JP2013242431A - Zoom lens and imaging apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which can reduce occurrence of chromatic aberration at the telephoto end, has a wide angle of view and a high zoom ratio, and achieves excellent optical performance over the entire zoom range.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; an aperture stop; a third lens group having a positive refractive power; and a rear group having one or more lens groups, and performs zooming operation by changing the distances between the lens groups. In the zoom lens, the positions of the first lens group and the aperture stop move nearer to the object side at the telephoto end than at the wide-angle end. The third lens group includes one or more positive lenses. A partial dispersion ratio θgF3P of the material of one positive lens in the third lens group, the Abbe number νd3P thereof, the focal length fT of the entire system at the telephoto end, and the focal length f3 of the third 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 a video camera, an electronic still camera, a broadcast camera, a surveillance camera, or a camera using a silver salt film. It is suitable for an imaging device.

  In recent years, imaging devices such as a video camera using a solid-state imaging device, a digital still camera, a broadcasting camera, a surveillance camera, and a camera using a silver salt film have been improved in function, and the entire device has been downsized. The photographic optical system used therefor is required to be a zoom lens having a short overall lens length, a compact size and a wide angle of view and a high zoom ratio (high zoom ratio).

  In particular, in addition to correction of monochromatic (short wavelength) aberrations such as spherical aberration and coma aberration, it is required to be a zoom lens with high resolution in which chromatic aberration is also corrected well. A zoom lens that meets these requirements includes a first, second, and third lens group having positive, negative, and positive refractive power in order from the object side to the image side, followed by one or more lens groups. A positive lead type zoom lens having a group is known.

  As a positive lead type zoom lens, there is known a four-group zoom lens including four lens groups having positive, negative, positive, and positive refractive powers in order from the object side to the image side. In this positive lead type four-group zoom lens, a zoom lens is known in which anomalous dispersion material is used as the material of the positive lens of the first lens group and the third lens group, and chromatic aberration (secondary spectrum) is corrected well. (Patent Document 1).

  In addition, a zoom lens using a lens made of a material having anomalous dispersion in the third lens group in a five-group zoom lens composed of lens groups of positive, negative, positive, negative, and positive refractive power in order from the object side is known. (Patent Document 2). In addition, a zoom lens having a wide angle of view and a high zoom ratio is known that includes five lens groups having positive, negative, positive, positive, and positive refractive power in order from the object side to the image side (Patent Document 3).

JP 2010-91788 A JP 2010-32700 A JP 2004-117826 A

  A positive lead type zoom lens is relatively easy to achieve a wide angle of view and a high zoom ratio while reducing the size of the entire system. In many positive lead type zoom lenses, if the zoom ratio is increased while the focal length at the telephoto end is increased, a secondary spectrum of axial chromatic aberration is frequently generated in the zoom region on the telephoto side. Therefore, in a positive lead type zoom lens, it is important to reduce chromatic aberration, particularly the secondary spectrum, in order to obtain high optical performance over the entire zoom range while achieving a high zoom ratio.

  In order to reduce chromatic aberration and secondary spectrum, it is effective to use a lens made of a material having low dispersion and anomalous dispersion at an appropriate position in the zoom lens. As for chromatic aberration, it is important to optimize each lens group constituting the zoom lens based on material characteristics (Abbe number and partial dispersion ratio).

  In particular, it is important to appropriately set the refractive power, lens configuration, and the like of the first lens group and the third lens group in the above-described positive lead type zoom lens including four or five groups. In addition, it is important to appropriately set the amount of movement of the first lens group, the third lens group, and the aperture stop during zooming. If these configurations are not set appropriately, the entire system can be reduced in size, with a wide angle of view, a high zoom ratio, a secondary spectrum reduced at the telephoto end, and a zoom lens with high optical performance in the entire zoom range. It becomes difficult.

  For example, when the focal length at the telephoto end includes a long focal length such that the converted focal length in a zoom lens using a silver salt film exceeds 1000 mm, a glass material having anomalous dispersion is simply used for the first lens group. Then, it is difficult to reduce longitudinal chromatic aberration.

  In order to reduce axial chromatic aberration at the telephoto end, it is preferable to use an anomalous dispersion glass material for the positive lenses of the first lens group and the third lens group. However, if an anomalous dispersion glass material is used for the positive lenses of the first lens group and the third lens group, the lateral chromatic aberration increases at the wide angle end. If an anomalous dispersion glass material is used to reduce the axial chromatic aberration at the telephoto end in this way, the chromatic aberration of magnification increases at the wide-angle end. Therefore, it is important to correct both chromatic aberrations in a balanced manner. .

  An object of the present invention is to provide a zoom lens capable of reducing the occurrence of chromatic aberration at the telephoto end, and having a wide angle of view and a high zoom ratio and obtaining good optical characteristics in the entire zoom range, and an imaging apparatus having the same.

The zoom lens according to the present invention 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, an aperture stop, a third lens group having a positive refractive power, and one or more. In the zoom lens that includes a rear group including the first lens group and performs zooming by changing the distance between the lens groups, the first lens group and the aperture stop are moved to the object side at the telephoto end compared to the wide-angle end. The third lens group includes one or more positive lenses, the partial dispersion ratio of the material of one positive lens of the third lens group is θgF3P, the Abbe number is νd3P, and the focal length of the entire system at the telephoto end is fT. When the focal length of the third lens group is f3,
θgF3P − (− 1.665 × 10 ⁻⁷ · νd3P ³ + 5.213 × 10 ⁻⁵ · νd3P ² −5.656 × 10 ⁻³ · νd3P + 0.737)> 0
50.0 <νd3P <100.0
8.0 <fT / f3 <20.0
It satisfies the following conditional expression.

  According to the present invention, it is possible to reduce the occurrence of chromatic aberration at the telephoto end, and it is possible to obtain a zoom lens having a wide field angle and a high zoom ratio and good optical characteristics over the entire zoom range.

Cross-sectional view of a lens according to Example 1 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, middle, and telephoto end of Example 1 of the present invention. Lens sectional drawing of Example 2 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, middle, and telephoto end of Example 2 of the present invention. Lens sectional view of Example 3 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the middle, and the telephoto end of the third embodiment of the present invention. Lens sectional view of Example 4 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, middle, and telephoto end of Example 4 of the present invention. Lens sectional drawing of Example 5 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate end, and the telephoto end according to the fifth embodiment of the present invention. Schematic diagram of main parts of an imaging apparatus of the present invention Explanatory drawing of “θgF-νd diagram”

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power (optical power = reciprocal of focal length), a second lens group having a negative refractive power, an aperture stop, a positive aperture A third lens group having a refractive power and a rear group including one or more lens groups. During zooming, the lens groups move so that the distance between the lens groups changes.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to the first exemplary embodiment of the present invention. FIGS. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively, of the zoom lens according to the first exemplary embodiment. Example 1 is a zoom lens having a zoom ratio of 41.6 and an aperture ratio of about 3.50 to 7.07.

  FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the second embodiment of the present invention. 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. The second exemplary embodiment is a zoom lens having a zoom ratio of 48.4 and an aperture ratio of about 2.87 to 7.07.

  FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. 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. The third embodiment is a zoom lens having a zoom ratio of 48.4 and an aperture ratio of about 2.87 to 7.07.

  FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the fourth exemplary embodiment of the present invention. 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 47.1 and an aperture ratio of about 3.50 to 7.07.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 5 of the present invention. 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 94.4 and an aperture ratio of about 3.50 to 9.00. FIG. 11 is a schematic diagram of a main part of a digital still camera (image pickup apparatus) including the zoom lens of the present invention. FIG. 12 is an explanatory diagram of the θgF-νd diagram.

  The zoom lens of each embodiment is a photographing lens system used for an imaging apparatus such as a video camera, a digital still camera, a silver salt film camera, and a TV camera. In addition, 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, when i is the order of the lens group from the object side, Li indicates the i-th lens group. LR is a rear group having one or more lens groups.

  SP is an aperture stop. G is an optical block corresponding to an optical filter, a face plate, a low-pass filter, an infrared cut filter, or the like. IP is the image plane. The image plane IP corresponds to an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor when a zoom lens is used as a photographing optical system of a video camera or a digital camera. When a zoom lens is used as a photographing optical system of a silver salt film camera, it corresponds to a film surface.

  The arrows indicate the movement trajectory of each lens unit during zooming (magnification) from the wide-angle end to the telephoto end and the moving direction of the lens unit during focusing. In the spherical aberration diagram, d is the d-line (wavelength 587.6 nm), and g is the g-line (wavelength 435.8 nm). In the astigmatism diagram, S and M are a sagittal image surface and a meridional image surface at the d-line. Distortion is shown for the d-line. In the lateral chromatic aberration diagram, g is a g-line. In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens group is positioned at both ends of a range in which the zoom lens unit can move on the optical axis.

  In each example, 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, and 1 The zoom lens having the rear lens group LR having a positive refractive power as a whole having the above lens group. During zooming, the distance between the lens groups changes.

  In each embodiment, all lens groups are moved. In Examples 1, 4, and 5, the rear group LR includes a fourth lens unit L4 having a negative refractive power and a fifth lens unit having a positive refractive power. The second exemplary embodiment includes the fourth lens unit L4 having a positive refractive power. The third exemplary embodiment includes a fourth lens unit L4 having a positive refractive power and a fifth lens unit L5 having a positive refractive power.

  Next, the lens configuration of the zoom lens of each embodiment will be described. The zoom lenses of Examples 1, 4, and 5 include, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and an aperture stop SP. Further, the lens unit is composed of five lens units, a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a negative refractive power, and a fifth lens unit L5 having a positive refractive power.

  During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves to the image side and then moves to the object side. That is, the first lens unit L1 moves along a locus convex toward the image side. The first lens unit L1 is located closer to the object side at the telephoto end than at the wide angle end. The second lens unit L2 moves to the image side, the third lens unit L3 moves to the object side, and the fourth lens unit L4 moves to the object side. The fifth lens unit L5 moves along a locus convex toward the object side. The aperture stop SP moves monotonically to the object side along a locus different from that of each lens group or moves along a convex locus toward the image side. Then, it moves to the object side at the telephoto end compared to the wide-angle end.

  In the zoom lenses of Examples 1, 4, and 5, main zooming is performed by moving the first lens unit L1, the second lens unit L2, and the third lens unit L3. During zooming, the total lens length (distance from the first lens surface to the image plane) at the wide-angle end is shortened by moving the first lens unit L1 so that it is positioned closer to the object side at the telephoto end than at the wide-angle end. A large zoom ratio is obtained.

  Also, during zooming, the second lens unit L2 has a large zooming effect by being moved so that the second lens unit L2 is positioned closer to the image side at the telephoto end than at the wide-angle end. Further, during zooming, the third lens unit L3 has a large zooming effect by moving the third lens unit L3 so that it is positioned closer to the object side at the telephoto end than at the wide angle end.

  In zooming, the fourth lens unit L4 is moved closer to the object side at the telephoto end than at the wide-angle end, so that a sufficient focus space for moving the fifth lens unit L5 as the focus lens unit is secured. doing.

  In the first, fourth, and fifth embodiments, a rear focus type that performs focusing (focus) by moving the fifth lens unit L5 on the optical axis is employed. Further, when the aperture stop SP is zoomed from the wide-angle end to the telephoto end, the effective diameter of the front lens is reduced by moving the aperture stop SP to the object side independently of each lens group. Further, by moving the aperture stop SP so that it is positioned closer to the object side at the telephoto end than at the wide angle end, the effective diameter of the front lens at the time of widening the angle of view is reduced.

  Then, the fifth lens unit L5 is moved to correct image plane fluctuations accompanying zooming, and focusing is performed. By moving the fifth lens unit L5 along the locus convex toward the object side during zooming, the space between the fourth lens unit L4 and the fifth lens unit L5 is effectively used, and the overall lens length is effectively shortened. doing. A solid line curve 5a and a dotted line curve 5b relating to the fifth lens unit L5 are movement trajectories for correcting image plane fluctuations due to zooming when focusing on an object at infinity and an object at close distance, respectively. It is.

  At the telephoto end, when focusing from an object at infinity to an object at a short distance is performed by extending the fifth lens unit L5 forward as indicated by an arrow 5C.

  The zoom lens of Embodiment 2 includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, an aperture stop SP, and a third lens having a positive refractive power. The lens unit includes four lens units, that is, a group L3 and a fourth lens unit L4 having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves along a convex locus toward the image side. The first lens unit L1 is located closer to the object side at the telephoto end than at the wide angle end. The second lens unit L2 moves to the image side, the third lens unit moves to the object side, and the fourth lens unit moves along a convex locus to the object side. The aperture stop SP moves along a locus convex to the image side along a locus different from each lens group.

  The zoom lens according to the present exemplary embodiment performs main zooming by moving the first lens unit L1, the second lens unit L2, and the third lens unit L3. During zooming, the first lens unit L1 is moved so as to be positioned closer to the object side at the telephoto end than at the wide-angle end, so that a large zoom can be obtained while shortening the total lens length at the wide-angle end. Also, during zooming, the second lens unit L2 has a large zooming effect by being moved so that the second lens unit L2 is positioned closer to the image side at the telephoto end than at the wide-angle end.

  Further, during zooming, the third lens unit L3 has a large zooming effect by moving the third lens unit L3 so that it is positioned closer to the object side at the telephoto end than at the wide angle end.

  The second embodiment employs a rear focus type in which focusing is performed by moving the fourth lens unit L4 on the optical axis. In addition, when the aperture stop SP is zoomed, the effective diameter of the front lens is reduced by moving the aperture stop SP independently of the other lens groups. Further, by moving the aperture stop SP so that it is positioned closer to the object side at the telephoto end than at the wide angle end, the effective diameter of the front lens at the time of widening the angle of view is reduced. Then, the fourth lens unit L4 is moved to correct the image plane variation caused by zooming, and focusing is performed.

  A solid curve 4a and a dotted curve 4b relating to the fourth lens unit L4 are movement trajectories for correcting image plane fluctuations accompanying zooming when focusing on an object at infinity and an object at close distance, respectively. At the telephoto end, when focusing from an object at infinity to an object at a short distance is performed by extending the fourth lens unit L4 forward as indicated by an arrow 4C.

  The zoom lens according to the third exemplary embodiment includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and an aperture stop SP. Further, the lens unit is composed of five lens units: a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a positive refractive power, and a fifth lens unit L5 having a positive refractive power.

  During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves along a convex locus toward the image side. The first lens unit L1 is located closer to the object side at the telephoto end than at the wide angle end. The second lens unit L2 moves to the image side, the third lens unit L3 moves to the object side, and the fourth lens unit L4 moves to the object side. The fifth lens unit L5 moves along a locus convex toward the object side. The aperture stop SP moves along a locus convex to the image side along a locus different from that of each lens group. In the zoom lens of Example 3, main zooming is performed by moving the first lens unit L1, the second lens unit L2, and the third lens unit L3.

  During zooming, the first lens unit L1 is moved closer to the object side at the telephoto end than at the wide-angle end, so that a large zoom ratio can be obtained while shortening the total lens length at the wide-angle end. .

  Also, during zooming, the second lens unit L2 has a large zooming effect by being moved so that the second lens unit L2 is positioned closer to the image side at the telephoto end than at the wide-angle end. Further, during zooming, the third lens unit L3 has a large zooming effect by moving the third lens unit L3 so that it is positioned closer to the object side at the telephoto end than at the wide angle end. In zooming, the fourth lens unit L4 is moved closer to the object side at the telephoto end than at the wide-angle end, so that a sufficient focus space for moving the fifth lens unit L5 as the focus lens unit is secured. doing.

  The third embodiment employs a rear focus type in which the fifth lens unit L5 is moved on the optical axis to perform focusing. Further, when the aperture stop SP is zoomed from the wide-angle end to the telephoto end, the effective diameter of the front lens is reduced by moving the aperture stop SP to the object side independently of each lens group. Further, by moving the aperture stop SP along the locus convex toward the image side so that it is positioned closer to the object side at the telephoto end than at the wide angle end, it is possible to reduce the effective diameter of the front lens at the time of widening the angle of view. I am trying. Then, the fifth lens unit L5 is moved to correct image plane fluctuations accompanying zooming, and focusing is performed.

  By moving the fifth lens unit L5 along the locus convex toward the object side during zooming, the space between the fourth lens unit L4 and the fifth lens unit L5 is effectively used, and the overall lens length is effectively shortened. doing. A solid line curve 5a and a dotted line curve 5b relating to the fifth lens unit L5 are movement trajectories for correcting image plane fluctuations caused by zooming when focusing on an object at infinity and an object at close distance, respectively. At the telephoto end, when focusing from an object at infinity to an object at a short distance is performed by extending the fifth lens unit L5 forward as indicated by an arrow 5C.

  As described above, in each embodiment, focusing from an object at infinity to a near object is performed by moving the lens group closest to the image side to the object side.

  Next, features of the zoom lens of the present invention will be described with examples. In general, in order to reduce the size of a zoom lens, it is only necessary to reduce the number of lenses while increasing the refractive power of each lens group constituting the zoom lens. However, a zoom lens having such a configuration increases the thickness of the lens (thickness in the optical axis direction), resulting in an insufficient lens system shortening effect and an increase in various aberrations, resulting in high optical performance. It becomes difficult. For this reason, in order to increase the zoom ratio and reduce the size of the entire lens system, it is important to appropriately set the zoom type, the refractive power of each lens group, the lens configuration constituting each lens group, and the like.

  In addition, it is important that the material used for the lens is appropriately selected in consideration of the refractive index and the Abbe number so that various aberrations including chromatic aberration are reduced at each zoom position. For example, in order to achieve a high zoom ratio while reducing the size of the entire system with a positive lead type zoom lens, the entire first lens group having the largest diameter (effective diameter) is made smaller. Becomes important.

  In order to reduce the entire first lens group, it is effective to reduce the number of lenses constituting the first lens group. In order to reduce the occurrence of chromatic aberration in the first lens group, it is important to select an appropriate material for the lenses constituting the first lens group in consideration of the refractive index and Abbe number.

  FIG. 12 is a graph in which the Abbe number is a large value on the horizontal axis on the horizontal axis (hereinafter referred to as “θgF −”) so that the partial dispersion ratio θgF is a large value on the vertical axis on a general optical glass. This is referred to as a “νd diagram”. It is known that when a material is mapped on the θgF-νd diagram, it is distributed along a straight line called a normal line.

Here, the Abbe number νd and the partial dispersion ratio θgF are the refractive indices of materials with respect to g-line (wavelength 435.8 nm), F-line (486.1 nm), C-line (656.3 nm), and d-line (587.6 nm). Are Ng, NF, NC, and Nd, respectively.
νd = (Nd−1) / (NF−NC)
θgF = (Ng−NF) / (NF−NC)
It is the quantity represented by.

  In general, in a positive lead zoom lens including a long focal length range, an axial ray passes through the highest position in the first lens group, and a secondary spectrum of axial chromatic aberration and spherical aberration due to color are likely to occur. If the correction of spherical aberration due to color is balanced, the amount of axial chromatic aberration may increase, so the secondary spectrum of axial chromatic aberration should be as small as possible. In this first lens group, in order to reduce the secondary spectrum of longitudinal chromatic aberration, in the θgF-νd diagram, the slope of the straight line connecting the glass material of the positive lens and negative lens constituting the first lens group is relaxed. It is necessary.

  For example, a glass material in a region away from the normal line in the direction in which the partial dispersion ratio θgF increases in the θgF-νd diagram, such as fluorite, is used for the positive lens in the first lens group. good. Further, a glass material in a region where the partial dispersion ratio θgF decreases from the normal line in the θgF-νd diagram, such as a lanthanum glass material, may be used for the negative lens in the first lens group. Such a combination has an effect of correcting the secondary spectrum of longitudinal chromatic aberration, since the inclination of the straight line connecting the glass material of the positive lens and the negative lens in the first lens group is significantly gentler than that of the normal line.

  Thus, by optimizing the glass material used for the first lens group, the secondary spectrum of axial chromatic aberration can be reduced in a predetermined focal length range. However, a long focal length photographing lens whose zoom magnification exceeds 40 times (zoom ratio is 40) and whose focal length at the telephoto end exceeds 1000 mm in terms of the focal length of the photographing lens using a silver salt film is on-axis. The amount of secondary spectrum of chromatic aberration increases. In order to suppress this secondary spectrum, it is necessary to use an anomalous dispersion glass material such as fluorite for other lens groups than the first lens group.

  As described above, the secondary spectrum of spherical aberration and axial chromatic aberration due to color is likely to occur when the axial ray passes through a high position. In the case of a zoom lens having a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, the on-axis ray is the third lens next to the first lens group. You will pass high in the group. If a glass material in a region away from the normal line in the θgF-νd diagram is used as the material of the positive lens of the third lens group, it becomes easier to further reduce the secondary spectrum of axial chromatic aberration.

  On the other hand, at the wide-angle end, if the angle of view is reduced to 28 mm or less in terms of the converted focal length with a photographic lens using a silver salt film, the chromatic aberration of magnification becomes worse. If a glass material having anomalous dispersion is used to reduce axial chromatic aberration at the telephoto end, lateral chromatic aberration may deteriorate at the wide-angle end.

  Thus, it is difficult to obtain high optical performance over the entire zoom range by simply using a glass material having anomalous dispersion for a zoom lens. In order to increase the zoom ratio and reduce the size of the entire lens system using a glass material in a region away from the normal line, it is necessary to appropriately set the zoom type and the refractive power of each lens group. In particular, it is necessary to appropriately set the refractive power of the lenses in each lens group, the lens configuration, the movement locus of each lens group during zooming, and the like.

  Generally, in a positive lead zoom lens, the diameter of the most object side surface of the first lens group is often determined by an off-axis light beam at the wide-angle end, and the effective diameter of the front lens increases as the field angle increases. For this reason, the overall length of the lens is reduced at the wide-angle end, the aperture stop is brought closer to the first lens group, and when zooming, the first lens group is moved to the object side to increase the magnification at the telephoto end. The effective diameter can be reduced.

  In addition, if the number of lenses in the first lens group is limited, distortion is allowed to some extent, and the distortion is corrected electronically, it is effective while reducing the number of lenses in the first lens group. It becomes easy to reduce the diameter, and the entire system can be downsized. In zooming, if the aperture stop is moved separately from the other lens groups, the entire system can be easily downsized.

  As described above, in a positive lead zoom lens, the effective diameter of the lens surface closest to the object side in the first lens group is often determined by off-axis rays at the wide-angle end. Therefore, the effective diameter of the front lens increases as the angle of view increases, but the effective diameter of the first lens group can be reduced as the position of the aperture stop is closer to the first lens group.

  In addition, by moving the aperture stop separately from the other lens units during zooming, the distance between the second lens unit and the third lens unit can be made closer at the telephoto end. For this reason, it is easy to ensure a long focal length without greatly increasing the total lens length at the telephoto end.

  In each embodiment, as described above, the aperture stop is moved separately from the other lens units, thereby reducing the effective diameter of the first lens unit L1 at the wide angle end and increasing the total lens length at the telephoto end. To achieve a high zoom ratio.

  In addition, moving the aperture stop separately from the other lens groups means that the amount of movement of the lens group is smaller than when the aperture stop is fixed or when the aperture stop is moved integrally with the third lens group, for example. The degree of freedom will increase.

  Increasing the degree of freedom of movement of the lens group increases the degree of freedom of refractive power with respect to the optical performance and specifications of each lens group. As a result, various aberrations such as spherical aberration, coma aberration, and longitudinal chromatic aberration can be easily corrected better than when the aperture stop is fixed or compared with a configuration in which the third lens unit and the like are moved together.

  Next, features common to the embodiments will be described. In each embodiment, the first lens unit L1 and the aperture stop SP are moved to the object side at the telephoto end compared to the wide-angle end. The third lens unit L3 includes one or more positive lenses. The partial dispersion ratio of the material of one positive lens in the third lens unit L3 is θgF3P, the Abbe number is νd3P, the focal length at the telephoto end is fT, and the focal length of the third lens unit L3 is f3.

At this time,
θgF3P − (− 1.665 × 10 ⁻⁷ · νd3P ³ + 5.213 × 10 ⁻⁵ · νd3P ² −5.656 × 10 ⁻³ · νd3P + 0.737)> 0 (1)
50.0 <νd3P <100.0 (2)
8.0 <fT / f3 <20.0 (3)
The following conditional expression is satisfied. Here, the Abbe number νd3P and the partial dispersion ratio θgF3P of the material are as described above.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) defines the partial dispersion ratio θgF3P of the material of the positive lens in the third lens unit L3. When the left side of conditional expression (1) is smaller than 0, the secondary spectrum of longitudinal chromatic aberration increases at the telephoto end. Conditional expression (2) defines the Abbe number νd3P of the material of the positive lens in the third lens unit L3.

  When the Abbe number νd3P increases beyond the upper limit value of the conditional expression (2), the difference from the Abbe number of the material of the negative lens in the third lens unit L3 increases. As a result, for example, when there is a cemented lens in the third lens unit L3, the cemented lens surface can be loosened, which is advantageous for downsizing the entire system, but there are fewer glass materials. Further, if the Abbe number νd3P becomes smaller than the lower limit value of the conditional expression (2), the curvature of the cemented lens surface becomes tight, the lens thickness increases and the entire system becomes larger, which is not preferable.

  Conditional expression (3) defines the ratio between the focal length of the entire system at the telephoto end and the focal length of the third lens unit L3. When the upper limit of conditional expression (3) is exceeded and the refractive power of the third lens unit L3 (the reciprocal of the focal length) increases, the amount of movement of the third lens unit L3 during zooming decreases. Although it is easy to reduce the size of the lens system, spherical aberration, coma aberration, and axial chromatic aberration increase at the telephoto end, making it difficult to correct these various aberrations.

  If the lower limit of conditional expression (3) is exceeded and the refractive power of the third lens unit L3 becomes weak, correction of spherical aberration, coma aberration, and longitudinal chromatic aberration becomes easy at the telephoto end, but the third lens unit L3. The amount of movement during zooming increases, and the entire system becomes larger.

  With the above configuration, various aberrations are corrected well, especially the generation of the secondary spectrum of axial chromatic aberration due to the high zoom ratio is reduced, and high optical performance over the entire zoom range with a wide angle of view and high zoom ratio. A zoom lens having In each embodiment, it is more preferable to satisfy one or more of the following conditional expressions. Let MS be the amount of movement of the aperture stop SP during zooming from the wide-angle end to the telephoto end. The focal length of the entire system at the wide angle end is fW, and the focal lengths of the first lens unit L1 and the second lens unit L2 are f1 and f2, respectively.

  The third lens unit L3 has a positive lens closest to the object side, and the focal length of the positive lens is f3A. The movement amounts of the first lens unit L1 and the third lens unit L3 during zooming from the wide-angle end to the telephoto end are M1 and M3, respectively. The first lens unit L1 includes three lenses including a positive lens, and the partial dispersion ratio of the material of at least one positive lens in the first lens unit L1 is θgF1P and the Abbe number is νd1P. The first lens unit L1 has one or more negative lenses, and the partial dispersion ratio of the material of at least one negative lens in the first lens unit L1 is θgF1N, and the Abbe number is νd1N.

  The first lens unit L1 has one or more negative lenses, and the refractive index of the material of at least one negative lens in the first lens unit L1 is nd. The distance from the most image side lens surface of the second lens unit L2 to the aperture stop SP at the wide angle end is D2, and the distance from the aperture stop SP to the most object side lens surface of the third lens unit L3 at the wide angle end is D3. To do. At this time, it is preferable to satisfy one or more of the following conditional expressions.

-20.0 <fT / MS <-11.0 (4)
15.0 <f1 / fW <30.0 (5)
3.5 <f3 / fW <6.5 (6)
10.0 <fT / f3A <22.0 (7)
−11.0 <M3 / fW <−4.5 (8)
-20.0 <M1 / fW <-7.5 (9)
θgF1P − (− 1.665 × 10 ⁻⁷ · νd1P ³ + 5.213 × 10 ⁻⁵ · νd1P ² −5.656 × 10 ⁻³ · νd1P + 0.737)> 0 (10)
50.0 <νd1P <100.0 (11)
30.0 <νd1N <50.0 (12)
0.52 <θgF1N (13)
θgF1N <−0.00203 × νd1N + 0.656 (14)
1.75 <nd <2.10 (15)
-40.0 <fT / f2 <-20.0 (16)
0.45 <MS / M3 <0.70 (17)
1.0 <D2 / D3 <5.0 (18)
Here, the sign of the movement amount of the lens group and the aperture stop is negative when the zoom lens is moved from the wide-angle end to the telephoto end, and its position is closer to the object side at the telephoto end than the wide-angle end. The time to do is positive.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (4) defines the ratio of the focal length of the entire system at the telephoto end to the amount of movement during zooming of the aperture stop SP. By moving the aperture stop SP during zooming, the amount of movement in zooming of the second lens unit L2 and the third lens unit L3 can be given a degree of freedom. When the aperture stop SP is fixed, the mechanical structure is simplified, but the zooming of the second lens unit L2 and the first lens unit L1 is performed by defining the amount of movement of the third lens unit L3 during zooming. The amount of movement at that time increases.

  When the amount of movement of the third lens unit L3 during zooming decreases, the refractive power of the third lens unit L3 increases, but axial chromatic aberration, spherical aberration, coma, and the like increase. Therefore, during zooming, the refractive power of each lens unit is set optimally by moving the aperture stop, and various aberrations are corrected favorably.

  If the amount of movement of the aperture stop decreases beyond the upper limit value of conditional expression (4), the amount of movement in zooming of the third lens unit L3 decreases, and the refractive power of the third lens unit L3 increases. When the refractive power of the third lens unit L3 is increased, axial chromatic aberration, spherical aberration, coma, and the like increase, which is not preferable. Further, in order to correct axial chromatic aberration, spherical aberration, coma aberration, and the like, it is necessary to increase the number of lenses in the third lens unit L3. As a result, the third lens unit L3 is undesirably enlarged.

  Further, if the amount of movement of the aperture stop SP is increased beyond the lower limit value of the conditional expression (4), the refractive power of the third lens unit L3 becomes weak. Therefore, in order to obtain a predetermined zoom ratio, the first lens unit L1 or It is necessary to increase the refractive power of the second lens unit L2. As the refractive power of the first lens unit L1 increases, axial chromatic aberration and spherical aberration increase. Further, if the refractive power of the second lens unit L2 becomes strong, coma aberration increases, which is not good. Moreover, since it is necessary to increase the number of lenses in both lens groups, the entire system becomes larger.

  Conditional expression (5) defines the ratio of the focal length of the entire system at the wide-angle end to the focal length of the first lens unit L1. If the lower limit of conditional expression (5) is exceeded and the refractive power of the first lens unit L1 becomes too strong, lateral chromatic aberration will increase at the wide-angle end and axial chromatic aberration will increase at the telephoto end. Further, since the refractive power of the first lens unit L1 is increased, axial chromatic aberration is increased at the telephoto end, and as a result, it is difficult to correct chromatic aberration even if an anomalous dispersion glass material is used as the lens material of the third lens unit L3. become.

  In order to correct spherical aberration, the number of lenses in the first lens unit L1 may be increased. However, in order to increase the field angle, the number of lenses increases and the effective diameter of the first lens unit L1 increases. If the upper limit of conditional expression (5) is exceeded and the refractive power of the first lens unit L1 becomes too weak, it becomes easy to correct lateral chromatic aberration at the wide-angle end, axial chromatic aberration, and spherical aberration at the telephoto end. However, since the refractive power becomes too weak, the amount of movement of the first lens unit L1 increases during zooming from the wide-angle end to the telephoto end, and the entire system increases in size.

  Conditional expression (6) defines the ratio between the focal length of the entire system at the wide angle end and the focal length of the third lens unit L3. If the upper limit of conditional expression (6) is exceeded and the refractive power of the third lens unit L3 becomes too weak, the amount of movement of the third lens unit L3 during zooming increases. As a result, the total lens length becomes large and it is difficult to reduce the size of the entire system.

  Further, if the refractive power of the third lens unit L3 increases beyond the lower limit value of the conditional expression (6), the moving amount of the third lens unit L3 during zooming becomes small, so that the entire system can be easily downsized. However, in the third lens unit L3, spherical aberration, coma aberration, axial chromatic aberration, and the like increase, making it difficult to correct these. Or, it becomes difficult to shorten the focal length on the wide angle side. In order to correct these various aberrations, it is necessary to increase the number of lenses, which is not preferable because the entire system becomes large.

  Conditional expression (7) defines the ratio between the focal length of the entire system at the telephoto end and the positive lens position closest to the object side of the third lens unit L3, and the focal length of the positive lens. Since the positive lens closest to the object side of the third lens unit L3 passes through the position where the axial ray is highest in the third lens unit L3, it affects the correction of spherical aberration, coma aberration, and axial chromatic aberration. When the upper limit of conditional expression (7) is exceeded and the refractive power of the positive lens increases, it becomes difficult to correct the above aberrations.

  If the refractive power of the positive lens is weakened beyond the lower limit of conditional expression (7), correction of spherical aberration, coma aberration, axial chromatic aberration, etc. becomes easy, but the lens configuration length of the third lens unit L3 is This is not preferable because the entire system becomes larger.

  Conditional expression (8) defines the ratio of the focal length of the entire system at the wide-angle end to the amount of movement during zooming of the third lens unit L3. If the lower limit of conditional expression (8) is exceeded and the amount of movement during zooming of the third lens unit L3 increases, the entire lens system becomes larger, which is not preferable. Further, if the amount of movement during zooming of the third lens unit L3 becomes smaller than the upper limit value of the conditional expression (8), the entire lens system is reduced in size.

  However, in order to ensure a predetermined zoom ratio, it is necessary to increase the refractive power of the third lens unit L3, and accordingly, spherical aberration and coma increase, and axial chromatic aberration increases particularly at the telephoto end. Absent. Or, it becomes difficult to shorten the focal length at the wide-angle end.

  Conditional expression (9) defines the ratio between the focal length of the entire system at the wide-angle end and the amount of movement during zooming of the first lens unit L1. If the amount of movement during zooming of the first lens unit L1 exceeds the lower limit value of the conditional expression (9), the entire lens system becomes large, which is not preferable. If the amount of movement during zooming of the first lens unit L1 becomes small beyond the upper limit value of conditional expression (9), the entire lens system is reduced in size. However, in order to ensure a predetermined zoom ratio, the refractive power of the first lens unit L1 must be increased, and as a result, lateral chromatic aberration at the wide-angle end and spherical aberration and coma at the telephoto end increase, which is not preferable.

  Here, the first lens unit L1 has a very important role in aberration correction in a positive lead zoom lens. The aberration generated in the first lens unit L1 is enlarged by the square of the lateral magnification of the lens unit that continues from the first lens unit L1 to the image plane. For this reason, it is necessary to suppress the aberration generated in the first lens L1 as much as possible in the first lens unit L1. In order to suppress the longitudinal chromatic aberration that occurs due to the high zoom ratio, in the aforementioned θgF-νd diagram, the inclination of the straight line connecting the negative lens and the positive lens glass material in the first lens unit L1 becomes gentle. Good to do. This facilitates correction of the secondary spectrum of longitudinal chromatic aberration.

  Conditional expressions (10) and (11) define the partial dispersion ratio θgF1P and the Abbe number νd1P of the material of the positive lens in the first lens unit L1. If conditional expression (10) is smaller than 0, the straightness connecting the glass material of the negative lens and the positive lens in the θgF-νd diagram cannot be loosened, the secondary spectrum of axial chromatic aberration increases, and a high zoom ratio can be achieved. It is difficult to obtain high optical performance when trying.

  When the Abbe number decreases beyond the lower limit of conditional expression (11), the cemented lens surface of the cemented lens in the first lens unit L1 becomes tight to correct chromatic aberration. When the cemented lens surface becomes tight, the edge of the lens is reduced. Therefore, in consideration of processing conditions, it is necessary to increase the lens thickness. If the lens is thickened, the effective diameter of the front lens increases as the angle of view increases, making it difficult to downsize the entire system. Further, when the Abbe number increases beyond the upper limit value of the conditional expression (11), the cemented lens surface becomes loose. Therefore, the entire system can be easily reduced in size, but the material to be selected is reduced.

  Conditional expressions (12), (13), and (14) define the Abbe number νd1N and the partial dispersion ratio θgF1N of the material of the negative lens in the first lens unit L1. When the Abbe number increases beyond the upper limit of conditional expression (12), the cemented lens surface of the cemented lens in the first lens unit L1 becomes tight in order to correct chromatic aberration. When the cemented lens surface becomes tight, the edge of the lens is reduced. Therefore, in consideration of processing conditions, it is necessary to increase the lens thickness. If the lens is thickened, the effective diameter of the front lens increases as the angle of view increases, making it difficult to reduce the entire system.

  Further, if the Abbe number is reduced beyond the lower limit value of the conditional expression (12), the cemented lens surface becomes loose, so that the entire system can be easily downsized. However, it is below the normal line in the θgF-νd diagram. This is not good because there is less glass. Further, in the θgF-νd graph, there are few materials that exist in the region where the partial dispersion ratio θgF1N becomes smaller than the lower limit value of the conditional expression (13).

  When the partial dispersion ratio θgF1N increases beyond the upper limit of conditional expression (14), the straight line connecting the glass material of the negative lens and the positive lens in the θgF-νd diagram cannot be loosened, and the secondary spectrum of axial chromatic aberration increases. It is difficult to obtain high optical performance when increasing the zoom ratio.

  Conditional expression (15) defines the refractive index of the material of the negative lens in the first lens unit L1. When the refractive index increases beyond the upper limit value of conditional expression (15), the effective diameter of the first lens unit L1 decreases as the refractive index increases, but the selected material decreases. When the refractive index decreases beyond the lower limit of conditional expression (15), the effective diameter of the first lens unit L1 increases as the refractive index decreases.

  Conditional expression (16) defines the focal length of the second lens unit L2. In each embodiment, a predetermined zoom ratio is ensured by appropriately setting the focal length of the second lens unit L2 in addition to the first lens unit L1 and the third lens unit L3. When the lower limit of conditional expression (16) is exceeded and the refractive power of the second lens unit L2 increases, the amount of movement of the second lens unit L2 during zooming decreases and the entire system can be easily downsized. Aberration increases. Further, when the refractive power of the second lens unit L2 becomes smaller than the upper limit value of the conditional expression (16), the amount of movement during zooming increases and the entire system becomes larger.

  Conditional expression (17) defines the ratio of the amount of movement in zooming between the third lens unit L3 and the aperture stop SP. When the amount of movement of the aperture stop SP increases beyond the upper limit value of the conditional expression (17), the distance between the aperture stop and the first lens unit L1 is further separated at the wide-angle end, and the effective diameter of the first lens unit L1 is increased. It will become larger. In order to reduce the size of the entire system, it is necessary to increase the refractive power of the first lens unit L1, but this is not preferable because spherical aberration and axial chromatic aberration increase.

  Further, when the amount of movement of the aperture stop SP decreases beyond the lower limit value of the conditional expression (17), the distance between the aperture stop SP and the third lens unit L3 becomes too close at the wide-angle end, and the effective diameter of the third lens unit L3. Is getting bigger. If an attempt is made to satisfy lens processing conditions such as the edge of each lens of the third lens unit L3, the lens thickness increases, and the lens becomes larger by the thickness, which is not good. Alternatively, for example, the moving amount of the third lens unit L3 is reduced by the thickness, and the refractive power of the third lens unit L3 must be increased in order to ensure a predetermined zoom ratio.

  When the refractive power of the third lens unit L3 is increased, it is not preferable that spherical aberration, coma aberration, and axial chromatic aberration increase.

  Conditional expression (18) defines the distance between the second lens unit L2 and the aperture and the stop SP and the interval between the third lens unit L3 and the aperture stop SP at the wide angle end. When the interval increases beyond the upper limit value of conditional expression (18), the distance between the first lens unit L1 and the aperture stop SP becomes closer at the wide-angle end, so that the effective diameter of the first lens unit L1 may be reduced. it can. However, since the aperture stop SP approaches the first lens unit L1, the aperture stop SP moves away from the third lens unit L3. In the third lens unit L3, the incident height of off-axis rays is increased and the effective diameter is increased. As a result, the size increases, which is not preferable.

  When the distance decreases beyond the lower limit value of conditional expression (18), the distance between the third lens unit L3 and the aperture stop SP decreases, so the incident height of off-axis rays passing through the first lens unit L1 increases. The effective diameter of the first lens unit L1 is increased. Furthermore, the first lens unit L1 is undesirably large. In each embodiment, it is preferable to set the numerical ranges of conditional expressions (2) to (9), (11) to (13), and (15) to (18) as follows.

60.0 <νd3P <98.0 (2a)
8.2 <fT / f3 <19.5 (3a)
-19.0 <fT / MS <-11.8 (4a)
15.3 <f1 / fW <28.5 (5a)
3.7 <f3 / fW <6.2 (6a)
10.3 <fT / f3A <21.5 (7a)
−10.5 <M3 / fW <−4.9 (8a)
-19.7 <M1 / fW <-7.8 (9a)
55.0 <νd1P <98.0 (11a)
33.0 <νd1N <45.0 (12a)
0.53 <θgF1N (13a)
1.80 <nd <2.00 (15a)
−39.0 <fT / f2 <−21.0 (16a)
0.50 <MS / M3 <0.66 (17a)
1.3 <D2 / D3 <4.5 (18a)
More preferably, if the numerical ranges of the conditional expressions (2a) to (9a), (11a) to (13a), and (15a) to (18a) are set as follows, each conditional expression described above means The effect is obtained to the maximum.

70.0 <νd3P <97.0 (2b)
8.4 <fT / f3 <19.0 (3b)
-18.5 <fT / MS <-12.0 (4b)
15.5 <f1 / fW <27.8 (5b)
3.8 <f3 / fW <5.8 (6b)
10.5 <fT / f3A <21.0 (7b)
−10.3 <M3 / fW <−5.2 (8b)
-19.4 <M1 / fW <-8.0 (9b)
60.0 <νd1P <96.0 (11b)
35.0 <νd1N <42.0 (12b)
0.54 <θgF1N (13b)
1.82 <nd <1.95 (15b)
-37.5 <fT / f2 <-21.3 (16b)
0.51 <MS / M3 <0.64 (17b)
1.5 <D2 / D3 <4.0 (18b)
Next, a preferable configuration in each embodiment will be described. The first lens unit L1 is preferably composed of three lenses including a negative lens and a positive lens.

  In the case of a wide-angle zoom lens, since the lens outer diameter of the first lens unit L1 is determined by off-axis rays, the smaller the number of lenses in the first lens unit L1, the more advantageous the size reduction of the entire system. In order to achieve a high zoom ratio, if the number of lenses in the first lens unit L1 is small, it is difficult to correct both spherical aberration and axial chromatic aberration in a balanced manner. Therefore, in order to achieve a wide angle of view and a high zoom ratio, it is preferable that the first lens unit L1 includes three lenses including a negative lens and a positive lens.

  Further, it is preferable that the first lens unit L1 includes three elements of a negative lens, a positive lens, and a positive lens in order from the object side to the image side. The second lens unit L2 is preferably composed of a negative lens, a negative lens, and a positive lens in order from the object side to the image side. By configuring the second lens unit L2 that moves during zooming to have such a lens configuration, it becomes easy to particularly suppress fluctuations in lateral chromatic aberration due to zooming.

  In each embodiment, the third lens unit L3 has a positive refractive power. At the wide angle end, the axial light beam becomes a divergent light beam when passing through the second lens unit L2 having a negative refractive power. Therefore, by making the third lens group located closest to the object side in the rear group following the second lens group L2 have a positive refractive power, it has a converging action on the light flux, and the effective lens diameter of the rear group is reduced. ing. The third lens unit L3 preferably includes a positive lens, a negative lens, and a cemented lens in which a negative lens and a positive lens are cemented in order from the object side to the image side.

  This configuration is called a so-called Tesser type in which one lens is added to the triplet configuration. By adding one lens to the triplet configuration, it becomes easy to finely adjust the Petzval sum. As a result, it becomes easy to maintain good flatness of the image plane in the entire zoom region. Further, by using an aspherical surface as the most object-side positive lens of the third lens unit L3 in which the axial ray spreads greatly, correction of spherical aberration, coma aberration, and the like is facilitated.

  In each embodiment, an aspheric surface is introduced into the third lens unit L3 or, if necessary, into the second lens unit L2, and particularly the refractive powers of the third lens unit L3 and the second lens unit L2 are set appropriately. Yes. This effectively corrects off-axis aberrations, particularly astigmatism and distortion, spherical aberration, coma, and the like that occur when a wide angle of view and a high zoom ratio are achieved.

  As described above, according to each embodiment, the zoom ratio is about 41.6 to 94.4, which is suitable for an imaging apparatus using a solid-state image sensor, and the shooting angle of view at the wide-angle end is 67 degrees or more. A zoom lens having excellent optical performance at a wide angle of view of 82 degrees can be achieved.

  Next, an embodiment of a digital camera (imaging device) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 11, reference numeral 20 denotes a digital camera body, and 21 denotes a photographing optical system constituted by the zoom lens of the above-described embodiment. Reference numeral 22 denotes an image pickup element (photoelectric conversion element) such as a CCD that receives a subject image (image) by the photographing optical system 21, and 23 denotes recording means for recording the subject image received by the image pickup element 22. Reference numeral 24 denotes a finder for observing a subject image displayed on a display element (not shown).

  The display element is constituted by a liquid crystal panel or the like, and a subject image formed on the image sensor 22 is displayed. Thus, by applying the zoom lens of the present invention to an imaging apparatus such as a digital camera, an imaging apparatus having a small size and high optical performance is realized.

  Hereinafter, specific numerical data of Numerical Examples 1 to 5 corresponding to Examples 1 to 5 will be shown. In each numerical example, i indicates the number of the surface counted from the object side. ri is the radius of curvature of the i-th optical surface (i-th surface). di is the axial distance between the i-th surface and the (i + 1) -th surface. 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 two surfaces closest to the image correspond to the glass block G. The aspherical shape 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 to A12 are each aspherical coefficients. ,

It is expressed by the following formula. * Means a surface having an aspherical shape. “E−x” means 10 ^−x . BF is a back focus and indicates a distance in terms of air from the final lens surface. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

Numerical example 1
Unit mm

Surface data surface number rd nd νd θgF
1 91.764 1.80 1.91082 35.3 0.582
2 49.636 4.38 1.49700 81.5 0.538
3 -171.988 0.18
4 40.807 3.01 1.49700 81.5 0.538
5 126.402 (variable)
6 157.210 0.95 1.88300 40.8
7 8.768 4.76
8 -35.634 0.70 1.77250 49.6
9 30.470 0.20
10 17.427 1.78 1.95906 17.5
11 65.831 (variable)
12 (Aperture) ∞ (Variable)
13 * 10.728 2.99 1.55332 71.7 0.540
14 * -2789.552 1.65
15 24.031 0.60 1.77250 49.62
16 11.205 0.36
17 15.956 0.60 2.00 100 29.1
18 11.273 2.37 1.49700 81.5 0.538
19 -28.103 (variable)
20 31.461 0.70 1.70154 41.2
21 16.418 (variable)
22 23.373 2.76 1.80 100 35.0
23 -20.628 0.60 1.84666 23.8
24 402.226 (variable)
25 ∞ 0.50 1.51633 64.1
26 ∞ 0.50
Image plane ∞

Aspherical data 13th surface
K = -8.61394e-001 B = 6.43510e-006 C = 4.28494e-007 D = -7.79572e-009 E = 2.62605e-010

14th page
K = -3.11524e + 006 B = 4.30164e-006 C = 5.58889e-007

Various data Zoom ratio 41.60
Wide angle Medium Telephoto focal length 5.00 12.64 208.00
F number 3.50 5.00 7.07
Half angle of view (degrees) 33.68 17.05 1.07
Total lens length 97.29 94.69 138.82
BF 11.72 19.65 11.73

d 5 0.78 13.96 59.59
d11 33.93 16.43 1.40
d12 11.32 4.43 0.00
d19 3.60 4.14 8.33
d21 5.56 5.69 27.38
d24 10.89 18.82 10.90

Zoom lens group data group Start surface Focal length
1 1 78.31
2 6 -9.68
3 12 ∞
4 13 19.63
5 20 -49.90
6 22 33.11
7 25 ∞

Numerical example 2
Unit mm

Surface data surface number rd nd νd θgF
1 118.898 1.00 1.83400 37.2 0.578
2 51.355 5.65 1.43875 94.9 0.534
3 -146.583 0.18
4 44.384 3.60 1.59282 68.6 0.544
5 180.112 (variable)
6 * 330.723 0.70 1.88300 40.8
7 * 8.391 4.69
8 -36.639 0.50 1.80 400 46.6
9 29.170 0.20
10 16.884 2.00 1.94595 18.0
11 84.719 (variable)
12 (Aperture) ∞ (Variable)
13 * 10.061 3.05 1.55332 71.7 0.540
14 * -71.895 2.21
15 26.902 0.50 1.64769 33.8
16 12.571 0.36
17 21.417 0.50 1.80 400 46.6
18 8.405 2.50 1.45600 90.3
19 -25.249 0.30
20 -273.798 0.50 1.43875 94.9 0.529
21 46.826 (variable)
22 24.630 2.50 1.74950 35.3
23 -27.309 0.50 1.94595 18.0
24 -144.500 (variable)
25 ∞ 0.50 1.51633 64.1
26 ∞ 0.50
Image plane ∞

Aspheric data 6th surface
K = -1.75187e + 004 B = 1.82087e-005 C = 2.83972e-007 D = -7.97912e-009 E = 4.09945e-011 F = 2.21220e-014

7th page
K = 1.20528e-001 B = -7.55082e-005 C = 1.39022e-006 D = -4.15841e-009 E = -7.59217e-010 F = -2.97367e-012

Side 13
K = -1.58517e-001 B = -2.35006e-005 C = -4.60642e-007 D = 3.31500e-009 E = 2.62605e-010

14th page
K = 9.03683e + 001 B = 1.28628e-004 C = 2.76898e-007

Various data Zoom ratio 48.37
Wide angle Medium Telephoto focal length 4.30 13.30 208.00
F number 2.87 5.00 7.07
Half angle of view (degrees) 37.77 16.25 1.07
Total lens length 94.75 94.56 138.99
BF 10.40 19.43 10.43

d 5 0.78 17.70 63.20
d11 34.26 13.22 0.90
d12 10.24 3.39 -0.50
d21 7.62 9.38 33.52
d24 9.57 18.60 9.60

Zoom lens group data group Start surface Focal length
1 1 79.99
2 6 -9.25
3 12 ∞
4 13 22.13
5 22 33.59
6 25 ∞

Numerical Example 3
Unit mm

Surface data surface number rd nd νd θgF
1 117.858 1.00 1.83400 37.2 0.578
2 51.351 5.70 1.43875 94.9 0.534
3 -146.230 0.18
4 44.371 3.60 1.59282 68.6 0.544
5 178.856 (variable)
6 * 284.299 0.70 1.88300 40.8
7 * 8.452 4.64
8 -34.894 0.50 1.80 400 46.6
9 28.442 0.20
10 16.926 2.00 1.94595 18.0
11 87.126 (variable)
12 (Aperture) ∞ (Variable)
13 * 10.061 3.65 1.55332 71.7 0.540
14 * -71.895 2.07
15 33.298 0.50 1.64769 33.8
16 10.865 0.18
17 12.867 0.50 1.80 400 46.6
18 8.112 2.55 1.43875 94.9 0.527
19 -26.710 0.30
20 -32.714 0.50 1.43875 94.9
21 33.396 (variable)
22 69.528 1.50 1.48749 70.2
23 -83.853 (variable)
24 24.716 2.50 1.74950 35.3
25 -36.247 0.50 1.94595 18.0
26 -7074.464 (variable)
27 ∞ 0.50 1.51633 64.1
28 ∞ 0.50
Image plane ∞

Aspheric data 6th surface
K = -1.66537e + 004 B = 1.59155e-005 C = 3.94905e-007 D = -1.02328e-008 E = 4.49998e-011 F = 9.41671e-014

7th page
K = 5.11487e-002 B = -8.45566e-005 C = 3.16949e-006 D = -3.44729e-008 E = -6.31977e-010 F = 1.78549e-012

Side 13
K = 1.42419e-002 B = -1.23913e-005 C = -2.77736e-007 D = 1.13051e-008 E = 2.62605e-010

14th page
K = 9.76358e + 001 B = 1.67979e-004 C = 1.19681e-006

Various data Zoom ratio 48.37
Wide angle Medium telephoto focal length 4.30 12.77 208.00
F number 2.87 5.00 7.07
Half angle of view (degrees) 37.77 16.88 1.07
Total lens length 95.30 95.35 140.35
BF 9.83 18.45 9.07

d 5 0.78 16.61 62.85
d11 34.33 13.65 0.87
d12 10.02 3.67 -0.50
d21 2.90 4.34 8.82
d23 4.17 5.36 25.96
d26 9.00 17.62 8.24

Zoom lens group data group Start surface Focal length
1 1 79.69
2 6 -9.15
3 12 ∞
4 13 24.29
5 22 78.22
6 24 39.58
7 27 ∞

Numerical Example 4
Unit mm

Surface data surface number rd nd νd θgF
1 91.809 1.80 1.91082 35.3 0.582
2 49.682 5.14 1.49700 81.5 0.538
3 -172.691 0.18
4 40.799 3.19 1.49700 81.5 0.538
5 125.399 (variable)
6 264.824 0.95 1.88300 40.8
7 8.654 4.75
8 -34.290 0.70 1.77250 49.6
9 29.514 0.20
10 17.261 2.03 1.95906 17.5
11 68.338 (variable)
12 (Aperture) ∞ (Variable)
13 * 10.682 2.55 1.55332 71.7 0.540
14 * -1301.722 1.88
15 25.419 0.60 1.77250 49.6
16 11.168 0.32
17 15.838 0.60 2.00330 28.3
18 11.699 2.19 1.49700 81.5 0.538
19 -26.225 (variable)
20 27.270 0.70 1.91082 35.3
21 16.857 (variable)
22 22.140 2.70 1.77250 49.6
23 -20.954 0.60 1.91082 35.3
24 -323.774 (variable)
25 ∞ 0.50 1.51633 64.1
26 ∞ 0.50
Image plane ∞

Aspherical data 13th surface
K = -1.00530e + 000 B = 1.06429e-005 C = 3.26152e-007 D = 9.58317e-009 E = 2.62605e-010

14th page
K = -5.46043e + 005 B = -1.36233e-005 C = 1.09625e-006

Various data Zoom ratio 47.06
Wide angle Medium telephoto focal length 4.42 12.67 208.00
F number 3.50 5.00 7.07
Half angle of view (degrees) 37.01 17.00 1.07
Total lens length 97.10 94.01 138.81
BF11.63 19.04 11.10

d 5 0.78 14.02 60.14
d11 35.95 17.16 1.31
d12 9.99 1.81 0.09
d19 2.98 4.99 8.58
d21 4.69 5.91 26.52
d24 10.80 18.21 10.27

Zoom lens group data group Start surface Focal length
1 1 78.55
2 6 -9.25
3 12 ∞
4 13 19.11
5 20 -50.07
6 22 31.97
7 25 ∞

Numerical Example 5
Unit mm

Surface data surface number rd nd νd θgF
1 110.420 0.50 1.88300 40.8 0.567
2 49.370 6.95 1.59282 68.6 0.544
3 -1197.279 0.18
4 46.135 4.25 1.43875 94.9 0.534
5 219.343 (variable)
6 * 3857.846 0.50 1.88 300 40.8
7 * 8.384 5.38
8 -37.530 0.50 1.77250 49.6
9 26.886 0.20
10 18.126 2.00 2.00178 19.3
11 104.140 (variable)
12 (Aperture) ∞ (Variable)
13 * 10.094 3.00 1.55332 71.7 0.540
14 * -75.681 1.46
15 26.802 0.50 1.64769 33.8
16 10.724 0.37
17 13.612 0.50 1.74320 49.3
18 7.503 3.45 1.45600 90.3 0.534
19 * -36.264 (variable)
20 51.283 0.50 1.51633 64.1
21 16.483 (variable)
22 24.725 2.40 1.78590 44.2
23 -29.675 0.50 1.92286 18.9
24 -86.407 (variable)
25 ∞ 0.50 1.51633 64.1
26 ∞ 0.50
Image plane ∞

Aspheric data 6th surface
K = 9.27342e + 004 B = 3.81002e-005 C = -3.08623e-007 D = 9.42749e-010

7th page
K = -1.01331e-001 B = 2.19036e-005 C = 1.40543e-006 D = -2.72919e-008

Side 13
K = -8.51411e-002 B = -1.17522e-004 C = -1.30376e-007 D = -2.15967e-008 E = 2.62605e-010

14th page
K = -3.49998e + 001 B = -2.57554e-005 C = -4.66479e-007

19th page
K = -1.12299e + 000 B = 1.68053e-006 C = 6.56435e-007 D = 1.63883e-009

Various data Zoom ratio 94.44
Wide angle Medium Telephoto focal length 3.60 14.51 340.00
F number 3.50 5.00 9.00
Half angle of view (degrees) 42.12 14.95 0.65
Total lens length 95.91 97.40 165.41
BF10.48 21.86 2.28

d 5 0.50 20.50 79.15
d11 29.12 9.42 1.17
d12 17.55 2.60 0.00
d19 2.28 2.57 11.94
d21 2.85 7.32 37.74
d24 9.65 21.03 1.45

Zoom lens group data group Start surface Focal length
1 1 98.89
2 6 -9.14
3 12 ∞
4 13 18.17
5 20 -47.27
6 22 26.66
7 25 ∞

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

Claims (20)

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, an aperture stop, a third lens group having a positive refractive power, and a rear group including one or more lens groups Consists of
In zoom lenses that perform zooming by changing the distance between each lens group,
At the telephoto end compared to the wide angle end, the first lens group and the aperture stop move to the object side,
The third lens group includes one or more positive lenses,
When the partial dispersion ratio of the material of one positive lens of the third lens group is θgF3P, the Abbe number is νd3P, the focal length of the entire system at the telephoto end is fT, and the focal length of the third lens group is f3,
θgF3P − (− 1.665 × 10 ⁻⁷ · νd3P ³ + 5.213 × 10 ⁻⁵ · νd3P ² −5.656 × 10 ⁻³ · νd3P + 0.737)> 0
50.0 <νd3P <100.0
8.0 <fT / f3 <20.0
A zoom lens satisfying the following conditional expression: When the movement amount of the aperture stop in zooming from the wide-angle end to the telephoto end is MS,
-20.0 <fT / MS <-11.0
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 and the focal length of the first lens group is f1,
15.0 <f1 / fW <30.0
The zoom lens according to claim 1 or 2, wherein the following conditional expression is satisfied. When the focal length of the entire system at the wide angle end is fW,
3.5 <f3 / fW <6.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the third lens group has a positive lens closest to the object side and the focal length of the positive lens is f3A,
10.0 <fT / f3A <22.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the amount of movement of the third lens group in zooming from the wide-angle end to the telephoto end is M3,
−11.0 <M3 / fW <−4.5
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, and the amount of movement of the first lens unit during zooming from the wide angle end to the telephoto end is M1,
-20.0 <M1 / fW <-7.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The first lens group includes three lenses including a positive lens. When the partial dispersion ratio of the material of at least one positive lens of the first lens group is θgF1P and the Abbe number is νd1P,
θgF1P − (− 1.665 × 10 ⁻⁷ · νd1P ³ + 5.213 × 10 ⁻⁵ · νd1P ² −5.656 × 10 ⁻³ · νd1P + 0.737)> 0
50.0 <νd1P <100.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the first lens group has one or more negative lenses, the partial dispersion ratio of the material of at least one negative lens of the first lens group is θgF1N, and the Abbe number is νd1N.
30.0 <νd1N <50.0
0.52 <θgF1N
θgF1N <−0.00203 × νd1N + 0.656
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The first lens group has one or more negative lenses, and when the refractive index of the material of at least one negative lens of the first lens group is nd,
1.75 <nd <2.10
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,
-40.0 <fT / f2 <-20.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   12. The zoom lens according to claim 1, wherein all the lens units move during zooming from the wide-angle end to the telephoto end. When the moving amounts of the third lens group and the aperture stop in zooming from the wide-angle end to the telephoto end are M3 and MS, respectively.
0.45 <MS / M3 <0.70
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The distance from the most image side lens surface of the second lens group at the wide angle end to the aperture stop is D2, and the distance from the aperture stop at the wide angle end to the most object side lens surface of the third lens group is D3. and when,
1.0 <D2 / D3 <5.0
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 14, wherein, during zooming from the wide-angle end to the telephoto end, the first lens group moves to the object side after moving to the image side.   16. The zoom lens according to claim 1, wherein the lens group closest to the image moves to the object side during focusing from an infinitely distant object to a close object.   17. The rear group includes a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power in order from the object side to the image side. Zoom lens.   The zoom lens according to any one of claims 1 to 16, wherein the rear group includes a fourth lens group having a positive refractive power.   17. The rear group includes, in order from the object side to the image side, a fourth lens group having a positive refractive power and a fifth lens group having a positive refractive power. Zoom lens.   An image pickup apparatus comprising: the zoom lens according to claim 1; and a photoelectric conversion element that receives an image formed by the zoom lens.