JP2019091099A - Zoom lens and image capturing device having the same - Google Patents

Abstract

To provide a zoom lens which offers a wide view angle, reduced aberration variation while focusing, and high optical performance over an entire object distance range.SOLUTION: A zoom lens has a plurality of lens groups configured such that a distance between each pair of adjacent lens groups changes while zooming. A lens group BR located on the most image-side in the zoom lens is configured to move in an optical axis direction while focusing. A lens element A disposed next to the lens group BR on the object side has refractive power of a sign opposite that of refractive power of the lens group BR, and comprises a single lens or a cemented lens. A distance di between a most image-side surface of the lens element A and an image plane at the wide-angle end, a distance df between the most image-side surface of the lens element A and a most object-side surface of the lens group BR at the wide-angle end, and a focal length fw of the entire system at the wide-angle end are each set appropriately.SELECTED DRAWING: Figure 1

Description

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

  2. Description of the Related Art In recent years, imaging devices using solid-state imaging devices have been sophisticated, and the entire device has been miniaturized. As an imaging optical system used therefor, a zoom lens having a short overall lens length, a compact size, a high zoom ratio (high zoom ratio), and a high resolving power is required. As a zoom lens that meets these requirements, for example, a zoom lens using a so-called rear focus system in which focusing is performed by a lens unit other than the first lens unit on the object side is known.

  As one of the reasons why the rear focusing system is adopted, in the focusing lens group (hereinafter referred to as "focus lens group"), the aberration at the time of focusing is caused because the incident height h of the on-axis marginal ray is low. It is possible to reduce fluctuations (especially spherical aberration fluctuations).

  As another reason for this, when the size of the imaging device used in the imaging device is small, the focus lens group is light in weight and the amount of extension at the time of focusing is reduced, which may facilitate downsizing of the entire imaging device. In addition, in order to make the imaging apparatus compact in recent years, among the various aberrations of the zoom lens used therein, electronic distortion correction that electrically performs distortion correction in the wide-angle range has been introduced. An imaging device incorporating electronic distortion correction is advantageous for compactness. However, there is known a problem that the aberration fluctuation at the time of focusing becomes large.

In aberration theory, the process of focusing from long distance to short distance is the process of moving the object distance from long distance to the short distance (moving the object distance) and the process of moving the focusing lens group for focusing on the object distance (focusing Lens group movement). Using this aberration theory, it can be seen that the fluctuation of curvature of field increases in principle when moving the object distance, and the fluctuation of curvature of field during focusing also tends to become large. According to Non-Patent Document 1, the third-order aberration coefficient III for astigmatism is large because the third-order aberration coefficient V for distortion is large.
Amount of movement when moving object distance

It is proved from becoming large. (Where δ is the object distance movement parameter, II ^S is the third-order aberration coefficient related to coma of the pupil, and I ^S is the third-order aberration coefficient related to the spherical aberration of the pupil). However, when the size of the imaging device is small, the variation of the curvature of field at the time of focusing is inconspicuous, and the problem is hardly discussed.

  For example, there is known a zoom lens in which a rear focusing system is adopted and an electronic distortion correction is introduced in a negative lead type having a lens group of negative refractive power most on the object side (Patent Document 1). In addition to this, there is known a zoom lens in which a rear focusing system is adopted in a positive lead type having a lens group of positive refractive power most on the object side and electronic distortion correction is introduced (Patent Document 2).

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

Yoshiya Matsui "lens design method" Chapter 4

  In a zoom lens using a rear focus system, downsizing and weight reduction of the focusing lens group become easy, and focusing becomes easy. However, aberration variation tends to increase during focusing. In addition, when the size of an image pickup element generally used in an image pickup apparatus is increased, a zoom lens used in the image pickup apparatus is required to have high optical performance over an entire zoom range and an entire object distance. For example, it is required that the variation in aberration during focusing be small, and the variation in curvature of field be small in order to maintain high optical performance over the entire screen.

  On the other hand, since the zoom lens used in the image pickup apparatus having the function of performing the electronic distortion correction is permitted to increase the distortion, it is easy to achieve the downsizing of the entire system while achieving the wide angle of view. However, in such a zoom lens, when focusing in the wide angle region, fluctuation of curvature of field and fluctuation of spherical aberration increase.

  In Patent Document 1, distortion is set to -14% or less at the wide-angle end, the image height is set to 3.84 mm, and the size of the imaging device is small. Relatively small. However, when applied to a large image pickup device, fluctuation of curvature of field at the time of focusing tends to increase. In Patent Document 2, distortion is set to -14% or less at the wide-angle end, and the image height is set to 3.83 mm, and the size of the imaging device is small. Relatively small.

  However, when applied to a large image pickup device, fluctuation of curvature of field at the time of focusing tends to increase. In addition, in this zoom lens, the variation of spherical aberration together with the variation of curvature of field is caused by the large ratio of the incident height h of the axial marginal ray in the focusing lens group to the incident height h / of the off-axis chief ray. Also tend to increase.

  In order to obtain a high optical performance over the entire screen with little variation in aberration during focusing while having a predetermined angle of view for the zoom lens, set the zoom type, the refractive power of the focus lens group, the lens configuration, etc. appropriately. It will be necessary to Furthermore, it is necessary to appropriately set the lens configuration of the lens unit positioned on the object side of the focus lens unit.

  An object of the present invention is to provide a zoom lens having high optical performance over the entire object distance and an image pickup apparatus having the same, which reduces aberration fluctuation when focusing at a wide angle of view.

The zoom lens according to the present invention is a zoom lens that has a plurality of lens groups and in which the distance between adjacent lens groups changes during zooming.
The lens unit BR of negative refractive power disposed closest to the image side of the zoom lens moves in the optical axis direction during focusing,
The sign of the refractive power of a lens element composed of a single lens or a cemented lens disposed adjacent to the object side of the lens group BR is positive,
The distance between the most image side surface of the lens element at the wide angle end and the image plane 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 unit BR is df. Assuming that 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 following conditional expression.

  According to the present invention, it is possible to reduce the aberration fluctuation at the time of focusing at a wide angle of view, and to obtain a zoom lens having high optical performance over the entire object distance.

Lens cross-sectional view at the wide-angle end when the zoom lens according to Embodiment 1 of the present invention is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens of Reference Example 1 is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, the middle zoom position, and the telephoto end when the zoom lens of Reference Example 1 is focused on a near object Lens cross-sectional view at the wide-angle end when the zoom lens according to Embodiment 1 of the present invention is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens of Embodiment 1 is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens according to Example 1 is focused on a near object Lens cross-sectional view at the wide-angle end when the zoom lens according to Embodiment 2 of the present invention is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, an intermediate zoom position, and the telephoto end when the zoom lens of Reference Example 2 is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at the middle zoom position, and at the telephoto end when the zoom lens of Reference Example 2 is focused on a near object Lens cross-sectional view at the wide-angle end when the zoom lens according to Embodiment 2 of the present invention is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens of Embodiment 2 is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens according to Example 2 is focused on a near object Lens cross-sectional view at the wide-angle end when focusing on an infinite distance object of a zoom lens according to Embodiment 3 of the present invention (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens of Reference Example 3 is focused on an infinite distance object (A), (B), (C) Aberrations at the wide-angle end, at an intermediate zoom position, and at the telephoto end when the zoom lens of Reference Example 3 is focused on a near object Principal part schematic view of the imaging device of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The zoom lens according to the present invention is a zoom lens which has a plurality of lens groups and in which the distance between adjacent lens groups changes during zooming. The lens unit BR disposed closest to the image side of the zoom lens moves in the optical axis direction during focusing. The lens element disposed adjacent to the object side of the lens group BR is composed of a single lens or a cemented 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 zoom lens according to a first reference example of the zoom lens of the present invention at the wide-angle end (short focal length end) when an object at infinity is in focus.

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

  FIG. 4 is a cross-sectional view of a zoom lens according to a first embodiment of the present invention at the wide-angle end when an object at infinity is in focus. FIGS. 5A, 5B, and 5C are longitudinal aberration diagrams at the wide-angle end, an intermediate zoom position, and the telephoto end, respectively, when the zoom lens of Embodiment 1 is focused on an infinite distance object. FIGS. 6A, 6B, and 6C are longitudinal aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, when the zoom lens of Embodiment 1 is focused on a near object. Here, the near-field 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 middle zoom position, and 200 mm from the first lens surface to the object side at the telephoto end. It means an object.

  FIG. 7 is a cross-sectional view of a zoom lens according to a second embodiment of the present invention at the wide-angle end when an object at infinity is in focus. FIGS. 8A, 8B, and 8C are longitudinal aberration diagrams at the wide-angle end, an intermediate zoom position, and the telephoto end, respectively, when the zoom lens of Reference Example 2 is focused on an infinite distance object. FIGS. 9A, 9B, and 9C are longitudinal aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, when the zoom lens of Reference Example 2 is focused on a near object. Here, the near 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 middle zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. It means an object.

  FIG. 10 is a cross-sectional view of a zoom lens according to a second embodiment of the present invention at the wide-angle end when an object at infinity is in focus. FIGS. 11A, 11B, and 11C are longitudinal aberration diagrams at the wide-angle end, at an intermediate zoom position, and at the telephoto end, respectively, when the zoom lens of Embodiment 2 is focused on an infinite distance object. FIGS. 12A, 12B, and 12C are longitudinal aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end, respectively, when the zoom lens of Embodiment 2 is focused on a near object. Here, the near 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 middle zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. It means an object.

  FIG. 13 is a cross-sectional view of a zoom lens according to a third embodiment of the present invention at the wide-angle end when an object at infinity is in focus. FIGS. 14A, 14B, and 14C are longitudinal aberration diagrams at the wide-angle end, at an intermediate zoom position, and at the telephoto end, respectively, when the zoom lens of Reference Example 3 is focused on an infinite distance object. FIGS. 15A, 15B, and 15C are longitudinal aberration diagrams at the wide-angle end, at the middle zoom position, and at the telephoto end, respectively, when the zoom lens of Reference Example 3 is focused on a near object. Here, the near 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 middle zoom position, and 500 mm from the first lens surface to the object side at the telephoto end. It means an object. FIG. 16 is a schematic view of the essential parts of the imaging device 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, a film camera, and the like. The zoom lens of each embodiment is a positive lead type zoom lens having a lens unit of positive refractive power on the most object side or a negative lead type zoom lens having negative refractive power. The focusing lens group also has positive refracting power or negative refracting power.

  In the lens 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 sectional view, i indicates the order of the lens units from the object side, and Bi indicates the i-th lens unit. SP is an aperture stop. FP is a flare cut stop. IP is an image plane. The image plane IP is used as an imaging optical system of a silver halide photography camera on an image plane of a solid-state imaging device (photoelectric conversion device) such as a CMOS sensor when using a zoom lens as a photographing optical system of a digital camera or video camera. If it does, it corresponds to the film surface. Arrows indicate movement loci of the respective lens units in zooming from the wide-angle end to the telephoto end. An arrow relating to focus indicates the moving direction of the lens unit at the time of focusing from infinity to a close distance.

  In the aberration diagrams of the examples, the solid line d and the two-dot chain line g in spherical aberration represent the d and g lines, respectively, and the dotted line (ΔM) and the solid line (ΔS) in the astigmatism each represent the meridional image plane and the sagittal image plane, and the magnification The two-dot chain line of the 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 indicate zoom positions when the magnification varying lens unit is positioned at both ends of the range in which the optical axis of the optical system is movable.

  The zoom lens of each embodiment has a plurality of lens groups, and the distance between adjacent lens groups changes during zooming. A 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 cemented lens. The sign of the refractive power of the lens element A is opposite to the sign of the refractive power of the focus lens group BR.

  When the lens element A and the focus lens group BR are configured to have refractive powers of opposite signs, the refractive powers of the lens element A and the focus lens group BR both decrease. At the wide angle end, the incident angle α of the on-axis marginal ray in the focusing lens unit BR and the incident angle α / of the off-axis chief ray are increased. Thereby, in the rear focus type zoom lens, the amount of fluctuation of curvature of field at the time of movement of the focus lens group

The Thus, the fluctuation of the curvature of field at the time of movement of the object distance at the wide angle end is corrected at the time of movement of the focus lens unit. In equation (X1), f is the focal length of the focusing lens unit.

Is the incident angle of the on-axis marginal ray to the focusing lens group before the movement of the focusing lens group, the incident angle of the off-axis chief ray, and the incident height of the off-axis chief ray. (Δh ₂ ) is a fluctuation amount of the incident height of the on-axis marginal ray of the focus lens group due to the movement of the focus lens group.

In addition, in the zoom lens according to the present invention, the lens element A adjacent to the object side with respect to the focus lens group BR is configured of a single lens or a cemented lens. The distance between the surface of the lens element A closest to the image and the image plane at the wide angle end is denoted by di. The distance between the surface of the lens element A at the wide angle end and the surface at the most object side of the focusing lens unit BR is denoted by df. The focal length of the entire system at the wide angle end is fw.
0.2 <di / fw <1.4 (1)
0.2 <df / fw <1.2 (2)
Is satisfied.

  Conditional expression (1) shows that 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 in order to reduce variation of spherical aberration and variation of curvature of field during focusing at the wide-angle end. The distance between the surface of the lens and the image plane is properly determined. When the lens element A moves away from the image plane beyond the upper limit value of the conditional expression (1), the emission angle of the on-axis marginal ray at the lens element A decreases, and the incident angle of the on-axis marginal ray at the focus lens group Also becomes smaller. Then, when focusing, the variation amount of the incident height of the on-axis marginal ray in the focusing lens unit decreases, and it becomes difficult to cancel the curvature of field variation.

  When the lens element A becomes closer to the image plane beyond the lower limit value of the conditional expression (1), it becomes difficult to provide a sufficiently large moving amount of the focusing lens unit BR at the time of focusing. It becomes difficult.

  Conditional expression (2) is for reducing the variation of spherical aberration and the variation of curvature of field at the time of 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 lens element A moves away from the focus lens group BR beyond the upper limit value of the conditional expression (2), the lens element A is also far from the image plane, and the emission angle of the on-axis marginal ray at the lens element A decreases. Furthermore, the incident angle α of the on-axis marginal ray in the focus lens group BR also decreases. Then, when focusing, the variation amount of the incident height of the on-axis marginal ray in the focus lens unit BR decreases, and it becomes difficult to reduce the variation of the curvature of field.

  When the lens element A approaches the focus lens group BR beyond the lower limit value of the conditional expression (2), it becomes difficult to provide a sufficiently large amount of movement of the focusing lens group BR at the time of focusing. It becomes difficult to focus. In addition, since the incident height of the on-axis marginal ray in the focus lens group BR is not sufficiently small, it is difficult to reduce the variation of the spherical aberration at the time of focusing.

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

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 unit BR at the wide angle end is βw. The focusing lens group BR is composed of a single lens of positive refractive power or a cemented lens of positive refractive power, and the radii of curvature of the surface on the most object side and the surface on the most image side of the focusing lens group BR are respectively rf and rr. . The focal length of the lens element A is fa. It is preferable to satisfy one or more of the following conditional expressions at this time.
0.7 <β w <1.0 (3P)
−5.0 <(rf + rr) / (rf−rr) <0.0 (4P)
1.0 <−fa / fw <4.0 (5P)

  Next, technical meanings of the above-mentioned conditional expressions will be described. Conditional expression (3P) defines the lateral magnification βw of the focus lens unit BR at the wide-angle end when the focus lens unit BR has positive refractive power.

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

  If the lower limit value of the conditional expression (3P) is exceeded, the focus sensitivity becomes too large, and the fluctuation of the incident height of the on-axis marginal ray in the focus lens group BR becomes small. Will be difficult.

  The conditional expression (4P) defines the shape factor (lens shape) of the focus lens unit BR in order to reduce the change of the curvature of field and the change of the spherical aberration when focusing at the wide angle end. The conditional expression (4P) allows the off-axis chief ray to be incident obliquely to the refracting surface in order to reduce the variation of the curvature of field, and the axial marginal ray is refracting surface in order to reduce the variation of the spherical aberration. It is for making it inject near normal to.

  If the values of the radius of curvature of the surface on the object side and the surface on the image side are close to each other beyond the upper limit value of the conditional expression (4P), it is difficult to reduce the variation of curvature of field and the variation of spherical aberration become. When the object side having a strong curvature of the object side surface approaches the convex meniscus shape beyond the lower limit value of the conditional expression (4P), 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 surface or the focus lens unit BR for reducing the fluctuation of spherical aberration and the fluctuation of curvature of field at the time of focusing at the wide angle end. Do.

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

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

When the focus lens group BR has negative refractive power, it is preferable to satisfy one or more of the following conditional expressions. The lateral magnification of the focus lens unit BR at the wide angle end is βw. The focusing lens group BR is composed of a single lens of negative refractive power or a cemented lens of negative refractive power, and the radii of curvature of the surface on the most object side and the surface on the most image side of the focusing lens group BR are respectively rf and rr. . The focal length of the lens element A is fa. 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, technical meanings of the above-mentioned conditional expressions are described. Conditional expression (3N) defines the lateral magnification βw of the lens unit BR at the wide-angle end when the focus lens unit BR has negative refractive power. Conditional expression (3N) is for reducing the variation of spherical aberration and the variation of curvature of field at the time of focusing at the wide angle end. By setting the lateral magnification of the focus lens group BR to a value close to 1.0, the focus sensitivity (1-βw ² ) is reduced. According to this, since the fluctuation of the incident height of the on-axis marginal ray in the focus lens group BR becomes large, the correction of the fluctuation of the curvature of field becomes easy.

  If the upper limit value of the conditional expression (3N) is exceeded, the focus sensitivity becomes too large, and the fluctuation of the incident height of the on-axis marginal ray in the focus lens group BR becomes small. Will be difficult. Beyond the lower limit value of the conditional expression (3N), the lateral magnification does not become 1 when focusing.

  The conditional expression (4N) defines the shape factor of the focus lens unit BR in order to reduce the variation of the curvature of field and the variation of the spherical aberration when focusing at the wide angle end. The conditional expression (4N) allows the off-axis chief ray to be incident obliquely to the refracting surface in order to reduce the variation of the curvature of field, and the axial marginal ray is the refracting surface in order to reduce the variation of the spherical aberration. It is for making it inject near normal to.

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

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

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

  The conditional expression (6) is provided to reduce the variation of the curvature of field at the wide-angle end, with respect to the distance between the most image-side surface of the lens element A at the wide-angle end and the image plane. The optical effective diameter is properly defined. The conditional expression (6) is a variation of the incident height of the on-axis marginal ray at the focus lens BR by increasing the incident angle of the on-axis marginal ray in the focus lens group BR in order to reduce the variation of the curvature of field. To increase the

  If the optical effective diameter of the surface on the most image side of the lens element A becomes too large beyond the upper limit value of the conditional expression (6), the optical effective diameter of the focus lens group BR also becomes large, 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 chief ray in the focus lens group BR increases, so that the fluctuation of the curvature of field at the telephoto end can be reduced. It will be difficult.

  If the optical effective diameter of the surface on the most image side of the lens element A becomes too small beyond the lower limit value of the conditional expression (6), the incident angle of the on-axis marginal ray in the focus lens group BR becomes small and the on-axis The variation of 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 apparatus having an image pickup element, a half angle of view of a photographing angle of view specified by the effective range of the image pickup element is ωw. At this time,
ω w 30 30 °
It is preferable to use a wide angle zoom lens which satisfies the following conditional expression.

At this time, when the distortion amount at a 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 following conditional expression.

  The conditional expression (7) is premised on the fact that, when the zoom lens according to the present invention focuses at the wide angle end, the fluctuation of the curvature of field in principle becomes large due to the movement of the object distance. If the distortion at the wide angle end is small beyond the upper limit value of the conditional expression (7), the fluctuation of the curvature of field does not increase due to the movement of the object distance. For this reason, it is not necessary to reduce the fluctuation of the curvature of field when moving the lens unit BR for focusing, and the fluctuation of the curvature of field is corrected excessively, and it is difficult to reduce the fluctuation of the curvature of field as a result It becomes.

More preferably, the numerical range of the conditional expressions (1), (2), (3P), (4P), (5P), (3N), (4N), (5N), (6), (7) It is desirable to set
1.0 <di / fw <1.4 (1a)
0.2 <df / fw <1.0 (2a)
0.8 <β w <1.0 ... (3 Pa)
−1.0 <(rf + rr) / (rf−rr) <0.0 (4 Pa)
1.0 <-fa / fw <3.5 ... (5 Pa)
1.2 <β w <1.3 (3 Na)
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)

  The lens configuration of the zoom lens of each embodiment will be described below. The zoom lens of the first reference example is composed of the following lens groups arranged in order from the object side to the image side. First lens group B1 of positive refractive power, second lens group B2 of negative refractive power, third lens group B3 of positive refractive power, fourth lens group B4 of positive refractive power, fourth of negative refractive power The fifth lens unit B5 is composed of a sixth lens unit B6 of positive refractive power. The sixth lens unit B6 is the lens unit BR located closest to the image side, and the fifth lens unit B5 corresponds to the lens element A.

  During zooming from the wide-angle end to the telephoto end, the change in distance between adjacent lens units is as follows. The distance between the first lens group B1 and the second lens group B2 increases, the distance between the second lens group B2 and the third lens group B3 narrows, and the distance between the third lens group B3 and the fourth lens group B4 narrows. The distance between the lens unit B4 and the fifth lens unit B5 increases. The distance between the fifth lens group B5 and the sixth lens group B6 increases. During zooming, the lens units move along different trajectories. In addition, a rear focusing system is employed in which the sixth lens unit B6 is moved on the optical axis to perform focusing.

  When focusing from infinity to near distance at the telephoto end, the sixth lens unit B6 is moved forward as shown by an arrow 6c. A solid curve 6a and a dotted curve 6b relating to the sixth lens unit B6 are movement trajectories for correcting the image plane fluctuation accompanying zooming when focusing at infinity and near distance, respectively.

  The first lens group B1 is composed of, in order from the object side to the image side, a positive cemented lens in which a negative lens and a positive lens are cemented, in order to achieve high zoom ratio and compactness of the entire system (miniaturization) by positive lead. There is. The second lens unit B2 includes, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens to achieve a wide angle of view and generate large distortion in a wide angle range. The third lens group B3 is composed of, in order from the object side to the image side, a positive cemented lens and a negative cemented lens in which a positive lens and a negative lens are cemented, to suppress fluctuation of 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 in order to make the entire system compact.

  The zoom lens of Embodiment 1 is composed of the following lens groups arranged in order from the object side to the image side. First lens group B1 of positive refractive power, second lens group B2 of negative refractive power, third lens group B3 of positive refractive power, fourth lens group B4 of negative refractive power, fourth of negative refractive power 5 lens unit B5. In addition, a rear focus system in which focusing is performed by moving the fifth lens unit B5 on the optical axis is adopted. When focusing from an infinite distance object to a near distance object at the telephoto end, as shown by an arrow 5c, the fifth lens unit B5 is retracted backward.

  A solid curve 5a and a dotted curve 5b related to the fifth lens group B5 are movement trajectories for correcting the image plane variation accompanying the magnification change when focusing on an infinite distance object and a near distance object. During zooming from the wide-angle end to the telephoto end, the change in distance between adjacent lens units is as follows. The distance between the first lens group B1 and the second lens group B2 increases, the distance between the second lens group B2 and the third lens group B3 narrows, and the distance between the third lens group B3 and the fourth lens group B4 increases. The distance between the fourth lens unit B4 and the fifth lens unit B5 is narrowed. During zooming, the lens units move along different trajectories.

  The first lens unit B1 is composed of, in order from the object side to the image side, a cemented lens in which a negative lens and a positive lens are cemented, in order to achieve a high zoom ratio by the positive lead and a compact system. The second lens unit B2 includes, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens to achieve a wide angle of view and generate large distortion in a wide angle range.

  The third lens unit B3 is composed of, in order from the object side to the image side, a positive lens, a negative cemented lens in which a positive lens and a negative lens are cemented, and a positive lens, to suppress variation of spherical aberration over the entire zoom range. . The fourth lens unit B4 is configured of one negative lens and one positive lens (corresponding to the lens element A), and the fifth lens unit B5 is configured of one negative lens to achieve a compact system. There is.

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

  During zooming from the wide-angle end to the telephoto end, the distances between adjacent lens units are as follows. The distance between the first lens group B1 and the second lens group B2 narrows, the distance between the second lens group B2 and the third lens group B3 narrows, and the distance between the third lens group B3 and the fourth lens group B4 widens. The distance between the fourth lens unit B4 and the fifth lens unit B5 increases. During zooming, the lens units move along different trajectories.

  In addition, a rear focusing system is employed in which the fifth lens unit B5 is moved on the optical axis to perform focusing. When focusing from an infinite distance object to a near distance object at the telephoto end, the fifth lens unit B5 is moved forward as shown by an arrow 5c in the lens cross sectional view. The curve 5a of the solid line and the curve 5b of the dotted line related to the fifth lens unit B5 correct the image plane variation during zooming from the wide-angle end to the telephoto end when focusing on an infinite distance object and a close distance object, respectively. Shows the movement trajectory of

  The first lens group B1 comprises, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens to achieve a wide angle of view by the negative lead and compactification of the entire system, and large distortion in the wide-angle range. It is generated. The second lens unit B2 is composed of, in order from the object side to the image side, a positive cemented lens and a negative cemented lens in which a positive lens and a negative lens are cemented, to suppress variation of spherical aberration over the entire zoom range.

  The third lens unit B3 is composed of a positive cemented lens in which a negative lens and a positive lens are cemented. The fourth lens unit B4 is composed of a negative cemented lens in which a positive lens and a negative lens are cemented. The third lens unit B3 and the fourth lens unit B4 are each constituted by a single cemented lens to make the whole system compact and to suppress the variation of spherical aberration over the entire zoom range. The fifth lens unit B5 is configured of one lens to make the entire system compact.

  The zoom lens of Embodiment 2 is composed of the following lens groups arranged in order from the object side to the image side. First lens group B1 of negative refractive power, second lens group B2 of positive refractive power, third lens group B3 of positive refractive power, fourth lens group B4 of negative refractive power, fourth of positive refractive power The fifth lens unit B5 is composed of a sixth lens unit B6 of negative refractive power. The fifth lens unit B5 corresponds to the lens element A. In addition, a rear focus system in which focusing is performed by moving the sixth lens unit B6 on the optical axis is adopted. When focusing from an infinite distance object to a near distance object at the telephoto end, as shown by an arrow 6c, the sixth lens unit B6 is retracted backward.

  A solid curve 6a and a dotted curve 6b relating to the sixth lens unit B6 are movement trajectories for correcting the image plane fluctuation accompanying the magnification change when focusing on an infinite distance object and a near distance object. During zooming from the wide-angle end to the telephoto end, the change in distance between adjacent lens units 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 lens unit B4 and the fifth lens unit B5 increases. The distance between the fifth lens unit B5 and the sixth lens unit B6 is narrowed. During zooming, the lens units move along different trajectories. When focusing from an infinite distance object to a close distance object, the sixth lens unit B6 moves on the optical axis toward the image side. The movement of the sixth lens unit B6 during zooming and focusing is the same as that of the first embodiment.

  The first lens group B1 comprises, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens to achieve a wide angle of view by the negative lead and compactification of the entire system, and large distortion in the wide-angle range. It is generated. The second lens unit B2 is composed of, in order from the object side to the image side, a positive cemented lens and a negative cemented lens in which a positive lens and a negative lens are cemented, to suppress variation of spherical aberration over the entire zoom range.

  The third lens unit B3 is composed of a positive cemented lens in which a negative lens and a positive lens are cemented. The fourth lens unit B4 is composed of a negative cemented lens in which a positive lens and a negative lens are cemented. The third lens unit B3 and the fourth lens unit B4 are each constituted by a single cemented lens to make the whole system compact and to suppress the variation of 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 unit B5 and the sixth lens unit B6 are respectively configured by one lens to make the entire system 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 comprises a first lens group B1 of negative refractive power, a second lens group B2 of positive refractive power, a third lens group B3 of negative refractive power, and a fourth lens group B4 of positive refractive power. The fourth lens unit B4 is the lens unit located closest to the image side, and the third lens unit B3 corresponds to the lens element A.

  During zooming from the wide-angle end to the telephoto end, the change in distance between adjacent lens units 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 increased, and the distance between the third lens group B3 and the fourth lens group B4 is increased. During zooming, the lens units move along different trajectories.

  In addition, a rear focusing method is employed in which the fourth lens unit B4 is moved on the optical axis to perform focusing. When focusing from an infinite distance object to a near distance object at the telephoto end, the fourth lens unit B4 is moved forward as shown by an arrow 4c in the lens cross sectional view. A solid curve 4a and a dotted curve 4b relating to the fourth lens unit B4 correct the image plane fluctuation during zooming from the wide-angle end to the telephoto end when focusing on an infinite distance object and a close distance object, respectively. Shows the movement trajectory of

  The first lens group B1 comprises, in order from the object side to the image side, a negative lens, a negative lens, and a positive lens to achieve a wide angle of view by the negative lead and compactification of the entire system, and large distortion in the wide-angle range. It is generated. The second lens unit B2 is composed of, in order from the object side to the image side, a positive lens, a negative lens obtained by cementing a positive lens and a negative lens, and a positive lens, to suppress variation in spherical aberration over the entire zoom range. The third lens unit B3 is composed of one negative lens to make the entire system compact. The fourth lens unit B4 is composed of, in order from the object side to the image side, a positive cemented lens in which a positive lens and a negative lens are cemented, to suppress fluctuations in magnification chromatic aberration during focusing.

  The configuration of the lens group from a cemented lens in which a single lens or a plurality of lenses are cemented can be changed as appropriate.

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

  The display element is constituted by a liquid crystal panel or the like, and an object image formed on the image sensor 22 is displayed. As described above, by applying the zoom lens of the present invention to an imaging device such as a digital camera, a compact imaging device having high optical performance is realized.

  Next, numerical data 1 to 5 respectively 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 represents the order of the surface from the object side, ri is the radius of curvature of the i-th lens surface, di is the distance between the i-th surface and the (i + 1) -th surface, ndi and didi are each d The refractive index and Abbe number of the material between the i-th surface and the (i + 1) th surface with respect to the line are shown.

In addition, k, A4, A6, A8, A10, A12, A14, and A16 are aspheric coefficients, and the aspheric shape uses the amount of displacement in the optical axis direction at the height h from the optical axis as the surface vertex Let x be
x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² } ^1/2 ] + A ⁴ h ⁴ + A ⁶ h ⁶ + A ⁸ h ⁸ + A ¹⁰ h ¹⁰ + A ¹² h ¹² + A ¹⁴ h ¹⁴ + A ¹⁶ h ¹⁶
Is represented by Where R is a paraxial radius of curvature.

  The back focus BF indicates the distance from the lens last surface to the paraxial image plane. The total lens length is obtained by adding back focus to the distance from the surface closest to the object side to the lens final surface. Table 1 shows the correspondence with each conditional expression in each example.

(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 (stop) ∞ (variable)
11 * 13.563 2.97 1.76802 49.2
12 * -600.092 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 ∞

Aspheric surface data surface 6
K = 0.00000 e + 000 A 4 =-5. 10 955 e-007 A 6 =-1. 36 690 e-007 A 8 =-5. 888 9 e-009 A 10 = 4. 89 476 e-01 1

11th
K = 0.00000e + 000 A 4 =-8.03559e-005 A 6 = 2. 214434e-007

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

Face 20
K = 0.00000e + 000A 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 Intermediate 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
Lens total 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 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 vd
1 30.219 0.85 1.94595 18.0
2 23.034 3.14 1.80420 46.5
3 100.588 (variable)
4 68.300 0.67 1.77250 49.6
5 9.513 5.39
6 *-20.967 0.40 1.76802 49.2
7 126.105 0.10
8 44.402 1.19 1.95906 17.5
9 -148.917 (variable)
10 (stop) ∞ (variable)
11 * 13.976 2.77 1.76802 49.2
12 *-51.203 0.10
13 18.059 1.20 1.83481 42.7
14 33.155 0.45 1.85478 24.8
15 9.908 3.55
16 1. 1.17
17 37.555 3.81 1.49700 81.5
18 -10.777 (variable)
19-23.857 0.40 1.69471 40.9
20 * 45.075 (variable)
21 22.926 2.60 1.59131 62.1
22 -28.370 (variable)
23 -125.862 0.65 1.51714 65.3
24 17.813 (variable)
Image plane ∞

Aspheric surface data surface 6
K = 0.00000e + 000 A 4 = -1.89098e-006 A 6 = 8.68537e-008 A 8 = -1.12956e-008 A10 = 1.05283e-010

11th
K = 0.00000e + 000A 4 =-1.09399e-004 A 6 = 1. 29175e-006

12th
K = 0.00000e + 000A 4 = 3.87557e-006 A 6 = 1.85771e-006 A 8 = 1.08940e-009 A10 = -2.50035e-011

Face 20
K = 0.00000e + 000A 4 = 1.03579e-004 A 6 = 6.12350e-007 A 8 = -1.03921e-008 A10 = -3.33788e-011

Various data Zoom ratio 4.74
Wide-angle Intermediate telephoto focal length 9.00 19.52 42.68
F number 2.06 3.09 4.12
Half angle of view (degrees) 35.71 21.41 10.47
Image height 6.47 7.65 7.89
Lens total length 62.00 62.21 77.00
BF 7.37 14.74 18.57

d 3 0.31 5.91 19.03
d 9 14.03 3.83 0.70
d10 5.38 3.18 0.99
d18 0.79 1.67 3.59
d20 1.72 1.45 4.88
d22 3.98 2.98 0.80
d24 7.37 14.74 18.57

Lens group data group Start focal length
B1 1 56.50
B2 4-11.32.
SP 10 ∞
B3 11 13.90
B4 19 -22.40
B5 21 21.86
B6 23 -30.13

(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 (F-stop) ∞ (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 1.8465 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 ∞

Aspheric data first surface
K = 0.00000e + 000 A 4 =-7.98556 5e-006 A 6 =-1.67674e-008 A 8 = 2.77032e-010 A10 =-5.91334e-013

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

Eighth side
K = 0.00000e + 000 A 4 =-9.98361 1-006 A 6 =-3.47467e-008 A 8 = 2.21342e-010 A10 =-. 24169e-012

18th
K = 0.00000e + 000A 4 = 5.35227e-005 A 6 = 9.26754e-008 A 8 = -1. 21473e-009

Various data zoom ratio 2.75
Wide-angle Intermediate 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
Lens total 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 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 (F-stop) ∞ (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 ∞

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

Third side
K = 0.00000e + 000A 4 = 2.63433e-006 A 6 = -5.70372e-008 A 8 = 3.175559e-010 A10 = -2.46690e-012

Eighth side
K = 0.00000e + 000A 4 = -6.73244e-007 A 6 = 5.48987e-009 A 8 = -1. 15789e-010 A 10 = 2.43864e-013

18th
K = 0.00000e + 000A 4 = 6.56717e-005 A 6 =-1. 90965e-007 A 8 =-5.11771e-011

Various data zoom ratio 2.75
Wide-angle Intermediate 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
Lens total 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 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 (F-stop) ∞ (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 ∞

Aspheric data first surface
K = 0.00000e + 000 A 4 = -4.10144e-005 A 6 =-6.85 696e-007 A 8 = 6.10172e-009 A10 =-2.70985e-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 + 000A 4 = 1.71033e-005 A 6 =-1.20446e-007 A 8 = 8.32533e-010 A10 = 2.57147e-011

Eighth side
K = 0.00000e + 000A 4 =-6.49780e-005 A 6 = 2. 13806e-007 A 8 =-1.04721e-008 A10 = 7.23248e-011

9th surface
K = 0.00000e + 000A 4 = 2. 76384e-005 A 6 = 4.61738e-007 A 8 =-1. 42403e-008 A10 = 1.20091e-010

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

Various data zoom ratio 3.66
Wide-angle Intermediate 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
Lens total 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 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 stop FP flare cut diaphragm BR lens group located on the most image side A lens group

Claims (8)

A zoom lens having a plurality of lens groups and in which the distance between adjacent lens groups changes during zooming,
The lens unit BR of negative refractive power disposed closest to the image side of the zoom lens moves in the optical axis direction during focusing,
The sign of the refractive power of a lens element composed of a single lens or a cemented lens disposed adjacent to the object side of the lens group BR is positive,
The distance between the most image side surface of the lens element at the wide angle end and the image plane 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 unit BR is df. Assuming that 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 following conditional expression. When the lateral magnification of the lens unit BR at the wide angle end is βw
1.0 <βw <1.3
The zoom lens according to claim 1, which satisfies the following conditional expression. The lens group BR is composed of a single lens of negative refractive power or a cemented lens of negative refractive power,
Assuming that the radii of curvature of the surface on the most object side and the surface on the most image side of the lens unit BR are rf and rr, respectively.
0.0 <(rf + rr) / (rf−rr) <5.0
The zoom lens according to claim 1 or 2, wherein the following conditional expression is satisfied.
Lens element The zoom lens includes, in order from the object side to the image side, a first lens group of positive refractive power, a second lens group of negative refractive power, a third lens group of positive refractive power, and a fourth lens of negative refractive power. It consists of a lens group and a fifth lens group of negative refractive power,
The zoom lens according to any one of claims 1 to 3, wherein the lens units move along different trajectories during zooming. The zoom lens includes, in order from the object side to the image side, a first lens group of negative refractive power, a second lens group of positive refractive power, a third lens group of positive refractive power, and a fourth lens of negative refractive power. It is composed of a lens group, a fifth lens group of positive refractive power, and a sixth lens group of negative refractive power,
The zoom lens according to any one of claims 1 to 4, wherein the lens units move along different trajectories during zooming. The zoom lens has an aperture stop that determines an open F-number light flux, and the optical effective diameter of the surface closest to the image of the lens element is φa.
0.7 <φa / di <1.4
The zoom lens according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.   An image pickup apparatus comprising: the zoom lens according to any one of claims 1 to 6; and an image pickup element for receiving an image formed by the zoom lens. When the shooting half angle of view at the wide angle end is ωw,
ω w 30 30 °
An image pickup apparatus according to claim 7, satisfying the following conditional expression.