JP2014109664A - Zoom lens and imaging apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which has a high zoom ratio, achieves high optical performance over the entire zoom range, and, when applied to an imaging apparatus, allows reduction in thickness of the imaging apparatus.SOLUTION: The zoom lens includes, 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 reflection member for bending the optical path, and a rear group including a plurality of lens groups, and during zooming from the wide angle end to the telephoto end, at least the first lens group and the second lens group are moved and the reflection member is stationary. The focal distance ft of the entire system at the telephoto end, and the focal distance f2 of the second lens group are appropriately set, respectively.

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same. For example, an image pickup apparatus using a solid-state image pickup device such as an electronic still camera, a video camera, a broadcast camera, a surveillance camera, or a camera using a silver halide photographic film. This is suitable for the imaging apparatus.

  In recent years, zoom lenses used in imaging devices (cameras) have been required to have a high zoom ratio and be small, and when applied to imaging devices, the thickness of the imaging device can be reduced. It is required to be. In order to realize a high zoom ratio while reducing the size of the image pickup device, the lens unit is retracted by reducing the interval between the lens groups to an interval different from the shooting state when not shooting, and storing the shooting optical system in the housing of the image pickup device. A zoom lens of the type is known. In order to reduce the thickness of the imaging device, a bending zoom lens is known in which a reflecting prism is disposed in the optical path and the optical axis of the photographing optical system is bent by 90 °.

  Furthermore, as a collapsible type and a bending type, the reflecting prism moves during non-photographing, and the bending collapsible in which the lens group located on the object side from the reflecting prism is retracted and stored in the space created by the movement of the reflecting prism. A zoom lens of the type is known (Patent Documents 1, 2, and 3).

JP 2010-152318 A JP 2011-053295 A JP 2012-027084 A

  In general, in order to obtain a zoom lens that has a high zoom ratio and achieves downsizing of the entire system, while increasing the refractive power (optical power, that is, the reciprocal of the focal length) of each lens group constituting the zoom lens What is necessary is to reduce the number of lenses. However, in such a zoom lens, since the refractive power of each lens becomes strong, it is necessary to increase the edge thickness. As a result, the lens thickness and the front lens diameter increase, and it becomes difficult to shorten the total lens length.

  In order to achieve a high zoom ratio and to reduce the size of the entire lens system, it is also important to appropriately set the movement conditions accompanying zooming of each lens group. Furthermore, the thickness of the imaging device can be reduced by using a reflecting member (a reflecting prism or a reflecting mirror) that bends the optical path. However, if the amount of movement of each lens unit during zooming and the arrangement of the reflecting members in the optical path are not appropriate, fluctuations in various aberrations associated with zooming increase, and further downsizing of the imaging device cannot be realized. .

  The present invention provides a zoom lens having a high zoom ratio, high optical performance in the entire zoom range, and capable of reducing the thickness of the imaging device when applied to the imaging device, and an imaging device using the same. The purpose is to do.

The zoom lens of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a reflecting member for bending an optical path, and a plurality of lens groups in order from the object side to the image side. And at least the first lens group and the second lens group are moved during zooming from the wide-angle end to the telephoto end, and the reflecting member is stationary.
When the focal length of the entire system at the telephoto end is ft and the focal length of the second lens group is f2,
17.00 <ft / | f2 | <30.00
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens that has a high zoom ratio, has high optical performance in the entire zoom range, and can reduce the thickness of the imaging device when applied to the imaging device.

Sectional view of the lens at the wide-angle end when the optical path of the zoom lens of Example 1 is developed (A), (B), and (C) are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the intermediate zoom position, and the telephoto end. Sectional view of the lens at the wide-angle end when the optical path of the zoom lens of Example 2 is developed (A), (B), and (C) are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, the intermediate zoom position, and the telephoto end. Sectional view of the lens at the wide-angle end when the optical path of the zoom lens of Example 3 is developed (A), (B), and (C) are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, the intermediate zoom position, and the telephoto end. Sectional view of the lens at the wide-angle end when the optical path of the zoom lens of Example 4 is developed (A), (B), and (C) are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the intermediate zoom position, and the telephoto end. Lens cross-sectional view at the wide-angle end when the optical path of the zoom lens of Example 5 is developed (A), (B), and (C) are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Example 5. 1 is a lens cross-sectional view of a zoom lens according to a first embodiment of the present invention. Schematic diagram of main parts of an imaging apparatus of the present invention

  The zoom lens and the image pickup apparatus having the same according to each embodiment of the present invention will be described below. The zoom lens according to each embodiment of the present invention has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and an optical axis of the optical system of 90 degrees (90 degrees) in order from the object side to the image side. It has a reflection prism that can be bent. Further, a rear group including a plurality of lens groups is provided on the image side of the reflecting prism. During zooming from the wide-angle end (short focal length end) to the telephoto end (long focal length end), the first lens group moves to the object side, and the second lens group moves to the image side. When retracted, the reflecting prism moves to a position different from that at the time of photographing, and at least a part of the first lens group and the second lens group is retracted and accommodated in the space generated by the movement of the reflecting prism.

  In the zoom lenses according to the first to third embodiments, the rear group includes, in order from the object side to the image side, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, and a first lens having a negative refractive power. 5 lens groups and a sixth lens group having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the third lens group does not move, and the fourth, fifth, and sixth lens groups move.

  In the zoom lenses according to the fourth and fifth embodiments, the rear group includes, in order from the object side to the image side, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, and a first lens having a positive refractive power. It consists of five lens groups. During zooming from the wide-angle end to the telephoto end, the third lens group does not move, and the fourth and fifth lens groups move.

  FIG. 1 is a lens cross-sectional view at the wide-angle end when the optical path of the zoom lens of Example 1 is developed. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens of Example 1. FIGS. Example 1 is a zoom lens having a zoom ratio of 44.4 and an aperture ratio of about 3.91 to 9.00.

  FIG. 3 is a lens cross-sectional view at the wide-angle end when the optical path of the zoom lens of Example 2 is developed. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the second embodiment. Example 2 is a zoom lens having a zoom ratio of 30.2 and an aperture ratio of about 3.51 to 7.10.

  FIG. 5 is a lens cross-sectional view at the wide-angle end when the optical path of the zoom lens of Example 3 is developed. FIGS. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the third exemplary embodiment. Example 3 is a zoom lens having a zoom ratio of 36.6 and an aperture ratio of about 3.62 to 7.10.

  FIG. 7 is a lens cross-sectional view at the wide-angle end when the optical path of the zoom lens of Example 4 is developed. 8A, 8B, and 8C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the fourth exemplary embodiment. Example 4 is a zoom lens having a zoom ratio of 44.2 and an aperture ratio of about 3.91 to 9.00.

  FIG. 9 is a lens cross-sectional view at the wide-angle end when the optical path of the zoom lens of Example 5 is developed. FIGS. 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. Example 5 is a zoom lens having a zoom ratio of 30.2 and an aperture ratio of about 3.51 to 6.89.

  FIG. 11 is a lens cross-sectional view when the optical path is bent at the internal reflection surface provided on the reflecting prism in Embodiment 1 of the present invention.

  FIG. 12 is a schematic diagram of a main part of a digital still camera provided with the zoom lens of the present invention. The zoom lens of each embodiment is an imaging lens system used in an imaging apparatus such as a video camera, a digital still camera, a silver salt film camera, or a television camera. The zoom lens of each embodiment can also be used as a projection optical system for a projection apparatus (projector). In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In the lens cross-sectional view, Li indicates the i-th lens group, where i is the order of the lens group from the object side.

  In the lens cross-sectional views of each embodiment, SP is an aperture stop, FP is a flare cut stop, and G is an optical block corresponding to an optical filter, a face plate, a low pass filter, an infrared cut filter, and the like. The aperture stop SP and the flare cut stop FP are disposed in the fourth lens unit L4 and move along the same locus as the fourth lens unit L4 during zooming.

  PR is a reflecting prism including a reflecting surface that bends the optical axis of the optical system by 90 degrees (may be within 90 degrees ± 10 degrees), and IP is an image plane. When a zoom lens is used as an imaging optical system of a video camera or a digital camera, the image plane IP corresponds to a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor. When a zoom lens is used as an imaging optical system of a silver salt film camera, the image plane IP corresponds to a film plane. The arrows in the lens cross-sectional view indicate the movement trajectory of each lens unit during zooming or focusing from the wide-angle end to the telephoto end.

  In the spherical aberration diagram, Fno is an F number. The solid line is the d-line (wavelength 587.6 nm), and the two-dot chain line is the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line is the sagittal image plane at the d line, and the dotted line is the meridional image plane. Distortion is shown for the d-line. In the lateral chromatic aberration diagram, the two-dot chain line is the g-line. ω is an imaging half angle of view. In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit is positioned at both ends of a range that can move on the optical axis due to the mechanism.

  In each embodiment, the lens group located closest to the image side is moved non-linearly to correct the image plane variation caused by zooming. Further, focusing is performed by moving the lens group located closest to the image side in the optical axis direction. When focusing from an infinitely distant object to a close object at the telephoto end, as shown by arrows 5c and 6c in the lens cross-sectional view, the lens group located closest to the image side is extended forward. Curves 5a and 6a indicate movement trajectories for correcting image plane variation accompanying zooming from the wide-angle end to the telephoto end when focusing on an object at infinity. Curves 5b and 6b show movement trajectories for correcting image plane fluctuations accompanying zooming from the wide-angle end to the telephoto end when focusing on a short-distance object.

  In each embodiment, during zooming from the wide-angle end to the telephoto end, the lens unit located closest to the image side is moved as close as possible to the image plane IP, thereby increasing the magnification burden on the lens unit located closest to the image side. Yes. Furthermore, by increasing the refractive power of the second lens unit L2, the zooming load of the second lens unit L2 is increased. By increasing the zooming load of the second lens unit, the lens unit located closest to the image side, the zooming load of the first lens unit L1 becomes relatively low, and the amount of movement of the first lens unit L1 toward the object side Can be reduced. As a result, an increase in the overall length of the lens can be suppressed.

  Further, in each embodiment, all or a part of the fourth lens unit L4 is moved so as to have a component in a direction perpendicular to the optical axis, thereby correcting blurring of a captured image when the zoom lens vibrates. You may do it.

In each embodiment, when the focal length of the entire system at the telephoto end is ft and the focal length of the second lens unit L2 is f2,
17.00 <ft / | f2 | <30.00 (1)
The following conditional expression is satisfied.

  Conditional expression (1) defines the ratio between the focal length f2 of the second lens unit L2 and the focal length ft of the entire system at the telephoto end. If the absolute value | f2 | of the focal length of the second lens unit L2 exceeds the upper limit value of the conditional expression (1), correction of field curvature and lateral chromatic aberration becomes difficult mainly at the wide-angle end, and zooming is also difficult. It becomes difficult to suppress the accompanying fluctuations in the image plane. Furthermore, since the refractive power of the second lens unit L2 that greatly contributes to zooming becomes strong, the inclination and parallel eccentricity sensitivity of each lens unit increase. As a result, when the camera is assembled or photographed, eccentricity is likely to occur due to backlash of mechanical parts, and it becomes difficult to obtain good optical performance.

  If the absolute value | f2 | of the focal length of the second lens unit L2 exceeds the lower limit value of the conditional expression (1), the amount of movement of the second lens unit L2 needs to be increased in order to achieve a high zoom ratio. . As a result, the total lens length increases and the camera becomes undesirably large. Further, the effective diameters of the first lens unit L1 and the second lens unit L2 increase, which is not preferable.

In each embodiment, as described above, each element is appropriately set so as to satisfy the conditional expression (1). Accordingly, a zoom lens having a high zoom ratio, high optical performance in the entire zoom range, and capable of reducing the thickness of the imaging device when applied to the imaging device is obtained. In each embodiment, it is preferable to set the numerical range of conditional expression (1) as follows.
18.00 <ft / | f2 | <29.00 (1a)
More preferably, the numerical range of the conditional expression (1) is set as follows.
18.50 <ft / | f2 | <28.00 (1b)

  In each embodiment, it is preferable to satisfy one or more of the following conditional expressions. Here, the distance between the most image side surface of the second lens unit L2 and the most object side surface of the third lens unit L3 at the wide angle end is D23w, and the most image side surface of the second lens unit L2 at the telephoto end is The distance from the most object side surface of the third lens unit L3 is D23t. The amount of movement of the first lens unit L1 during zooming from the wide-angle end to the telephoto end is M1, and the amount of movement of the second lens unit L2 during zooming from the wide-angle end to the telephoto end is M2. The amount of movement is the absolute value of the difference in position on the optical axis of each lens group at the wide-angle end and the telephoto end. The lateral magnification of the second lens unit L2 at the wide-angle end is β2w, the lateral magnification of the second lens unit L2 at the telephoto end is β2t, the focal length of the first lens unit L1 is f1, and the focal length of the third lens unit L3 is Let f3 be the focal length of the fourth lens unit L4.

At this time,
4.00 <ft / f1 <7.00 (2)
1.00 <D23w / D23t <3.00 (3)
15.00 <β2t / β2w <40.00 (4)
7.00 <| f3 | / | f2 | <12.00 (5)
2.50 <| f3 | / f4 <5.00 (6)
1.70 <ft / | f3 | <5.00 (7)
9.00 <ft / M1 <16.00 (8)
13.00 <ft / M2 <23.00 (9)
1.20 <M1 / M2 <1.70 (10)
It is preferable to satisfy one or more of the following conditional expressions.

  Conditional expression (2) defines the ratio between the focal length f1 of the first lens unit L1 and the focal length ft at the telephoto end. If the value of f1 decreases beyond the upper limit value of conditional expression (2), the spherical aberration at the telephoto end increases, and it becomes necessary to dispose a lens for correcting the aberration. An increase in the number of lenses causes an increase in the total lens length, which is not preferable. If the value of f1 increases beyond the lower limit of conditional expression (2), the spherical aberration at the telephoto end can be corrected well, but the first lens group moves during zooming from the wide-angle end to the telephoto end. The amount increases. As a result, the total lens length increases, which is not preferable.

  Conditional expression (3) indicates that the distance D23w between the most image side surface of the second lens unit L2 and the most object side surface of the third lens unit L3 at the wide angle end and the most image of the second lens unit L2 at the telephoto end. The ratio of the distance D23t between the side surface and the most object side surface of the third lens unit L3 is defined. When the value of D23t becomes smaller than the upper limit value of conditional expression (3), it is necessary to increase the refractive power of the second lens unit L2 in order to realize a high zoom ratio. As a result, it becomes difficult to correct curvature of field and lateral chromatic aberration at the wide-angle end, and it is difficult to suppress fluctuations in the image plane around the screen in the entire zoom region. If the value of D23t increases beyond the lower limit value of conditional expression (3), the amount of movement of the second lens unit L2 increases and the total lens length increases, which is not preferable.

  Conditional expression (4) defines the ratio between the lateral magnification β2w of the second lens unit L2 at the wide-angle end and the lateral magnification β2t of the second lens unit L2 at the telephoto end. When the value of β2t increases beyond the upper limit of conditional expression (4), the zoom ratio of the second lens unit L2 increases and the refractive power of the second lens unit L2 increases. As a result, it is difficult to correct curvature of field and lateral chromatic aberration at the wide-angle end, and it is difficult to suppress fluctuations in the image plane around the screen in the entire zoom region. If the value of β2t becomes smaller than the lower limit value of conditional expression (4), the magnification burden on the first lens unit L1 and the second lens unit L2 becomes small. It becomes necessary to increase the double burden. As a result, the movement amount of the rear group increases and the total lens length increases, which is not preferable.

  Conditional expression (5) defines the ratio between the focal length f2 of the second lens unit L2 and the focal length f3 of the third lens unit L3. When the absolute value | f2 | of the focal length of the second lens unit L2 becomes smaller than the upper limit value of the conditional expression (5), the refractive power of the second lens unit L2 becomes relatively strong. As a result, it is difficult to correct curvature of field and lateral chromatic aberration at the wide-angle end, axial chromatic aberration at the telephoto end, and image plane variation in the entire zoom region, which is not preferable. If the absolute value | f2 | of the focal length of the second lens unit L2 increases beyond the lower limit value of the conditional expression (5), the refractive power of the second lens unit L2 becomes relatively weak. As a result, in order to achieve a high zoom ratio, the amount of movement of the second lens unit L2 is increased, which increases the total lens length, which is not preferable.

  Conditional expression (6) defines the ratio between the focal length f3 of the third lens unit L3 and the focal length f4 of the fourth lens unit L4. When the focal length f4 of the fourth lens unit L4 becomes shorter than the upper limit value of the conditional expression (6), the refractive power of the fourth lens unit L4 becomes strong, so that it is possible to reduce the total lens length. However, on the other hand, since the refractive power of the fourth lens unit L4 becomes strong, it becomes difficult to correct spherical aberration and coma aberration in the entire zoom region. When the lower limit of conditional expression (6) is exceeded and the focal length f4 of the fourth lens unit L4 becomes longer, the refractive power of the fourth lens unit L4 becomes weaker. As a result, in order to realize a high zoom ratio, the amount of movement of the fourth lens unit L4 becomes large, which increases the total lens length, which is not preferable.

  Conditional expression (7) defines the ratio between the focal length f3 of the third lens unit L3 and the focal length ft of the entire system at the telephoto end. When the upper limit of conditional expression (7) is exceeded and the absolute value | f3 | of the focal length of the third lens unit L3 decreases, the refractive power of the third lens unit L3 increases. As a result, the refractive power of the second lens unit L2 is relatively weak, and the amount of movement of the second lens unit L2 is increased in order to achieve a high zoom ratio, which increases the front lens diameter. When the absolute value | f3 | of the focal length of the third lens unit L3 increases beyond the lower limit value of the conditional expression (7), the refractive power of the third lens unit L3 decreases. As a result, the refractive power of the second lens unit L2 becomes relatively strong, and it is difficult to correct field curvature and lateral chromatic aberration at the wide-angle end, axial chromatic aberration at the telephoto end, and image plane variation in the entire zoom region. This is not preferable.

  Conditional expression (8) defines the ratio between the amount of movement M1 of the first lens unit L1 during zooming from the wide-angle end to the telephoto end and the focal length ft of the entire system at the telephoto end. When the movement amount M1 of the first lens unit L1 is reduced beyond the upper limit value of the conditional expression (8), it is necessary to increase the refractive power of the first lens unit L1 in order to realize high zoom. As a result, the effective diameter of the front lens increases, and it becomes difficult to correct spherical aberration, axial chromatic aberration, and coma aberration in the entire zoom region at the telephoto end, which is not preferable. If the amount of movement of the first lens unit L1 exceeds the lower limit of conditional expression (8), the total lens length at the telephoto end increases, which is not preferable.

  Conditional expression (9) defines the ratio between the amount of movement M2 of the second lens unit L2 during zooming from the wide-angle end to the telephoto end and the focal length ft of the entire system at the telephoto end. If the movement amount M2 of the second lens unit L2 becomes smaller than the upper limit value of the conditional expression (9), it is necessary to increase the refractive power of the second lens unit L2 in order to realize high zoom. As a result, it becomes difficult to correct curvature of field and lateral chromatic aberration at the wide-angle end, axial chromatic aberration at the telephoto end, and image plane variation in the entire zoom region, which is not preferable. If the amount of movement of the second lens unit L2 exceeds the lower limit of conditional expression (9), the total lens length at the telephoto end increases, which is not preferable.

  Conditional expression (10) shows the amount of movement M1 of the first lens unit L1 during zooming from the wide-angle end to the telephoto end, and the amount of movement M2 of the second lens unit L2 during zooming from the wide-angle end to the telephoto end. The ratio is defined. When the movement amount M2 of the second lens unit L2 becomes smaller than the upper limit value of the conditional expression (10), it is necessary to increase the refractive power of the second lens unit L2 in order to realize a high zoom ratio. As a result, it becomes difficult to correct curvature of field and lateral chromatic aberration at the wide-angle end, axial chromatic aberration at the telephoto end, and coma aberration in the entire zoom region, which is not preferable. When the movement amount M1 of the first lens unit L1 becomes smaller than the lower limit value of the conditional expression (10), it is necessary to increase the refractive power of the first lens unit L1 in order to realize a high zoom ratio. As a result, it is difficult to correct spherical aberration, axial chromatic aberration, and coma aberration in the entire zoom range at the telephoto end.

It is preferable to set the numerical range of conditional expression (2) to conditional expression (10) as follows.
4.02 <ft / f1 <6.50 (2a)
1.50 <D23w / D23t <2.50 (3a)
15.20 <β2t / β2w <37.00 (4a)
7.30 <| f3 | / | f2 | <11.50 (5a)
2.70 <| f3 | / f4 <4.70 (6a)
1.73 <ft / | f3 | <4.00 (7a)
9.50 <ft / M1 <15.00 (8a)
14.00 <ft / M2 <22.00 (9a)
1.25 <M1 / M2 <1.67 (10a)

More preferably, if the numerical range of conditional expression (2) to conditional expression (10) is set as follows, the effects brought about by each conditional expression can be maximized.
4.04 <ft / f1 <6.00 (2b)
1.80 <D23w / D23t <2.00 (3b)
15.30 <β2t / β2w <35.00 (4b)
7.60 <| f3 | / | f2 | <11.00 (5b)
2.90 <| f3 | / f4 <4.60 (6b)
1.75 <ft / | f3 | <3.50 (7b)
9.90 <ft / M1 <14.50 (8b)
14.20 <ft / M2 <21.80 (9b)
1.28 <M1 / M2 <1.65 (10b)

  In each embodiment, by configuring each element as described above, the zoom ratio is high, high optical performance is obtained in the entire zoom range, and the thickness of the imaging device can be reduced when applied to the imaging device. A zoom lens that can be obtained is obtained. The effect of the present invention can be further enhanced by arbitrarily combining a plurality of the above conditional expressions.

  Next, the lens configuration of each example will be described. Each lens is arranged in order from the object side to the image side unless otherwise specified. In each embodiment, the configurations of the first lens unit L1, the second lens unit L2, and the third lens unit L3 are common. The first lens unit L1 having a positive refractive power is composed of a cemented lens of a meniscus negative lens having a convex surface facing the object side and a positive lens, and a meniscus positive lens having a convex surface facing the object side. By configuring the first lens unit L1 with three lenses, it is possible to satisfactorily correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration while realizing a high zoom ratio.

  The second lens unit L2 having negative refractive power includes, in order from the object side to the image side, a negative lens having a concave surface on both sides, a negative lens having a concave surface on both surfaces, and a positive lens having a convex surface on both surfaces. Fluctuation is suppressed. With such a configuration, it is possible to suppress variation in lateral chromatic aberration associated with zooming. The third lens unit L3 having negative refractive power is composed of a meniscus negative lens having a concave surface facing the object side. The fourth lens unit L4 has at least one negative lens and at least two positive lenses. Thereby, spherical aberration and coma are corrected satisfactorily in all zoom regions. The fourth lens unit L4 has at least one surface that is aspheric. Thereby, the fluctuation | variation of the spherical aberration accompanying zooming is correct | amended favorably.

  The final lens group has a cemented lens of a positive lens and a negative lens. Thereby, the fluctuation | variation of the magnification chromatic aberration accompanying zooming can be suppressed.

  In the zoom lenses of Examples 1 to 3, in order from the object side to the image side, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, and the third lens unit L3 having a negative refractive power. The fourth lens unit L4 has a positive refractive power, the fifth lens unit L5 has a negative refractive power, and the sixth lens unit L6 has a positive refractive power.

  In the zoom lens of Example 1, the fourth lens unit L4 has a meniscus positive lens with a convex surface facing the object side, a meniscus negative lens with a concave surface facing the image side, and a concave surface facing the image side. It consists of a cemented lens of a meniscus negative lens and a biconvex positive lens. The fifth lens unit L5 is composed of a biconcave negative lens. The sixth lens unit L6 includes a cemented lens of a negative lens having a concave surface directed toward the image side and a biconvex positive lens.

  In the zoom lenses of Example 2 and Example 3, the fourth lens unit L4 includes a meniscus positive lens having a convex surface facing the object side, a meniscus negative lens having a concave surface facing the image side, and a biconvex shape. A positive lens and a meniscus negative lens having a convex surface facing the image side. The fifth lens unit L5 is composed of a biconcave negative lens. The sixth lens unit L6 includes a cemented lens of a biconvex positive lens and a negative lens having a concave surface facing the object side.

  In the zoom lenses of Example 4 and Example 5, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, and the third lens having a negative refractive power are sequentially arranged from the object side to the image side. The lens unit L3 includes a fourth lens unit L4 having a positive refractive power and a fifth lens unit L5 having a positive refractive power.

  In the zoom lens of Embodiment 4, the fourth lens unit L4 includes a meniscus positive lens convex toward the object side, a meniscus negative lens with a concave surface facing the image side, and a meniscus shape with a concave surface facing the image side. A negative lens and a biconvex positive lens, and a biconcave negative lens. The fifth lens unit L5 includes a cemented lens of a negative lens having a concave surface directed toward the object side and a biconvex positive lens.

  In the zoom lens of Example 5, the fourth lens unit L4 includes a meniscus positive lens convex toward the object side, a meniscus negative lens with a concave surface facing the image side, a biconvex positive lens, and the image side. It consists of a cemented lens of a meniscus negative lens with a convex surface facing to and a biconcave negative lens. The fifth lens unit L5 includes a cemented lens of a biconvex positive lens and a negative lens having a convex surface directed toward the image side.

  As shown in FIG. 11, the zoom lens of each embodiment includes a reflecting prism PR that bends light from the object side between the second lens unit L2 and the third lens unit L3, thereby easily reducing the thickness of the camera. can do.

Next, numerical examples 1 to 5 corresponding to the first to fifth embodiments of the present invention will be described. In each numerical example, i indicates the order of the optical surfaces from the object side. ri is the radius of curvature of the i-th optical surface (i-th surface), di is the distance between the i-th surface and the i + 1-th surface, and ndi and νdi are the refractions of the material of the i-th optical member with respect to the d-line, respectively. Indicates the rate and Abbe number. Also, when k is the eccentricity, A4, A6, A8, and A10 are aspherical coefficients, and the displacement in the optical axis direction at the position of the height h from the optical axis with respect to the surface vertex is x, the aspherical shape is
x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² } ^1/2 ] + A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰
It is represented by Where R is the paraxial radius of curvature. Table 1 shows the correspondence with the above-described conditional expressions in each numerical example.

[Numerical Example 1]
Unit: mm

Surface data surface number rd nd νd
1 48.702 0.85 2.00330 28.3
2 22.510 6.65 1.43875 94.9
3 -152.022 0.05
4 24.050 3.85 1.74400 44.8
5 488.190 (variable)
6 -457.939 0.50 1.85135 40.1
7 * 7.464 4.34
8 -16.387 0.40 1.88300 40.8
9 25.890 0.15
10 24.891 2.00 2.10205 16.8
11 -44.080 (variable)
12 ∞ 8.50 2.00 330 28.3
13 ∞ 1.00
14 -18.365 0.50 1.77250 49.6
15 -31.087 (variable)
16 * 9.158 1.90 1.55332 71.7
17 * -2178.349 0.50
18 (Aperture) ∞ 3.17
19 10.714 0.65 1.88 100 40.1
20 7.570 1.40
21 11.494 0.50 1.88300 40.8
22 7.846 1.95 1.49700 81.5
23 -58.233 0.65
24 ∞ (variable)
25 -77.173 0.50 1.88300 40.8
26 24.730 (variable)
27 14.783 0.50 1.77250 49.6
28 9.278 3.95 1.55332 71.7
29 -29.911 (variable)
30 ∞ 0.80 1.51633 64.1
31 ∞ 0.50
Image plane ∞

Aspheric data 7th surface
K = -1.45247e-001 A 4 = -7.82786e-005 A 6 = -1.54198e-006 A 8 = 5.23943e-008 A10 = -7.86689e-010

16th page
K = 6.57313e-001 A 4 = -1.63431e-004 A 6 = 8.93903e-006 A 8 = 3.33620e-007

17th page
K = 3.34004e + 005 A 4 = 1.12690e-004 A 6 = 1.19421e-005 A 8 = 5.49179e-007

Various data Zoom ratio 44.41
Wide angle Medium telephoto focal length 4.62 13.02 205.00
F number 3.91 6.14 9.00
Angle of view 36.14 16.58 1.08
Total lens length 99.33 103.38 113.64
BF 12.11 10.81 4.28

d 5 0.37 7.52 24.26
d11 10.36 7.26 0.78
d15 21.79 10.72 0.59
d24 1.23 8.49 6.37
d26 8.76 13.86 32.63
d29 11.08 9.78 3.25

Zoom lens group data group Start surface Focal length
1 1 35.10
2 6 -7.36
3 14 -59.10
4 16 15.74
5 25 -21.16
6 27 21.81

[Numerical Example 2]
Unit: mm

Surface data surface number rd nd νd
1 37.360 0.85 2.00069 25.5
2 22.248 4.95 1.43875 94.9
3 2667.345 0.05
4 24.595 2.55 1.80 400 46.6
5 155.530 (variable)
6 * 185.057 0.50 1.85 135 40.1
7 * 6.827 4.42
8 -16.956 0.40 1.88300 40.8
9 29.157 0.15
10 20.003 2.20 1.95906 17.5
11 -47.441 (variable)
12 ∞ 8.50 1.80610 33.3
13 ∞ 1.00
14 -18.442 0.50 1.77250 49.6
15 -28.657 (variable)
16 * 8.325 1.90 1.55332 71.7
17 * -165.109 0.50
18 (Aperture) ∞ 1.21
19 11.058 0.60 1.88 100 40.1
20 7.421 1.40
21 407.211 1.75 1.49700 81.5
22 -7.172 0.50 1.88300 40.8
23 -10.031 0.65
24 ∞ (variable)
25 -62.841 0.50 1.88300 40.8
26 34.107 (variable)
27 19.700 2.30 1.55332 71.7
28 -17.931 0.50 1.77250 49.6
29 -29.645 (variable)
30 ∞ 0.80 1.51633 64.1
31 ∞ 0.44
Image plane ∞

Aspheric data 6th surface
K = -6.01490e + 003 A 4 = 3.34474e-005 A 6 = -1.51686e-006 A 8 = 1.20457e-008 A10 = -1.32590e-011

7th page
K = -9.32776e-001 A 4 = 1.94764e-004 A 6 = 5.95526e-006 A 8 = -1.48468e-007 A10 = 1.58405e-009

16th page
K = -6.83175e-001 A 4 = 2.79585e-005 A 6 = 6.10503e-006 A 8 = 4.69690e-008

17th page
K = -4.96978e + 003 A 4 = 1.81992e-005 A 6 = 1.28192e-005 A 8 = -1.75048e-007

Various data Zoom ratio 30.16
Wide angle Medium Telephoto focal length 4.64 14.48 140.00
F number 3.51 5.39 7.10
Angle of view 35.99 14.99 1.59
Total lens length 86.88 90.89 99.58
BF 14.01 13.96 4.46

d 5 0.35 7.85 22.88
d11 10.39 6.90 0.57
d15 16.99 5.24 0.24
d24 1.54 10.11 7.19
d26 5.44 8.67 26.09
d29 13.05 12.99 3.49

Zoom lens group data group Start surface Focal length
1 1 34.56
2 6 -7.48
3 14 -68.43
4 16 15.14
5 25 -24.98
6 27 24.26

[Numerical Example 3]
Unit: mm

Surface data surface number rd nd νd
1 45.245 0.85 2.00330 28.3
2 22.305 5.90 1.43875 94.9
3 -251.125 0.05
4 23.959 3.55 1.80 400 46.6
5 213.126 (variable)
6 * 205.978 0.50 1.85 135 40.1
7 * 6.939 4.43
8 -16.540 0.40 1.88300 40.8
9 30.126 0.15
10 23.596 2.00 2.10205 16.8
11 -51.570 (variable)
12 ∞ 8.50 1.80610 33.3
13 ∞ 1.00
14 -13.001 0.50 1.77250 49.6
15 -18.724 (variable)
16 * 9.194 1.90 1.55332 71.7
17 * -147.030 0.50
18 (Aperture) ∞ 1.24
19 11.044 0.60 1.88 100 40.1
20 8.019 1.40
21 134.475 1.90 1.49700 81.5
22 -7.336 0.50 1.88300 40.8
23 -10.670 0.65
24 ∞ (variable)
25 -77.950 0.50 1.88300 40.8
26 26.547 (variable)
27 18.613 3.20 1.55332 71.7
28 -12.255 0.50 1.77250 49.6
29 -23.950 (variable)
30 ∞ 0.80 1.51633 64.1
31 ∞ 0.50
Image plane ∞

Aspheric data 6th surface
K = -2.53503e + 003 A 4 = 8.82909e-005 A 6 = -2.03879e-006 A 8 = 5.93855e-010 A10 = 1.04615e-010

7th page
K = -7.06230e-001 A 4 = 1.97596e-004 A 6 = 2.55012e-006 A 8 = -6.68249e-008 A10 = -1.42955e-009

16th page
K = -2.83894e-001 A 4 = -4.16756e-006 A 6 = 8.50455e-006 A 8 = 1.24111e-007

17th page
K = -9.47143e + 001 A 4 = 1.55082e-004 A 6 = 9.29921e-006 A 8 = 1.29244e-007

Various data Zoom ratio 36.64
Wide angle Medium Telephoto focal length 4.64 14.08 170.00
F number 3.62 5.38 7.10
Angle of view 36.00 15.39 1.31
Total lens length 92.76 96.85 106.23
BF 13.65 13.60 4.58

d 5 0.35 7.75 23.48
d11 10.23 6.91 0.56
d15 18.51 6.75 0.26
d24 2.31 10.40 6.18
d26 6.73 10.44 30.17
d29 12.62 12.57 3.55

Zoom lens group data group Start surface Focal length
1 1 34.54
2 6 -7.52
3 14 -57.25
4 16 15.21
5 25 -22.38
6 27 23.20

[Numerical Example 4]
Unit: mm

Surface data surface number rd nd νd
1 48.389 0.85 2.00330 28.3
2 22.511 6.65 1.43875 94.9
3 -149.842 0.05
4 24.003 3.85 1.74400 44.8
5 465.143 (variable)
6 -256.522 0.50 1.85135 40.1
7 * 7.602 4.20
8 -16.847 0.40 1.88300 40.8
9 27.409 0.15
10 25.939 2.00 2.10205 16.8
11 -41.028 (variable)
12 ∞ 8.50 2.00 330 28.3
13 ∞ 1.00
14 -18.360 0.50 1.77250 49.6
15 -31.040 (variable)
16 * 9.173 1.90 1.55332 71.7
17 * -2058.714 0.50
18 (Aperture) ∞ 2.26
19 10.728 0.65 1.88 100 40.1
20 7.584 1.40
21 11.281 0.50 1.88 300 40.8
22 7.931 1.95 1.49700 81.5
23 -39.786 0.65
24 ∞ 2.00
25 -69.516 0.50 1.88300 40.8
26 24.143 (variable)
27 15.637 0.50 1.77250 49.6
28 9.752 3.50 1.55332 71.7
29 -35.945 (variable)
30 ∞ 0.80 1.51633 64.1
31 ∞ 0.50
Image plane ∞

Aspheric data 7th surface
K = -1.08157e-001 A 4 = -1.05811e-004 A 6 = -1.65146e-007 A 8 = -1.42280e-008 A10 = -1.33930e-010

16th page
K = 3.24025e-001 A 4 = -1.10408e-004 A 6 = 1.16455e-005 A 8 = 3.82088e-007

17th page
K = 3.02547e + 005 A 4 = 1.15022e-004 A 6 = 1.30951e-005 A 8 = 6.25706e-007

Various data Zoom ratio 44.20
Wide angle Medium Telephoto focal length 4.64 11.71 205.00
F number 3.91 5.36 9.00
Angle of view 36.01 18.31 1.08
Total lens length 98.72 102.61 113.05
BF 9.70 20.85 4.30

d 5 0.39 7.27 24.18
d11 10.06 7.07 0.60
d15 23.96 9.39 0.29
d26 9.37 12.79 38.44
d29 8.67 19.83 3.28

Zoom lens group data group Start surface Focal length
1 1 34.92
2 6 -7.72
3 14 -59.20
4 16 20.28
5 27 24.11

[Numerical Example 5]
Unit: mm

Surface data surface number rd nd νd
1 36.776 0.85 2.00069 25.5
2 22.110 4.95 1.43875 94.9
3 1351.311 0.05
4 24.652 2.55 1.80 400 46.6
5 157.681 (variable)
6 * 228.980 0.50 1.85 135 40.1
7 * 6.782 4.42
8 -17.023 0.40 1.88300 40.8
9 29.583 0.15
10 20.003 2.20 1.95906 17.5
11 -47.260 (variable)
12 ∞ 8.50 1.80610 33.3
13 ∞ 1.00
14 -19.436 0.50 1.77250 49.6
15 -28.791 (variable)
16 * 8.252 1.90 1.55332 71.7
17 * -181.321 0.50
18 (Aperture) ∞ 1.21
19 11.131 0.60 1.88 100 40.1
20 7.440 1.40
21 249.542 1.75 1.49700 81.5
22 -7.343 0.50 1.88300 40.8
23 -10.222 0.65
24 ∞ 2.67
25 -66.991 0.50 1.88300 40.8
26 40.302 (variable)
27 19.599 2.30 1.55332 71.7
28 -21.072 0.50 1.77250 49.6
29 -47.867 (variable)
30 ∞ 0.80 1.51633 64.1
31 ∞ 0.50
Image plane ∞

Aspheric data 6th surface
K = -1.22295e + 004 A 4 = 3.57110e-005 A 6 = -1.59013e-006 A 8 = 1.07047e-008 A10 = 4.38915e-012

7th page
K = -8.44791e-001 A 4 = 1.56920e-004 A 6 = 6.70337e-006 A 8 = -1.67386e-007 A10 = 1.34759e-009

16th page
K = -6.79751e-001 A 4 = 5.82769e-006 A 6 = 7.65461e-006 A 8 = 3.00753e-008

17th page
K = -5.77904e + 003 A 4 = 9.92798e-006 A 6 = 1.45266e-005 A 8 = -2.27070e-007

Various data Zoom ratio 30.18
Wide angle Medium Telephoto focal length 4.64 11.46 140.00
F number 3.51 4.90 6.89
Angle of view 36.01 18.69 1.59
Total lens length 85.69 88.33 99.76
BF 11.60 19.63 4.56

d 5 0.35 5.96 23.06
d11 9.22 6.25 0.57
d15 18.96 7.19 0.24
d26 4.74 8.48 30.50
d29 10.57 18.60 3.53

Zoom lens group data group Start surface Focal length
1 1 34.47
2 6 -7.44
3 14 -79.28
4 16 19.22
5 27 29.72

  Next, an embodiment of a digital still camera using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 12, reference numeral 20 denotes a camera body, and reference numeral 21 denotes a photographing optical system constituted by any of the zoom lenses described in the first to fifth embodiments. Reference numeral 22 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 21 and is built in the camera body. A memory 23 stores information corresponding to the subject image photoelectrically converted by the solid-state imaging device 22. Reference numeral 24 denotes a finder for observing a subject image formed on the solid-state image sensor 22, which includes a liquid crystal display panel or the like.

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group SP Aperture stop FP Flare cut stop G Glass block such as face plate and low pass filter IP Image surface PR reflecting prism d d line g g line S sagittal image plane M meridional image plane ω half angle of view Fno F number

Claims (15)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a reflecting member for bending an optical path, and a rear group including a plurality of lens groups in order from the object side to the image side, During zooming from the telephoto end to the telephoto end, at least the first lens group and the second lens group are moved, and the reflecting member is stationary.
When the focal length of the entire system at the telephoto end is ft and the focal length of the second lens group is f2,
17.00 <ft / | f2 | <30.00
A zoom lens satisfying the following conditional expression:   The reflecting member moves to a position different from the photographing state when retracted, and at least a part of the first lens group and the second lens group is retracted and accommodated in a space generated by the movement of the reflecting member. The zoom lens according to claim 1. When the focal length of the first lens group is f1,
4.00 <ft / f1 <7.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The lens group located closest to the object side in the rear group as a third lens group,
The distance between the most image side surface of the second lens group and the most object side surface of the third lens group at the wide angle end is D23w, and the most image side surface of the second lens group at the telephoto end is When the distance from the most object side surface of the third lens group is D23t,
1.00 <D23w / D23t <3.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the lateral magnification of the second lens group at the wide angle end is β2w and the lateral magnification of the second lens group at the telephoto end is β2t,
15.00 <β2t / β2w <40.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the lens group located closest to the object side in the rear group is the third lens group, and the focal length of the third lens group is f3,
7.00 <| f3 | / | f2 | <12.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The rear group has a third lens group and a fourth lens group in order from the object side to the image side. When the focal length of the third lens group is f3 and the focal length of the fourth lens group is f4,
2.50 <| f3 | / f4 <5.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the lens group located closest to the object side in the rear group is the third lens group, and the focal length of the third lens group is f3,
1.70 <ft / | f3 | <5.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the amount of movement of the first lens unit during zooming from the wide-angle end to the telephoto end is M1,
9.00 <ft / M1 <16.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end is M2,
13.00 <ft / M2 <23.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the movement amounts of the first lens group and the second lens group during zooming from the wide-angle end to the telephoto end are M1 and M2, respectively.
1.20 <M1 / M2 <1.70
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom lens according to claim 1, wherein focusing from an object at infinity to an object at a short distance is performed by moving a lens group located closest to the image side.   The rear group includes, in order from the object side to the image side, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power. The zoom lens according to claim 1.   The rear group includes, in order from the object side to the image side, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, and a sixth lens having a positive refractive power. The zoom lens according to claim 1, comprising a group.   An image pickup apparatus comprising: the zoom lens according to claim 1; and a solid-state image pickup device that receives an image formed by the zoom lens.

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