JP6797960B2 - Zoom lens and imaging device with it - Google Patents

Description

The present invention relates to a zoom lens and an imaging device having the same, and is suitable as an imaging optical system used in an imaging device such as a digital still camera, a surveillance camera, or a camera for silver halide photography.

In recent years, an image pickup device using a solid-state image sensor has become more sophisticated, and the entire device has been miniaturized. The image pickup optical system used for this is required to have a short overall lens length, a compact (small size), a high zoom ratio (high magnification ratio), and a zoom lens having a high resolution. As a zoom lens that meets these demands, for example, a zoom lens using a so-called rear focus method in which focusing is performed with a lens group other than the first lens group on the object side is known.

One of the reasons why the rear focus method is adopted is that in the lens group for focusing (hereinafter referred to as "focus lens group"), the incident height h of the axial marginal light ray is low, so that the aberration during focusing occurs. The purpose is to reduce fluctuations (particularly fluctuations in spherical aberration).

Another reason is that if the size of the image sensor used in the image sensor is small, the focus lens group is lightweight and the amount of extension during focusing is small, so that the entire image sensor can be easily miniaturized. In addition, in recent years, in order to make the photographing apparatus compact, many electronic distortion corrections that electrically perform distortion correction in a wide-angle range have been introduced among various aberrations of the zoom lens used therefor. An imaging device that introduces electronic distortion correction is advantageous for compactification. However, it is known that the aberration fluctuation during focusing becomes large.

In aberration theory, the process of focusing from a long distance to a short distance is the process of moving an object distance from a long distance to a short distance (object distance movement) and the process of moving the focus lens group to focus on that object distance (focus). It can be separated into (lens group movement). Using that aberration theory, it can be seen that the curvature of field tends to increase in principle when the object distance moves, and the curvature of field tends to increase when focusing. According to Non-Patent Document 1, since the third-order aberration coefficient V related to distortion is large, the third-order aberration coefficient III related to astigmatism III.
Amount of fluctuation when moving the object distance

Is also proved to be large. (However, [delta] is the object distance movement parameter, II ^S is third order aberration coefficients for the coma aberration of the pupil, the I ^S is a third-order aberration coefficients for spherical aberration of the pupil). However, if the size of the image sensor is small, the variation in curvature of field during focusing is not noticeable, and the problem is rarely mentioned.

For example, there is known a zoom lens that employs a rear focus method and introduces electronic distortion correction in a negative lead type that has a lens group having a negative refractive power on the most object side (Patent Document 1). In addition, a zoom lens that employs a rear focus method and introduces electronic distortion correction in a positive lead type that has a lens group having a positive refractive power on the most object side is known (Patent Document 2).

JP-A-2010-181787 Japanese Unexamined Patent Publication No. 2010-181543

Yoshiya Matsui "Lens Design Method" Chapter 4

A zoom lens using the rear focus method facilitates miniaturization and weight reduction of the focus lens group, and facilitates quick focusing. However, aberration fluctuations tend to increase during focusing. Further, as the image sensor generally used in an image pickup device becomes larger, it is required that the zoom lens used in the image pickup device has high optical performance over the entire zoom range and the entire object distance. For example, it is required that there is little variation in aberration during focusing, and that there is little variation in curvature of field in order to maintain high optical performance over the entire screen.

On the other hand, since the zoom lens used in the imaging device having a function of performing electronic distortion correction is allowed to increase the distortion aberration, it becomes easy to reduce the size of the entire system while increasing the angle of view. However, when focusing in such a zoom lens in a wide-angle region, fluctuations in curvature of field and fluctuations in spherical aberration increase.

In Patent Document 1, distortion is set to -14% or less and image height is set to 3.84 mm at the wide-angle end, and due to the small size of the image sensor, fluctuations in spherical aberration and curvature of field during focusing are observed. Relatively small. However, when applied to a large image sensor, the variation in curvature of field during focusing tends to increase. In Patent Document 2, distortion is set to -14% or less and image height is set to 3.83 mm at the wide-angle end, and due to the small size of the image sensor, fluctuations in spherical aberration and curvature of field during focusing are observed. Relatively small.

However, when applied to a large image sensor, the variation in curvature of field during focusing tends to increase. In addition, in this zoom lens, the incident height h of the on-axis marginal ray in the focus lens group is a large ratio with respect to the incident height h / of the off-axis main ray, so that the curvature of field and the spherical aberration fluctuate. Also tends to increase.

In order to obtain a zoom lens with a predetermined shooting angle of view, less aberration fluctuation during focusing, and high optical performance over the entire screen, the zoom type, the refractive power of the focus lens group, the lens configuration, etc. are appropriately set. It will be necessary to do. Further, it is necessary to appropriately set the lens configuration of the lens group located on the object side of the focus lens group.

An object of the present invention is to provide a zoom lens capable of reducing aberration fluctuations during focusing at a wide angle of view and having high optical performance over a entire object distance, and an imaging device having the same.

The zoom lens of the present invention is a zoom lens having a plurality of lens groups and changing the distance between adjacent lens groups during zooming.
The lens group BR having a negative refractive power arranged on the image side of the zoom lenses moves in the optical axis direction during focusing.
The sign of the refractive power of the lens element composed of a single lens or a junction lens arranged adjacent to the object side of the lens group BR is positive.
The lens group BR is composed of a single lens having a negative refractive power or a junction lens having a negative refractive power.
The distance between the most image-side surface of the lens element at the wide-angle end and the image surface is di, and the distance between the most image-side surface of the lens element at the wide-angle end and the most object-side surface of the lens group BR is df. The focal length of the entire system at the wide-angle end is fw, the focal length of the lens element is fa, the radius of curvature of the most object-side surface and the most image-side surface of the lens group BR are rf and rr , respectively, and the lens at the wide-angle end. When the lateral magnification of the group BR is βw ,
0.2 <di / fw <1.4
0.2 <df / fw <1.2
1.412 ≤ fa / fw <4.0
0.0 <(rf + rr) / (rf-rr) <5.0
1.0 <βw <1.3
It is characterized by satisfying the conditional expression.
Further, the other zoom lenses of the present invention include a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power arranged in order from the object side to the image side. It is a zoom lens consisting of a group, a fourth lens group with negative power, and a fifth lens group with negative power, and each lens group moves on different trajectories during zooming and the distance between adjacent lens groups changes. There,
The fifth lens group moves in the optical axis direction during focusing, and the fifth lens group moves in the optical axis direction.
The sign of the refractive power of the lens element composed of a single lens or a junction lens arranged adjacent to the object side of the fifth lens group is positive.
The distance between the most image-side surface of the lens element at the wide-angle end and the image surface is di, and the distance between the most image-side surface of the lens element at the wide-angle end and the most object-side surface of the fifth lens group is df. When the focal length of the entire system at the wide-angle end is fw and the focal length of the lens element is fa,
0.2 <di / fw <1.4
0.2 <df / fw <1.2
1.412 ≤ fa / fw <4.0
It is characterized by satisfying the conditional expression.
Further, the other zoom lenses of the present invention are a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a positive refractive power arranged in order from the object side to the image side. It is composed of a group, a fourth lens group with negative power, a fifth lens group with positive power, and a sixth lens group with negative power, and each lens group moves adjacent to each other in different trajectories during zooming. A zoom lens that changes the distance between the lens groups.
The sixth lens group moves in the optical axis direction during focusing, and the sixth lens group moves in the optical axis direction.
The sign of the refractive power of the lens element composed of a single lens or a junction lens arranged adjacent to the object side of the sixth lens group is positive.
The distance between the most image-side surface of the lens element at the wide-angle end and the image surface is di, and the distance between the most image-side surface of the lens element at the wide-angle end and the most object-side surface of the sixth lens group is df. When the focal length of the entire system at the wide-angle end is fw and the focal length of the lens element is fa,
0.2 <di / fw <1.4
0.2 <df / fw <1.2
1.412 ≤ fa / fw <4.0
It is characterized by satisfying the conditional expression.

According to the present invention, it is possible to obtain a zoom lens that reduces aberration fluctuations when focusing at a wide angle of view and has high optical performance over the entire object distance.

Cross-sectional view of the lens at the wide-angle end when the zoom lens of Reference Example 1 of the present invention is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, intermediate zoom position, and telephoto end when focusing on an infinity object of the zoom lens of Reference Example 1. (A), (B), (C) Aberration diagram at the wide-angle end, intermediate zoom position, and telephoto end when focusing on a short-distance object of the zoom lens of Reference Example 1. Cross-sectional view of the lens at the wide-angle end when the zoom lens of Example 1 of the present invention is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end when the zoom lens of Example 1 is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end when focusing on a short-distance object of the zoom lens of Example 1. Cross-sectional view of the lens at the wide-angle end when the zoom lens of Reference Example 2 of the present invention is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens of Reference Example 2 is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, intermediate zoom position, and telephoto end when focusing on a short-distance object of the zoom lens of Reference Example 2. Cross-sectional view of the lens at the wide-angle end when the zoom lens of the second embodiment of the present invention is focused on an infinite object. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end when the zoom lens of Example 2 is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end when focusing on a short-distance object of the zoom lens of Example 2. Cross-sectional view of the lens at the wide-angle end when the zoom lens of Reference Example 3 of the present invention is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, intermediate zoom position, and telephoto end when the zoom lens of Reference Example 3 is focused on an infinity object. (A), (B), (C) Aberration diagram at the wide-angle end, intermediate zoom position, and telephoto end when focusing on a short-distance object of the zoom lens of Reference Example 3. Schematic diagram of the main part of the image pickup apparatus of the present invention

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens of the present invention is a zoom lens having a plurality of lens groups and changing the distance between adjacent lens groups during zooming. The lens group BR arranged on the image side of the zoom lenses moves in the optical axis direction during focusing. The lens element arranged adjacent to the object side of the lens group BR is composed of a single lens or a bonded lens, and the sign of the refractive power of the lens element is the opposite sign of the sign of the refractive power of the lens group BR.

FIG. 1 is a cross-sectional view of a lens at a wide-angle end (short focal length end) when focusing on an infinity object of Reference Example 1 of the zoom lens of the present invention.

2 (A), (B), and (C) show longitudinal aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end) when the zoom lens of Reference Example 1 is focused on an infinity object, respectively. It is a figure. 3 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the short-distance object of the zoom lens of Reference Example 1 is focused, respectively. Here, the short-range object is 50 mm from the first lens surface to the object side at the wide-angle end, 500 mm from the first lens surface to the object side at the intermediate zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. An object. The object distance is when the numerical example described later is expressed in mm. This is the same in each embodiment.

FIG. 4 is a cross-sectional view of the lens at the wide-angle end when the zoom lens of the present invention is focused on an object at infinity. 5 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the zoom lens of the first embodiment is focused on an infinity object, respectively. 6A, 6B, and 6C are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the short-distance object of the zoom lens of Example 1 is focused, respectively. Here, the short-range object is 50 mm from the first lens surface to the object side at the wide-angle end, 200 mm from the first lens surface to the object side at the intermediate zoom position, and 200 mm from the first lens surface to the object side at the telephoto end. An object.

FIG. 7 is a cross-sectional view of the lens at the wide-angle end when the zoom lens of the present invention is focused on an infinity object of Reference Example 2. 8 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the zoom lens of Reference Example 2 is focused on an infinity object, respectively. 9 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the short-distance object of the zoom lens of Reference Example 2 is focused, respectively. Here, the short-range object is 50 mm from the first lens surface to the object side at the wide-angle end, 500 mm from the first lens surface to the object side at the intermediate zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. An object.

FIG. 10 is a cross-sectional view of the lens at the wide-angle end when the zoom lens of the present invention is focused on an object at infinity according to the second embodiment. 11 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the zoom lens of the second embodiment is focused on an infinity object, respectively. 12 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the short-distance object of the zoom lens of the second embodiment is focused, respectively. Here, the short-range object is 50 mm from the first lens surface to the object side at the wide-angle end, 500 mm from the first lens surface to the object side at the intermediate zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. An object.

FIG. 13 is a cross-sectional view of the lens at the wide-angle end when the zoom lens of the present invention is focused on an infinity object of Reference Example 3. 14 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the zoom lens of Reference Example 3 is focused on an infinity object, respectively. 15 (A), (B), and (C) are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end when the short-distance object of the zoom lens of Reference Example 3 is focused, respectively. Here, the short-range object is 50 mm from the first lens surface to the object side at the wide-angle end, 500 mm from the first lens surface to the object side at the intermediate zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. An object. FIG. 16 is a schematic view of a main part of the image pickup apparatus of the present invention.

The zoom lens of each embodiment is used in an imaging device such as a digital camera, a video camera, a TV camera, a surveillance camera, and a film camera. The zoom lens of each embodiment is a positive lead type zoom lens having a lens group having a positive refractive power on the most object side or a negative lead type zoom lens having a negative refractive power. Further, the focus lens group has a positive refractive power or a negative refractive power.

In the lens cross-sectional view of the zoom lens of each embodiment, the left side is the object side (front) and the right side is the image side (rear). In the lens cross-sectional view, i indicates the order of the lens groups from the object side, and Bi indicates the i-th lens group. SP is an aperture stop. FP is a flare cut aperture. IP is an image plane. The image plane IP is used as the image plane of a solid-state image sensor (photoelectric conversion element) such as a CMOS sensor when a zoom lens is used as the image pickup optical system of a digital camera or a video camera, and as an image pickup optical system of a silver salt photography camera. When this is done, it corresponds to the film surface. The arrows show the movement locus of each lens group during zooming from the wide-angle end to the telephoto end. The arrow related to focus indicates the direction of movement of the lens group when focusing from infinity to close range.

In the aberration diagram of each embodiment, the solid line d and the two-dot chain line g in the spherical aberration are the d line and the g line, respectively, and the dotted line (ΔM) and the solid line (ΔS) in the astigmatism are the meridional image plane, the sagittal image plane, and the magnification. The two-dot chain line of chromatic aberration represents the g line. ω is a half angle of view (shooting half angle of view), and Fno is an F number. The wide-angle end and the telephoto end in each of the following embodiments represent zoom positions when the variable magnification lens group is located at both ends of a movable range on the optical axis on the mechanism.

The zoom lens of each embodiment has a plurality of lens groups, and the distance between adjacent lens groups changes during zooming. The lens group (final lens group) BR located closest to the image side is a focus lens group that moves in the optical axis direction to perform focusing. The lens element A adjacent to the object side with respect to the focus lens group BR is composed of a single lens or a junction lens. The sign of the refractive power of the lens element A is the opposite sign of the sign of the refractive power of the focus lens group BR.

By configuring the lens element A and the focus lens group BR to have oppositely signed refractive powers, the refractive powers of both the lens element A and the focus lens group BR are reduced. At the wide-angle end, the incident angle α of the on-axis marginal ray and the incident angle α / of the off-axis main ray in the focus lens group BR are increased. As a result, in a rear focus type zoom lens, the amount of variation in curvature of field when the focus lens group moves.

Is getting bigger. As a result, fluctuations in curvature of field when the object distance moves at the wide-angle end are corrected when the focus lens group moves. In equation (X1), f is the focal length of the focus lens group.

Is the angle of incidence of the on-axis marginal ray on the focus lens group before the movement of the focus lens group, the angle of incidence of the off-axis main ray, and the incident height of the off-axis main ray. (Δh ₂ ) is the amount of change in the incident height of the axial marginal light beam of the focus lens group due to the movement of the focus lens group.

In addition, in the zoom lens of the present invention, the lens element A adjacent to the object side with respect to the focus lens group BR is composed of a single lens or a junction lens. Let di be the distance between the image plane and the image plane of the lens element A at the wide-angle end. Let df be the distance between the surface on the image side of the lens element A at the wide-angle end and the surface on the object side of the focus lens group BR. Let fw be the focal length of the entire system at the wide-angle end.
0.2 <di / fw <1.4 ... (1)
0.2 <df / fw <1.2 ... (2)
Satisfies the conditional expression.

In the conditional equation (1), in order to reduce the fluctuation of spherical aberration and the fluctuation of curvature of field when focusing at the wide-angle end, the focal length fw of the entire system at the wide-angle end and the most image side of the lens element A at the wide-angle end The distance between the surface and the image surface is properly determined. When the lens element A becomes far from the image plane beyond the upper limit of the conditional expression (1), the emission angle of the axial marginal ray at the lens element A becomes smaller, and the incident angle of the axial marginal ray at the focus lens group becomes smaller. Also becomes smaller. Then, when focusing, the amount of fluctuation in the incident height of the axial marginal ray in the focus lens group becomes small, and it becomes difficult to cancel the curvature of field variation.

When the lower limit value of the conditional expression (1) is exceeded and the lens element A approaches the image plane, it becomes difficult to provide a sufficiently large amount of movement of the focusing lens group BR during focusing, and focusing is performed in a wide object distance range. It becomes difficult.

The conditional expression (2) is for reducing the fluctuation of spherical aberration and the fluctuation of curvature of field when focusing at the wide-angle end. Conditional expression (2) appropriately defines the focal length fw of the entire system at the wide-angle end and the distance between the most image-side surface of the lens element A at the wide-angle end and the most object-side surface of the focus lens group BR.

When the upper limit value of the conditional expression (2) is exceeded and the lens element A is separated from the focus lens group BR, the lens element A is also far from the image plane and the emission angle of the axial marginal ray at the lens element A becomes smaller. Further, the incident angle α of the axial marginal ray in the focus lens group BR is also reduced. Then, when focusing, the fluctuation amount of the incident height of the axial marginal ray in the focus lens group BR becomes small, and it becomes difficult to reduce the fluctuation of the curvature of field.

When the lower limit value of the conditional expression (2) is exceeded and the lens element A approaches the focus lens group BR, it becomes difficult to provide a sufficiently large amount of movement of the focusing lens group BR during focusing, and in a wide object distance range, Focusing becomes difficult. In addition, since the incident height of the axial marginal ray in the focus lens group BR is not sufficiently small, it becomes difficult to reduce the fluctuation of spherical aberration during focusing.

In the present invention, it is more preferable that at least one of the following conditional expressions is satisfied.

When the focus lens group BR has a positive refractive power, it is preferable to satisfy one or more of the following conditional expressions. The lateral magnification of the focus lens group BR at the wide-angle end is βw. The focus lens group BR is composed of a single lens having a positive refractive power or a junction lens having a positive refractive power, and the radii of curvature of the surface on the most object side and the surface on the image side of the focus lens group BR are rf and rr, respectively. .. Let fa be the focal length of the lens element A. It is preferable to satisfy one or more of the following conditional expressions at this time.
0.7 <βw <1.0 ... (3P)
-5.0 <(rf + rr) / (rf-rr) <0.0 ... (4P)
1.0 <-fa / fw <4.0 ... (5P)

Next, the technical meaning of each of the above conditional expressions will be described. The conditional expression (3P) defines the lateral magnification βw of the focus lens group BR at the wide-angle end when the focus lens group BR has a positive refractive power.

The conditional expression (3P) is for reducing the fluctuation of spherical aberration and the fluctuation of curvature of field when focusing at the wide-angle end. The focus sensitivity (1-βw ² ) is reduced by setting the lateral magnification of the focus lens group BR to a value close to 1.0. According to this, since the fluctuation of the incident height of the axial marginal ray in the lens group BR becomes large, it becomes easy to correct the fluctuation of the curvature of field. The lateral magnification of the lens group BR at the time of focusing does not exceed the upper limit of the conditional expression (3P) to 1.

When the lower limit of the conditional expression (3P) is exceeded, the focus sensitivity becomes too large and the fluctuation of the incident height of the axial marginal ray in the focus lens group BR becomes small, so that the fluctuation of the curvature of field should be reduced. Becomes difficult.

The conditional expression (4P) defines the shape factor (lens shape) of the focus lens group BR in order to reduce the fluctuation of curvature of field and the fluctuation of spherical aberration when focusing at the wide-angle end. In the conditional equation (4P), the off-axis main ray is obliquely incident on the refracting surface in order to reduce the fluctuation of curvature of field, and the axial marginal ray is directed to the refracting surface in order to reduce the fluctuation of spherical aberration. It is intended to be incident near perpendicular to the vertical.

When the value of the radius of curvature of the surface on the object side and the surface on the image side becomes close to each other beyond the upper limit of the conditional expression (4P), it is difficult to reduce the fluctuation of curvature of field and the fluctuation of spherical aberration. become. When the lower limit of the conditional expression (4P) is exceeded and the object side having a strong curvature of the surface on the object side approaches a convex meniscus shape, it becomes difficult to reduce the fluctuation of the curvature of field.

The conditional expression (5P) defines the refractive power of the lens element A arranged near the image plane and the focus lens group BR in order to reduce fluctuations in spherical aberration and curvature of field when focusing at the wide-angle end. To do.

When the absolute value of the focal length of the lens element A increases (when the absolute value of the refractive power decreases) beyond the upper limit of the conditional expression (5P), when the aperture diaphragm SP is arranged closer to the object than the lens element A, , The emission angle of the off-axis main ray at the lens element A becomes smaller. Then, the incident angle of the off-axis main ray in the focus lens group BR becomes small, and it becomes difficult to reduce the fluctuation of the curvature of field. When the aperture diaphragm SP is arranged on the image side of the lens element A, the incident height of the axial marginal ray in the focus lens group BR becomes a large ratio to the incident height of the off-axis main ray, so that it is spherical. It becomes difficult to reduce the fluctuation of aberration.

When the absolute value of the focal length of the lens element A becomes smaller (when the absolute value of the refractive power becomes larger) beyond the lower limit of the conditional expression (5P), the aperture stop SP is arranged closer to the object than the lens element A. , The incident height of the axial marginal ray at the lens element A is not sufficiently small. Then, the incident height of the axial marginal ray in the focus lens group BR also becomes large, and it becomes difficult to reduce the fluctuation of the spherical aberration. Further, when the aperture diaphragm SP is arranged on the image side of the lens element A, the incident height of the axial marginal ray in the focus lens group BR becomes a large ratio to the incident height of the off-axis main ray. It becomes difficult to reduce the fluctuation of spherical aberration.

When the focus lens group BR has a negative refractive power, it is preferable to satisfy one or more of the following conditional expressions. The lateral magnification of the focus lens group BR at the wide-angle end is βw. The focus lens group BR is composed of a single lens having a negative refractive power or a junction lens having a negative refractive power, and the radii of curvature of the surface on the most object side and the surface on the image side of the focus lens group BR are rf and rr, respectively. .. Let fa be the focal length of the lens element A. At this time, it is preferable to satisfy one or more of the following conditional expressions.
1.0 <βw <1.3 ... (3N)
0.0 <(rf + rr) / (rf-rr) <5.0 ... (4N)
1.412 ≤ fa / fw <4.0 ... (5N)

Next, the technical meaning of each of the above conditional expressions will be described. The conditional expression (3N) defines the lateral magnification βw of the lens group BR at the wide-angle end when the focus lens group BR has a negative refractive power. The conditional expression (3N) is for reducing fluctuations in spherical aberration and curvature of field during focusing at the wide-angle end. The focus sensitivity (1-βw ² ) is reduced by setting the lateral magnification of the focus lens group BR to a value close to 1.0. According to this, since the fluctuation of the incident height of the axial marginal ray in the focus lens group BR becomes large, it becomes easy to correct the fluctuation of the curvature of field.

When the upper limit of the conditional expression (3N) is exceeded, the focus sensitivity becomes too large and the fluctuation of the incident height of the axial marginal ray in the focus lens group BR becomes small, so that the fluctuation of the curvature of field should be reduced. Becomes difficult. The lateral magnification does not become 1 when focusing beyond the lower limit of the conditional expression (3N).

The conditional expression (4N) defines the shape factor of the focus lens group BR in order to reduce the fluctuation of curvature of field and the fluctuation of spherical aberration when focusing at the wide-angle end. The conditional expression (4N) is such that the off-axis main ray is obliquely incident on the refracting surface in order to reduce the fluctuation of curvature of field, and the axial marginal ray is directed to the refracting surface in order to reduce the fluctuation of spherical aberration. It is intended to be incident near perpendicular to the vertical.

If the upper limit of the conditional expression (4N) is exceeded and the object side having a strong surface curvature becomes close to a convex meniscus shape, it becomes difficult to reduce the variation in curvature of field. When the value of the radius of curvature of the surface on the object side and the surface on the image side becomes close to each other beyond the lower limit of the conditional expression (4N), it is difficult to reduce the fluctuation of curvature of field and the fluctuation of spherical aberration. become.

The conditional expression (5N) defines the focal length fa of the lens element A when the focus lens group BR has a negative refractive power. The above-mentioned conditional expression (5P) is when the focus lens group BR has a positive refractive power. The technical content of the conditional expression (5N) is the same as that of the conditional expression (5P).

In the zoom lens of each embodiment, it is preferable to have an aperture diaphragm SP that determines the open F number regardless of whether the lens group BR has a positive refractive power or a negative refractive power. Then, let φa be the optically effective diameter of the surface of the lens element A on the most image side. At this time,
0.7 <φa / di <1.4 ... (6)
It is good to satisfy the conditional expression.

In the conditional expression (6), in order to reduce the variation in curvature of field at the wide-angle end, the surface of the lens element A on the most image side with respect to the distance between the image side and the image plane of the lens element A at the wide-angle end. The optical effective diameter is properly specified. In the conditional expression (6), in order to reduce the fluctuation of curvature of field, the incident angle of the axial marginal ray is increased in the focus lens group BR, and the fluctuation amount of the incident height of the axial marginal ray in the focus lens BR is increased. It is for increasing the size.

If the upper limit of the conditional expression (6) is exceeded and the optical effective diameter of the surface of the lens element A on the image side becomes too large, the optical effective diameter of the focus lens group BR also increases, and the entire lens system is miniaturized. It becomes difficult. Further, at the telephoto end, the optical effective diameter of the focus lens group BR also increases, and the incident height of the off-axis main ray at the focus lens group BR also increases, so that the variation in curvature of field can be reduced at the telephoto end. It will be difficult.

If the lower limit of the conditional expression (6) is exceeded and the optical effective diameter of the surface on the image side of the lens element A becomes too small, the incident angle of the axial marginal light beam in the focus lens group BR becomes small and is on the axis. The amount of fluctuation in the incident height of the marginal ray becomes small. As a result, it becomes difficult to reduce the fluctuation of curvature of field.

When the zoom lens of the present invention is applied to an image pickup device having an image pickup element, the half angle of view of the shooting angle of view specified in the effective range of the image pickup element is defined as ωw. At this time,
ωw ≧ 30 °
It is preferable to use a zoom lens having a wide angle of view that satisfies the conditional expression.

At this time, when the amount of distortion at the half angle of view ωw of the zoom lens at the wide-angle end is d (%),
d (%) <-10% ・ ・ ・ (7)
It is desirable to satisfy the conditional expression.

Conditional expression (7) is based on the premise that when the zoom lens according to the present invention focuses at the wide-angle end, the curvature of field becomes large in principle due to the movement of the object distance. If the distortion at the wide-angle end exceeds the upper limit of the conditional expression (7) and the distortion is small, the curvature of field does not increase due to the movement of the object distance. Therefore, it is not necessary to reduce the fluctuation of the curvature of field when the lens group BR for focusing is moved, and the fluctuation of the curvature of field is excessively corrected, and as a result, it is difficult to reduce the fluctuation of the curvature of field. It becomes.

More preferably, the numerical ranges of the conditional expressions (1), (2), (3P), (4P), (5P), (3N), (4N), (5N), (6), and (7). It is desirable to set as follows.
1.0 <di / fw <1.4 ... (1a)
0.2 <df / fw <1.0 ... (2a)
0.8 <βw <1.0 ... (3Pa)
-1.0 <(rf + rr) / (rf-rr) <0.0 ... (4Pa)
1.0 <-fa / fw <3.5 ... (5Pa)
1.2 <βw <1.3 ... (3Na)
0.0 <(rf + rr) / (rf-rr) <1.0 ... (4Na)
1.412 ≤ fa / fw <3.5 ... (5Na)
0.70 <φa / di <1.35 ... (6a)
-25% <d <-15% ... (7a)

Hereinafter, the lens configuration of the zoom lens of each embodiment will be described. The zoom lens of Reference Example 1 is composed of the following lens groups arranged in order from the object side to the image side. Positive refractive power first lens group B1, negative refractive power second lens group B2, positive refractive power third lens group B3, positive refractive power fourth lens group B4, negative refractive power first It is composed of 5 lens groups B5 and a 6th lens group B6 having a positive refractive power. The sixth lens group B6 is the lens group BR located closest to the image side, and the fifth lens group B5 corresponds to the lens element A.

When zooming from the wide-angle end to the telephoto end, the change in the distance between adjacent lens groups is as follows. The distance between the first lens group B1 and the second lens group B2 is widened, the distance between the second lens group B2 and the third lens group B3 is narrowed, the distance between the third lens group B3 and the fourth lens group B4 is narrowed, and the fourth is The distance between the lens group B4 and the fifth lens group B5 is widened. The distance between the 5th lens group B5 and the 6th lens group B6 is widened. During zooming, each lens group moves in different trajectories. Further, a rear focus method is adopted in which the sixth lens group B6 is moved on the optical axis to perform focusing.

When focusing from infinity to a short distance at the telephoto end, the sixth lens group B6 is extended forward as shown by arrow 6c. The solid line curve 6a and the dotted line curve 6b with respect to the sixth lens group B6 are movement trajectories for correcting image plane fluctuations due to zooming when focusing at infinity and a short distance, respectively.

The first lens group B1 is composed of a positive bonded lens in which a negative lens and a positive lens are bonded in order from the object side to the image side, aiming at a high zoom ratio by positive lead and compactification (miniaturization) of the entire system. There is. The second lens group B2 is composed of a negative lens, a negative lens, and a positive lens in this order from the object side to the image side to widen the angle of view and generate a large distortion in the wide angle range. The third lens group B3 is composed of a positive lens and a negative bonded lens in which a positive lens and a negative lens are bonded in this order from the object side to the image side, and suppresses fluctuations in spherical aberration over the entire zoom range. The fourth lens group B4 is composed of one positive lens, the fifth lens group B5 is composed of one negative lens, and the sixth lens group B6 is composed of one positive lens to make the whole system compact.

The zoom lens of the first embodiment is composed of the following lens groups arranged in order from the object side to the image side. 1st lens group B1 with positive power, 2nd lens group B2 with negative power, 3rd lens group B3 with positive power, 4th lens group B4 with negative power, 1st negative power It is composed of 5 lens groups B5. Further, a rear focus type is adopted in which the fifth lens group B5 is moved on the optical axis to perform focusing. When focusing from an infinity object to a short-distance object at the telephoto end, the fifth lens group B5 is retracted backward as shown by arrow 5c.

The solid line curve 5a and the dotted line curve 5b with respect to the fifth lens group B5 are movement trajectories for correcting image plane fluctuations due to scaling when focusing on an infinity object and a short-distance object, respectively. When zooming from the wide-angle end to the telephoto end, the change in the distance between adjacent lens groups is as follows. The distance between the first lens group B1 and the second lens group B2 is widened, the distance between the second lens group B2 and the third lens group B3 is narrowed, and the distance between the third lens group B3 and the fourth lens group B4 is widened. The distance between the 4th lens group B4 and the 5th lens group B5 is narrowed. During zooming, each lens group moves in different trajectories.

The first lens group B1 is composed of a bonded lens in which a negative lens and a positive lens are joined in this order from the object side to the image side, aiming at a high zoom ratio and a compact system by positive lead. The second lens group B2 is composed of a negative lens, a negative lens, and a positive lens in this order from the object side to the image side to widen the angle of view and generate a large distortion in the wide angle range.

The third lens group B3 is composed of a positive lens, a negative junction lens in which a positive lens and a negative lens are joined, and a positive lens in this order from the object side to the image side, and suppresses fluctuations in spherical aberration over the entire zoom range. .. The fourth lens group B4 is composed of one negative lens and one positive lens (corresponding to the lens element A), and the fifth lens group B5 is composed of one negative lens to make the whole system compact. There is.

The zoom lens of Reference Example 2 is composed of the following lens groups arranged in order from the object side to the image side. Negative power first lens group B1, positive power second lens group B2, positive power third lens group B3, negative power fourth lens group B4, positive power first It is composed of 5 lens groups B5. The fifth lens group B5 is the lens group located closest to the image side, and the fourth lens group B4 corresponds to the lens element A.

When zooming from the wide-angle end to the telephoto end, the distance between adjacent lens groups is as follows. The distance between the first lens group B1 and the second lens group B2 is narrowed, the distance between the second lens group B2 and the third lens group B3 is narrowed, and the distance between the third lens group B3 and the fourth lens group B4 is widened. The distance between the 4th lens group B4 and the 5th lens group B5 is widened. During zooming, each lens group moves in different trajectories.

Further, a rear focus method is adopted in which the fifth lens group B5 is moved on the optical axis to perform focusing. When focusing from an infinity object to a short-range object at the telephoto end, the fifth lens group B5 is extended forward as shown by the arrow 5c in the lens cross-sectional view. The solid line curve 5a and the dotted line curve 5b for the fifth lens group B5 are used to correct the curvature of field due to zooming from the wide-angle end to the telephoto end when focusing on an infinity object and a short-range object, respectively. Shows the movement trajectory of.

The first lens group B1 is composed of a negative lens, a negative lens, and a positive lens in this order from the object side to the image side, aiming at wide angle of view by negative lead and compactness of the whole system, and large distortion in the wide angle range. It is occurring. The second lens group B2 is composed of a positive lens and a negative bonded lens in which a positive lens and a negative lens are bonded in this order from the object side to the image side, and suppresses fluctuations in spherical aberration over the entire zoom range.

The third lens group B3 is composed of a positive bonded lens in which a negative lens and a positive lens are bonded. The fourth lens group B4 is composed of a negative bonded lens in which a positive lens and a negative lens are bonded. The third lens group B3 and the fourth lens group B4 are each composed of one junction lens to reduce the size of the entire system and suppress fluctuations in spherical aberration over the entire zoom range. The fifth lens group B5 is composed of one lens to make the entire system compact.

The zoom lens of the second embodiment is composed of the following lens groups arranged in order from the object side to the image side. Negative power first lens group B1, positive power second lens group B2, positive power third lens group B3, negative power fourth lens group B4, positive power first It is composed of five lens groups B5 and a sixth lens group B6 having a negative refractive power. The fifth lens group B5 corresponds to the lens element A. Further, a rear focus type is adopted in which the sixth lens group B6 is moved on the optical axis to perform focusing. When focusing from an infinity object to a short-distance object at the telephoto end, the sixth lens group B6 is moved backward as shown by the arrow 6c.

The solid line curve 6a and the dotted line curve 6b with respect to the sixth lens group B6 are movement trajectories for correcting image plane fluctuations due to scaling when focusing on an infinity object and a short-distance object, respectively. When zooming from the wide-angle end to the telephoto end, the change in the distance between adjacent lens groups is as follows.

The distance between the first lens group B1 and the second lens group B2 is narrowed, the distance between the second lens group B2 and the third lens group B3 is narrowed, the distance between the third lens group B3 and the fourth lens group B4 is widened, and the fourth is The distance between the lens group B4 and the fifth lens group B5 is widened. The distance between the 5th lens group B5 and the 6th lens group B6 is narrowed. During zooming, each lens group moves in different trajectories. Further, when focusing from an infinity object to a short-distance object, the sixth lens group B6 moves toward the image side on the optical axis. The movement of the sixth lens group B6 during zooming and focusing is the same as in the first embodiment.

The first lens group B1 is composed of a negative lens, a negative lens, and a positive lens in this order from the object side to the image side, aiming at wide angle of view by negative lead and compactness of the whole system, and large distortion in the wide angle range. It is occurring. The second lens group B2 is composed of a positive lens and a negative bonded lens in which a positive lens and a negative lens are bonded in this order from the object side to the image side, and suppresses fluctuations in spherical aberration over the entire zoom range.

The third lens group B3 is composed of a positive bonded lens in which a negative lens and a positive lens are bonded. The fourth lens group B4 is composed of a negative bonded lens in which a positive lens and a negative lens are bonded. The third lens group B3 and the fourth lens group B4 are each composed of one junction lens to reduce the size of the entire system and suppress fluctuations in spherical aberration over the entire zoom range. The fifth lens group B5 is composed of one positive lens, and the sixth lens group B6 is composed of one negative lens. The fifth lens group B5 and the sixth lens group B6 are each composed of one lens, and the entire system is made compact.

The zoom lens of Reference Example 3 is composed of the following lens groups arranged in order from the object side to the image side. It is composed of a first lens group B1 having a negative refractive power, a second lens group B2 having a positive refractive power, a third lens group B3 having a negative refractive power, and a fourth lens group B4 having a positive refractive power. The fourth lens group B4 is the lens group located closest to the image side, and the third lens group B3 corresponds to the lens element A.

When zooming from the wide-angle end to the telephoto end, the change in the distance between adjacent lens groups is as follows. The distance between the first lens group B1 and the second lens group B2 is narrowed, the distance between the second lens group B2 and the third lens group B3 is widened, and the distance between the third lens group B3 and the fourth lens group B4 is widened. During zooming, each lens group moves in different trajectories.

Further, a rear focus method is adopted in which the fourth lens group B4 is moved on the optical axis to perform focusing. When focusing from an infinity object to a short-distance object at the telephoto end, the fourth lens group B4 is extended forward as shown by arrow 4c in the lens cross-sectional view. The solid line curve 4a and the dotted line curve 4b for the fourth lens group B4 are used to correct the curvature of field due to zooming from the wide-angle end to the telephoto end when focusing on an infinity object and a short-range object, respectively. Shows the movement trajectory of.

The first lens group B1 is composed of a negative lens, a negative lens, and a positive lens in this order from the object side to the image side, aiming at wide angle of view by negative lead and compactness of the whole system, and large distortion in the wide angle range. It is occurring. The second lens group B2 is composed of a positive lens, a negative lens obtained by joining a positive lens and a negative lens, and a positive lens in this order from the object side to the image side, and suppresses fluctuations in spherical aberration over the entire zoom range. The third lens group B3 is composed of one negative lens to make the entire system compact. The fourth lens group B4 is composed of a positive bonded lens in which a positive lens and a negative lens are bonded in this order from the object side to the image side, and suppresses fluctuations in chromatic aberration of magnification during focusing.

It should be noted that the lens group may be appropriately changed to be composed of a single lens or a bonded lens in which a plurality of lenses are joined.

Next, an embodiment of a digital camera (imaging apparatus) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 16, 20 is a digital camera main body, and 21 is a photographing optical system composed of the zoom lens of the above-described embodiment. Reference numeral 22 denotes an image pickup element (photoelectric conversion element) such as a CCD that receives a subject image (image) by the photographing optical system 21, and reference numeral 23 denotes a recording means for recording the subject image received by the image pickup element 22. Reference numeral 24 denotes a finder for observing a subject image displayed on a display element (not shown).

The display element is composed of a liquid crystal panel or the like, and a subject image formed on the image sensor 22 is displayed. By applying the zoom lens of the present invention to an imaging device such as a digital camera in this way, an imaging device that is compact and has high optical performance is realized.

Next, numerical data 1 to 5 corresponding to Reference Example 1, Example 1, Reference Example 2, Example 2, and Reference Example 3 of the present invention are shown. In each numerical data, i indicates the order of the planes from the object side, ri is the radius of curvature of the i-th lens plane, di is the distance between the i-th plane and the i + 1 plane, and ndi and νdi are d, respectively. The refractive index and Abbe number of the material between the i-th plane and the i + 1-th plane with respect to the line are shown.

Further, k, A4, A6, A8, A10, A12, A14, and A16 are aspherical coefficients, and the aspherical shape is based on the displacement amount in the optical axis direction at the position of height h from the optical axis with respect to the surface apex. When it is set to x
x = (h ² / R) / [1 + {1- (1 + k) (h / R) ² } ^1/2 ] + A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰ + A12h ¹² + A14h ¹⁴ + A16h ¹⁶
It is represented by. However, R is the radius of curvature of the paraxial axis.

The back focus BF indicates the distance from the final surface of the lens to the paraxial image plane. The total length of the lens is the distance from the surface closest to the object to the final surface of the lens with back focus added. Table 1 shows the correspondence with each conditional expression in each embodiment.

(Reference example 1)
Unit mm

Surface data Surface number rd nd vd
1 35.308 0.75 1.94595 18.0
2 27.205 2.91 1.80420 46.5
3 172.941 (variable)
4 123.444 0.67 1.77250 49.6
5 9.747 5.49
6 * -18.661 0.40 1.76802 49.2
7 261.996 0.12
8 54.636 1.15 1.95906 17.5
9 -95.030 (variable)
10 (Aperture) ∞ (Variable)
11 * 13.563 2.97 1.76802 49.2
12 * -60.092 0.10
13 14.068 1.95 1.83481 42.7
14 74.969 0.45 1.85478 24.8
15 8.737 2.60
16 ∞ (variable)
17 15.255 4.55 1.49700 81.5
18 -12.697 (variable)
19 -10.432 0.40 1.75521 52.4
20 * 96.817 (variable)
21 23.816 2.94 1.61469 52.8
22 -63.096 (variable)
Image plane ∞

Aspherical data surface 6
K = 0.00000e + 000 A 4 = -5.10955e-007 A 6 = -1.36690e-007 A 8 = -5.98879e-009 A10 = 4.89476e-011

Page 11
K = 0.00000e + 000 A 4 = -8.03559e-005 A 6 = 2.21434e-007

12th page
K = 0.00000e + 000 A 4 = 1.11462e-005 A 6 = 4.78150e-007 A 8 = 1.96917e-009 A10 = -1.63267e-011

20th page
K = 0.00000e + 000 A 4 = 9.17733e-005 A 6 = 4.10444e-007 A 8 = -2.09626e-008 A10 = 2.23093e-010

Various data Zoom ratio 4.74
Wide-angle medium telephoto focal length 9.00 22.58 42.68
F number 2.06 3.09 4.12
Half angle of view (degrees) 35.71 18.73 10.47
Image height 6.47 7.65 7.89
Total lens length 60.38 65.31 77.00
BF 3.00 10.18 8.34

d 3 0.31 10.90 18.52
d 9 12.31 1.65 0.70
d10 6.83 4.03 1.23
d16 2.48 1.75 1.17
d18 3.36 4.09 5.02
d20 4.64 5.27 14.56
d22 3.00 10.18 8.34

Lens group data group Start surface focal length
B1 1 58.16
B2 4 -10.64
SP 10 ∞
B3 11 20.27
B4 17 14.74
B5 19 -12.45
B6 21 28.49

(Example 1)
Unit mm

Surface data
Surface number rd nd νd
1 31.296 0.85 1.94595 18.0
2 23.955 3.11 1.80420 46.5
3 106.557 (variable)
4 57.646 0.67 1.77250 49.6
5 9.143 5.81
6 * -17.113 0.40 1.76802 49.2
7 2352.440 0.10
8 45.462 1.14 1.95906 17.5
9 -128.137 (variable)
10 (Aperture) ∞ (Variable)
11 * 14.583 2.86 1.76802 49.2
12 * -47.081 1.06
13 14.632 1.59 1.83481 42.7
14 65.330 0.45 1.85478 24.8
15 8.902 3.16
16 ∞ 1.17
17 25.593 4.00 1.49700 81.5
18 -10.938 (variable)
19 -25.901 0.40 1.83621 42.8
20 * 43.886 2.32
21 17.379 2.49 1.60656 43.0
22 -65.776 (variable)
23 -121.548 0.65 1.60935 62.2
24 24.758 (variable)
Image plane ∞

Aspherical data
Side 6
K = 0.00000e + 000 A 4 = 1.28641e-006 A 6 = 1.21491e-007 A 8 = -1.31342e-008 A10 = 1.25681e-010

Page 11
K = 0.00000e + 000 A 4 = -1.07907e-004 A 6 = 1.16792e-006

12th page
K = 0.00000e + 000 A 4 = -1.76924e-005 A 6 = 1.64990e-006 A 8 =-8.50384e-010 A10 = -1.53185e-011

20th page
K = 0.00000e + 000 A 4 = 9.64784e-005 A 6 = 3.89331e-007 A 8 = 1.27553e-009 A10 = -2.48616e-010

Various data
Zoom ratio 4.72
Wide-angle intermediate telephoto
Focal length 9.04 18.02 42.68
F number 2.06 3.09 4.12
Half angle of view (degrees) 35.59 23.02 10.47
Image height 6.47 7.65 7.89
Total lens length 62.00 63.40 77.00
BF 7.42 14.23 20.28

d 3 0.31 5.84 19.80
d 9 13.19 5.06 0.70
d10 5.94 3.40 0.86
d18 0.79 1.21 2.36
d22 2.15 1.46 0.80
d24 7.42 14.23 20.28

Zoom lens group data
Focal length
B1 1 57.95
B2 4 -10.83
SP 10 ∞
B3 11 13.62
B4 19 -625.21
B5 23 -33.70

(Reference example 2)
Unit mm

Surface data Surface number rd nd vd
1 * 98.173 1.73 1.71166 48.2
2 16.453 4.76
3 * -90.329 0.99 1.85135 40.1
4 57.235 0.38
5 35.708 1.69 1.94595 18.0
6 113.336 (variable)
7 (Aperture) ∞ (Variable)
8 * 21.957 3.01 1.83614 42.5
9 -231.870 1.32
10 19.661 3.48 1.83586 42.7
11 -86.236 1.40 1.85478 24.8
12 12.500 (variable)
13 16.786 0.68 1.83781 39.2
14 9.994 5.45 1.73277 53.8
15 -33.504 (variable)
16 -32.117 2.03 1.84653 23.8
17 -13.459 0.58 1.83629 40.8
18 * 26.978 (variable)
19 49.908 3.15 1.49700 81.5
20 -60.395 (variable)
Image plane ∞

Aspherical data first surface
K = 0.00000e + 000 A 4 = -7.98556e-006 A 6 = -1.67674e-008 A 8 = 2.77032e-010 A10 = -5.91334e-013

Third side
K = 0.00000e + 000 A 4 = 7.53013e-007 A 6 = -1.77568e-008 A 8 = -2.20841e-010 A10 = -2.23602e-013

8th page
K = 0.00000e + 000 A 4 = -9.98361e-006 A 6 = -3.47467e-008 A 8 = 2.21342e-010 A10 = -1.24169e-012

Page 18
K = 0.00000e + 000 A 4 = 5.35227e-005 A 6 = 9.26754e-008 A 8 = -1.21473e-009

Various data Zoom ratio 2.75
Wide-angle medium telephoto focal length 15.62 28.71 42.97
F number 2.50 2.88 3.15
Half angle of view (degrees) 35.65 24.78 17.63
Image height 11.20 13.25 13.66
Total lens length 85.01 71.06 73.01
BF 3.00 19.72 16.57

d 6 23.87 0.90 0.83
d 7 5.69 5.98 0.09
d12 7.91 6.38 3.87
d15 0.77 2.32 4.69
d18 13.12 5.10 16.31
d20 3.00 19.72 16.57

Lens group data group Start surface focal length
B1 1 -23.50
SP 7 ∞
B2 8 30.50
B3 13 17.14
B4 16 -17.32
B5 19 55.51

(Example 2)
Unit mm

Surface data Surface number rd nd vd
1 * 71.757 1.73 1.72593 54.0
2 16.634 4.36
3 * -845.569 0.99 1.85135 40.1
4 41.806 0.39
5 38.970 1.48 1.94595 18.0
6 91.513 (variable)
7 (Aperture) ∞ (Variable)
8 * 22.484 2.42 1.83635 40.4
9 70.946 1.28
10 28.848 3.39 1.83556 42.7
11 -69.857 1.40 1.85478 24.8
12 53.498 (variable)
13 20.045 0.69 1.83862 35.3
14 9.968 7.17 1.61385 60.6
15 -50.851 (variable)
16 -44.516 2.49 1.72800 28.5
17 -8.679 0.59 1.79389 30.4
18 * 25.617 (variable)
19 41.856 3.72 1.83662 42.9
20 -31.671 (variable)
21 -49.442 0.68 1.49700 81.5
22 44.324 (variable)
Image plane ∞

Aspherical data first surface
K = 0.00000e + 000 A 4 = -9.74919e-006 A 6 = -6.24164e-009 A 8 = 2.08320e-010 A10 = -3.58322e-013

Third side
K = 0.00000e + 000 A 4 = 2.63433e-006 A 6 = -5.7072e-008 A 8 = 3.17559e-010 A10 = -2.46690e-012

8th page
K = 0.00000e + 000 A 4 = -6.73244e-007 A 6 = 5.48987e-009 A 8 = -1.15789e-010 A10 = 2.43864e-013

Page 18
K = 0.00000e + 000 A 4 = 6.56717e-005 A 6 = -1.90965e-007 A 8 = -5.11771e-011

Various data Zoom ratio 2.75
Wide-angle medium telephoto focal length 15.62 29.46 42.97
F number 2.50 2.88 2.88
Half angle of view (degrees) 35.65 24.22 17.63
Image height 11.20 13.25 13.66
Total lens length 77.50 70.79 71.01
BF 13.14 17.03 20.07

d 6 24.56 2.60 0.95
d 7 0.09 4.80 0.09
d12 1.52 1.28 0.39
d15 0.28 2.49 7.44
d18 1.95 4.51 6.32
d20 3.18 5.32 2.97
d22 13.14 17.03 20.07

Lens group data group Start surface focal length
B1 1 -24.07
SP 7 ∞
B2 8 25.09
B3 13 32.82
B4 16 -17.83
B5 19 22.06
B6 21 -46.91

(Reference example 3)
Unit mm

Surface data Surface number rd nd vd
1 * 14.969 1.00 1.70724 54.9
2 * 7.253 7.31
3 * -26.832 0.69 1.78561 48.3
4 68.183 0.11
5 41.935 1.12 1.94595 18.0
6 405.588 (variable)
7 (Aperture) ∞ (Variable)
8 * 12.221 3.01 1.76753 49.3
9 * -69.299 0.20
10 12.446 2.89 1.62048 60.3
11 73.727 0.81 1.85478 24.8
12 8.110 4.93
13 19.599 2.27 1.62961 59.7
14 -20.408 1.09
15 ∞ (variable)
16 * -15.524 0.40 1.78979 47.7
17 -215.472 (variable)
18 19.030 2.91 1.54701 46.9
19 -49.109 0.70 1.83813 35.0
20 -356.363 (variable)
Image plane ∞

Aspherical data first surface
K = 0.00000e + 000 A 4 = -4.10144e-005 A 6 = -6.85696e-007 A 8 = 6.10172e-009 A10 = -2.770985e-011

Second side
K = -1.16909e + 000 A 4 = 2.47573e-004 A 6 = 1.69133e-007 A 8 = -7.54338e-010 A10 = 2.12282e-010 A12 = 3.28956e-013 A14 = -2.84460e-015 A16 = 1.25465e-017

Third side
K = 0.00000e + 000 A 4 = 1.71033e-005 A 6 = -1.20446e-007 A 8 = 8.32533e-010 A10 = 2.57147e-011

8th page
K = 0.00000e + 000 A 4 = -6.49780e-005 A 6 = 2.13806e-007 A 8 = -1.04721e-008 A10 = 7.23248e-011

Side 9
K = 0.00000e + 000 A 4 = 2.76384e-005 A 6 = 4.61738e-007 A 8 = -1.42403e-008 A10 = 1.20091e-010

16th page
K = 0.00000e + 000 A 4 = -9.52012e-005 A 6 = -2.25032e-007 A 8 = 6.13684e-009

Various data Zoom ratio 3.66
Wide-angle medium telephoto focal length 6.79 12.87 24.88
F number 1.85 2.50 2.88
Half angle of view (degrees) 43.60 30.74 17.59
Image height 6.47 7.65 7.89
Total lens length 60.00 54.02 54.00
BF 3.00 4.04 6.02

d 6 17.77 4.27 0.46
d 7 5.16 5.83 0.09
d15 1.67 2.57 9.00
d17 2.95 7.87 9.00
d20 3.00 4.04 6.02

Lens group data group Start surface focal length
B1 1 -13.46
SP 7 ∞
B2 8 13.70
B3 16 -21.20
B4 18 39.46

B1 1st lens group B2 2nd lens group B3 3rd lens group B4 4th lens group B5 5th lens group B6 6th lens group SP Aperture aperture FP Flare cut aperture BR Lens group located closest to the image side A Lens group

Claims (8)

A zoom lens that has multiple lens groups and changes the distance between adjacent lens groups during zooming.
The lens group BR having a negative refractive power arranged on the image side of the zoom lenses moves in the optical axis direction during focusing.
The sign of the refractive power of the lens element composed of a single lens or a junction lens arranged adjacent to the object side of the lens group BR is positive.
The lens group BR is composed of a single lens having a negative refractive power or a junction lens having a negative refractive power.
The distance between the most image-side surface of the lens element at the wide-angle end and the image surface is di, and the distance between the most image-side surface of the lens element at the wide-angle end and the most object-side surface of the lens group BR is df. The focal length of the entire system at the wide-angle end is fw, the focal length of the lens element is fa, the radius of curvature of the most object-side surface and the most image-side surface of the lens group BR are rf and rr , respectively, and the lens at the wide-angle end. When the lateral magnification of the group BR is βw ,
0.2 <di / fw <1.4
0.2 <df / fw <1.2
1.412 ≤ fa / fw <4.0
0.0 <(rf + rr) / (rf-rr) <5.0
1.0 <βw <1.3
A zoom lens characterized by satisfying the conditional expression. The zoom lenses are, 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 fourth lens group having a negative refractive power. It is composed of a lens group and a fifth lens group with negative power.
The zoom lens of claim 1, wherein each lens group, characterized in that move at different trajectories from each other during zooming. A first lens group with a positive refractive power, a second lens group with a negative refractive power, a third lens group with a positive refractive power, and a fourth lens group with a negative refractive power arranged in order from the object side to the image side. It is a zoom lens composed of a fifth lens group having a negative refractive power, and each lens group moves in different trajectories during zooming to change the distance between adjacent lens groups.
The fifth lens group moves in the optical axis direction during focusing, and the fifth lens group moves in the optical axis direction.
The sign of the refractive power of the lens element composed of a single lens or a junction lens arranged adjacent to the object side of the fifth lens group is positive.
The distance between the most image-side surface of the lens element at the wide-angle end and the image surface is di, and the distance between the most image-side surface of the lens element at the wide-angle end and the most object-side surface of the fifth lens group is df. When the focal length of the entire system at the wide-angle end is fw and the focal length of the lens element is fa,
0.2 <di / fw <1.4
0.2 <df / fw <1.2
1.412 ≤ fa / fw <4.0
A zoom lens characterized by satisfying the conditional expression. The zoom lenses are, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, and a fourth lens group having a negative refractive power. It is composed of a lens group, a fifth lens group with a positive power, and a sixth lens group with a negative power.
The zoom lens of claim 1, wherein each lens group, characterized in that move at different trajectories from each other during zooming. The first lens group with negative power, the second lens group with positive power, the third lens group with positive power, and the fourth lens group with negative power, arranged in order from the object side to the image side. It is a zoom lens composed of a fifth lens group with a positive refractive power and a sixth lens group with a negative refractive power, and each lens group moves on different trajectories during zooming and the distance between adjacent lens groups changes. hand,
The sixth lens group moves in the optical axis direction during focusing, and the sixth lens group moves in the optical axis direction.
The sign of the refractive power of the lens element composed of a single lens or a junction lens arranged adjacent to the object side of the sixth lens group is positive.
The distance between the most image-side surface of the lens element at the wide-angle end and the image surface is di, and the distance between the most image-side surface of the lens element at the wide-angle end and the most object-side surface of the sixth lens group is df. When the focal length of the entire system at the wide-angle end is fw and the focal length of the lens element is fa,
0.2 <di / fw <1.4
0.2 <df / fw <1.2
1.412 ≤ fa / fw <4.0
A zoom lens characterized by satisfying the conditional expression. The zoom lens has an aperture diaphragm that determines an open F-number luminous flux, and when the optical effective diameter of the surface closest to the image side of the lens element is φa,
The zoom lens according to any one of claims 1 to 5 , wherein the conditional expression of 0.7 <φa / di <1.4 is satisfied. An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 6 and an image pickup element that receives an image formed by the zoom lens. When the shooting half angle of view at the wide-angle end is ωw,
The imaging device according to claim 7 , wherein the conditional expression of ωw ≧ 30 ° is satisfied.