JP7793322B2 - Zoom lens and imaging device - Google Patents

Description

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

In recent years, there has been a demand for zoom lenses that offer a wide angle of view, a high zoom ratio, and are compact (short overall optical length). Patent documents 1 and 2 disclose zoom lenses that, from the object side to the image side, consist 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, with the rear group having at least an rn lens group with negative refractive power.

Japanese Patent Application Laid-Open No. 2019-200254 Japanese Patent Application Laid-Open No. 2019-132887

The zoom lens disclosed in Patent Document 1 has a too large ratio between the total optical length at the telephoto end and the focal length at the telephoto end, so attempts to further reduce its size could result in increased aberration fluctuations throughout the entire zoom range. The zoom lens disclosed in Patent Document 2 has a too large ratio between the magnification sharing of the second lens group and the magnification sharing of the third lens group, so attempts to further reduce its size could result in increased aberration fluctuations throughout the entire zoom range.

The present invention aims to provide an advantageous zoom lens that, for example, has a wide angle of view, a high zoom ratio, is compact, and has high optical performance across the entire zoom range.

A zoom lens according to one aspect of the present invention comprises, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. and a rear group including two or more lens groups , wherein the first lens group has, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens, and the rear group has an rn lens group with negative refractive power , wherein the first lens group is fixed, the second lens group and the third lens group move, and a spacing between adjacent lens groups changes during zooming, and a lateral magnification β2t of the second lens group at a telephoto end, a lateral magnification β2w of the second lens group at a wide-angle end, a lateral magnification β3t of the third lens group at a telephoto end, a lateral magnification β3w of the third lens group at a wide-angle end, a total optical length TDt of the zoom lens, a focal length ft of the zoom lens at a telephoto end, a focal length fw of the zoom lens at a wide-angle end, a focal length f1 of the first lens group , and a focal length f2 of the second lens group satisfy predetermined conditional expressions.

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

The present invention makes it possible to provide a zoom lens that is advantageous in terms of, for example, a wide angle of view, a high zoom ratio, compact size, and high optical performance across the entire zoom range.

FIG. 2 is a cross-sectional view of the zoom lens at the wide-angle end in the first embodiment. 4A to 4C are aberration diagrams of the zoom lens in Example 1 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 2. 10A to 10C are aberration diagrams of the zoom lens in Example 2 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 3. 10A to 10C are aberration diagrams of the zoom lens in Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 4. 10A to 10C are aberration diagrams of the zoom lens in Example 4 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 5. 10A to 10C are aberration diagrams of the zoom lens in Example 5 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. FIG. 13 is a cross-sectional view of a zoom lens at the wide-angle end in Example 6. 10A to 10C are aberration diagrams of the zoom lens in Example 6 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. 1 is a schematic diagram of an imaging device equipped with a zoom lens in each embodiment.

The following describes in detail an embodiment of the present invention with reference to the drawings.

First, an overview of the zoom lens in each embodiment will be described. The zoom lens in each embodiment consists, in order from the object side to the image side, of a first lens unit B1 with positive refractive power, a second lens unit B2 with negative refractive power, a third lens unit B3 with positive refractive power, and a rear unit. This allows the front lens diameter to be reduced when a high zoom ratio is achieved. The first lens unit B1 includes, in order from the object side to the image side, a negative lens unit B11, a positive lens unit B12, and a positive lens unit B13. The rear unit includes an rn lens unit with a negative refractive index (B4 in Examples 1 to 5, B5 in Example 6). This allows the diameter of the final lens unit to be reduced while reducing the overall optical length at the telephoto end. For zooming, the first lens unit B11 is fixed, while the second lens unit B2 and the third lens unit B3 move, changing the spacing between adjacent lens units. This allows the overall optical length to be reduced when a high zoom ratio is achieved.

Furthermore, the zoom lens of each embodiment satisfies the following conditional expressions (1) to (3).

1.50<(β2t/β2w)/(β3t/β3w)<8.60...(1)
0.30<T D t/ft<0.70 (2)
1.50<f1/fw<20.00...(3)
Here, β2t is the lateral magnification of the second lens unit B2 at the telephoto end, β2w is the lateral magnification of the second lens unit B2 at the wide-angle end, β3t is the lateral magnification of the third lens unit B3 at the telephoto end, and β3w is the lateral magnification of the third lens unit B3 at the wide-angle end. TDt is the total optical length (in air), that is, the distance on the optical axis from the front surface (the lens surface closest to the object) of the zoom lens to the final surface (the lens surface closest to the image) plus the back focus. ft is the focal length of the zoom lens (entire system) at the telephoto end, fw is the focal length of the zoom lens (entire system) at the wide-angle end, and f1 is the focal length of the first lens unit B1.

Conditional formula (1) appropriately sets the magnification sharing ratio between the second lens group B2 and the third lens group B3. By setting it in this way, it becomes possible to appropriately set astigmatism and spherical aberration while suppressing the overall optical length at the telephoto end. If the upper limit of conditional formula (1) is exceeded, the magnification sharing ratio of the second lens group B2 becomes too large, and as the zoom ratio increases, the movement amount of the second lens group B2 increases, making it difficult to suppress the overall optical length at the telephoto end. On the other hand, if the lower limit of conditional formula (1) is exceeded, the magnification sharing ratio of the third lens group B3 becomes too large, and the refractive index of the third lens group B3 increases in order to suppress the overall optical length at the telephoto end, making it difficult to suppress field curvature throughout the entire zoom range.

Conditional formula (2) appropriately sets the ratio between the axial length from the first lens surface (foreground) at the telephoto end to the image plane IP and the focal length at the telephoto end. Exceeding the upper limit of conditional formula (2) makes it difficult to reduce the overall optical length at the telephoto end relative to the focal length at the telephoto end. Alternatively, the focal length at the telephoto end becomes too large relative to the overall optical length, making it difficult to reduce axial chromatic aberration and lateral chromatic aberration at the telephoto end. On the other hand, exceeding the lower limit of conditional formula (2) makes the overall optical length at the telephoto end too small relative to the focal length at the telephoto end, making it difficult to reduce spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end.

Conditional formula (3) is a conditional formula that appropriately sets the ratio between the focal length of the first lens group B1 and the focal length of the zoom lens at the telephoto end. If the upper limit of conditional formula (3) is exceeded, the focal length of the first lens group B1 will become too large relative to the focal length at the wide-angle end, making it difficult to suppress the overall optical length. On the other hand, if the lower limit of conditional formula (3) is exceeded, the focal length of the first lens group B1 will become too small relative to the focal length of the zoom lens at the wide-angle end, making it difficult to suppress spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the wide-angle end.

Preferably, the numerical ranges of conditional expressions (1) to (3) are set as shown in the following conditional expressions (1a) to (3a), respectively.

1.85<(β2t/β2w)/(β3t/β3w)<8.53...(1a)
0.44<T D t/ft<0.67 (2a)
4.65<f1/fw<14.60...(3a)
More preferably, the numerical ranges of the conditional expressions (1) to (3) are set as shown in the following conditional expressions (1b) to (3b), respectively.

2.20<(β2t/β2w)/(β3t/β3w)<8.45 (1b)
0.58<T D t/ft<0.64 (2b)
7.80<f1/fw<9.20...(3b)
In each embodiment, in order to maintain good optical performance while suppressing the total optical length, it is preferable to satisfy at least one of the following conditional expressions (4) to (10).

1.30<f1/f3<6.80...(4)
-12.00<f1/f2<-2.00...(5)
0.10<f1/ft<0.80 (6)
-8.00<frn/fw<-1.00...(7)
0.30<βrnt/βrnw<2.00 (8)
1.20<fr/fw<5.20...(9)
-8.00<m2/m3<-0.50...(10)
Here, f2 is the focal length of the second lens group B2, f3 is the focal length of the third lens group B3, and frn is the focal length of the rn lens group. βrnt is the lateral magnification of the rn lens group at the telephoto end, βrnw is the lateral magnification of the rn lens group at the wide-angle end, and fr is the focal length of the final lens group in the rear group that is positioned closest to the image. m2 is the distance between the second lens group B2 at the wide-angle end and the second lens group B2 at the telephoto end (this is considered positive if the second lens group B2 moves from the object side to the image side). m3 is the distance between the third lens group B3 at the wide-angle end and the third lens group B3 at the telephoto end (this is considered positive if the third lens group B3 moves from the object side to the image side).

Conditional formula (4) is a conditional formula for appropriately setting the ratio between the focal length of the first lens group B1 and the focal length of the third lens group B3. If the upper limit of conditional formula (4) is exceeded, it becomes difficult to reduce the overall optical length at the telephoto end. On the other hand, if the lower limit of conditional formula (4) is exceeded, it becomes difficult to reduce the front lens diameter.

Conditional formula (5) is a conditional formula for appropriately setting the ratio between the focal length of the first lens group B1 and the focal length of the second lens group B2. If the upper limit of conditional formula (5) is exceeded, it becomes difficult to reduce the overall optical length at the telephoto end. On the other hand, if the lower limit is exceeded, it becomes difficult to reduce spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end.

Conditional formula (6) is a conditional formula for appropriately setting the ratio between the focal length of the first lens group B1 and the focal length of the zoom lens at the telephoto end. If the upper limit of conditional formula (6) is exceeded, the focal length of the first lens group B1 will be too small relative to the focal length of the zoom lens at the telephoto end, making it difficult to reduce the overall optical length. On the other hand, if the lower limit of conditional formula (6) is exceeded, the focal length of the first lens group B1 will be too small relative to the focal length of the zoom lens at the telephoto end, making it difficult to reduce spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end.

Conditional formula (7) is a conditional formula for appropriately setting the ratio between the focal length of the rn lens group and the focal length of the zoom lens at the wide-angle end. If the upper limit of conditional formula (7) is exceeded, the focal length of the rn lens group will become too large relative to the focal length of the zoom lens at the wide-angle end, making it difficult to suppress the overall optical length. On the other hand, if the lower limit of conditional formula (7) is exceeded, the focal length of the rn lens group will become too small relative to the focal length of the zoom lens at the wide-angle end, making it difficult to suppress field curvature and coma throughout the entire zoom range.

Conditional formula (8) is a conditional formula for appropriately setting the magnification sharing ratio of the r n lens group. If the upper limit of conditional formula (8) is exceeded, the magnification sharing ratio of the r n lens group increases, and the amount of movement of the r n lens group increases with increasing magnification, making it difficult to suppress coma aberration and field curvature throughout the entire zoom range. On the other hand, if the lower limit of conditional formula (8) is exceeded, the magnification sharing ratio of the r n lens group decreases too much, making it difficult to suppress the overall optical length.

Conditional formula (9) is a conditional formula for appropriately setting the ratio between the focal length of the final lens group and the focal length of the zoom lens at the wide-angle end. If the range of conditional formula (9) is exceeded, it becomes difficult to ensure telecentricity within a range compatible with the image sensor (solid-state image sensor).

Conditional formula (10) is a conditional formula for appropriately setting the ratio between the amount of movement of the second lens group B2 and the amount of movement of the third lens group B3. If the upper limit of conditional formula (10) is exceeded, the magnification sharing ratio of the second lens group B2 increases too much, and the movement amount of the fourth lens group B4 increases as the magnification increases, making it difficult to suppress coma aberration and field curvature throughout the entire zoom range. On the other hand, if the lower limit of conditional formula (10) is exceeded, the magnification sharing ratio of the second lens group B2 decreases too much, making it difficult to suppress the overall optical length.

More preferably, the numerical ranges of conditional expressions (4) to (10) are set as shown in the following conditional expressions (4a) to (10a), respectively.

1.95<f1/f3<5.10...(4a)
-8.80<f1/f2<-3.45...(5a)
0.15<f1/ft<0.60...(6a)
-5.70<frn/fw<-1.80...(7a)
0.45<βrnt/βrnw<1.50 (8a)
1.80<fr/fw<3.90...(9a)
-5.45<m2/m3<-1.30...(10a)
More preferably, the numerical ranges of the conditional expressions (4) to (10) are set as shown in the following conditional expressions (4b) to (10b), respectively.

2.60<f1/f3<3.40...(4b)
-5.60<f1/f2<-4.90...(5b)
0.20<f1/ft<0.40...(6b)
-3.40<frn/fw<-2.60...(7b)
0.60<βrnt/βrnw<1.00 (8b)
2.40<fr/fw<2.60...(9b)
-2.90<m2/m3<-2.10...(10b)
The zoom lens of each embodiment may also satisfy the following conditions: The fourth lens unit B4 moves at the telephoto end relative to the wide-angle end to perform zooming; or the fifth lens unit B5 moves at the telephoto end relative to the wide-angle end to perform zooming; or the sixth lens unit B6 moves at the telephoto end relative to the wide-angle end to perform zooming. The zoom lens of each embodiment may also correct distortion and chromatic aberration of magnification, among various aberrations, by electrical image processing. The aperture may also move on a separate trajectory from the lens units.

Next, the configuration of the zoom lens of each embodiment will be described in detail with reference to FIGS. 1 to 12. FIG. 1 is a cross-sectional view of the zoom lens of Example 1 at the wide-angle end. FIG. 2 is a diagram of aberrations of the zoom lens of Example 1 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto end. FIG. 3 is a cross-sectional view of the zoom lens of Example 2 at the wide-angle end. FIG. 4 is a diagram of aberrations of the zoom lens of Example 2 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto end. FIG. 5 is a cross-sectional view of the zoom lens of Example 3 at the wide-angle end. FIG. 6 is a diagram of aberrations of the zoom lens of Example 3 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto end. FIG. 7 is a cross-sectional view of the zoom lens of Example 4 at the wide-angle end. FIG. 8 is a diagram of aberrations of the zoom lens of Example 4 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto end. FIG. 9 is a cross-sectional view of the zoom lens of Example 5 at the wide-angle end. Figure 10 shows aberration diagrams of the zoom lens in Example 5 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto end. Figure 11 is a cross-sectional view of the zoom lens in Example 6 at the wide-angle end. Figure 12 shows aberration diagrams of the zoom lens in Example 6 at (a) the wide-angle end, (b) the intermediate zoom position, and (c) the telephoto end.

The zoom lens of each example is a photographic lens system used in an image pickup device, and in each cross-sectional view, the left is the object side and the right is the image side. The zoom lenses of Examples 1 to 5 consist, from the object side to the image side, of a first lens unit B1 with positive refractive power, a second lens unit B2 with negative refractive power, a third lens unit B3 with positive refractive power, and a rear group. The rear group consists of a fourth lens unit B4 with negative refractive power and a fifth lens unit B5 with positive refractive power. The fourth lens unit B4 is an rn lens unit with negative refractive power. The zoom lens of Example 6 consists of a first lens unit B1 with positive refractive power, a second lens unit B2 with negative refractive power, a third lens unit B3 with positive refractive power, and a rear group. The rear group consists of a fourth lens unit B4 with positive refractive power, a fifth lens unit B5 with negative refractive power, and a sixth lens unit B6 with positive refractive power. The fifth lens unit B5 is an rn lens unit with a negative refractive index. In each embodiment, SP is the aperture stop (aperture stop), F is a glass block such as a low-pass filter, and IP is the image plane.

In the zoom lenses of Examples 1 to 5, when zooming from the wide-angle end to the telephoto end, the first lens unit B1 is fixed with respect to the image plane IP, as shown by the arrows in the figure. Zooming is achieved by moving the second lens unit B2 toward the image side and the third lens unit B3 toward the object side. Furthermore, image plane fluctuations associated with zooming are corrected by moving the fourth lens unit B4 along a locus convex toward the image side. Furthermore, zooming is achieved by moving the fifth lens unit B5 along a locus convex toward the object side. In the zoom lens of Example 6, when zooming from the wide-angle end to the telephoto end, the first lens unit B1 is fixed with respect to the image plane IP, as shown by the arrows in the figure. Zooming is achieved by moving the second lens unit B2 toward the image side, the third lens unit B3 toward the object side, and the fourth lens unit B4 toward the object side. Furthermore, image plane fluctuations associated with zooming are corrected by moving the fifth lens unit B5 along a locus convex toward the image side. Additionally, zooming is performed by moving the sixth lens unit B6 along a convex locus toward the object side.

In the zoom lens of each embodiment, the first lens group B1 consists, in order from the object side to the image side, of a cemented lens consisting of a negative meniscus lens B11 and a positive lens B12, a positive meniscus lens B13, and a positive meniscus lens B14. This makes it possible to suppress spherical aberration and chromatic aberration that occur as the zoom ratio increases. Also, in the zoom lens of each embodiment, the second lens group B2 consists, in order from the object side to the image side, of independent lenses: a negative lens, a negative lens, a positive lens, and a negative lens. This makes it possible to reduce aberration fluctuations during zooming and effectively suppress spherical aberration, etc., particularly at the telephoto end.

In the zoom lenses of Examples 1 to 5, the third lens group B3 consists, in order from the object side to the image side, of a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens. This reduces the distance between the principal points of the second lens group B2 and the third lens group B3, and shortens the length of the lenses from the third lens group B3 onwards. The fourth lens group B4 consists, in order from the object side to the image side, of a cemented lens of a positive lens and a negative lens. This effectively suppresses aberration fluctuations that occur during zooming. The fifth lens group B5 consists of two positive lenses. This controls the exit pupil position so that it does not get too close to the image plane, ensuring telecentricity within a range compatible with the image sensor.

In the zoom lens of Example 6, the third lens group B3 consists, in order from the object side to the image side, of a positive lens and a cemented lens of a positive lens and a negative lens. The fourth lens group B4 consists of a positive lens. This reduces the distance between the principal points of the second lens group B2 and the third lens group B3, and shortens the length of the lenses from the third lens group B3 onwards. The fifth lens group B5 consists of a cemented lens of a positive lens and a negative lens. This effectively suppresses aberration fluctuations that occur during zooming. The sixth lens group B6 consists of two positive lenses. This controls the exit pupil position so that it does not get too close to the image plane, ensuring telecentricity within a range compatible with the image sensor.

While each cross-sectional view shows movement with the image plane IP fixed, this represents the amount of movement relative to the image plane IP at the wide-angle and telephoto ends; in other words, the image plane IP may move. In Examples 1 to 5, the solid-line curve 4a and dotted-line curve 4b for the fourth lens group B4 represent movement loci for correcting image plane fluctuations associated with magnification changes when focusing on an object at infinity and a close distance, respectively. In Example 6, the solid-line curve 5a and dotted-line curve 5b for the fifth lens group B5 represent movement loci for correcting image plane fluctuations associated with magnification changes when focusing on an object at infinity and a close distance, respectively. By focusing with a negative lens group with strong refractive power, the amount of focus movement at close distances can be reduced when focusing from infinity to a close distance object. This makes it possible to shorten the distance between the lenses before and after the focus group, making it easier to reduce the overall optical length, particularly at the telephoto end.

In each aberration diagram, d and g represent the d-line and g-line, and M and S represent the meridional and sagittal image planes. F is the F-number, and ω is the half angle of view (degrees). For spherical aberration, the d-line (solid line) and g-line (dotted line) are shown. For astigmatism, M and S at the d-line are shown, for distortion, the d-line is shown, for lateral chromatic aberration, the aberration at the g-line relative to the d-line is shown, and for lateral chromatic aberration, the aberration at the g-line relative to the d-line is shown.

Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below. In each numerical example, each surface of the zoom lens is assigned a surface number i (i is a natural number) from the object side. r is the radius of curvature of each surface (mm), d is the lens thickness or distance (air gap) (mm) on the optical axis between the surface with surface number i and the surface with surface number (i+1), and nd is the refractive index with respect to the d-line of the material of the optical element that has each surface. νd is the Abbe number with respect to the d-line of the material of the optical element that has each surface. When 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 are Nd, NF, and NC, respectively, the Abbe number νd of a certain material is given as follows:
νd=(Nd-1)/(NF-NC)
It is expressed as:

The focal length (mm), F-number, and half angle of view (°) are values when the zoom lens is focused on an object at infinity. The total optical length is the distance on the optical axis from the front surface (the lens surface closest to the object) of the zoom lens to the final surface (the lens surface closest to the image) plus the back focus BF. The back focus BF is the distance from the final surface of the zoom lens to the image plane. In each numerical example, the two surfaces closest to the image are flat surfaces corresponding to the optical block G.

An "*" next to a surface number indicates that the surface has an aspherical shape. The aspherical shape is expressed by the following formula, where x is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in a direction perpendicular to the optical axis, the direction of light travel is positive, r is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are aspherical coefficients. The aspherical coefficient "e-Z" means 10 ^-Z .

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
(Numerical Example 1)
Unit: mm

Surface data surface number rd nd νd
1 91.037 1.40 1.91082 35.3
2 36.894 8.14 1.49700 81.6
3 2772.896 0.05
4 42.187 4.31 1.58700 64.6
5 144.291 0.10
6 40.891 4.57 1.49700 81.6
7 349.009 (variable)
8 143.239 0.75 1.75015 50.0
9* 10.039 5.46
10 -21.497 0.50 1.72902 54.7
11 43.276 0.05
12 28.076 3.17 1.96376 23.4
13 -25.082 0.58
14* -17.268 0.40 1.79380 42.9
15 485.930 (variable)
16 (Aperture) ∞ (Variable)
17* 12.407 3.50 1.49700 81.6
18* -25.205 1.81
19 9.016 3.00 1.49700 81.6
20 29.229 0.50 1.59945 31.7
21 6.215 2.10
22* 13.149 1.83 1.49700 81.6
23* 49.260 (variable)
24 19.543 1.79 1.87516 19.8
25 -15.421 0.40 2.05090 26.9
26 10.292 (variable)
27* -13.230 1.27 1.49700 81.6
28 -8.890 0.15
29* -50.370 3.00 1.49700 81.6
30* -8.477 (variable)
31 ∞ 0.50 1.51633 64.1
32 ∞ 0.53
Image plane ∞

Aspherical data No. 9
K = 0.00000e+000 A 4=-5.26838e-006 A 6=-3.25482e-007 A 8= 1.31158e-009

Side 14
K = 0.00000e+000 A 4= 2.41340e-005 A 6=-8.30706e-008 A 8= 2.17546e-009
A10=-1.42704e-011

Page 17
K =-3.64846e+000 A 4= 1.91257e-004 A 6=-1.43749e-006 A 8= 7.65779e-009

Page 18
K = 0.00000e+000 A 4= 1.00000e-004 A 6=-8.74518e-007 A 8= 5.53154e-009

Page 22
K = 0.00000e+000 A 4= 4.33657e-004 A 6= 5.97264e-007 A 8= 2.20555e-008
A10= 2.60482e-009

Page 23
K = 0.00000e+000 A 4= 3.65098e-004
Page 27
K = 0.00000e+000 A 4=-1.37088e-003 A 6= 3.69642e-005 A 8=-4.61708e-007
A10=-1.75267e-008

Page 29
K = 0.00000e+000 A 4= 7.97026e-004 A 6=-4.16885e-005 A 8= 5.31402e-007
A10=-2.12688e-009

Page 30
K = 0.00000e+000 A 4= 1.91568e-004 A 6=-6.87596e-006 A 8=-4.73290e-008
A10=-6.48093e-010

Various data Zoom ratio 29.06
Wide Angle Mid Telephoto Focal Length 5.74 13.04 166.91
F-number 3.05 3.16 4.50
Half angle of view 38.3 17.6 1.5
Image height 4.43 4.43 4.43
Optical total length 104.84 104.84 104.84
BF 6.63 5.84 1.79

d 7 0.30 10.95 30.44
d15 41.68 28.32 -0.17
d16 2.32 0.90 0.31
d23 1.00 3.37 12.18
d26 4.07 6.62 11.47
d30 5.77 4.98 0.93

Zoom lens data group Starting surface Focal length
1 1 52.37
2 8 -9.40
3 17 15.79
4 24 -15.82
5 27 14.47

(Numerical Example 2)
Unit: mm

Surface data surface number rd nd νd
1 110.785 1.40 1.91082 35.3
2 39.837 8.59 1.49700 81.6
3 -509.982 0.05
4 43.985 4.52 1.58789 64.5
5 174.612 0.10
6 41.274 4.89 1.49700 81.6
7 317.942 (variable)
8 139.775 0.75 1.74906 47.1
9* 10.036 5.94
10 -19.684 0.50 1.72886 54.7
11 53.737 0.05
12 32.693 3.26 1.96411 23.3
13 -22.181 0.88
14* -15.997 0.40 1.79353 43.0
15 -471.875 (variable)
16 (Aperture) ∞ (Variable)
17* 12.603 3.50 1.49700 81.6
18* -23.152 2.33
19 9.653 3.00 1.49700 81.6
20 52.040 0.50 1.60659 33.3
21 6.443 2.30
22* 18.175 1.76 1.49700 81.6
23* 376.283 (variable)
24 23.810 1.85 1.92006 20.2
25 -14.473 0.40 2.05090 26.9
26 10.925 (variable)
27* -13.230 2.33 1.49700 81.6
28 -7.551 0.05
29* 87.365 3.07 1.49700 81.6
30* -15.876 (variable)
31 ∞ 0.50 1.51633 64.1
32 ∞ 0.53
Image plane ∞

Aspherical data No. 9
K = 0.00000e+000 A 4=-1.03717e-005 A 6=-2.70614e-007 A 8= 1.07035e-009

Side 14
K = 0.00000e+000 A 4= 2.50552e-005 A 6=-6.22429e-008 A 8= 2.97134e-009
A10=-2.35556e-011

Page 17
K =-3.74318e+000 A 4= 1.78683e-004 A 6=-1.40282e-006 A 8= 7.66798e-009

Page 18
K = 0.00000e+000 A 4= 1.00000e-004 A 6=-7.47119e-007 A 8= 4.74866e-009

Page 22
K = 0.00000e+000 A 4= 4.23689e-004 A 6= 3.09981e-007 A 8= 5.64567e-008
A10= 1.50124e-009

Page 23
K = 0.00000e+000 A 4= 2.88058e-004

Page 27
K = 0.00000e+000 A 4=-1.14621e-003 A 6= 1.42580e-005 A 8=-5.64524e-007
A10= 3.18195e-009

Page 29
K = 0.00000e+000 A 4= 4.32437e-004 A 6=-1.70645e-005 A 8= 3.87378e-007
A10=-4.67811e-009

Page 30
K = 0.00000e+000 A 4=-1.31281e-004 A 6=-7.88826e-006 A 8= 2.61029e-007
A10=-3.44229e-009

Various data Zoom ratio 28.50
Wide Angle Mid Telephoto Focal Length 6.04 13.08 172.28
F-number 3.05 3.16 4.50
Half angle of view 37.1 17.8 1.43
Image height 4.43 4.43 4.43
Optical total length 108.66 108.66 108.66
BF 7.16 5.79 2.13

d 7 0.30 10.46 30.48
d15 41.08 28.51 0.11
d16 2.56 1.49 0.19
d23 1.00 4.08 11.45
d26 4.14 5.91 11.88
d30 6.30 4.93 1.27

Zoom lens data group Starting surface Focal length
1 1 51.75
2 8 -9.40
3 17 16.65
4 24 -16.10
5 27 14.55

(Numerical Example 3)
Unit: mm

Surface data surface number rd nd νd
1 124.053 1.40 1.91082 35.3
2 41.584 8.95 1.49700 81.6
3 -332.111 0.05
4 46.040 4.62 1.58734 64.6
5 203.683 0.10
6 42.779 5.20 1.49700 81.6
7 470.058 (variable)
8 163.056 0.75 1.74737 44.9
9* 10.730 5.73
10 -17.866 0.50 1.72524 54.9
11 48.396 0.08
12 32.849 3.35 1.96909 23.4
13 -20.399 0.65
14* -15.483 0.40 1.78795 41.5
15 -393.655 (variable)
16 (Aperture) ∞ (Variable)
17* 12.757 3.50 1.49700 81.6
18* -24.331 2.61
19 10.365 3.00 1.49700 81.6
20 1261.531 0.50 1.61337 34.9
21 7.078 1.86
22* 22.876 1.66 1.49700 81.6
23* -554.559 (variable)
24 23.565 1.77 1.94227 19.8
25 -22.792 0.45 2.05090 26.9
26 11.358 (variable)
27* -13.230 2.65 1.49700 81.6
28 -7.577 0.05
29* 90.583 3.50 1.49700 81.6
30* -18.627 (variable)
31 ∞ 0.50 1.51633 64.1
32 ∞ 0.53
Image plane ∞

Aspherical data No. 9
K = 0.00000e+000 A 4= 4.22972e-007 A 6=-1.77411e-007 A 8= 2.23764e-009

Side 14
K = 0.00000e+000 A 4= 2.45928e-005 A 6=-4.98011e-008 A 8= 1.62588e-009
A10=-1.07856e-011

Page 17
K =-3.12212e+000 A 4= 1.42621e-004 A 6=-8.49458e-007 A 8= 3.21494e-009

Page 18
K = 0.00000e+000 A 4= 1.00000e-004 A 6=-7.22796e-007 A 8= 3.23223e-009

Page 22
K = 0.00000e+000 A 4= 4.38988e-004 A 6=-6.99245e-007 A 8= 4.60593e-008
A10= 4.38910e-010

Page 23
K = 0.00000e+000 A 4= 3.33978e-004

Page 27
K = 0.00000e+000 A 4=-1.22038e-003 A 6= 4.23463e-006 A 8=-1.81845e-007
A10=-4.64322e-010

Page 29
K = 0.00000e+000 A 4= 5.11014e-004 A 6=-5.44117e-006 A 8= 8.06710e-008
A10=-2.31970e-010

Page 30
K = 0.00000e+000 A 4=-1.17048e-004 A 6=-1.46277e-007 A 8= 1.14002e-007
A10=-7.50376e-010

Various data Zoom ratio 28.50
Wide Angle Mid Telephoto Focal Length 6.26 13.08 178.53
F-number 3.05 3.16 4.50
Half angle of view 37.3 18.0 1.38
Image height 4.43 4.43 4.43
Optical total length 110.94 110.94 110.94
BF 7.96 5.89 1.77

d 7 0.30 10.26 30.59
d15 40.96 30.71 0.10
d16 3.17 0.72 0.98
d23 1.00 4.94 9.67
d26 4.21 5.08 14.49
d30 7.10 5.03 0.91

Zoom lens data group Starting surface Focal length
1 1 51.56
2 8 -9.73
3 17 17.47
4 24 -18.85
5 27 15.56

(Numerical Example 4)
Unit: mm

Surface data surface number rd nd νd
1 121.881 1.40 1.91082 35.3
2 41.458 8.91 1.49700 81.6
3 -352.278 0.05
4 46.543 4.69 1.58733 64.6
5 201.364 0.10
6 43.027 5.42 1.49700 81.6
7 619.498 (variable)
8 181.962 0.75 1.74683 43.7
9* 11.071 5.60
10 -18.021 0.50 1.72351 54.9
11 41.907 0.09
12 31.054 3.37 1.97147 23.0
13 -20.722 0.60
14* -15.748 0.65 1.78522 40.4
15 -929.746 (variable)
16 (Aperture) ∞ (Variable)
17* 12.594 3.50 1.49700 81.6
18* -26.679 2.56
19 10.656 3.00 1.49700 81.6
20 -179.338 0.50 1.61687 35.6
21 7.390 1.61
22* 22.160 1.63 1.49700 81.6
23* 436.689 (variable)
24 24.976 1.61 1.94236 18.7
25 -37.812 0.52 2.05090 26.9
26 11.966 (variable)
27* -13.230 2.03 1.49700 81.6
28 -7.098 0.58
29* -38.927 3.50 1.49700 81.6
30* -12.650 (variable)
31 ∞ 0.50 1.51633 64.1
32 ∞ 0.53
Image plane ∞

Aspherical data No. 9
K = 0.00000e+000 A 4= 4.84452e-006 A 6=-1.36574e-007 A 8= 2.19223e-009

Side 14
K = 0.00000e+000 A 4= 2.42533e-005 A 6=-3.98989e-008 A 8= 6.03323e-010
A10=-1.72829e-012

Page 17
K =-2.80970e+000 A 4= 1.38861e-004 A 6=-6.24826e-007 A 8= 2.29531e-009

Page 18
K = 0.00000e+000 A 4= 1.00000e-004 A 6=-6.92341e-007 A 8= 2.92631e-009

Page 22
K = 0.00000e+000 A 4= 4.37178e-004 A 6=-1.37992e-006 A 8= 4.62382e-008
A10=-2.03572e-010

Page 23
K = 0.00000e+000 A 4= 3.60899e-004

Page 27
K = 0.00000e+000 A 4=-1.90728e-003 A 6= 1.67932e-005 A 8=-2.90590e-007
A10=-2.40209e-009

Page 29
K = 0.00000e+000 A 4= 1.39267e-003 A 6=-2.52827e-005 A 8= 3.57520e-007
A10=-1.90223e-009

Page 30
K = 0.00000e+000 A 4= 3.19079e-004 A 6=-6.86427e-006 A 8= 2.55866e-007
A10=-1.95696e-009

Various data Zoom ratio 28.50
Wide Angle Mid Telephoto Focal Length 6.38 13.08 181.87
F-number 3.05 3.16 4.50
Half angle of view 37.1 18.1 1.37
Image height 4.43 4.43 4.43
Optical total length 111.99 111.99 111.99
BF 8.86 6.77 1.36

d 7 0.30 10.17 30.67
d15 41.55 31.57 0.10
d16 2.87 0.37 2.09
d23 1.00 5.29 8.48
d26 4.24 4.64 16.10
d30 8.00 5.91 0.50

Zoom lens data group Starting surface Focal length
1 1 51.58
2 8 -9.83
3 17 17.90
4 24 -20.27
5 27 16.33

(Numerical Example 5)
Unit: mm

Surface data surface number rd nd νd
1 129.209 1.40 1.91082 35.3
2 42.505 8.95 1.49700 81.6
3 -273.631 0.05
4 49.486 4.44 1.58707 64.6
5 175.267 0.10
6 40.886 5.71 1.49700 81.6
7 987.942 (variable)
8 226.300 0.75 1.74076 46.1
9* 12.025 5.70
10 -19.028 0.50 1.71384 55.4
11 29.133 0.17
12 27.914 3.79 1.98223 24.4
13 -20.491 0.38
14* -16.849 0.49 1.77236 40.6
15 204.925 (variable)
16 (Aperture) ∞ (Variable)
17* 12.493 3.50 1.49700 81.6
18* -30.217 2.65
19 11.653 3.00 1.49700 81.6
20 -49.112 0.50 1.62752 38.9
21 7.424 1.21
22* 14.619 1.72 1.49700 81.6
23* 53.263 (variable)
24 33.697 1.45 1.95906 17.5
25 -54.672 0.66 2.05090 26.9
26 14.140 (variable)
27* -13.230 3.45 1.49700 81.6
28 -7.506 0.11
29* 59.984 3.50 1.49700 81.6
30* -25.147 (variable)
31 ∞ 0.50 1.51633 64.1
32 ∞ 0.53
Image plane ∞

Aspherical data No. 9
K = 0.00000e+000 A 4= 5.90197e-006 A 6=-8.45290e-008 A 8= 1.85200e-009

Side 14
K = 0.00000e+000 A 4= 2.17655e-005 A 6= 3.22610e-009 A 8=-6.84525e-010
A10= 5.66074e-012

Page 17
K =-2.34650e+000 A 4= 1.22219e-004 A 6=-4.25134e-007 A 8= 1.52597e-009

Page 18
K = 0.00000e+000 A 4= 1.00000e-004 A 6=-8.65937e-007 A 8= 3.99036e-009

Page 22
K = 0.00000e+000 A 4= 4.97925e-004 A 6=-1.01721e-006 A 8= 4.32865e-008
A10= 1.63864e-011

Page 23
K = 0.00000e+000 A 4= 4.02264e-004

Page 27
K = 0.00000e+000 A 4=-1.33779e-003 A 6= 4.80584e-006 A 8=-6.33822e-008
A10=-5.07648e-009

Page 29
K = 0.00000e+000 A 4= 7.19978e-004 A 6=-7.46000e-006 A 8= 6.46233e-008
A10= 1.00650e-010

Page 30
K = 0.00000e+000 A 4= 1.71957e-004 A 6=-2.00891e-006 A 8= 6.83964e-008
A10=-1.88061e-010

Various data Zoom ratio 28.50
Wide Angle Mid Telephoto Focal Length 6.59 13.08 187.68
F-number 3.05 3.16 4.70
Half angle of view 36.5 18.2 1.31
Image height 4.43 4.43 4.43
Optical total length 116.19 116.19 116.19
BF 10.60 8.30 1.36

d7 0.30 9.92 30.90
d15 43.73 33.82 0.10
d16 1.93 0.05 4.09
d23 1.17 6.61 6.56
d26 4.27 3.31 18.99
d30 9.74 7.44 0.50

Zoom lens data group Starting surface Focal length
1 1 51.68
2 8 -10.44
3 17 19.41
4 24 -22.07
5 27 15.93

(Numerical Example 6)
Unit: mm

Surface data surface number rd nd νd
1 97.715 1.40 1.91082 35.3
2 37.962 8.67 1.49700 81.6
3 -995.909 0.05
4 42.798 4.47 1.57965 65.4
5 115.972 0.10
6 41.153 5.85 1.49700 81.6
7 648.879 (variable)
8 101.046 0.75 1.74710 50.6
9* 11.110 5.20
10 -19.503 0.50 1.72698 54.8
11 34.672 0.06
12 25.103 2.93 1.96915 22.4
13 -29.947 0.64
14* -18.417 0.40 1.78919 43.5
15 362.287 (variable)
16 (Aperture) ∞ (Variable)
17* 15.688 3.50 1.49700 81.6
18* -22.718 2.92
19 9.077 3.00 1.49700 81.6
20 30.332 0.50 1.59827 30.2
21 7.120 (variable)
22* 22.576 1.84 1.49700 81.6
23* -115.477 (variable)
24 1853.022 1.63 1.95906 17.5
25 -14.391 0.40 2.05090 26.9
26 19.452 (variable)
27* -13.230 2.11 1.49700 81.6
28 -7.611 0.10
29* -22.267 3.50 1.49700 81.6
30* -9.384 (variable)
31 ∞ 0.50 1.51633 64.1
32 ∞ 0.53
Image plane ∞

Aspherical data No. 9
K = 0.00000e+000 A 4= 7.41946e-006 A 6=-1.17647e-007 A 8= 2.66505e-009

Side 14
K = 0.00000e+000 A 4= 1.28101e-005 A 6=-8.00281e-008 A 8= 3.69768e-010
A10=-1.27585e-012

Page 17
K =-3.92000e+000 A 4= 1.12641e-004 A 6=-8.41448e-007 A 8= 5.69171e-009

Page 18
K = 0.00000e+000 A 4= 1.00000e-004 A 6=-8.29650e-007 A 8= 5.99865e-009

Page 22
K = 0.00000e+000 A 4= 4.23164e-004 A 6=-1.19411e-006 A 8= 4.23316e-008
A10=-1.63899e-011

Page 23
K = 0.00000e+000 A 4= 3.64818e-004

Page 27
K = 0.00000e+000 A 4=-1.92579e-003 A 6= 2.52928e-005 A 8=-5.02513e-007
A10= 1.18932e-010

Page 29
K = 0.00000e+000 A 4= 1.30345e-003 A 6=-3.03414e-005 A 8= 4.72520e-007
A10=-3.70634e-009

Page 30
K = 0.00000e+000 A 4= 3.70215e-004 A 6=-7.25407e-006 A 8= 2.16139e-007
A10=-2.04517e-009

Various data Zoom ratio 28.50
Wide Angle Mid Telephoto Focal Length 6.50 13.08 185.13
F-number 3.05 3.16 4.50
Half angle of view 36.9 18.3 1.36
Image height 4.43 4.43 4.43
Optical total length 109.09 109.09 109.09
BF 9.35 8.22 1.36

d7 0.30 10.59 30.35
d15 41.18 30.03 0.10
d16 0.96 -0.54 0.20
d21 1.69 2.17 1.68
d23 1.00 3.72 12.13
d26 4.09 4.39 12.74
d30 8.49 7.36 0.50

Zoom lens data group Starting surface Focal length
1 1 53.43
2 8 -9.60
3 17 20.14
4 22 38.16
5 24 -16.69
6 27 16.02

The values of the conditional expressions in the respective numerical examples are summarized in Table 1 below.

Next, referring to FIG. 13, an imaging device using the zoom lens of each embodiment as an imaging optical system will be described. FIG. 13 is a structural diagram of the imaging device 100. Reference numeral 10 denotes the surveillance camera body. Reference numeral 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the surveillance camera body 10 and receives the subject image formed by the imaging optical system 11 (capturing the image formed by the zoom lens). Reference numeral 13 denotes a memory that records information corresponding to the subject image photoelectrically converted by the imaging element 12. Reference numeral 14 denotes a network cable for transferring the subject image photoelectrically converted by the imaging element 12. Note that the imaging device of each embodiment is not limited to surveillance cameras and can also be used as other imaging devices, such as video cameras and digital cameras. Furthermore, the imaging device of each embodiment may include a circuit that electrically corrects either distortion aberration or lateral chromatic aberration, or both, along with any of the zoom lenses of Examples 1 to 6. In this way, by configuring the zoom lens to tolerate distortion aberration and other aberrations, the number of lenses in the entire zoom lens can be reduced, facilitating miniaturization.

Each embodiment can provide a zoom lens and an imaging device that are advantageous in terms of, for example, a wide angle of view, a high zoom ratio, compact size, and high optical performance across the entire zoom range.

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 invention.

B1: First lens unit B2: Second lens unit B3: Third lens unit B4: Fourth lens unit (rear unit)
B5 Fifth lens group (rear group)
B6 6th lens group (rear group)

Claims (8)

A zoom lens comprising, in order from the object side to the 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, and a rear group including two or more lens groups,
the first lens group includes, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens;
the rear group has an rn lens group with negative refractive power,
For zooming, the first lens group is fixed, the second lens group and the third lens group are moved, and the interval between adjacent lens groups is changed;
When the lateral magnification of the second lens group at the telephoto end is β2t, the lateral magnification of the second lens group at the wide-angle end is β2w, the lateral magnification of the third lens group at the telephoto end is β3t, the lateral magnification of the third lens group at the wide-angle end is β3w, the total optical length of the zoom lens is TDt, the focal length of the zoom lens at the telephoto end is ft, the focal length of the zoom lens at the wide-angle end is fw, the focal length of the first lens group is f1, and the focal length of the second lens group is f2,
1.50<(β2t/β2w)/(β3t/β3w)<4.998
0.30< TD t/ft<0.70
1.50<f1/fw<20.00
-5.60<f1/f2<-4.90
A zoom lens characterized by satisfying the following conditional expressions: When the focal length of the third lens group is f3,
1.30<f1/f3<6.80
2. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.10<f1/ft<0.80
3. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of the rn lens group is frn,
-8.00<frn/fw<-1.00
4. The zoom lens according to claim 1, wherein the following condition is satisfied: When the lateral magnification of the rn lens group at the telephoto end is βrnt and the lateral magnification of the rn lens group at the wide-angle end is βrnw,
0.30<βrnt/βrnw<2.00
5. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal length of the final lens unit in the rear group, which is located closest to the image side, is fr,
1.20<fr/fw<5.20
6. The zoom lens according to claim 1, wherein the following condition is satisfied: Let m2 be the distance between the second lens group at the wide-angle end and the second lens group at the telephoto end (this distance is considered to be positive when the second lens group moves from the object side to the image side), and m3 be the distance between the third lens group at the wide-angle end and the third lens group at the telephoto end (this distance is considered to be positive when the third lens group moves from the object side to the image side),
-8.00<m2/m3<-0.50
7. The zoom lens according to claim 1, wherein the following condition is satisfied: a zoom lens according to any one of claims 1 to 7;
an image sensor for capturing an image formed by the zoom lens.