zoom lens of Example 3 at the telephoto end after the image position is displaced by 0.3 degrees.

Figure 10 is a lens cross-sectional view of the zoom lens of Example 4 of the present invention at the wide-angle end. Figures 11(A), (B), and (C) are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens of Example 4 is a zoom lens with a zoom ratio of 2.77 and an aperture ratio of approximately 4.1 to 7.3. Figure 12 is a lateral aberration diagram of the zoom lens of Example 4 at the telephoto end after the image position is displaced by 0.3 degrees.

Figure 13 is a lens cross-sectional view of the zoom lens of Example 5 of the present invention at the wide-angle end. Figures 14 (A), (B), and (C) are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens of Example 5 is a zoom lens with a zoom ratio of 2.78 and an aperture ratio of approximately 4.1 to 7.3. Figure 15 is a lateral aberration diagram of the zoom lens of Example 5 at the telephoto end after the image position is displaced by 0.3 degrees.

The zoom lens as the optical system of each embodiment is used in imaging devices such as digital still cameras, video cameras, surveillance cameras, and vehicle-mounted cameras.

In the lens cross-sectional views of each embodiment, the left side is the object side (front) and the right side is the image side (rear). SP is the aperture. IP is the image plane, on which the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed when used as the imaging optical system of a digital still camera or video camera. Also, when used as the imaging optical system of a silver halide film camera, the photosensitive surface of the film surface is placed.

In the zoom lenses of Examples 1 and 2, the rear group LP has, in order from the object side to the image side, a first subgroup SL1 with positive refractive power, a second subgroup SL2 with positive refractive power, a third subgroup SL3 with negative refractive power, a fourth subgroup SL4 with positive refractive power, and a fifth subgroup SL5 with negative refractive power. The second subgroup SL2 moves during image blur correction. During zooming, the intervals between adjacent subgroups from the first subgroup SL1 to the third subgroup SL3 are fixed, and the intervals between the third subgroup SL3 and the fourth subgroup SL4 and the intervals between the fourth subgroup SL4 and the fifth subgroup SL5 change. During focusing from infinity to a close distance, the fourth subgroup moves from the image side to the object side. The rear group LP further has a diaphragm arranged between the first subgroup SL1 and the second subgroup SL2.

In the zoom lens of Example 3, the rear group LP has, in order from the object side to the image side, a first subgroup SL1 with positive refractive power, a second subgroup SL2 with positive refractive power, a third subgroup SL3 with negative refractive power, and a fourth subgroup SL4 with positive refractive power. The second subgroup SL2 moves during image blur correction. During zooming, the interval between adjacent subgroups from the first subgroup SL1 to the third subgroup SL3 is fixed, and the interval between the third subgroup SL3 and the fourth subgroup SL4 changes. During focusing from infinity to a close distance, some lenses of the fourth subgroup SL4 move from the image side to the object side. The rear group LP further has a diaphragm arranged between the first subgroup SL1 and the second subgroup SL2.

In the zoom lens of Example 4, the rear group LP has, in order from the object, a first subgroup SL1 with positive refractive power, a second subgroup SL2 with positive refractive power, a third subgroup SL3 with negative refractive power, a fourth subgroup SL4 with positive refractive power, and a fifth subgroup SL5 with negative refractive power. The second subgroup SL2 moves during image blur correction. During zooming, the spacing between adjacent subgroups from the first subgroup SL1 to the fifth subgroup SL5 changes. During focusing from infinity to a close distance, the fourth subgroup SL4 moves from the image side to the object side. The rear group LP further has a diaphragm arranged between the first subgroup SL1 and the second subgroup SL2.

In the zoom lens of Example 5, the rear group LP has, in order from the object, a first subgroup SL1 with positive refractive power, a second subgroup SL2 with positive refractive power, a third subgroup SL3 with negative refractive power, a fourth subgroup SL4 with positive refractive power, and a fifth subgroup SL5 with negative refractive power. The second subgroup SL2 moves during image blur correction. During zooming, the distance between the first subgroup SL1 and the second subgroup SL2 is fixed, and the distance between the second subgroup SL2 and the third subgroup SL3, the distance between the third subgroup SL3 and the fourth subgroup SL4, and the distance between the fourth subgroup SL4 and the fifth subgroup SL5 change. During focusing from infinity to a close distance, the fourth subgroup SL4 moves from the image side to the object side. The rear group LP further has a diaphragm disposed between the first subgroup SL1 and the second subgroup SL2.

Each subgroup may consist of a single lens or multiple lenses.

In the aberration diagrams of each example, Fno is the F-number and ω is the half angle of view (°). In the spherical aberration diagrams, d is the d-line (wavelength 587.56 nm) and g is the g-line (wavelength 435.835 nm).

In the astigmatism diagram, ΔS is the sagittal image plane for the d-line, and ΔM is the meridional image plane for the d-line. Distortion is shown for the d-line. Magnification chromatic aberration diagrams are shown for the g-line.

The zoom lens of the present invention is composed of, in order from the object side to the image side, a front group LN with negative refractive power, and a rear group LP with positive refractive power overall. The rear group LP has, in order from the object side to the image side, at least a first subgroup SL1 with positive refractive power, a second subgroup SL2 with positive refractive power, a third subgroup SL3 with negative refractive power, and a fourth subgroup SL4. During image blur correction, the first subgroup SL1, the third subgroup SL3, and the fourth subgroup SL4 do not move, but the second subgroup SL2 moves so as to have a component perpendicular to the optical axis. During zooming, at least the distance between the front group LN and the rear group LP changes.

In a negative-lead zoom lens, by appropriately arranging lens subgroups with vibration isolation mechanisms, it is possible to increase the number of vibration isolation stages and reduce the size of the lens by suppressing the amount of movement during image blur correction. By arranging the first subgroup SL1 with positive refractive power on the object side of the second subgroup SL2, which is a vibration isolation group with positive refractive power, it is possible to prevent the positive refractive power of the vibration isolation group SL2 from becoming too strong. This makes it possible to achieve both correction of axial chromatic aberration and spherical aberration and correction of optical performance during image blur correction.

In addition, by disposing the third subgroup SL3, which has negative refractive power, on the image side of the vibration-reduction group SL2, the positive refractive power of the vibration-reduction group SL2 can be optimized, making it possible to ensure optical performance during image shake correction while also increasing the number of vibration-reduction stages.

Furthermore, in the zoom lens of each embodiment, the fourth sub-group SL4 is disposed on the image side of the third sub-group SL3, which has negative refractive power. The distance between the third sub-group SL3 and the fourth sub-group SL4 changes during at least one of zooming and focusing. When focusing is performed on the image side of the third sub-group SL3, it is possible to have good optical performance from infinity shooting to close-up shooting while appropriately correcting the field curvature and lateral chromatic aberration that are mainly generated by off-axis light rays. Also, by changing the distance between the third sub-group SL3 and the fourth sub-group SL4 during zooming, it is possible to effectively correct the fluctuations in various aberrations that accompany zooming.

As described above, in a negative-lead type zoom lens, it is possible to obtain a small zoom lens that effectively corrects aberration fluctuations during image shake correction and has high optical performance even during image shake correction.

In each embodiment, it is more preferable to satisfy one or more of the following conditional expressions (1) to (7).

Here, the lateral magnification of the second subgroup SL2 at the telephoto end is β22t, and the lateral magnification of all lenses on the image side of the second subgroup SL2 at the telephoto end is β22rt. The focal length of the first subgroup SL1 is f21p, the focal length of the second subgroup SL2 is f22p, and the focal length of the third subgroup SL3 is f23n. The combined focal length of the first subgroup SL1 to the third subgroup SL3 at the wide-angle end is f2w. The distance from the aperture stop SP to the object side vertex of the second subgroup SL2 at the wide-angle end is dw, and the total optical length of the entire system at the wide-angle end is Lw. The radius of curvature of the lens surface closest to the object of the third subgroup SL3 is rn1, and the radius of curvature of the surface closest to the image of the third subgroup SL3 is rn2.

1.0<(1-β22t)×β22rt<3.0 (1)
0.5<f21p/f22p<2.0...(2)
-1.5<f22p/f23n<-0.5...(3)
0.5<f22p/f2w<2.0...(4)
-2.0<f23n/f2w<-0.5...(5)
0.01<|dw/Lw|<0.10...(6)
-8.0<(rn1+rn2)/(rn1-rn2)<2.0...(7)
Conditional formula (1) specifies the image shift sensitivity of the second sub-group SL2 at the telephoto end, where the image shift sensitivity TS is the ratio (TS=ΔI/ΔL) of the vertical movement amount ΔL of the image blur correction group when the image blur correction group is moved in the direction perpendicular to the optical axis to the movement amount ΔI of the image (imaging position) on the image plane at that time in the direction perpendicular to the optical axis.

By optimizing conditional expression (1), the amount of vertical movement of the second subgroup SL2 during image blur correction can be reduced, making it possible to reduce the size of the lens.

If the upper limit of conditional expression (1) is exceeded, the amount of movement of the vibration reduction mechanism during image blur correction can be reduced, but the refractive power of the second subgroup SL2 becomes stronger, resulting in deterioration of spherical aberration. If the lower limit of conditional expression (1) is exceeded, the refractive power of the second subgroup SL2 becomes weaker, increasing the amount of movement of the second subgroup SL2 to achieve a predetermined image blur correction, which is undesirable as it results in an increase in the size of the vibration reduction mechanism.

Conditional formula (2) specifies the ratio of the focal length f21p of the first subgroup SL1 to the focal length f22p of the second subgroup SL2. By optimizing the refractive power of the two subgroups with positive refractive power, mainly within the rear group LP, it is possible to suppress the amount of movement of the vibration isolation mechanism while achieving good optical performance.

If the upper limit of conditional expression (2) is exceeded, the refractive power of the second subgroup SL2 becomes strong, which makes it possible to reduce the amount of movement of the vibration reduction mechanism during image blur correction, but this leads to deterioration of spherical aberration. If the lower limit of conditional expression (2) is exceeded, the refractive power of the first subgroup SL1 becomes strong, which is advantageous for reducing the overall lens length, but the angle of incidence of marginal rays of the axial rays to the second subgroup SL2 having the vibration reduction mechanism becomes large. As a result, the optical performance during image blur correction is likely to deteriorate.

Conditional formula (3) specifies the ratio of the focal length f22p of the second subgroup SL2 to the focal length f23n of the third subgroup SL3. Mainly within the rear group LP, the third subgroup SL3 with negative refractive power is disposed on the image side of the second subgroup SL2 with positive refractive power and equipped with an anti-vibration mechanism, and by optimizing its focal length, it is possible to suppress the amount of movement of the anti-vibration mechanism while achieving good optical performance.

If the upper limit of conditional expression (3) is exceeded, the refractive power of the second subgroup SL2 having the vibration isolation mechanism becomes weak, and the amount of movement of the second subgroup SL2 during image blur correction increases, which is undesirable. If the lower limit of conditional expression (3) is exceeded, the refractive power of the third subgroup SL3 becomes strong, which is advantageous for reducing the overall lens length, but off-axis rays are largely diverged, resulting in an increase in the effective diameter of the subgroup on the image side of the third subgroup SL3.

Conditional formula (4) specifies the ratio of the focal length f22p of the second subgroup SL2 to the combined focal length f2w of the first subgroup SL1 to the third subgroup SL3 at the wide-angle end. By optimizing the focal length of the second subgroup SL2, it is possible to suppress the amount of movement during image shake correction while also achieving good optical performance.

If the upper limit of conditional expression (4) is exceeded, the refractive power of the second subgroup SL2 becomes weak, which is advantageous for suppressing the occurrence of various aberrations, but is undesirable because it increases the amount of movement of the second subgroup SL2 during image blur correction. If the lower limit of conditional expression (4) is exceeded, the refractive power of the second subgroup SL2 becomes strong, which makes it possible to suppress the amount of movement of the second subgroup SL2 during image blur correction, but it leads to an increase in spherical aberration.

Conditional formula (5) specifies the ratio of the focal length f23n of the third subgroup SL3 to the composite focal length f2w of the first subgroup SL1 to the third subgroup SL3 at the wide-angle end. By optimizing the focal length of the third subgroup SL3, it is possible to suppress the amount of movement during image shake correction while achieving good optical performance.

When the upper limit of conditional expression (5) is exceeded, the refractive power of the third subgroup SL3 becomes strong, the refractive power of the second subgroup SL2 can be optimized, and the amount of movement of the second subgroup SL2 can be reduced, but this is not preferred because it leads to a deterioration in optical performance due to the occurrence of field curvature and distortion aberration caused mainly by off-axis light rays. When the lower limit of conditional expression (5) is exceeded, the refractive power of the third subgroup SL3 becomes weak, and the occurrence of field curvature and distortion aberration caused mainly by off-axis light rays can be reduced, but it becomes difficult to optimize the refractive power of the second subgroup SL2, and the amount of movement of the second subgroup SL2 during image shake correction increases, which is not preferred.

Conditional formula (6) specifies the ratio of the distance dw from the aperture stop SP to the object-side vertex of the second subgroup SL2 at the wide-angle end to the total optical length Lw of the entire system at the wide-angle end.

If the upper limit of conditional expression (6) is exceeded, the distance between the aperture stop SP and the second sub-group SL2 becomes longer and the on-axis marginal rays become higher, which is undesirable as it leads to a deterioration in optical performance during image blur correction. If the lower limit of conditional expression (6) is exceeded, the distance between the aperture stop SP and the second sub-group SL2 becomes shorter and it becomes difficult to arrange the vibration isolation mechanism, which is undesirable.

Conditional formula (7) defines the shape factor (lens shape) of the third subgroup SL3.

If the upper limit of conditional expression (7) is exceeded, the refractive power of the third subgroup SL3 becomes strong, making it difficult to correct the field curvature and distortion aberration that are mainly generated by off-axis rays, which is not preferable. If the lower limit of conditional expression (7) is exceeded, the refractive power of the third subgroup SL3 becomes weak, making it difficult to optimize the refractive power of the second subgroup SL2, and the amount of movement of the second subgroup SL2 during image shake correction increases, which is not preferable.

It is preferable to set the numerical ranges of conditional expressions (1) to (7) as follows:

1.3<(1-β22)×β22r<2.7 (1a)
0.7<f21p/f22p<1.7...(2a)
-1.4<f22p/f23n<-0.6...(3a)
0.7<f22p/f2w<1.7...(4a)
-1.8<f23n/f2w<-0.8...(5a)
0.015<|dw/Lw|<0.080...(6a)
-7.0<(rn1+rn2)/(rn1-rn2)<-2.5...(7a)
It is more preferable to set the numerical ranges of the conditional expressions (1a) to (7a) as follows:

1.4<(1-β22)×β22r<2.6 (1b)
0.75<f21p/f22p<1.60...(2b)
-1.30<f22p/f23n<-0.75...(3b)
0.90<f22p/f2w<1.55...(4b)
-1.7<f23n/f2w<-0.9...(5b)
0.018<|dw/Lw|<0.070...(6b)
-6.3<(rn1+rn2)/(rn1-rn2)<-3.0...(7b)
It is desirable for the front lens unit LN to move in the optical axis direction during zooming, which allows the overall lens length to be reduced at the wide-angle end or at an intermediate zoom position.

It is desirable for the front group LN to have at least one negative lens and at least one positive lens. This makes it possible to correct chromatic aberration of magnification at the wide-angle end and optimize distortion.

It is desirable for the first subgroup SL1 in the rear group LP to have at least one positive lens and at least one negative lens. This makes it possible to correct axial chromatic aberration while increasing the refractive index of the first subgroup SL1.

It is desirable for the third subgroup SL3 to be made up of a single lens having negative refractive power. This makes it possible to both shorten the overall lens length and suppress various aberrations that are mainly caused by off-axis rays.

It is desirable that the fourth subgroup SL4 has positive refractive power, and that some or all of the lenses in the fourth subgroup SL4 move in the optical axis direction during focusing. This makes it possible to more effectively suppress aberration fluctuations during focusing.

Below are numerical examples 1 to 5 corresponding to examples 1 to 5, respectively.

In the surface data of each numerical example, ri is the radius of curvature of the ith surface from the object side, di (mm) is the axial distance (distance on the optical axis) between the ith and (i+1)th surfaces from the object side, and ndi is the refractive index for the d-line of the material of the ith optical component from the object side. νdi is the Abbe number of the material of the ith optical component from the object side. The Abbe number νd of a material is expressed as νd=(Nd-1)/(NF-NC), where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines.

In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values when the optical system of each example is focused on an object at infinity. "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image surface expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final surface of the zoom lens plus the back focus.

In addition, when an optical surface is aspheric, a symbol * is added to the right of the surface number. When X is the displacement from the apex of the surface in the optical axis direction, h is the height from the optical axis in a direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, A8, A10, and A12 are aspheric coefficients of each order, the aspheric shape is expressed as follows:
x=(h ² /R)/[1+{1-(1+k)(h/R) ² } ^1/2 +A4×h ⁴ +A6×h ⁶ +A8×h ⁸ +A10×h ¹⁰ +A12×h ¹²
In addition, "e±XX" in each aspheric coefficient means "×10± ^XX ."

(Numerical Example 1)
Unit: mm

Surface data surface number rd nd νd
1 123.708 1.20 1.83481 42.7
2 21.374 5.46
3 120.122 1.20 1.60311 60.6
4 34.846 0.78
5 26.625 3.00 1.92286 20.9
6 40.918 (variable)
7 49.621 2.14 1.77250 49.6
8 -159.258 0.50
9 13.760 4.50 1.49700 81.5
10 -134.994 1.00 1.78590 44.2
11 23.310 6.69
12 (Aperture) ∞ (Variable)
13 19.343 1.04 1.74077 27.8
14 12.179 4.75 1.51742 52.4
15 -93.662 (variable)
16 -11.456 1.20 1.96300 24.1
17 -17.629 (variable)
18 -98.079 4.12 1.80000 29.8
19 -20.057 (variable)
20* -19.075 2.50 1.53110 55.9
21* -19.677 2.86
22 -17.003 2.00 1.88300 40.8
23 -44.739 (variable)
Image plane ∞

Aspheric data No. 20
K=0.00000e+000 A4=4.20157e-006 A6=5.72660e-007 A8=-6.94053e-010

Page 21
K=0.00000e+000 A4=6.01118e-006 A6=4.23733e-007

Various data Zoom ratio 2.74
Wide Angle Mid Telephoto Focal Length 24.86 38.85 68.13
F-number 4.12 5.10 7.31
Angle of view 38.31 29.11 17.62
Image height 19.64 21.64 21.64
Lens length 102.91 97.95 104.95
BF 13.00 22.13 37.46

d6 30.06 14.38 1.41
d12 3.72 3.72 3.72
d15 4.00 4.00 4.00
d17 5.68 4.71 4.51
d19 1.50 4.07 8.90
d23 13.00 22.13 37.46

Zoom lens data group Starting surface Focal length
1 1 -31.10
2 7 36.27
3 13 39.34
4 16 -37.56
5 18 30.79
6 20 -31.13

(Numerical Example 2)
Unit: mm

Surface data surface number rd nd νd
1 108.586 1.20 1.80400 46.6
2 21.327 5.86
3 169.244 1.20 1.51633 64.1
4 28.330 0.50
5 24.780 3.42 1.85478 24.8
6 40.442 (variable)
7 74.376 2.00 1.51633 64.1
8 -73.781 0.51
9 14.459 4.50 1.49700 81.5
10 -60.889 1.00 1.81600 46.6
11 51.262 6.01
12 (Aperture) ∞ (Variable)
13 25.706 2.45 1.48749 70.2
14 -67.886 (variable)
15 -12.288 1.20 1.84666 23.8
16 -24.422 (variable)
17 -128.155 4.27 1.77047 29.7
18 -21.345 (variable)
19* -18.859 2.50 1.53110 55.9
20* -19.913 2.89
21 -16.231 2.00 1.88300 40.8
22 -36.115 (variable)
Image plane ∞

Aspheric data No. 19
K=0.00000e+000 A4=-1.96892e-005 A6=5.89993e-007 A8=-4.51652e-010

Page 20
K=0.00000e+000 A4=-1.91709e-005 A6=4.20764e-007

Various data Zoom ratio 2.77
Wide Angle Mid Telephoto Focal Length 24.60 37.07 68.20
F-number 4.12 5.06 7.31
Angle of view 38.60 30.27 17.60
Image height 19.64 21.64 21.64
Lens length 103.78 98.47 104.49
BF 13.00 21.01 35.63

d6 31.23 16.31 1.43
d12 6.29 6.29 6.29
d14 4.00 4.00 4.00
d16 6.24 5.27 5.08
d18 1.50 4.08 10.55
d22 13.00 21.01 35.63

Zoom lens data group Starting surface Focal length
1 1 -31.00
2 7 33.01
3 13 38.58
4 15 -30.60
5 17 32.67
6 19 -33.19

(Numerical Example 3)
Unit: mm

Surface data surface number rd nd νd
1 1336.663 1.30 1.77250 49.6
2 20.570 1.41
3* 28.036 1.50 1.58313 59.4
4* 21.838 2.53
5 23.042 4.46 2.00100 29.1
6 37.777 (variable)
7* 12.861 4.00 1.58313 59.4
8* 12.683 2.14
9 14.404 7.00 1.49700 81.5
10 -15.409 1.00 1.61340 44.3
11 70.334 2.00
12 (Aperture) ∞ (Variable)
13 28.878 1.04 1.96300 24.1
14 16.340 3.00 1.80100 35.0
15 430.130 (variable)
16 -9.734 1.20 1.62041 60.3
17 -15.681 (variable)
18 -137.087 4.74 1.87070 40.7
19 -25.226 3.19
20 -22.989 2.00 1.85478 24.8
21 -68.069 1.20
22 -295.419 2.50 1.92286 20.9
23 -92.087 (variable)
Image plane ∞

Aspheric data surface 3
K=0.00000e+000 A4=5.21412e-005 A6=-2.20073e-007 A8=5.43077e-010

Side 4
K=0.00000e+000 A4=4.72381e-005 A6=-2.55452e-007 A8=5.94739e-010

Side 7
K=0.00000e+000 A4=-1.55805e-005 A6=-5.36694e-008 A8=-1.62591e-010

Side 8
K=0.00000e+000 A4=-7.68425e-007 A6=-3.05208e-008 A8=1.00578e-009

Various data Zoom ratio 2.35
Wide Angle Mid Telephoto Focal Length 28.68 42.81 67.45
F-number 4.12 5.25 7.16
Angle of view 34.41 26.81 17.78
Image height 19.64 21.64 21.64
Lens length 105.26 102.53 115.51
BF 13.00 20.64 36.88

d6 29.19 13.69 1.44
d12 2.00 2.00 2.00
d15 7.64 7.64 7.64
d17 7.24 12.37 21.36
d23 13.00 20.64 36.88

Zoom lens data group Starting surface Focal length
1 1 -43.14
2 7 42.73
3 13 45.77
4 16 -44.83
5 18 80.93

(Numerical Example 4)
Unit: mm

Surface data surface number rd nd νd
1 120.883 1.20 1.77250 49.6
2 21.592 5.17
3 122.600 1.20 1.60311 60.6
4 26.671 0.64
5 24.605 3.37 1.85478 24.8
6 41.898 (variable)
7 52.842 1.93 1.72916 54.7
8 -119.758 0.84
9 15.021 4.50 1.49700 81.5
10 -119.427 1.00 1.85150 40.8
11 30.787 4.89
12 (Aperture) ∞ (Variable)
13 28.451 1.04 1.72047 34.7
14 12.857 3.46 1.63854 55.4
15 -174.840 (variable)
16 -11.274 1.20 2.00100 29.1
17 -15.540 (variable)
18 -104.670 3.91 1.72825 28.5
19 -21.550 (variable)
20* -29.913 2.50 1.53110 55.9
21* -28.530 3.33
22 -18.626 2.00 1.95375 32.3
23 -46.003 (variable)
Image plane ∞

Aspheric data No. 20
K=0.00000e+000 A4=-5.61900e-006 A6=3.75750e-007 A8=-3.79977e-010

Page 21
K=0.00000e+000 A4=-3.66808e-006 A6=3.08570e-007

Various data Zoom ratio 2.77
Wide Angle Mid Telephoto Focal Length 24.50 39.36 67.92
F-number 4.12 5.17 7.31
Angle of view 38.72 28.80 17.67
Image height 19.64 21.64 21.64
Lens length 100.87 96.84 103.49
BF 13.00 19.58 32.75

d6 28.68 12.85 1.70
d12 5.44 5.50 3.37
d15 6.26 6.99 9.15
d17 3.81 5.01 5.57
d19 1.50 4.74 8.77
d23 13.00 19.58 32.75

Zoom lens data group Starting surface Focal length
1 1 -30.23
2 7 36.12
3 13 44.45
4 16 -47.74
5 18 36.54
6 20 -34.81

(Numerical Example 5)
Unit: mm

Surface data surface number rd nd νd
1 161.056 1.20 1.77250 49.6
2 21.356 5.11
3 78.020 1.20 1.78800 47.4
4 30.696 1.11
5 26.430 4.03 1.85478 24.8
6 56.461 (variable)
7 36.811 2.04 1.74320 49.3
8 -991.629 0.50
9 13.277 4.50 1.49700 81.5
10 -148.848 1.00 1.80400 46.6
11 17.826 5.13
12 (Aperture) ∞ (Variable)
13 22.846 1.04 1.80518 25.4
14 12.936 4.28 1.63854 55.4
15 -73.785 (variable)
16 -11.221 1.20 1.90043 37.4
17 -16.862 (variable)
18 -85.938 3.77 1.70585 30.2
19 -19.442 (variable)
20* -27.738 2.50 1.53110 55.9
21* -23.379 5.61
22 -20.950 2.00 1.88300 40.8
23 -119.884 (variable)
Image plane ∞

Aspheric data No. 20
K=0.00000e+000 A4=6.95149e-005 A6=6.67973e-007 A8=-1.48716e-009

Page 21
K=0.00000e+000 A4=7.78983e-005 A6=6.15996e-007

Various data Zoom ratio 2.78
Wide Angle Mid Telephoto Focal Length 24.56 39.58 68.24
F-number 4.12 5.34 7.31
Angle of view 38.66 28.66 17.59
Image height 19.64 21.64 21.64
Lens length 102.04 98.69 105.78
BF 13.00 23.10 38.31

d6 28.77 13.92 1.43
d12 4.42 4.42 4.42
d15 4.96 5.64 6.57
d17 3.10 3.88 4.93
d19 1.57 1.50 3.90
d23 13.00 23.10 38.31

Zoom lens data group Starting surface Focal length
1 1 -34.65
2 7 47.62
3 13 32.69
4 16 -41.43
5 18 34.78
6 20 -32.83

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

[Imaging device]
Next, an embodiment of a digital still camera (imaging device) using the optical system of the present invention as an imaging optical system will be described with reference to Fig. 16. In Fig. 16, 10 denotes a camera body, and 11 denotes an imaging optical system constituted by any of the optical systems described in Examples 1 to 5. 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or 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 10 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 optical system of the present invention to an imaging device such as a digital still camera, an imaging device with a small lens can be obtained.

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

LN front group LP rear group SL1 1st subgroup SL2 2nd subgroup SL3 3rd subgroup

Claims (14)

A zoom lens comprising, in order from an object side to an image side, a front group having negative refractive power and a rear group having positive refractive power as a whole,
the rear group comprises, arranged in order from the object side to the image side, a first sub group having positive refractive power, a second sub group having positive refractive power, a third sub group having negative refractive power, a fourth sub group , and a fifth sub group having negative refractive power;
the front group has a positive meniscus lens having a convex surface facing the object side,
During zooming, the distance between the front group and the rear group changes,
a distance between the third subgroup and the fourth subgroup changes during at least one of zooming and focusing;
During zooming, the distance between the fourth subgroup and the fifth subgroup changes,
the first sub-group, the third sub-group, and the fourth sub-group are stationary during image blur correction,
The zoom lens according to claim 1, wherein the second subgroup moves so as to have a component perpendicular to an optical axis during the image blur correction. When the lateral magnification of the second sub group at the telephoto end is β22t and the lateral magnification of all lenses on the image side of the second sub group at the telephoto end is β22rt,
1.0<(1-β22t)×β22rt<3.0
2. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the first subgroup is f21p and the focal length of the second subgroup is f22p,
0.5<f21p/f22p<2.0
3. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of the second subgroup is f22p and the focal length of the third subgroup is f23n,
-1.5<f22p/f23n<-0.5
4. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of the second partial group is f22p and the composite focal length of the first partial group to the third partial group at the wide-angle end is f2w,
0.5<f22p/f2w<2.0
5. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the third partial group is f23n and the composite focal length from the first partial group to the third partial group at the wide-angle end is f2w,
-2.0<f23n/f2w<-0.5
6. The zoom lens according to claim 1, which satisfies the following condition: a diaphragm disposed between the first subgroup and the second subgroup;
When the distance from the stop to the object side vertex of the second subgroup at the wide-angle end is dw, and the total optical length of the entire system at the wide-angle end is Lw,
0.01<|dw/Lw|<0.10
7. The zoom lens according to claim 1, which satisfies the following condition: When the radius of curvature of the lens surface closest to the object side in the third subgroup is rn1 and the radius of curvature of the lens surface closest to the image side in the third subgroup is rn2,
-8.0<(rn1+rn2)/(rn1-rn2)<-2.0
8. The zoom lens according to claim 1, wherein the following condition is satisfied: the fourth subgroup has a positive refractive power;
9. The zoom lens according to claim 1, wherein some or all of the lenses in the fourth subgroup move during focusing. The zoom lens according to any one of claims 1 to 9, characterized in that the front group moves during the zooming. A zoom lens according to any one of claims 1 to 10, characterized in that the front group has a negative lens and a positive lens. The zoom lens according to any one of claims 1 to 11, characterized in that the first subgroup has a positive lens and a negative lens. The zoom lens according to any one of claims 1 to 12, characterized in that the third subgroup is made up of a single lens having negative refractive power. A zoom lens according to any one of claims 1 to 13 ;
and an image sensor that receives an image formed by the zoom lens.