JP2021026111A - Zoom lens and image capturing device having the same - Google Patents

Abstract

To provide a zoom lens which is compact, has a high zoom ratio, and offers superior optical performance over an entire zoom range.SOLUTION: A zoom lens 1a provided herein consists of a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having positive refractive power, and at least one succeeding lens group L5 arranged in order from the object side to the image side, and is configured such that distances between adjacent lens groups change while zooming. The third lens group L3 consists of two lenses. When zooming, the first lens group L1 is stationary while the second and fourth lens groups L2, L4 move along an optical axis. Lateral magnifications of the second, third, and fourth lens groups L2, L3, L4 at the wide-angle end and the telephoto end, a focal length of the fourth lens group L4, and a displacement of the fourth lens group L4 while zooming from the wide-angle end to the telephoto end satisfy given conditional expressions.SELECTED DRAWING: Figure 1

Description

The present invention relates to a zoom lens and an image pickup device having the same, and is particularly suitable as an image pickup optical system used for an image pickup device such as a digital still camera, a video camera, a surveillance camera, and a broadcasting camera.

In recent years, zoom lenses used in surveillance cameras, digital still cameras, video cameras, and broadcast cameras are required to have a high zoom ratio and good optical performance over the entire zoom range. In the surveillance camera market, a compact zoom lens with a high zoom ratio is required because it is necessary to change the shooting range according to the situation in order to clearly shoot the subject regardless of the installation environment.

As a compact and high zoom ratio zoom lens, a positive lead zoom lens having a first lens group having a positive refractive power is known. Patent Document 1 discloses a zoom lens in which the refractive power of each lens group is positive, negative, positive, positive, positive, and the zoom ratio is about 13 times. Patent Document 2 discloses a zoom lens in which the refractive power of each lens group is positive, negative, positive, positive, positive, and the zoom ratio is about 18 times.

Japanese Unexamined Patent Publication No. 2012-88618 Japanese Unexamined Patent Publication No. 2016-99548

By the way, in order to realize a zoom lens that is compact and has a high zoom ratio and has high optical performance over the entire zoom range, the configuration and focal length of each lens group and the amount of movement of each moving group in zooming are not changed without changing the total length of the lens. Must be set appropriately. However, in the zoom lenses disclosed in Patent Document 1 and Patent Document 2, the coma aberration fluctuates due to the increase in zoom because the variable magnification sharing of each moving group is not appropriate.

Therefore, an object of the present invention is to provide a zoom lens, an image pickup device, and an image pickup system which are compact and have a high zoom ratio and have high optical performance over the entire zoom range.

The zoom lens as one aspect of the present invention has a first lens group having a positive refractive force, a second lens group having a negative refractive force, and a positive refractive force arranged in order from the object side to the image side. A zoom lens consisting of a third lens group, a fourth lens group having a positive refractive power, and at least one subsequent lens group, and the distance between adjacent lens groups changes during zooming. The third lens group is a zoom lens. It has two lenses, the first lens group is immobile during zooming, the second lens group and the fourth lens group move on the optical axis, and the side of the second lens group at the wide angle end. The magnification is β2w, the lateral magnification of the second lens group at the telephoto end is β2t, the lateral magnification of the third lens group at the wide-angle end is β3w, the lateral magnification of the third lens group at the telescopic end is β3t, and the lateral magnification at the wide-angle end is β3t. When the lateral magnification of the 4th lens group is β4w and the lateral magnification of the 4th lens group at the telephoto end is β4t, β2 = β2t / β2w, β3 = β3t / β3w, β4 = β4t / β4w, β34 = β3 * β4 When the focal distance of the 4th lens group is f4 and the amount of movement of the 4th lens group in the zooming from the wide-angle end to the telephoto end is M4,
4.0 <β2 / β34 <40
0.5 <f4 / M4 <3.7
Satisfies the conditional expression.

An image pickup device as another aspect of the present invention includes the zoom lens and an image pickup element that receives an image formed by the zoom lens.

An imaging system as another aspect of the present invention includes the zoom lens and a control unit that controls the zoom lens during zooming.

Other objects and features of the present invention will be described in the following embodiments.

According to the present invention, it is possible to provide a zoom lens, an imaging device, and an imaging system that are compact, have a high zoom ratio, and have high optical performance over the entire zoom range.

It is sectional drawing of the lens at a wide-angle end in Example 1. FIG. It is a diagram of various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end in the first embodiment. It is a cross-sectional view of the lens at the wide-angle end in Example 2. It is a diagram of various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end in the second embodiment. It is a cross-sectional view of a lens at a wide-angle end in Example 3. It is a diagram of various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end in the third embodiment. It is a cross-sectional view of a lens at a wide-angle end in Example 4. It is a diagram of various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end in the fourth embodiment. It is a cross-sectional view of a lens at a wide-angle end in Example 5. It is a diagram of various aberrations at a wide-angle end, an intermediate zoom position, and a telephoto end in Example 5. It is a cross-sectional view of a lens at a wide-angle end in Example 6. 6 is a diagram of various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end in Example 6. It is a cross-sectional view of a lens at a wide-angle end in Example 7. It is a diagram of various aberrations at a wide-angle end, an intermediate zoom position, and a telephoto end in Example 7. It is a block diagram of the image pickup apparatus in each Example.

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

The zoom lens of the present embodiment is compact, has a high zoom ratio (high magnification ratio), and has high optical performance over the entire zoom range. The zoom lenses are arranged in order from the object side to the image side, the first lens group L1 having a positive refractive power, the second lens group L2 having a negative refractive power, and the third lens group L3 having a positive refractive power. It consists of a fourth lens group L4 having a positive refractive power, and at least one subsequent lens group. Further, in the zoom lens of the present embodiment, the distance between adjacent lens groups changes during zooming. Further, the third lens group L3 has two lenses. Further, during zooming, the first lens group L1 is immobile, and the second lens group L2 and the fourth lens group L4 move on the optical axis. The lateral magnification of the second lens group L2 at the wide-angle end is β2w, and the lateral magnification of the second lens group L2 at the telephoto end is β2t. Further, the lateral magnification of the third lens group L3 at the wide-angle end is β3w, and the lateral magnification of the third lens group L3 at the telephoto end is β3t. Further, the lateral magnification of the fourth lens group L4 at the wide-angle end is β4w, and the lateral magnification of the fourth lens group L4 at the telephoto end is β4t. In addition, β2 = β2t / β2w, β3 = β3t / β3w, β4 = β4t / β4w, β34 = β3 * β4, the focal length of the fourth lens group L4 is f4, and the fourth lens group in zooming from the wide-angle end to the telephoto end. Let the movement amount of L4 be M4. Here, "*" means multiplication. The sign of the movement amount M4 is negative when it is located on the object side at the telephoto end as compared with the wide-angle end, and positive when it is located on the image side at the telephoto end as compared with the wide-angle end. At this time, the following conditional expressions (1) and (2) are satisfied.

4.0 <β2 / β34 <40 ... (1)
0.5 <f4 / M4 <3.7 ... (2)
As described above, in order to secure a high zoom ratio and satisfactorily correct the aberration, the zoom lens of the present embodiment has a lens group having positive, negative, positive, and positive refractive powers in order from the object side to the image side, and , Consists of at least one subsequent lens group. Further, during zooming from the wide-angle end to the telephoto end, the first lens group L1 is immovable, and at least the second lens group L2 and the fourth lens group L4 are moved along the optical axis OA, so that the entire system of the zoom lens can be used. It has both miniaturization and a high zoom ratio. Further, the third lens group L3 has at least two positive lenses. As a result, spherical aberration and coma aberration from the wide-angle end to the intermediate zoom position can be corrected particularly well, and zoom fluctuation caused by the movement of the fourth lens group L4 located on the image side of the third lens group L3. It is possible to suppress. Further, by satisfying the conditional expressions (1) and (2), it is possible to realize a zoom lens which is compact but has a high zoom ratio and has high optical performance over the entire zoom range.

The conditional expression (1) is the ratio of the lateral magnification of the second lens group L2, the lateral magnification of the third lens group L3, and the lateral magnification of the fourth lens group L4, and defines the variable magnification sharing. When the upper limit of the conditional expression (1) is exceeded, the variable magnification of the second lens group L2 becomes excessively large with respect to the third lens group L3 and the fourth lens group L4. In this case, since the amount of movement of the second lens group L2 becomes large, the entire system of the zoom lens becomes large, which is not preferable. Alternatively, since the refractive power of the second lens group L2 becomes large, the curvature of field at the wide-angle end deteriorates, which is not preferable. On the other hand, when the lower limit value of the conditional expression (1) is exceeded, the variable magnification of the third lens group L3 and the fourth lens group L4 becomes excessively large with respect to the second lens group L2. In this case, since the refractive power of the third lens group L3 and the fourth lens group L4 becomes large, spherical aberration at the wide-angle end, coma aberration over the entire zoom range, and curvature of field deteriorate, which is not preferable.

Conditional expression (2) defines the ratio between the focal length f4 of the fourth lens group L4 and the amount of movement M4 of the fourth lens group L4 in zooming from the wide-angle end to the telephoto end. If the upper limit of the conditional expression (2) is exceeded, the refractive power of the fourth lens group L4 with respect to the moving amount M4 becomes excessively small, which makes it difficult to increase the zoom. On the other hand, if the lower limit of the conditional expression (2) is exceeded, the refractive power of the fourth lens group L4 with respect to the moving amount M4 becomes excessively large, so that coma aberration in the entire zoom range is deteriorated, which is not preferable.

In the present embodiment, each element of the zoom lens is appropriately set so as to satisfy the conditional expressions (1) and (2). As a result, it is possible to realize a zoom lens that is compact, has a high zoom ratio, and has high optical performance over the entire zoom range.

Further, the focal length of the first lens group L1 is f1, the focal length of the second lens group L2 is f2, and the focal length of the third lens group L3 is f3. Further, the back focus at the wide-angle end (the distance from the final surface of the lens to the paraxial image plane is the air-equivalent length) is BF, the focal length of the zoom lens at the wide-angle end is fw, and the F number at the wide-angle end is Fnow. At this time, preferably, at least one of the following conditional expressions (3) to (7) is satisfied.

0.40 <f1 / f3 <3.0 ... (3)
0.050 << | f2 | / f3 <0.50 ... (4)
0.20 <f3 / f4 <4.5 ... (5)
0.20 <BF / fw <3.5 ... (6)
0 <Fnow <1.6 ... (7)
The conditional expression (3) defines the ratio between the focal length f1 of the first lens group L1 and the focal length f3 of the third lens group L3. When the upper limit of the conditional expression (3) is exceeded, the refractive power of the first lens group L1 with respect to the refractive power of the third lens group L3 becomes weaker, so that the occurrence of spherical aberration at the telephoto end is suppressed, but particularly at a wide angle. This is not preferable because the spherical aberration at the edge is deteriorated. On the other hand, if the lower limit of the conditional equation (3) is exceeded, the refractive power of the first lens group L1 becomes stronger than the refractive power of the third lens group L3, which worsens the spherical aberration at the telephoto end, which is not preferable. ..

Conditional expression (4) defines the ratio between the focal length of the second lens group L2 and the focal length of the third lens group L3. If the upper limit of the conditional expression (4) is exceeded, the refractive power of the second lens group L2 with respect to the refractive power of the third lens group L3 becomes weak, and it becomes difficult to achieve both high zoom and large diameter. On the other hand, if the lower limit of the conditional equation (4) is exceeded, the refractive power of the second lens group L2 becomes stronger than the refractive power of the third lens group L3, which increases the fluctuation of the curvature of field during zooming, which is not preferable. ..

The conditional expression (5) defines the ratio between the focal length f3 of the third lens group L3 and the focal length f4 of the fourth lens group L4. When the upper limit of the conditional expression (5) is exceeded, the refractive power of the third lens group L3 with respect to the refractive power of the fourth lens group L4 becomes weak, so that the fourth lens group L4 is excessively refracted due to the increase in diameter. It is not preferable because it has a force and coma at the wide-angle end is deteriorated. On the other hand, if the upper limit of the conditional equation (5) is exceeded, the refractive power of the third lens group L3 with respect to the refractive power of the fourth lens group L4 becomes stronger, which worsens the spherical aberration at the wide-angle end, which is not preferable.

The conditional expression (6) defines the ratio between the back focus BF and the focal length fw of the entire system of the zoom lens at the wide-angle end. If the upper limit of the conditional expression (6) is exceeded, the luminous flux diameter passing through the lens group on the image side of the aperture becomes larger when the aperture is increased, and the spherical aberration and coma aberration become worse especially at the wide-angle end. Therefore, it is not preferable. On the other hand, if the lower limit of the conditional expression (6) is exceeded, there is not enough space for mounting an optical element such as a low-pass filter or an infrared cut filter, which is not preferable.

The conditional expression (7) defines the F number Fno at the wide-angle end. If the upper limit of the conditional expression (7) is exceeded, it becomes difficult to obtain the effect of the present embodiment.

In the present embodiment, preferably, the numerical ranges of the conditional expressions (1) to (7) are set as in the following conditional expressions (1a) to (7a), respectively.

5.0 <β2 / β34 <35 ... (1a)
1.0 <f4 / M4 <3.6 ... (2a)
0.70 <f1 / f3 <2.3 ... (3a)
0.10 << | f2 | / f3 <0.35 ... (4a)
0.30 <f3 / f4 <3.0 ... (5a)
0.50 <BF / fw <3.0 ... (6a)
0 <Fnow <1.4 ... (7a)
More preferably, the numerical ranges of the conditional expressions (1a) to (7a) are set as in the following conditional expressions (1b) to (7b), respectively.

5.5 <β2 / β34 <25 ... (1b)
1.5 <f4 / M4 <3.6 ... (2b)
0.90 <f1 / f3 <1.7 ... (3b)
0.14 << | f2 | / f3 <0.26 ... (4b)
0.40 <f3 / f4 <2.2 ... (5b)
0.70 <BF / fw <2.4 ... (6b)
0 <Fnow <1.2 ... (7b)
Further, in the present embodiment, preferably, the third lens group L3 is immobile and the fourth lens group L4 moves to the object side during zooming from the wide-angle end to the telephoto end. This makes it possible to correct spherical aberration, especially at the wide-angle end, and to increase the zoom. As a result, it is possible to realize a zoom lens that is compact, has a high zoom ratio, and has high optical performance over the entire zoom range. Further, the effect of the present embodiment can be further enhanced by arbitrarily combining a plurality of the above conditional expressions.

The zoom lens of the present embodiment is an image pickup lens system used in an image pickup device such as a digital still camera, a video camera, a silver halide film camera, and a television camera. 1, FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, and FIG. 13 are cross-sectional views of the lenses of Examples 1 to 7 described later. In each figure, the left side shows the object side and the right side shows the image side. Further, in each figure, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a positive refractive power. A fourth lens group having a positive or negative refractive power, L5 is a fifth lens group (successor lens group) having a positive or negative refractive power. In FIGS. 3, 5, and 7, L6 is a sixth lens group (successor lens group) having a positive refractive power.

P is an optical block corresponding to an optical filter, a face plate, a low-pass filter, an infrared cut filter, and the like, and I is an image plane. When a zoom lens is used as an image pickup optical system of a digital still camera or a video camera, the image plane I corresponds to a solid-state image pickup element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor. When a zoom lens is used as the imaging optical system of a silver halide film camera, the image plane I corresponds to the film plane.

Zooming from the wide-angle end to the telephoto end is performed by moving the second lens group L2 to the image side and the fourth lens group L4 to the object side, and the accompanying image plane fluctuation is to move the fifth lens group L5. Is corrected by. Further, by using the (immovable) third lens group L3 which is arranged between the second lens group L2 and the fourth lens group L4 and is fixed at the time of zooming, the spherical aberration generated by increasing the diameter is improved. Correct to. As described above, the zoom lens of each embodiment has a configuration advantageous for increasing the zoom and particularly increasing the diameter at the wide-angle end.

The arrows in each figure indicate the movement locus of each lens group during zooming. The curve drawn with a solid line shows the curvature of field due to zooming from the wide-angle end to the telephoto end when the curve drawn with a dotted line is focused on a short-range object. The movement locus for correction is shown. In each embodiment, focusing may be performed by moving the fourth lens group L4 or the sixth lens group L6 on the optical axis OA instead of the fifth lens group L5.

In each embodiment, the SP is an aperture diaphragm and is arranged on the object side of the third lens group L3. The aperture diameter of the aperture diaphragm SP can be constant or changed during zooming. By changing the diameter of the aperture diaphragm SP, coma aberration due to an off-axis luminous flux that is greatly generated at the telephoto end can be cut, and better optical performance can be obtained.

2, FIG. 4, FIG. 6, FIG. 8, FIG. 10, FIG. 12, and FIG. 14, respectively, show various aspects at (A) wide-angle end, (B) intermediate zoom position, and (C) telephoto end in Examples 1 to 7, respectively. It is an aberration diagram. In the spherical aberration diagram in each figure, Fno is an F number. The solid line shows the d line (wavelength 587.56 nm), and the chain line shows the g line (wavelength 435.84 nm). In the astigmatism diagram, the solid line is the sagittal image plane on the d line, and the dotted line is the meridional image plane. Distortion is shown for line d. The chromatic aberration of magnification diagram shows the aberration of the g-line with respect to the d-line. ω is the imaging half angle of view (degrees).

Hereinafter, the lens configuration of each embodiment will be specifically described.

[Example 1]
First, the zoom lens 1a according to the first embodiment will be described with reference to FIG. The first lens group L1 is composed of a lens in which a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a biconvex shape are joined, a positive lens having a convex surface on the object side and a meniscus shape, and a positive lens having a convex surface on the object side and a meniscus shape. Will be done. With such a configuration, axial chromatic aberration can be satisfactorily corrected, especially at the telephoto end.

The second lens group L2 is composed of a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a biconcave shape, a negative lens having a concave surface on the object side and a meniscus shape, and a positive lens having a biconvex shape. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a biconvex positive lens and a biconcave negative lens joined together. With such a configuration, it is possible to suppress the occurrence of spherical aberration and axial chromatic aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a lens in which a positive lens having a convex surface on the object side and a meniscus shape and a negative lens having a convex surface on the object side and a meniscus shape are joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a biconvex positive lens and a lens in which a meniscus-shaped negative lens with a concave object side is joined. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

[Example 2]
Next, the zoom lens 1b according to the second embodiment will be described with reference to FIG. The first lens group L1 is a lens in which a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a convex surface on the object side and a meniscus shape are joined, a positive lens having a convex surface on the object side and a meniscus shape, and a positive lens having a convex surface on the object side and a meniscus shape. It consists of a lens. With such a configuration, axial chromatic aberration can be satisfactorily corrected, especially at the telephoto end.

The second lens group L2 is composed of a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a biconcave shape, a negative lens having a concave surface on the object side and a meniscus shape, and a positive lens having a biconvex shape. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a positive lens having a convex surface on the object side and a meniscus shape, and a negative lens having a convex surface on the object side and a meniscus shape. With such a configuration, it is possible to suppress the occurrence of spherical aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a biconvex positive lens, and a lens in which a meniscus-shaped negative lens with a concave object side is joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a lens in which a positive lens having a meniscus shape and a negative lens having a concave shape on the object side are joined. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

The sixth lens group L6 is composed of a positive lens having a meniscus shape with a convex object side. By setting the final lens group as a lens group having a positive refractive power, the telecentricity is enhanced, and the off-axis luminous flux is incident on the image plane at an angle close to vertical. Therefore, in an image pickup device or the like provided with a solid-state image sensor on the image plane, it is possible to suppress a drop in the amount of light around the screen due to shading.

[Example 3]
Next, the zoom lens 1c according to the third embodiment will be described with reference to FIG. The first lens group L1 is composed of a lens in which a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a convex surface on the object side and a meniscus shape are joined, a biconvex positive lens, and a positive lens having a convex surface on the object side and a meniscus shape. Will be done. With such a configuration, axial chromatic aberration can be satisfactorily corrected, especially at the telephoto end.

The second lens group L2 is composed of a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a biconcave shape, a negative lens having a concave surface on the object side and a meniscus shape, and a positive lens having a biconvex shape. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a positive lens having a convex surface on the object side and a meniscus shape, and a negative lens having a convex surface on the object side and a meniscus shape. With such a configuration, it is possible to suppress the occurrence of spherical aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a biconvex positive lens, and a lens in which a meniscus-shaped negative lens with a concave object side is joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a lens in which a positive lens having a meniscus shape and a negative lens having a concave shape on the object side are joined. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

The sixth lens group L6 is composed of a positive lens having a convex surface on the object side, a meniscus shape, and a double-sided aspherical shape. By setting the final lens group as a lens group having a positive refractive power, the telecentricity is enhanced, and the off-axis luminous flux is incident on the image plane at an angle close to vertical. Therefore, in an image pickup device or the like provided with a solid-state image sensor on the image plane, it is possible to suppress a drop in the amount of light around the screen due to shading.

[Example 4]
Next, the zoom lens 1d in the fourth embodiment will be described with reference to FIG. 7. The first lens group L1 is a lens in which a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a convex surface on the object side and a meniscus shape are joined, a positive lens having a convex surface on the object side and a meniscus shape, and a positive lens having a convex surface on the object side and a meniscus shape. It consists of a lens. With such a configuration, axial chromatic aberration can be satisfactorily corrected, especially at the telephoto end.

The second lens group L2 is composed of a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a biconcave shape, a negative lens having a concave surface on the object side and a meniscus shape, and a positive lens having a biconvex shape. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a positive lens having a convex surface on the object side and a meniscus shape, and a negative lens having a convex surface on the object side and a meniscus shape. With such a configuration, it is possible to suppress the occurrence of spherical aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a biconvex positive lens, and a lens in which a meniscus-shaped negative lens with a concave object side is joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a lens in which a biconvex positive lens and a biconcave negative lens are joined. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

The sixth lens group L6 is composed of a positive lens having a convex surface on the object side, a meniscus shape, and a double-sided aspherical shape. By setting the final lens group as a lens group having a positive refractive power, the telecentricity is enhanced, and the off-axis luminous flux is incident on the image plane at an angle close to vertical. Therefore, in an image pickup device or the like provided with a solid-state image sensor on the image plane, it is possible to suppress a drop in the amount of light around the screen due to shading.

[Example 5]
Next, the zoom lens 1e according to the fifth embodiment will be described with reference to FIG. The first lens group L1 is a junction lens of a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a convex surface on the object side and a meniscus shape, a positive lens having a convex surface on the object side and a meniscus shape, and a positive lens having a convex surface on the object side and a meniscus shape. It consists of a positive lens with a convex surface on the object side and a meniscus shape. With such a configuration, it is possible to satisfactorily correct axial chromatic aberration especially at the telephoto end and suppress the occurrence of spherical aberration.

The second lens group L2 is composed of a meniscus-shaped negative lens having a convex surface on the object side, a biconcave negative lens, a biconcave negative lens, and a biconvex positive lens. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a biconvex positive lens, and a meniscus-shaped negative lens with a convex object side. With such a configuration, it is possible to suppress the occurrence of spherical aberration and axial chromatic aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a lens in which a positive lens having a convex surface on the object side and a meniscus shape and a negative lens having a convex surface on the object side and a meniscus shape are joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a biconvex positive lens and a lens in which a meniscus-shaped negative lens with a concave object side is joined. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

[Example 6]
Next, the zoom lens 1f in the sixth embodiment will be described with reference to FIG. The first lens group L1 is a lens in which a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a convex surface on the object side and a meniscus shape are joined, a positive lens having a convex surface on the object side and a meniscus shape, and a positive lens having a convex surface on the object side and a meniscus shape. It consists of a lens. With such a configuration, axial chromatic aberration can be satisfactorily corrected, especially at the telephoto end.

The second lens group L2 is composed of a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a biconcave shape, and a positive lens having a biconvex shape. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a positive lens having a convex surface on the object side and a meniscus shape, and a negative lens having a convex surface on the object side and a meniscus shape. With such a configuration, it is possible to suppress the occurrence of spherical aberration and axial chromatic aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a lens in which a positive lens having a convex surface on the object side and a meniscus shape and a negative lens having a convex surface on the object side and a meniscus shape are joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a positive lens having a biconvex shape and an aspherical surface on the object side and a negative lens having a concave surface on the object side and a meniscus shape. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

[Example 7]
Next, the zoom lens 1g in the seventh embodiment will be described with reference to FIG. The first lens group L1 is composed of a lens in which a negative lens having a convex surface on the object side and a meniscus shape and a positive lens having a biconvex shape are joined, a positive lens having a convex surface on the object side and a meniscus shape, and a positive lens having a convex surface on the object side and a meniscus shape. Will be done. With such a configuration, axial chromatic aberration can be satisfactorily corrected, especially at the telephoto end.

The second lens group L2 is composed of a negative lens having a convex surface on the object side and a meniscus shape, a negative lens having a biconcave shape, a negative lens having a concave surface on the object side and a meniscus shape, and a positive lens having a biconvex shape. With such a configuration, it is possible to effectively correct curvature of field at the wide-angle end and chromatic aberration of magnification over the entire zoom range.

The third lens group L3 is composed of a biconvex and double-sided aspherical positive lens, a lens in which a meniscus-shaped negative lens and a biconvex positive lens are joined with a convex surface on the object side, and a biconcave negative lens. Will be done. With such a configuration, it is possible to suppress the occurrence of spherical aberration and axial chromatic aberration at the wide-angle end.

The fourth lens group L4 is composed of a biconvex positive lens, a lens in which a positive lens having a convex surface on the object side and a meniscus shape and a negative lens having a convex surface on the object side and a meniscus shape are joined. With such a configuration, it is possible to suppress the occurrence of coma aberration at the wide-angle end.

The fifth lens group L5 is composed of a biconvex positive lens and a lens in which a meniscus-shaped negative lens with a concave object side is joined. By using only one bonded lens, fluctuations in chromatic aberration of magnification during focusing can be suppressed, and weight reduction facilitates control during focusing.

[Imaging device]
Next, an imaging device (imaging system) using the zoom lens of each embodiment as an imaging optical system will be described with reference to FIG. FIG. 15 is a configuration diagram of the image pickup apparatus 10. In FIG. 15, 11 is a surveillance camera main body, and 16 is an imaging optical system composed of any of the zoom lenses 1a to 1g of Examples 1 to 7. Reference numeral 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that is built in the camera body and receives a subject image formed by the imaging optical system 16. Reference numeral 13 denotes a memory for recording information corresponding to the subject image photoelectrically converted by the solid-state image sensor 12. Reference numeral 14 denotes a network cable for transferring a subject image photoelectrically converted by the solid-state image sensor 12.

[Imaging system]
An imaging system (surveillance camera system) including the zoom lens of each embodiment and a control unit that controls the zoom lens may be configured. In this case, the control unit can control the zoom lens so that each lens group moves as described above during zooming. At this time, the control unit does not have to be integrally configured with the zoom lens, and the control unit may be configured as a separate body from the zoom lens. For example, a control unit (control device) arranged far away from the drive unit that drives each lens of the zoom lens is provided with a transmission unit that sends a control signal (command) for controlling the zoom lens. You may. According to such a control unit, the zoom lens can be remotely controlled.

Further, the control unit may be provided with an operation unit such as a controller or a button for remotely controlling the zoom lens, so that the zoom lens may be controlled in response to an input to the operation unit of the user. For example, an enlargement button and a reduction button are provided as an operation unit, and the zoom lens is driven from the control unit so that the magnification of the zoom lens increases when the user presses the enlargement button and decreases when the user presses the reduction button. It may be configured so that a signal is sent to the unit.

Further, the imaging system may have a display unit such as a liquid crystal panel that displays information (moving state) regarding the zoom of the zoom lens. The information regarding the zoom of the zoom lens is, for example, the zoom magnification (zoom state) and the movement amount (movement state) of each lens group. In this case, the user can remotely control the zoom lens via the operation unit while viewing the information regarding the zoom of the zoom lens displayed on the display unit. At this time, the display unit and the operation unit may be integrated by adopting, for example, a touch panel.

According to each embodiment, it is possible to provide a zoom lens, an imaging device, and an imaging system that are compact, have a high zoom ratio, and have high optical performance over the entire zoom range.

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

For example, further aberration correction may be performed by dividing the bonded lens and providing an air gap between the lenses, or by changing the spherical lens to an aspherical lens. Further, the image pickup apparatus composed of any of the above zoom lenses and a solid-state image pickup device may have a circuit for electrically correcting either or both of distortion and chromatic aberration of magnification. Further, the image pickup device is not limited to the surveillance camera, and can be used in a video camera, a digital camera, or the like.

Next, numerical examples 1 to 7 corresponding to Examples 1 to 7, respectively, are shown. 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 plane and the (m + 1) th plane. .. However, m is the number of the surface counted from the light incident side (object side). In each numerical embodiment, the last two surfaces are the surfaces of optical blocks such as filters and face plates. Further, nd represents the refractive index of each optical member with respect to the d line, νd represents the Abbe number based on the d line of the optical member, and θgF represents the partial dispersion ratio. The Abbe number νd and the partial dispersion ratio θgF of a certain material are those of the material with respect to the g-line (wavelength 435.8 nm), F-line (486.1 nm), C-line (656.3 nm), and d-line (587.6 nm). When the refractive indexes are Ng, NF, NC, and Nd, respectively, they are expressed by the following equations.

νd = (Nd-1) / (NF-NC) ... (8)
θgF = (Ng-NF) / (NF-NC) ... (9)
In each numerical example, d, focal length f (mm), F number Fno, and half angle of view (degrees) are all values when the zoom lens of each example focuses on an infinity object. "Back focus" is the distance on the optical axis from the final surface of the lens (the lens surface on the most image side) to the paraxial image plane in terms of air equivalent length. The "total lens length" is the length obtained by adding the back focus to the distance on the optical axis from the frontmost surface (lens surface on the most object side) of the zoom lens to the final surface. The "lens group" is not limited to the case of being composed of a plurality of lenses, but also includes the case of being composed of one lens.

When the optical surface is an aspherical surface, a * symbol is attached to the right side of the surface number. For the aspherical shape, x is the amount of displacement from the surface apex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conical constant, A4, A6, When A8 and A10 are the aspherical coefficients of each order, the aspherical shape is represented by the following equation (10).

x = (h ² / R) / [1 + {1- (1 + k) (h / R) ² } ^1/2 ] + A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰ ... (10)
Incidentally, "e ± XX" in each aspherical coefficient means "× 10 ^{± XX".}

Table 1 shows the relationship between each of the above conditional expressions and various numerical values in each numerical value embodiment.

<Numerical Example 1>
Unit mm

Surface data Surface number rd nd ν d
1 76.661 1.50 2.00069 25.5
2 50.867 6.26 1.43875 94.7
3 -1987.329 0.15
4 50.357 4.73 1.59522 67.7
5 238.979 0.15
6 54.814 3.06 1.59522 67.7
7 104.288 (variable)
8 377.951 0.90 1.95375 32.3
9 11.801 4.09
10 -68.968 0.70 1.83481 42.7
11 35.314 2.98
12 -19.141 0.70 1.80400 46.6
13 -98.184 0.10
14 69.973 2.56 1.95906 17.5
15 -32.423 (variable)
16 (Aperture) ∞ 1.00
17 * 25.344 5.10 1.85135 40.1
18 * -100.215 1.00
19 29.708 4.46 1.49700 81.5
20 -105.273 1.00 1.85478 24.8
21 18.705 (variable)
22 30.147 2.87 1.90806 37.6
23 -262.783 0.10
24 15.352 3.90 1.69680 55.5
25 171.937 0.70 2.00100 29.1
26 13.602 (variable)
27 * 14.328 4.96 1.62263 58.2
28 -28.159 0.60 1.85478 24.8
29 -93.753 (variable)
30 ∞ 1.72 1.51500 70.0
31 ∞ 2.77
Image plane ∞

17th surface of aspherical data
K = 0.00000e + 000 A 4 = -4.78092e-006 A 6 = -1.33377e-008 A 8 = 2.19023e-011 A10 = -7.75796e-014

18th page
K = 0.00000e + 000 A 4 = 7.15682e-006 A 6 = -1.59628e-008 A 8 = 1.87001e-011

Page 27
K = 0.00000e + 000 A 4 = -2.190110e-005 A 6 = -2.28426e-009 A 8 = -8.01563e-010

Various data Zoom ratio 21.50
Wide-angle medium telephoto focal length 5.71 44.40 122.79
F number 1.03 2.55 2.88
Half angle of view (degrees) 35.00 5.15 1.87
Image height 4.00 4.00 4.00
Lens total length 129.40 129.40 129.40
BF 7.93 13.01 5.90

d 7 1.00 32.35 39.24
d15 39.73 8.38 1.50
d21 23.54 2.96 2.96
d26 3.63 19.13 26.24
d29 4.03 9.11 2.00

Zoom lens group Data group Start surface Focal length
1 1 60.06
2 8 -10.11
3 16 43.99
4 22 43.60
5 27 22.67

<Numerical Example 2>
Unit mm

Surface data Surface number rd nd ν d
1 85.568 1.69 2.00069 25.5
2 57.747 5.85 1.43875 94.7
3 744.669 0.17
4 59.821 5.61 1.49700 81.5
5 867.236 0.17
6 49.314 3.84 1.59522 67.7
7 104.689 (variable)
8 65.152 0.79 1.83481 42.7
9 13.168 5.56
10 -21.922 0.68 1.80400 46.5
11 26.231 3.29
12 -22.294 0.68 1.69680 55.5
13 -38.321 0.09
14 68.470 2.22 1.95906 17.5
15 -55.926 (variable)
16 (Aperture) ∞ 1.40
17 * 25.240 8.29 1.85135 40.1
18 * -104.064 1.27
19 25.906 4.91 1.49700 81.5
20 785.526 0.68 1.96042 22.3
21 17.674 (variable)
22 37.937 4.99 1.74404 53.8
23 -159.380 1.00
24 42.389 4.95 1.69680 55.5
25 -32.378 0.63 2.00101 29.1
26 -98.839 (variable)
27 -113.183 3.02 1.53997 47.6
28 -20.373 0.42 1.51432 54.4
29 22.482 (variable)
30 13.520 3.55 1.65265 62.4
31 134.883 1.46
32 ∞ 1.94 1.51500 70.0
33 ∞ 3.09
Image plane ∞

17th surface of aspherical data
K = -1.91227e-001 A 4 = -5.03595e-006 A 6 = 1.36752e-009 A 8 = -3.999439e-012 A10 = -9.55880e-015

18th page
K = 0.00000e + 000 A 4 = 6.39758e-006 A 6 = -1.81234e-009 A 8 = -3.56829e-012

Various data Zoom ratio 21.48
Wide-angle medium telephoto focal length 6.52 54.37 140.02
F number 1.03 2.55 2.88
Half angle of view (degrees) 34.71 4.75 1.85
Image height 4.51 4.51 4.51
Lens overall length 139.31 139.31 139.31
BF 5.84 5.84 5.84

d 7 0.59 34.96 42.51
d15 43.71 9.34 1.80
d21 17.37 3.72 3.24
d26 3.46 14.99 2.47
d29 2.58 4.70 17.70

Zoom lens group Data group Start surface Focal length
1 1 64.93
2 8 -10.16
3 16 41.58
4 22 25.23
5 27 -37.58
6 30 22.76

<Numerical Example 3>
Unit mm

Surface data Surface number rd nd ν d
1 74.880 1.69 2.00069 25.5
2 47.787 4.80 1.43875 94.9
3 261.148 0.17
4 61.732 4.21 1.49700 81.5
5 -1629.175 0.17
6 48.614 3.22 1.69680 55.5
7 133.556 (variable)
8 136.388 0.79 1.83481 42.7
9 11.667 4.98
10 -32.526 0.68 1.80400 46.5
11 28.946 2.90
12 -23.346 0.68 1.69680 55.5
13 -68.831 -0.05
14 51.700 2.28 1.95906 17.5
15 -61.413 (variable)
16 (Aperture) ∞ 1.39
17 * 23.402 6.88 1.69350 53.2
18 * -252.072 3.68
19 25.482 3.89 1.49700 81.5
20 71.170 0.68 1.74269 27.2
21 17.127 (variable)
22 27.640 5.13 1.49700 81.5
23 -51.865 0.35
24 27.070 4.66 1.49700 81.5
25 -28.210 0.63 1.92971 29.5
26 -82.700 (variable)
27 -719.458 3.06 1.62720 36.2
28 -16.811 0.42 1.59292 45.1
29 23.319 (variable)
30 * 12.433 3.46 1.59522 67.7
31 * 477.549 1.56
32 ∞ 1.72 1.51500 70.0
33 ∞ 2.77
Image plane ∞

17th surface of aspherical data
K = 2.17114e-002 A 4 = -5.55319e-006 A 6 = 1.02306e-009 A 8 = -2.11588e-013 A10 = 2.75829e-015

18th page
K = -2.57500e + 002 A 4 = 7.45793e-006 A 6 = 7.57185e-009 A 8 = -2.90197e-012

30th page
K = -1.92447e-001 A 4 = -6.60874e-005 A 6 = -8.21407e-007 A 8 = 2.64157e-009 A10 =-3.25201e-010

31st page
K = -9.74564e + 003 A 4 = -6.83182e-005 A 6 = -9.80794e-007

Various data Zoom ratio 20.98
Wide-angle medium telephoto focal length 5.63 46.04 118.17
F number 1.03 2.55 2.88
Half angle of view (degrees) 38.72 5.60 2.19
Image height 4.51 4.51 4.51
Lens total length 129.40 129.40 129.40
BF 5.47 5.47 5.47

d 7 0.27 31.99 38.95
d15 40.42 8.70 1.73
d21 15.11 3.15 2.97
d26 4.30 15.00 2.45
d29 3.10 4.35 17.09

Zoom lens group Data group Start surface Focal length
1 1 57.96
2 8 -9.54
3 16 45.04
4 22 24.59
5 27 -41.17
6 30 21.39

<Numerical Example 4>
Unit mm

Surface data Surface number rd nd ν d
1 74.547 1.69 2.00069 25.5
2 48.010 5.77 1.43875 94.9
3 210.859 0.17
4 61.595 4.49 1.49700 81.5
5 1568.203 0.17
6 49.984 3.47 1.69680 55.5
7 147.800 (variable)
8 165.336 0.79 1.83481 42.7
9 11.513 5.04
10 -36.199 0.68 1.80400 46.5
11 29.165 2.84
12 -23.447 0.68 1.69680 55.5
13 -73.620 0.42
14 54.698 2.93 1.95906 17.5
15 -58.391 (variable)
16 (Aperture) ∞ 1.40
17 * 23.409 6.67 1.69350 53.2
18 * -357.081 3.08
19 27.313 3.98 1.49700 81.5
20 88.566 0.68 1.77198 32.1
21 17.324 (variable)
22 28.416 6.35 1.49700 81.5
23 -56.583 0.42
24 27.742 4.73 1.49700 81.5
25 -28.010 0.63 1.96176 24.1
26 -78.713 (variable)
27 662.770 4.03 1.62719 36.2
28 -14.214 0.42 1.58715 46.8
29 25.648 (variable)
30 * 12.592 4.13 1.59522 67.7
31 * 411.427 1.62
32 ∞ 1.72 1.51500 70.0
33 ∞ 2.77
Image plane ∞

17th surface of aspherical data
K = 4.62259e-003 A 4 = -4.69709e-006 A 6 = 2.27857e-009 A 8 = -2.41847e-012 A10 = 2.44152e-014

18th page
K =-8.41719e + 001 A 4 = 7.70338e-006 A 6 = 4.50999e-009 A 8 = 6.62241e-012

30th page
K = -2.41598e-001 A 4 = -6.65186e-005 A 6 = -2.98269e-007 A 8 = -1.24804e-009 A10 = -3.18555e-010

31st page
K = 1.31206e + 003 A 4 = -9.14316e-005 A 6 = -9.86278e-007

Various data Zoom ratio 22.37
Wide-angle medium telephoto focal length 5.46 47.91 122.15
F number 1.03 2.88 3.61
Half angle of view (degrees) 39.59 5.38 2.12
Image height 4.51 4.51 4.51
Lens total length 140.28 140.28 140.28
BF 5.52 5.52 5.52

d 7 0.55 33.77 41.06
d15 42.31 9.09 1.79
d21 17.97 3.25 2.85
d26 4.77 16.91 2.57
d29 3.52 6.10 20.85

Zoom lens group Data group Start surface Focal length
1 1 60.78
2 8 -9.82
3 16 52.96
4 22 25.99
5 27 -52.47
6 30 21.74

<Numerical Example 5>
Unit mm

Surface data Surface number rd nd ν d
1 59.147 1.69 2.00069 25.5
2 47.573 12.03 1.43875 94.9
3 613.083 0.17
4 58.225 5.72 1.49700 81.5
5 134.635 0.17
6 64.984 4.06 1.49700 81.5
7 126.022 0.17
8 48.715 4.00 1.49700 81.5
9 80.176 (variable)
10 239.698 1.02 1.95375 32.3
11 13.299 8.51
12 -513.029 0.79 1.83481 42.7
13 42.031 2.55
14 -25.271 0.79 1.80400 46.6
15 57.667 0.43
16 42.548 2.35 1.95906 17.5
17 -59.754 (variable)
18 (Aperture) ∞ 0.98
19 * 33.040 4.82 1.49710 81.6
20 * 1051.561 1.00
21 122.637 3.57 1.49700 81.5
22 -81.260 0.10
23 27.185 1.13 1.85478 24.8
24 21.427 (variable)
25 64.618 4.27 1.49700 81.5
26 -81.820 6.17
27 26.619 4.59 1.49700 81.5
28 199.260 0.79 1.72825 28.5
29 27.489 (variable)
30 * 26.518 7.10 1.76802 49.2
31 -32.422 0.68 1.85478 24.8
32 -123.606 (variable)
33 ∞ 1.94 1.51500 70.0
34 ∞ 3.13
Image plane ∞

Aspherical data surface 19
K = 0.00000e + 000 A 4 = -6.51850e-006 A 6 = -4.71682e-008 A 8 = 1.09642e-010 A10 = 5.13048e-014

20th page
K = 0.00000e + 000 A 4 = 1.99746e-006 A 6 = -5.52001e-008 A 8 = 1.37179e-010

30th page
K = 0.00000e + 000 A 4 = -5.42730e-006 A 6 = -6.27207e-009 A 8 = 9.83036e-012

Various data Zoom ratio 28.63
Wide-angle medium telephoto focal length 8.01 52.68 229.34
F number 1.03 3.14 3.61
Half angle of view (degrees) 29.40 4.90 1.13
Image height 4.51 4.51 4.51
Lens overall length 169.33 169.33 169.33
BF 17.63 24.16 6.39

d 9 0.96 27.97 33.90
d17 34.43 7.42 1.49
d24 34.55 13.78 5.30
d29 2.13 16.37 42.61
d32 13.23 19.75 1.99

Zoom lens group Data group Start surface Focal length
1 1 60.43
2 10 -9.28
3 18 56.86
4 25 96.04
5 30 30.64

<Numerical Example 6>
Unit mm

Surface data Surface number rd nd ν d
1 75.852 1.50 2.00069 25.5
2 50.376 6.62 1.43875 94.7
3 683.845 0.15
4 53.204 5.14 1.59522 67.7
5 282.753 0.15
6 45.580 3.98 1.59522 67.7
7 111.955 (variable)
8 567.703 0.90 1.95375 32.3
9 11.471 4.02
10 839.467 0.70 1.83481 42.7
11 21.657 2.85
12 -21.092 0.70 1.80400 46.6
13 338.294 0.08
14 39.540 2.25 1.95906 17.5
15 -47.988 (variable)
16 (Aperture) ∞ 0.99
17 * 28.027 5.83 1.85135 40.1
18 * -106.929 0.99
19 28.928 4.15 1.49700 81.5
20 373.299 1.00 1.85478 24.8
21 20.796 (variable)
22 45.562 2.23 1.90806 37.6
23 -3524.725 0.10
24 14.178 5.23 1.69680 55.5
25 226.974 0.70 2.00100 29.1
26 13.097 (variable)
27 * 17.393 5.43 1.62263 58.2
28 -22.153 0.60 1.85478 24.8
29 -36.576 (variable)
30 ∞ 1.72 1.51500 70.0
31 ∞ 2.77
Image plane ∞

17th surface of aspherical data
K = 0.00000e + 000 A 4 = -8.76562e-006 A 6 = -1.15267e-008 A 8 = 1.93481e-011 A10 = 1.27420e-013

18th page
K = 0.00000e + 000 A 4 = 1.15694e-006 A 6 = -1.64566e-008 A 8 = 8.00190e-011

Page 27
K = 0.00000e + 000 A 4 = -2.41611e-005 A 6 = -2.08437e-007 A 8 = 1.11575e-009

Various data Zoom ratio 19.97
Wide-angle medium telephoto focal length 6.13 42.90 122.43
F number 1.03 2.55 2.88
Half angle of view (degrees) 33.13 5.33 1.87
Image height 4.00 4.00 4.00
Lens total length 134.41 134.41 134.41
BF 10.29 19.74 13.13

d 7 0.94 29.89 36.24
d15 36.79 7.84 1.49
d21 26.99 4.16 4.16
d26 3.10 16.49 23.10
d29 6.39 15.83 9.22

Zoom lens group Data group Start surface Focal length
1 1 55.34
2 8 -8.45
3 16 40.52
4 22 79.90
5 27 21.30

<Numerical Example 7>
Unit mm

Surface data Surface number rd nd ν d
1 77.293 1.50 2.00069 25.5
2 50.915 6.54 1.43875 94.7
3 -761.626 0.15
4 48.730 4.80 1.59522 67.7
5 209.178 0.15
6 54.636 2.64 1.59522 67.7
7 101.715 (variable)
8 317.173 0.90 1.95375 32.3
9 11.551 4.19
10 -65.339 0.70 1.83481 42.7
11 38.013 2.91
12 -18.924 0.70 1.80400 46.6
13 -98.761 0.10
14 70.840 2.66 1.95906 17.5
15 -31.478 (variable)
16 (Aperture) ∞ 1.00
17 * 25.524 5.58 1.85135 40.1
18 * -133.158 1.00
19 31.612 1.00 1.85478 24.8
20 24.134 4.81 1.49700 81.5
21 -73.234 1.00
22 -116.654 1.00 1.85478 24.8
23 18.770 (variable)
24 32.729 2.77 1.90806 37.6
25 -224.026 0.10
26 14.732 3.98 1.69680 55.5
27 92.956 0.70 2.00100 29.1
28 13.612 (variable)
29 * 14.341 4.88 1.62263 58.2
30 -35.465 0.60 1.85478 24.8
31 -104.161 (variable)
32 ∞ 1.72 1.51500 70.0
33 ∞
Image plane ∞

17th surface of aspherical data
K = 0.00000e + 000 A 4 = -5.66206e-006 A 6 = -1.14639e-008 A 8 = 9.23483e-012 A10 = -1.23911e-014

18th page
K = 0.00000e + 000 A 4 = 8.07195e-006 A 6 = -1.43343e-008 A 8 = 2.70623e-011

Page 29
K = 0.00000e + 000 A 4 = -2.25566e-005 A 6 = -6.76708e-008 A 8 = -5.11972e-010

Various data Zoom ratio 21.50
Wide-angle medium telephoto focal length 5.78 44.36 124.16
F number 1.03 2.55 2.88
Half angle of view (degrees) 34.71 5.15 1.85
Image height 4.00 4.00 4.00
Lens total length 129.08 129.08 129.08
BF 8.16 13.63 5.95

d 7 1.00 32.25 39.11
d15 39.61 8.36 1.50
d23 21.57 2.73 2.73
d28 2.39 15.75 23.43
d31 4.25 9.73 2.05

Zoom lens group Data group Start surface Focal length
1 1 59.44
2 8 -10.18
3 16 42.47
4 24 41.02
5 29 22.34

1a ~ 1g Zoom lens L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group (following lens group)
L6 6th lens group (following lens group)

Claims (14)

The first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, and the third lens group having a positive refractive power arranged in order from the object side to the image side. A zoom lens consisting of a fourth lens group and at least one subsequent lens group in which the distance between adjacent lens groups changes during zooming.
The third lens group has two lenses.
During zooming, the first lens group is immobile, and the second lens group and the fourth lens group move on the optical axis.
The lateral magnification of the second lens group at the wide-angle end is β2w, the lateral magnification of the second lens group at the telephoto end is β2t, the lateral magnification of the third lens group at the wide-angle end is β3w, and the third lens group at the telescopic end. When the lateral magnification of the fourth lens group is β3t, the lateral magnification of the fourth lens group at the wide-angle end is β4w, and the lateral magnification of the fourth lens group at the telephoto end is β4t.
β2 = β2t / β2w
β3 = β3t / β3w
β4 = β4t / β4w
β34 = β3 * β4
When the focal length of the 4th lens group is f4 and the amount of movement of the 4th lens group in the zooming from the wide-angle end to the telephoto end is M4,
4.0 <β2 / β34 <40
0.5 <f4 / M4 <3.7
A zoom lens characterized by satisfying the conditional expression. When the focal length of the first lens group is f1 and the focal length of the third lens group is f3,
0.40 <f1 / f3 <3.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the conditional expression. The zoom lens according to claim 1 or 2, wherein the third lens group is immovable during zooming. When the focal length of the second lens group is f2 and the focal length of the third lens group is f3,
0.050 << | f2 | / f3 <0.50
The zoom lens according to any one of claims 1 to 3, wherein the zoom lens satisfies the conditional expression. When the focal length of the third lens group is f3,
0.20 <f3 / f4 <4.5
The zoom lens according to any one of claims 1 to 4, wherein the zoom lens satisfies the conditional expression. The zoom lens according to any one of claims 1 to 5, wherein the fourth lens group moves toward an object during the zooming from the wide-angle end to the telephoto end. The zoom lens according to any one of claims 1 to 6, wherein the third lens group has at least three lenses. When the back focus at the wide-angle end is BF and the focal length of the zoom lens at the wide-angle end is fw,
0.20 <BF / fw <3.5
The zoom lens according to any one of claims 1 to 7, wherein the zoom lens satisfies the conditional expression. When the F number at the wide-angle end is Fnow,
0 <Fnow <1.6
The zoom lens according to any one of claims 1 to 8, wherein the zoom lens satisfies the conditional expression. The zoom lens according to any one of claims 1 to 9,
An image pickup apparatus comprising: an image pickup element that receives an image formed by the zoom lens. The zoom lens according to any one of claims 1 to 9,
An imaging system characterized by having a control unit that controls the zoom lens during zooming. The imaging system according to claim 11, wherein the control unit is configured as a separate body from the zoom lens, and includes a transmission unit that transmits a control signal for controlling the zoom lens. The imaging system according to claim 11 or 12, wherein the control unit is configured as a separate body from the zoom lens, and includes an operation unit for operating the zoom lens. The imaging system according to any one of claims 11 to 13, further comprising a display unit for displaying information regarding the zoom of the zoom lens.