JP2017198887A - Zoom lens and imaging device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens that comprises a compact focusing lens group, emits a low drive sound in focusing, has made the entire system compact, and can easily provide a high zoom ratio.SOLUTION: A zoom lens includes, from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a negative refractive power. In zooming from a wide angle end to a telephoto end, the first lens group moves to the object side, and the intervals between the adjacent lens groups are changed in zooming. In focusing, the fifth lens group moves, and the focal distance f5 of the fifth lens group and the focal distance f6 of the sixth lens group are appropriately set.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is suitable as an image pickup optical system of an image pickup apparatus such as a digital camera, a video camera, a broadcast camera, a surveillance camera, and a silver salt photographic camera.

  In recent years, an imaging optical system used in an imaging apparatus is required to be a zoom lens having a high zoom ratio (magnification ratio) and high optical performance over the entire zoom range. Further, in order to perform quick focusing (focusing), the focus lens group is required to be small and light.

  2. Description of the Related Art Conventionally, there is known a positive lead type zoom lens in which a lens unit having a positive refractive power is disposed closest to the object side, and focusing is performed with a lens group other than the first lens group on the object side at a relatively high zoom ratio ( Patent Documents 1 to 3). In Patent Document 1, the first lens unit to the fifth lens unit having positive, negative, positive, negative, and positive refractive powers are arranged in order from the object side to the image side, and the distance between adjacent lens units changes during zooming. A zooming optical system in which the second lens group moves during focusing is disclosed.

  In Patent Document 2, the first lens unit to the sixth lens unit having positive, negative, positive, positive, negative, and positive refractive powers are arranged in order from the object side to the image side. A zoom lens is disclosed in which the second lens group is moved during the changing focusing. In Patent Document 3, the first lens unit to the fifth lens unit having positive, negative, positive, negative, and positive refractive powers are arranged in order from the object side to the image side, and the distance between adjacent lens units changes during zooming. A zoom lens in which a fourth lens group moves during focusing is disclosed.

JP 2010-015003 A JP-A-2005-242015 Japanese Patent Laid-Open No. 2015-072499

  There is a strong demand for a zoom lens used in an imaging apparatus that the entire lens system is small, that the focus lens group is small and light, that focusing can be performed at high speed, that the focusing lens is quiet, and that there is little variation in aberrations. Generally, when the number of constituent lenses in the focus lens group is reduced in order to make the focus lens group small and light, the residual aberration of the focus lens group increases. For this reason, aberration fluctuations increase during focusing, and it becomes difficult to obtain good optical performance over the entire object distance from a long distance to a short distance.

  On the other hand, if the power (refractive power) of the focus lens group is reduced in order to reduce aberration fluctuations during focusing, the amount of movement during focusing increases, and the total lens length increases. To obtain a zoom lens that is compact in size, fast in focusing, quiet, and has little aberration fluctuation during focusing, the number of lens groups and the refractive power of each lens group must be set appropriately. It becomes important.

  Although the variable magnification optical system of Patent Document 1 is easy to obtain a high zoom ratio, since the refractive power arrangement of each lens group is not always sufficient, the optical performance when each lens group is displaced due to a manufacturing error is lowered. There was a tendency to become easier. In particular, there has been a tendency for the optical performance to deteriorate due to manufacturing errors of the third lens group. In the zoom lens of Patent Document 2, with respect to the variable magnification optical system of Patent Document 1, since the positive refractive power is divided between the third lens group and the fourth lens group, the positive refractive power is dispersed, There is a tendency that the decrease in optical performance due to manufacturing errors is reduced.

  However, in both Patent Documents 1 and 2, since focusing is performed by the relatively large and heavy second lens group, there is a tendency that the silent focusing required for moving image shooting is difficult. In Patent Document 3, focusing is performed with a small and lightweight fourth lens group. For this reason, it is easy to perform silent focusing. However, since the refractive power arrangement is not always sufficient, it is difficult to achieve a high zoom ratio. Further, as in Patent Document 1, there has been a tendency for the optical performance to decrease due to manufacturing errors of each lens group.

  It is an object of the present invention to provide a zoom lens in which the focusing lens group is small, the driving sound during focusing is quiet, the entire system is small, and a high zoom ratio can be easily obtained.

The zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, arranged in order from the object side to the image side. A fourth lens group having a refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a negative refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group is located on the object side. A zoom lens in which the distance between adjacent lens groups changes during zooming, and the fifth lens group moves during focusing;
When the focal length of the fifth lens group is f5 and the focal length of the sixth lens group is f6,
0.0 <f5 / f6 <0.5
It is characterized by satisfying the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens in which the focusing lens group is small, the driving sound at the time of focusing is quiet, the entire system is small, and a high zoom ratio can be easily obtained.

Lens cross-sectional view at the wide-angle end when focusing on an object at infinity according to Example 1 (at the time of focusing) (A), (B) Aberration diagrams at the wide-angle end and the telephoto end during focusing on an infinitely distant object of Example 1. Lens cross-sectional view at the wide-angle end when focusing on an object at infinity according to Example 2 (A), (B) Aberration diagrams at the wide-angle end and the telephoto end during focusing on an infinitely distant object according to Example 2. Lens cross-sectional view at the wide-angle end when focusing on an infinitely distant object in Example 3 (during focusing) (A), (B) Aberration diagrams at the wide-angle end and the telephoto end during focusing on an infinitely distant object of Example 3. Lens cross-sectional view at the wide-angle end when focusing on an object at infinity according to Example 4 (during focusing) (A), (B) Aberration diagrams at the wide-angle end and the telephoto end during focusing on an infinitely distant object according to Example 4. Schematic diagram of the main part of a digital single lens reflex camera (imaging device) equipped with the zoom lens of the present invention.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, arranged in order from the object side to the image side. It has a fourth lens group having a refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens unit moves to the object side, and the interval between adjacent lens units changes during zooming. The fifth lens group moves during focusing.

  The lens group according to the present invention refers to a lens system that is divided by a change in the lens interval in the optical direction during zooming.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) at the time of focusing (focusing) on an object at infinity according to the first exemplary embodiment. FIGS. 2A and 2B are aberration diagrams at the wide-angle end and the telephoto end (long focal length end) when focusing on an infinitely distant object according to the first embodiment. Embodiment 1 is a zoom lens having a zoom ratio of 9.41 and an F number of 3.40 to 6.46. FIG. 3 is a lens cross-sectional view at the wide-angle end when focusing on an object at infinity according to the second embodiment. FIGS. 4A and 4B are aberration diagrams at the wide-angle end and the telephoto end when focusing on an infinitely distant object according to the second embodiment. The second embodiment is a zoom lens having a zoom ratio of 8.46 and an F number of 3.51 to 6.47.

  FIG. 5 is a lens cross-sectional view at the wide-angle end when focusing on an object at infinity according to the third embodiment. FIGS. 6A and 6B are aberration diagrams at the wide-angle end and the telephoto end during focusing on an infinitely distant object according to the third embodiment. The third embodiment is a zoom lens having a zoom ratio of 8.45 and an F number of 3.42 to 6.47. FIG. 7 is a lens cross-sectional view at the wide-angle end when focusing on an object at infinity according to the fourth embodiment. FIGS. 8A and 8B are aberration diagrams at the wide-angle end and the telephoto end during focusing on an infinitely distant object according to the fourth embodiment. Example 4 is a zoom lens having a zoom ratio of 7.05 and an F number of 3.73 to 6.47.

  FIG. 9 is a schematic view of the main part of a digital single-lens reflex camera (imaging device) equipped with the zoom lens of the present invention.

  The zoom lens of the present invention is used as an imaging optical system of an imaging apparatus such as a digital camera, a video camera, a broadcasting camera, a surveillance camera, and a silver halide photography camera. The zoom lens of the present invention 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, L0 is a zoom lens. If i is the order of the lens group from the object side, Li is the i-th lens group.

  SP is an aperture stop. IP is the image plane. The image plane IP corresponds to an imaging plane of an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor when a zoom lens is used as an imaging apparatus such as a digital camera or a video camera. When a zoom lens is used as an imaging device of a silver salt film camera, it corresponds to a film surface. The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. The arrow related to Focus indicates the moving direction of the focus lens group during focusing from infinity to a short distance.

  In the spherical aberration diagram, Fno is an F number. D is a d-line (wavelength 587.6 nm) and g is a g-line (wavelength 435.8 nm). In the astigmatism diagram, M is a meridional image plane at the d-line, and S is a sagittal image plane at the d-line. The distortion diagram shows the d-line. The lateral chromatic aberration diagram shows the g-line. ω is a half angle of view (degree).

  The zoom lens according to the present invention includes the following lens groups arranged 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, the third lens unit L3 having a positive refractive power, the fourth lens unit L4 having a positive refractive power, and the first lens unit L4 having a negative refractive power. 5 lens unit L5 and negative lens power sixth lens unit L6. A seventh lens unit L7 having a positive refractive power may be provided on the image side of the sixth lens unit L6 having a negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves to the object side.

  The distance between adjacent lens units changes during zooming. During focusing from infinity to a short distance, the fifth lens unit L5 (focus lens unit) moves to the image side. In general, a five-unit zoom lens including first to fifth lens units having positive, negative, positive, negative, and positive refractive power in order from the object side to the image side can easily achieve a high zoom ratio. Thus, a zoom lens in which a lens group having a positive refractive power and a lens group having a negative refractive power are alternately arranged can easily obtain a high zoom ratio due to a change in the interval between the lens groups. However, when the position of each lens group is shifted due to a manufacturing error, the optical performance tends to be greatly reduced.

  In particular, if the third lens group, where the incident height of the axial ray is high at both the wide-angle end and the telephoto end and the refractive power (power) is the strongest in the lens unit having a positive refractive power, there is a manufacturing error, the optical performance is large. It will decline. On the other hand, a 6-group zoom lens composed of first to sixth lens groups having positive, negative, positive, positive, negative, and positive refractive powers arranged in order from the object side to the image side is: A high zoom ratio is easy as in the case of a five-group zoom lens. In this 6-group zoom lens, both the third lens group and the fourth lens group have positive refractive power, and the positive refractive power can be dispersed. According to this, it is possible to reduce a decrease in optical performance due to manufacturing errors.

  In view of this, the zoom lens according to the present invention has first to fifth lens groups having positive, negative, positive, positive, and negative refractive powers arranged in order from the object side to the image side. As a result, a configuration in which the optical performance does not easily deteriorate due to manufacturing errors is obtained. At this time, the second lens group becomes large and heavy. For this reason, when focusing is performed with the second lens group, it is difficult to realize silent driving suitable for moving images.

  In the 5-group zoom lens having the refractive power arrangement described above, the fourth lens group having a negative refractive power is relatively small and light. For this reason, in the five-group zoom lens, when the fourth lens group performs focusing, it is easy to realize silent driving suitable for moving images.

  In general, when focusing is performed, if the focus sensitivity (image plane movement amount per unit drive) of the focus lens group is too high, drive control becomes very difficult. When focusing is performed with the fourth lens group in the five-group zoom lens having the above-described refractive power arrangement, the sensitivity of focusing tends to increase. In order to reduce the focusing sensitivity, it is necessary to relax the refractive power of the fourth lens group. If this happens, the zooming effect during movement of the fourth lens unit due to zooming becomes small, and it becomes difficult to achieve a high zoom ratio.

  Therefore, in the present invention, the fifth lens unit L5 having negative refractive power is divided into two lens groups, a lens unit having negative refractive power and a lens unit having negative refractive power. By focusing with the fifth lens unit L5 having negative refractive power on the object side, the combined refractive power of the two lens units having negative refractive power is increased while lowering the focusing sensitivity, and the zoom lens also has a high change in zooming. I try to get a double effect.

  Specifically, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, the third lens unit L3 having a positive refractive power, which are arranged in order from the object side to the image side, A fourth lens unit L4 having a negative refractive power, a fifth lens unit L5 having a negative refractive power, and a sixth lens unit L6 having a negative refractive power. The first lens unit L1 moves to the object side during zooming from the wide-angle end to the telephoto end, and the interval between adjacent lens units changes during zooming. The fifth lens unit L5 is moved during focusing.

The focal length of the fifth lens unit L5 is f5, and the focal length of the sixth lens unit L6 is f6. At this time,
0.0 <f5 / f6 <0.5 (1)
The following conditional expression is satisfied.

  In the zoom lens of the present invention, the first lens unit L1 and the second lens unit. If the interval of L2 is widened, the zooming effect is most efficiently obtained.

  At this time, the zooming effect can also be obtained by fixing the first lens unit L1 and moving the second lens unit L2 to the image side. In contrast, in the present invention, the first lens unit L1 is moved to the object side during zooming from the wide-angle end to the telephoto end. By adopting a method of moving the first lens unit L1 to the object side, the total lens length at the wide angle end is shortened. In the method of moving the second lens unit L2 to the image side, it is necessary to secure a moving space for the second lens unit L2 in advance.

  Conditional expression (1) is for improving the zooming effect in the combined lens unit of the fifth lens unit L5 and the sixth lens unit L6 while making the focus sensitivity appropriate when focusing with the fifth lens unit L5. Is. If the upper limit value of conditional expression (1) is deviated, the focus sensitivity of the fifth lens unit L5 becomes too loose, the driving amount of the fifth lens unit L5 during focusing increases, and the entire system increases in size. Furthermore, since the refractive power of the sixth lens unit L6 is too strong, the variation in field curvature during zooming becomes large, which is not preferable.

If the lower limit of conditional expression (1) is deviated, the focusing sensitivity of the fifth lens unit L5 becomes too high, and the drive control of the fifth lens unit L5 during focusing becomes difficult. Furthermore, since the refractive power of the sixth lens unit L6 is too weak to obtain a sufficient zooming effect, it is not preferable. Conditional expression (1) is more preferably set to the following numerical range.
0.10 <f5 / f6 <0.45 (1A)

  Next, more preferable conditions for implementing the present invention will be described. The focal length of the third lens unit L3 is f3, and the focal length of the fourth lens unit L4 is f4. The fifth lens unit L5 is preferably composed of three or less lenses. The fifth lens unit L5 may include a positive lens and a negative lens. The fifth lens unit L5 is preferably composed of a positive lens G5p and a negative lens G5n arranged in order from the object side to the image side. At this time, the Abbe number of the material of the positive lens G5p is ν5p, and the Abbe number of the material of the negative lens G5n is ν5n.

  Let fw be the focal length of the entire system at the wide-angle end. Let the focal length of the first lens unit L1 be f1. Let the focal length of the second lens unit L2 be f2. At this time, one or more of the following conditional expressions should be satisfied.

1.0 <f4 / f3 <8.0 (2)
1.3 <ν5n / ν5p <2.5 (3)
1.0 <−f5 / fw <2.5 (4)
0.0 <−f6 / fw <0.5 (5)
3.5 <f1 / fw <6.0 (6)
0.7 <−f2 / fw <1.2 (7)
1.0 <f3 / fw <2.0 (8)
1.5 <f4 / fw <3.5 (9)

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (2) appropriately sets the refractive power distribution of the positive refractive power of the third lens unit L3L3 and the positive refractive power of the fourth lens unit L4, and the optical performance due to the manufacturing error of the lens unit having the positive refractive power. This is to reduce the decrease. If the upper limit value of conditional expression (2) is deviated, the refractive power of the fourth lens unit L4 is too weak, and the optical performance is greatly degraded due to manufacturing errors of the third lens unit L3. If the lower limit value of conditional expression (2) is deviated, the positive refractive power of the fourth lens unit L4 is too strong, and the optical performance deteriorates due to manufacturing errors of the fourth lens unit L4.

Conditional expression (2) is more preferably set to the following numerical range.
1.2 <f4 / f3 <2.5 (2A)

  Next, the fifth lens unit L5 is preferably composed of three or less lenses. This is preferable because the fifth lens unit L5 for focusing can be reduced in size and weight and can be driven silently.

  Furthermore, the fifth lens unit L5 may include a positive lens and a negative lens. This is preferable because it makes it easier to compensate for aberration fluctuations during focusing. Furthermore, it is preferable that the fifth lens unit L5 be arranged in order of the positive lens G5p and the negative lens G5n from the object side to the image side. This is more preferable because the positive lens G5p is disposed on the object side where the incident height of the axial ray is high, and it becomes easy to compensate for variations in spherical aberration and axial chromatic aberration during focusing.

Conditional expression (3) is for satisfactorily compensating for variations in longitudinal chromatic aberration due to focusing of the fifth lens unit L5. Deviating from the lower limit value of conditional expression (3) is not preferable because the compensation effect of axial chromatic aberration at the positive lens G5p during focusing is reduced. A low dispersion material that deviates from the upper limit value of the conditional expression (3) is not preferable because the refractive index becomes relatively small in the material and astigmatism increases. Conditional expression (3) is more preferably set to the following numerical range.
1.4 <ν5n / ν5p <2.2 (3A)

Conditional expression (4) is for making the focus sensitivity appropriate when focusing with the fifth lens unit L5. Deviating from the upper limit value of conditional expression (4) is not preferable because the focus sensitivity of the fifth lens unit L5 becomes too loose, the driving amount during focusing increases, and the entire system increases in size. Deviating from the lower limit value of conditional expression (4) is not preferable because the focusing sensitivity of the fifth lens unit L5 becomes too high, and drive control during focusing becomes difficult. Conditional expression (4) is more preferably set to the following numerical range.
1.05 <−f5 / fw <2.10 (4A)

Conditional expression (5) is for appropriately adjusting the negative refractive power of the sixth lens unit L6 and effectively obtaining a zooming effect in the combined lens unit of the fifth lens unit L5 and the sixth lens unit L6. is there. Deviating from the upper limit value of conditional expression (5) is not preferable because the negative refractive power of the sixth lens unit L6 is too weak (the absolute value of the negative refractive power is too small) and the zooming effect is weakened. If the lower limit of conditional expression (5) is deviated, the negative refractive power of the sixth lens unit L6 is too strong (the absolute value of the negative refractive power becomes too large), and the variation in field curvature during zooming is large. It is not preferable. Conditional expression (5) is more preferably set to the following numerical range.
0.05 <−f6 / fw <0.30 (5A)

  Conditional expressions (6), (7), (8), and (9) indicate the refractive powers of the first lens unit L1, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4. This is to optimize the size of the entire system while suppressing aberration fluctuation during zooming.

  If the upper limit of conditional expression (6) is deviated, the positive refractive power of the first lens unit L1 is too weak, and it becomes difficult to achieve a high zoom ratio. Deviating from the lower limit value of conditional expression (6) is not preferable because the positive refractive power of the first lens unit L1 is too strong and the variation of spherical aberration becomes large during zooming. If the upper limit of conditional expression (7) is deviated, the negative refractive power of the second lens unit L2 is too weak, and it becomes difficult to achieve a high zoom ratio. Deviating from the lower limit value of conditional expression (7) is preferable because the negative refractive power of the second lens unit L2 is too strong and distortion increases at the wide-angle end, and astigmatism fluctuations increase during zooming. Absent.

  If the upper limit value of conditional expression (8) is deviated, the positive refractive power of the third lens unit L3 is too weak, and it becomes difficult to achieve a high zoom ratio. Deviating from the lower limit value of conditional expression (8) is not preferable because the positive refractive power of the third lens unit L3 is too strong and the variation of spherical aberration increases during zooming.

  Deviating from the upper limit of conditional expression (9) is not preferable because the positive refractive power of the fourth lens unit L4 is too weak and it is difficult to ensure a sufficient zoom ratio due to the movement of the fourth lens unit L4 during zooming. . Deviating from the lower limit value of conditional expression (9) is not preferable because the positive refractive power of the fourth lens unit L4 is too strong and the variation of spherical aberration increases during zooming. The conditional expressions (6) to (9) are more preferably set to the following numerical ranges.

4.0 <f1 / fw <5.5 (6A)
0.8 <−f2 / fw <1.0 (7A)
1.3 <f3 / fw <1.8 (8A)
1.8 <f4 / fw <2.8 (9A)

  Next, the lens configuration in each example will be described. The zoom lens according to the first exemplary embodiment includes the following lens groups arranged 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, the third lens unit L3 having a positive refractive power, the fourth lens unit L4 having a positive refractive power, and the first lens unit L4 having a negative refractive power. 5 lens group L5, 6th lens group L6 of negative refractive power, and 7th lens group L7 of positive refractive power. Example 1 is a seven-group zoom lens.

  During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the second lens unit L2, the third lens unit L3, the fourth lens unit L4, the fifth lens unit L5, and the sixth lens unit L6 move to the object side. To do. The seventh lens unit L7 does not move during zooming. The distance between the first lens group L1 and the second lens group L2 is wider at the telephoto end than at the wide-angle end, the distance between the second lens group L2 and the third lens group L3 is narrow, and the third lens group L3 and the fourth lens. The interval between the groups L4 is narrowed.

  Further, the distance between the fourth lens group L4 and the fifth lens group L5 is wide, the distance between the fifth lens group L5 and the sixth lens group L6 does not change, and the distance between the sixth lens group L6 and the seventh lens group L7 is the same. Become wider. During focusing from infinity to a short distance, the fifth lens unit L5 moves to the image side. When the refractive powers of the fifth lens unit L5 and the sixth lens unit L6 satisfy the conditional expressions (1), (4), and (5), the zooming effect is enhanced while maintaining the focus sensitivity appropriately. .

  The fifth lens unit L5 is composed of a positive lens G5p and a negative lens G5n in order from the object side to the image side, and satisfies the conditional expression (3). Good variation in spherical aberration and axial chromatic aberration during focusing It is corrected to. In addition, when the refractive power of the third lens unit L3 and the refractive power of the fourth lens unit L4 satisfy the conditional expression (2), the positive refractive power is appropriately dispersed, and reduction in optical performance due to manufacturing errors is reduced. ing. In this embodiment, image blur correction (anti-vibration) is performed by moving the fourth lens unit L4 so as to have a component perpendicular to the optical axis.

  The zoom lens of the second embodiment is the same as the first embodiment in zoom type such as the number of lens groups and the sign of the refractive power of each lens group. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the second lens unit L2, the third lens unit L3, the fourth lens unit L4, the fifth lens unit L5, and the sixth lens unit L6 move to the object side. To do. The seventh lens unit L7 does not move during zooming. The change in the distance between the lens units at the telephoto end compared to the wide-angle end is the same as in the first embodiment. The optical action of each lens group is the same as in the first embodiment.

  The zoom type in the zoom lens of Example 3 is the same as that of Example 1. In Example 3, during zooming from the wide-angle end to the telephoto end, the first lens unit L1, the third lens unit L3, the fourth lens unit L4, the fifth lens unit L5, and the sixth lens unit L6 move to the object side. The second lens unit L2 moves to the object side while drawing a convex locus on the object side.

  The distance between the first lens group L1 and the second lens group L2 is wider at the telephoto end than at the wide-angle end, the distance between the second lens group L2 and the third lens group L3 is narrow, and the third lens group L3 and the fourth lens. The distance between the groups L4 is narrow. The distance between the fourth lens group L4 and the fifth lens group L5 is wide, the distance between the fifth lens group L5 and the sixth lens group L6 is narrow, and the distance between the sixth lens group L6 and the seventh lens group L7 is wide. The optical action of each lens group is the same as in the first embodiment.

  The zoom lens according to the fourth exemplary embodiment includes the following lens groups arranged 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, the third lens unit L3 having a positive refractive power, the fourth lens unit L4 having a positive refractive power, and the first lens unit L4 having a negative refractive power. 5 lens unit L5 and negative lens power sixth lens unit L6. Example 4 is a 6-group zoom lens. During zooming from the wide-angle end to the telephoto end, the first lens unit L1, the third lens unit L3, the fourth lens unit L4, the fifth lens unit L5, and the sixth lens unit L6 move to the object side. The second lens unit L2 moves to the object side while drawing a convex shape on the image side.

  Compared to the wide-angle end, the distance between the first lens group L1 and the second lens group L2 is wider at the telephoto end, the distance between the second lens group L2 and the third lens group L3 is smaller, and the third lens group L3 and the fourth lens group. The interval between L4 is narrow and the interval between the fourth lens unit L4 and the fifth lens unit L5 is narrow. The distance between the fifth lens unit L5 and the sixth lens unit L6 is wide. The optical action of each lens unit of the first lens unit L1 to the sixth lens unit L6 is the same as that of the first embodiment.

  FIG. 9 illustrates a single-lens reflex camera as an example of the imaging apparatus of the present invention. In FIG. 9, reference numeral 10 denotes an interchangeable lens having the zoom lens 1 of any one of the first to fourth embodiments. The zoom lens 1 is held by a lens barrel 2 that is a holding member. Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects the light beam from the interchangeable lens 10 upward, and a focusing screen 4 that is disposed in the image forming apparatus of the interchangeable lens 10. Further, it is constituted by a penta roof prism 5 for converting an inverted image formed on the focusing screen 4 into an erect image, an eyepiece 6 for observing the erect image, and the like.

  Reference numeral 7 denotes a photosensitive surface, on which an imaging element (photoelectric conversion element) for receiving an image formed by a zoom lens such as a CCD sensor or a CMOS sensor, or a silver salt film is arranged. At the time of imaging, the quick return mirror 3 is retracted from the optical path, and an image is formed on the photosensitive surface 7 by the interchangeable lens 10. The benefits described in the first to fourth embodiments can be effectively enjoyed in the imaging apparatus disclosed in the present embodiment. The present invention can be similarly applied to a mirrorless single-lens reflex camera without the quick return mirror 3 as an imaging device.

  The preferred embodiments of the imaging optical system of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

  Hereinafter, specific numerical data of Examples 1 to 4 are shown. In each numerical data, i indicates the order counted from the object side, ri is the radius of curvature of the i-th optical surface (i-th surface), and di is on the axis between the i-th surface and the (i + 1) -th surface. Indicates the interval. Ndi and νdi are the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line, respectively. The aspheric coefficient is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are non-existent. Spherical coefficient

It is expressed by the following formula. * Means a surface having an aspherical shape. “E-x” means 10-x. BF is an air equivalent back focus. The total lens length is a value obtained by adding the value of the back focus BF to the distance from the first lens surface to the final lens surface. Table 1 shows the relationship between the above-described conditional expressions and numerical data.

(Numeric data 1)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 198.873 1.50 1.91082 35.3 41.97
2 40.323 7.14 1.49700 81.5 37.84
3 -264.154 0.15 36.51
4 46.385 4.93 1.76385 48.5 34.01
5 -673.110 (variable) 33.51
6 271.155 1.10 1.88300 40.8 22.30
7 12.848 5.33 17.35
8 -21.984 0.90 1.77250 49.6 17.20
9 185.815 0.15 17.29
10 32.682 4.98 1.76182 26.5 17.43
11 -21.267 0.37 17.09
12 -17.949 0.80 1.77250 49.6 17.09
13 -51.928 (variable) 17.07
14 (Aperture) ∞ 1.00 13.74
15 * 11.578 4.75 1.58313 59.4 15.02
16 * -80.796 1.54 14.38
17 36.810 0.80 1.88300 40.8 13.03
18 8.199 4.39 1.49700 81.5 11.75
19 -163.069 (variable) 11.56
20 35.246 3.44 1.80610 33.3 11.23
21 -13.251 0.70 1.84666 23.8 11.00
22 -116.680 (variable) 10.84
23 134.572 1.80 1.78472 25.7 10.93
24 -30.547 0.15 10.93
25 -37.012 0.70 1.88300 40.8 10.87
26 17.298 (variable) 10.88
27 * -38.909 1.40 1.52996 55.8 14.32
28 * -78.739 (variable) 15.64
29 -54.752 3.77 1.48749 70.2 25.34
30 -24.401 26.02

Aspheric data 15th surface
K = 0.00000e + 000 A 4 = -4.51435e-005 A 6 = 3.49602e-009 A 8 = -3.37383e-009 A10 = 1.18237e-011

16th page
K = 0.00000e + 000 A 4 = 3.21894e-005 A 6 = 2.02765e-007 A 8 = -4.59069e-009 A10 = 4.09901e-011

27th page
K = 0.00000e + 000 A 4 = -2.43806e-004 A 6 = -8.65291e-007 A 8 = 1.39952e-008 A10 = -5.71046e-011

28th page
K = 0.00000e + 000 A 4 = -1.91852e-004 A 6 = -2.19312e-007 A 8 = 9.88639e-009 A10 = -2.84875e-011

Various data

Zoom ratio 9.41

Wide angle Medium telephoto focal length 15.45 49.96 145.34
F number 3.40 5.69 6.46
Half angle of view (degrees) 38.52 13.83 4.84
Image height 12.30 12.30 12.30
Total lens length 103.56 119.51 145.46
BF 10.50 10.50 10.50

d 5 0.90 14.60 39.65
d13 26.78 8.35 2.01
d19 3.00 3.72 1.41
d22 1.51 4.85 3.11
d26 8.08 4.02 8.08
d28 1.00 21.71 28.95

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 70.12 13.71 7.46 -0.90
2 6 -13.84 13.64 0.61 -9.92
3 14 23.66 12.48 -0.78 -9.19
4 20 37.27 4.14 0.40 -1.90
5 23 -23.48 2.65 1.87 0.32
6 27 -146.93 1.40 -0.90 -1.83
7 29 86.77 3.77 4.39 1.96

Single lens Data lens Start surface Focal length
1 1 -55.78
2 2 70.94
3 4 56.98
4 6 -15.30
5 8 -25.40
6 10 17.62
7 12 -35.88
8 15 17.70
9 17 -12.11
10 18 15.84
11 20 12.34
12 21 -17.71
13 23 31.88
14 25 -13.27
15 27 -146.93
16 29 86.77

(Numeric data 2)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 182.490 1.50 1.91082 35.3 41.81
2 40.390 6.96 1.49700 81.5 37.73
3 -334.389 0.15 36.44
4 46.123 5.37 1.76385 48.5 36.28
5 -1009.243 (variable) 35.77
6 188.791 1.10 1.83481 42.7 21.39
7 12.282 4.86 16.53
8 -23.669 0.90 1.88300 40.8 16.36
9 117.175 0.68 16.31
10 32.609 5.80 1.78472 25.7 16.42
11 -22.439 0.41 15.92
12 -17.879 0.80 1.77250 49.6 15.92
13 -48.031 (variable) 15.96
14 (Aperture) ∞ 1.00 13.20
15 * 11.948 4.15 1.58313 59.4 14.36
16 * -181.947 2.21 13.84
17 43.363 0.80 1.88300 40.8 12.60
18 8.701 4.16 1.49700 81.5 11.63
19 -50.521 (variable) 11.57
20 28.134 3.07 1.63854 55.4 11.22
21 -21.933 0.70 1.90366 31.3 11.04
22 -55.997 (variable) 11.13
23 64.637 1.44 1.85478 24.8 11.27
24 1932.258 0.15 11.21
25 189.424 0.70 1.77250 49.6 11.19
26 14.844 (variable) 11.09
27 * -16.820 1.40 1.52996 55.8 14.29
28 * -28.684 (variable) 15.59
29 -54.143 3.81 1.51633 64.1 25.29
30 -24.120 26.00

Aspheric data 15th surface
K = 0.00000e + 000 A 4 = -3.45334e-005 A 6 = -1.26495e-008 A 8 = -1.60788e-009 A10 = 4.51942e-012

16th page
K = 0.00000e + 000 A 4 = 3.00782e-005 A 6 = 1.18316e-007 A 8 = -2.15861e-009 A10 = 2.03658e-011

27th page
K = 0.00000e + 000 A 4 = 3.18319e-005 A 6 = -2.00662e-007 A 8 = -5.37809e-009 A10 = 1.18688e-010

28th page
K = 0.00000e + 000 A 4 = 5.01150e-005 A 6 = -2.76469e-007 A 8 = -3.38645e-010 A10 = 3.46028e-011

Various data

Zoom ratio 8.45

Wide angle Medium Telephoto focal length 15.45 50.00 130.49
F number 3.51 5.82 6.47
Half angle of view (degrees) 38.52 13.82 5.38
Image height 12.30 12.30 12.30
Total lens length 103.56 120.68 145.50
BF 10.52 10.52 10.52

d 5 0.90 15.27 39.37
d13 24.90 6.92 2.00
d19 3.87 3.61 1.87
d22 1.60 5.74 3.60
d26 8.57 4.68 8.57
d28 1.11 21.81 27.47

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 71.68 13.98 7.14 -1.38
2 6 -13.58 14.55 0.57 -10.64
3 14 24.45 12.32 -0.03 -8.97
4 20 37.72 3.77 0.51 -1.76
5 23 -29.20 2.29 1.90 0.55
6 27 -80.00 1.40 -1.35 -2.31
7 29 80.76 3.81 4.34 1.93

Single lens Data lens Start surface Focal length
1 1 -57.24
2 2 72.96
3 4 57.87
4 6 -15.78
5 8 -22.23
6 10 17.76
7 12 -37.30
8 15 19.38
9 17 -12.46
10 18 15.29
11 20 19.77
12 21 -40.29
13 23 78.21
14 25 -20.89
15 27 -80.00
16 29 80.76

(Numerical data 3)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 143.012 1.50 1.90366 31.3 41.34
2 50.382 5.98 1.49700 81.5 38.12
3 -382.473 0.15 36.98
4 56.055 4.39 1.76385 48.5 36.29
5 1291.354 (variable) 35.73
6 -455.313 1.10 1.83481 42.7 22.42
7 13.420 4.63 17.63
8 -34.636 0.90 1.88300 40.8 17.51
9 125.903 2.64 17.42
10 37.434 3.51 1.80809 22.8 17.60
11 -49.100 1.00 1.77250 49.6 17.29
12 -595.129 (variable) 17.06
13 (Aperture) ∞ 1.00 13.82
14 * 12.342 3.97 1.58313 59.4 15.01
15 * 122.636 2.80 14.48
16 28.302 0.80 1.88300 40.8 13.25
17 8.731 4.54 1.49700 81.5 12.20
18 -72.467 (variable) 12.12
19 * 27.894 3.54 1.58313 59.4 11.89
20 -15.438 0.70 1.90366 31.3 11.43
21 -34.814 (variable) 11.38
22 25.339 1.72 1.84666 23.8 10.88
23 204.434 0.70 1.88300 40.8 10.72
24 12.469 (variable) 10.49
25 -15.510 0.70 1.77250 49.6 13.84
26 -22.064 (variable) 14.65
27 -46.743 3.43 1.48749 70.2 24.37
28 -24.000 25.10

Aspheric data 14th surface
K = 0.00000e + 000 A 4 = -2.70831e-005 A 6 = -3.24198e-008 A 8 = -1.00892e-009 A10 = -1.15926e-011

15th page
K = 0.00000e + 000 A 4 = 2.19792e-005 A 6 = 6.71481e-008 A 8 = -1.64666e-009 A10 = 1.16606e-013

19th page
K = 0.00000e + 000 A 4 = 5.71463e-006 A 6 = 7.53291e-008 A 8 = 7.27883e-010

Various data

Zoom ratio 8.45

Wide angle Medium Telephoto focal length 15.45 50.00 130.51
F number 3.42 5.75 6.47
Half angle of view (degrees) 38.52 13.82 5.38
Image height 12.30 12.30 12.30
Total lens length 103.56 121.86 145.49
BF 11.00 11.00 11.00

d 5 0.90 16.50 42.15
d12 27.84 8.74 2.00
d18 3.03 3.91 0.80
d21 1.53 4.55 3.91
d24 8.68 4.78 8.53
d26 0.90 22.70 27.41

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 78.93 12.02 4.98 -2.45
2 6 -14.72 13.77 -0.07 -11.83
3 13 25.83 13.10 0.09 -9.59
4 19 38.69 4.24 0.84 -1.83
5 22 -29.29 2.42 2.70 1.28
6 25 -70.88 0.70 -0.98 -1.39
7 27 96.42 3.43 4.51 2.32

Single lens Data lens Start surface Focal length
1 1 -86.75
2 2 89.99
3 4 76.60
4 6 -15.60
5 8 -30.68
6 10 26.77
7 11 -69.33
8 14 23.23
9 16 -14.58
10 17 15.97
11 19 17.57
12 20 -31.23
13 22 34.01
14 23 -15.06
15 25 -70.88
16 27 96.42

(Numeric data 4)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 106.598 1.50 1.91082 35.3 40.62
2 36.423 6.11 1.49700 81.5 36.53
3 253.154 0.15 36.34
4 43.322 5.33 1.76385 48.5 36.42
5 977.649 (variable) 35.90
6 97.697 1.10 1.83481 42.7 24.29
7 12.316 5.83 18.72
8 -33.346 0.90 1.88300 40.8 18.62
9 84.377 0.87 18.70
10 31.920 4.53 1.78472 25.7 19.17
11 -33.501 0.16 18.94
12 -30.150 0.80 1.77250 49.6 18.94
13 -70.824 (variable) 18.83
14 (Aperture) ∞ 1.00 13.19
15 * 11.376 4.22 1.58313 59.4 13.96
16 * -119.159 2.76 13.34
17 -293.303 0.80 1.88300 40.8 11.67
18 8.787 4.17 1.49700 81.5 10.93
19 -26.291 (variable) 11.05
20 26.902 2.83 1.69680 55.5 10.81
21 -30.073 0.70 1.90366 31.3 10.80
22 -117.954 (variable) 10.88
23 36.458 2.10 1.80000 29.8 11.22
24 -31.416 0.22 11.19
25 -27.170 0.70 1.77250 49.6 11.14
26 * 14.304 (variable) 11.10
27 604.082 0.70 1.83400 37.2 14.79
28 34.422 3.21 15.32
29 22.568 3.98 1.48749 70.2 21.91
30 95.890 22.36

Aspheric data 15th surface
K = 0.00000e + 000 A 4 = -3.51251e-005 A 6 = -4.07564e-008 A 8 = -1.25007e-009 A10 = -1.73201e-011

16th page
K = 0.00000e + 000 A 4 = 2.75794e-005 A 6 = 8.34718e-008 A 8 = -2.04727e-009 A10 = 3.94544e-012

26th page
K = 0.00000e + 000 A 4 = -8.58392e-006 A 6 = -7.04582e-008 A 8 = 1.45526e-009 A10 = -7.98802e-011

Various data

Zoom ratio 7.05

Wide angle Medium Telephoto focal length 18.50 50.00 130.44
F number 3.73 5.31 6.47
Half angle of view (degrees) 36.44 15.28 5.98
Image height 13.66 13.66 13.66
Total lens length 104.55 112.29 146.47
BF 10.50 19.69 37.01

d 5 1.00 17.18 42.59
d13 27.12 6.50 2.00
d19 2.02 0.80 1.61
d22 2.54 5.99 1.21
d26 6.71 7.47 7.40

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 81.59 13.09 5.26 -2.79
2 6 -17.34 14.19 -0.23 -12.17
3 14 28.63 12.95 -1.37 -10.80
4 20 37.60 3.53 0.16 -1.89
5 23 -30.94 3.02 3.26 1.34
6 27 -195.63 7.89 -7.42 -14.06

Single lens Data lens Start surface Focal length
1 1 -61.37
2 2 84.81
3 4 59.20
4 6 -16.98
5 8 -26.97
6 10 21.48
7 12 -68.55
8 15 18.02
9 17 -9.65
10 18 13.80
11 20 20.80
12 21 -44.84
13 23 21.39
14 25 -12.04
15 27 -43.79
16 29 59.49

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group L7 7th lens group

Claims (14)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, which are arranged in order from the object side to the image side. A fifth lens group having a negative refractive power and a sixth lens group having a negative refractive power, and when zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side and is adjacent to each other during zooming. A zoom lens in which the distance between the lens groups changes, and the fifth lens group moves during focusing;
When the focal length of the fifth lens group is f5 and the focal length of the sixth lens group is f6,
0.0 <f5 / f6 <0.5
A zoom lens characterized by satisfying the following conditional expression: When the focal length of the third lens group is f3 and the focal length of the fourth lens group is f4,
1.0 <f4 / f3 <8.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom lens according to claim 1, wherein the fifth lens group includes three or less lenses.   The zoom lens according to claim 3, wherein the fifth lens group includes a positive lens and a negative lens.   5. The zoom lens according to claim 4, wherein the fifth lens group includes a positive lens and a negative lens arranged in order from the object side to the image side. When the Abbe number of the material of the positive lens is ν5p and the Abbe number of the material of the negative lens is ν5n,
1.3 <ν5n / ν5p <2.5
The zoom lens according to claim 5, wherein the following conditional expression is satisfied. When the focal length of the entire system at the wide angle end is fw,
1.0 <-f5 / fw <2.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the entire system at the wide angle end is fw,
0.0 <−f6 / fw <0.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the first lens group is f1, and the focal length of the entire system at the wide angle end is fw,
3.5 <f1 / fw <6.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the second lens group is f2, and the focal length of the entire system at the wide angle end is fw,
0.7 <−f2 / fw <1.2
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the third lens group is f3 and the focal length of the entire system at the wide angle end is fw,
1.0 <f3 / fw <2.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the fourth lens group is f4 and the focal length of the entire system at the wide angle end is fw,
1.5 <f4 / fw <3.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom lens according to any one of claims 1 to 12, further comprising a seventh lens group that is stationary during zooming and has a positive refractive power on the image side of the sixth lens group.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup element that receives an image formed by the zoom lens.