JP2010175902A - Variable power optical system, optical equipment having the variable power optical system, and method for manufacturing variable power optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable power optical system having excellent imaging performance, optical equipment having the variable power optical system, and a method for manufacturing the variable power optical system. <P>SOLUTION: The variable power optical system ZL mounted on a digital single-reflex camera 1 or the like includes, in order from an object side, a first lens group G1 with positive refractive power, second lens group G2 with negative refractive power, and a rear group GR with positive refractive power. The second lens group G2 has at least one or more positive lenses, and a negative lens disposed adjacent to the object side of the positive lens having the largest refractive power. When zooming from the wide-angle end to the tele-photo end, intervals between the lens groups change. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a variable magnification optical system, an optical apparatus having the variable magnification optical system, and a method for manufacturing the variable magnification optical system.

  Conventionally, a variable magnification optical system suitable for a photographic camera, an electronic still camera, a video camera, and the like has been proposed (see, for example, Patent Document 1).

JP 2001-330777 A

  However, better optical performance is required than conventional variable power optical systems.

  The present invention has been made in view of such problems, and a variable magnification optical system capable of achieving good optical performance, an optical apparatus having the variable magnification optical system, and a method of manufacturing the variable magnification optical system The purpose is to provide.

In order to solve the above-described problem, the variable magnification optical system of the present invention has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. And the second lens group includes at least one positive lens and a negative lens disposed adjacent to the object side of the positive lens having the largest refractive power among the positive lenses. Have. When zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the rear group changes, and the second lens group. The radius of curvature of the object side surface of the negative lens is r1, the radius of curvature of the image side surface of the negative lens is r2, the focal length of the entire system in the wide-angle end state is fw, and the focal point of the second lens group When the distance is f2 and the back focus in the wide-angle end state is BFw, the following expression 0.80 <(r2 + r1) / (r2-r1) <3.50
0.30 <(− f2) / BFw <0.60
0.45 <fw / BFw <0.80
Satisfy the conditions.

  In such a variable magnification optical system, it is preferable that at least a part of the second lens group moves on the optical axis when focusing from infinity to a short-distance object point.

Further, such a variable magnification optical system has the following formula 0.50 <(− f2) / fw <0.90.
It is preferable to satisfy the following conditions.

  Further, in such a variable magnification optical system, the rear group has, in order from the object side, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a positive refractive power. And a fifth lens group.

  Alternatively, in such a variable magnification optical system, it is preferable that the rear group includes, in order from the object side, a third lens group having a positive refractive power and a fourth lens group having a positive refractive power.

  In such a variable magnification optical system, it is preferable that the most image side lens surface of the second lens group has an aspherical shape.

Further, in such a variable magnification optical system, when the focal length of the first lens group is f1 and the focal length of the fourth lens group is f4, the following expression 2.00 <f1 / | f4 | <6.00
It is preferable to satisfy the following conditions.

  In such a variable magnification optical system, it is preferable that a part of the rear group moves so as to have a component in a direction substantially perpendicular to the optical axis.

  In such a variable magnification optical system, it is preferable that at least a part of the fourth lens group moves so as to have a component in a direction substantially perpendicular to the optical axis.

  In such a variable magnification optical system, it is preferable that the most object side lens surface of the second lens group has an aspherical shape.

  Further, in such a variable magnification optical system, when changing the magnification from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is increased, and the second lens group and the rear group are separated from each other. The spacing is preferably reduced.

  An optical apparatus according to the present invention includes any one of the above-described variable magnification optical systems that forms an image of an object on a predetermined image plane.

The variable magnification optical system manufacturing method according to the present invention has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. A variable magnification optical system having a rear group, at least one positive lens, a negative lens adjacent to the object side of the positive lens having the largest refractive power among the positive lenses, and a second lens When the zoom lens is arranged in a group and zooming is performed from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the rear group changes. The radius of curvature of the object side surface of the negative lens in the second lens group is r1, the radius of curvature of the image side surface of the negative lens is r2, and the focal length of the entire system in the wide-angle end state is fw. The focal length of the second lens group is f2, and the back focus in the wide angle end state is When the fw, the following formula 0.80 <(r2 + r1) / (r2-r1) <3.50
0.30 <(− f2) / BFw <0.60
0.45 <fw / BFw <0.80
Arrange to satisfy the conditions of

  When the variable magnification optical system according to the present invention, the optical apparatus having the variable magnification optical system, and the method for manufacturing the variable magnification optical system are configured as described above, good optical performance can be achieved.

It is sectional drawing which shows the structure of the variable magnification optical system by 1st Example. FIG. 4 is a diagram illustrating various aberrations in the infinite focus state in the first embodiment, (a) is an aberration diagram in the infinite focus state at the wide-angle end state, and (b) is an infinite focus in the intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in an infinitely focused state at a telephoto end state. FIG. 4A is a diagram illustrating various aberrations in a close-up focus state according to the first embodiment, FIG. 5A is an aberration diagram in a close-up focus state in a wide-angle end state, and FIG. 5B is a close-up view in an intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in a short distance in-focus state at the telephoto end state. It is sectional drawing which shows the structure of the variable magnification optical system by 2nd Example. FIG. 6A is a diagram illustrating various aberrations in an infinite focus state according to the second embodiment, FIG. 5A is an aberration diagram in an infinite focus state in a wide-angle end state, and FIG. 5B is an infinite focus in an intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in an infinitely focused state at a telephoto end state. FIG. 6A is a diagram illustrating various aberrations in a close-up focus state according to the second embodiment, FIG. 5A is an aberration diagram in a close-up focus state in a wide-angle end state, and FIG. 5B is a close-up view in an intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in a short distance in-focus state at the telephoto end state. It is sectional drawing which shows the structure of the variable magnification optical system by 3rd Example. FIG. 10 is a diagram illustrating various aberrations in the infinite focus state according to the third example, (a) is an aberration diagram in the infinite focus state at the wide-angle end state, and (b) is an infinite focus in the intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in an infinitely focused state at a telephoto end state. FIG. 6A is a diagram illustrating various aberrations in a close-up focus state according to the third embodiment, FIG. 5A is an aberration diagram in a close-up focus state in a wide-angle end state, and FIG. 5B is a close-up view in an intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in a short distance in-focus state at the telephoto end state. It is sectional drawing which shows the structure of the variable magnification optical system by 4th Example. FIG. 9A is a diagram illustrating various aberrations in the infinite focus state according to the fourth embodiment, FIG. 10A is an aberration diagram in the infinite focus state in the wide-angle end state, and FIG. 9B is an infinite focus in the intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in an infinitely focused state at a telephoto end state. FIG. 6A is a diagram illustrating various aberrations in a close-up focus state according to a fourth embodiment, FIG. 5A is an aberration diagram in a close-up focus state in a wide-angle end state, and FIG. 5B is a close-up view in an intermediate shooting distance state. FIG. 4C is an aberration diagram in a focal state, and FIG. 4C illustrates various aberrations in a short distance in-focus state at the telephoto end state. 1 is a cross-sectional view of a digital single-lens reflex camera equipped with a variable magnification optical system according to the present embodiment. It is a flowchart for demonstrating the manufacturing method of the variable magnification optical system which concerns on a present Example.

  Hereinafter, preferred embodiments of the present application will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. And a rear group GR. The second lens group G2 includes at least one positive lens and a negative lens arranged adjacent to the object side of the positive lens having the largest refractive power among these positive lenses. . When zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the distance between the second lens group G2 and the rear group GR changes. With such a configuration, it is possible to satisfactorily correct a reduction in the size of the lens barrel and an aberration variation during zooming.

  Now, conditions for constructing such a variable magnification optical system ZL will be described. First, in the zoom optical system ZL, when zooming from the wide-angle end state to the telephoto end state, the distance between the lens groups changes, and the radius of curvature of the object side surface of the negative lens in the second lens group G2 Is r1, the radius of curvature of the image side surface of the negative lens is r2, the focal length of the entire system in the wide-angle end state is fw, the focal length of the second lens group G2 is f2, and the back focus in the wide-angle end state Is preferably BFw, it is desirable to satisfy the following conditional expressions (1), (2) and (3).

0.80 <(r2 + r1) / (r2-r1) <3.50 (1)
0.30 <(− f2) / BFw <0.60 (2)
0.45 <fw / BFw <0.80 (3)

  Conditional expression (1) is a conditional expression for defining the shape of the negative lens adjacent to the object side of the positive lens having the largest refractive power in the second lens group G2. The present variable magnification optical system ZL can realize good optical performance by satisfying the conditional expression (1). Exceeding the upper limit of conditional expression (1) is not preferable because the radius of curvature of the object-side lens surface of the negative lens increases and it becomes difficult to correct coma in the wide-angle end state. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (1) to 3.00. On the other hand, if the lower limit value of conditional expression (1) is not reached, the radius of curvature of the object side lens surface of the negative lens becomes small, making it difficult to correct spherical aberration in the telephoto end state, and the distance between the negative lens and the positive lens. This is not preferable because the influence of the manufacturing error increases. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (1) to 0.90.

  Conditional expression (2) is a conditional expression for defining the ratio between the focal length f2 of the second lens group G2 and the focal length BFw of the entire system in the wide-angle end state. By satisfying the conditional expression (2), the zooming optical system ZL can achieve good optical performance and a predetermined zooming ratio while ensuring an effective back focus. If the upper limit of conditional expression (2) is exceeded, the refractive power of the second lens group G2 becomes weak, and the refractive power of other lens groups is strengthened in order to obtain an effective back focus in the wide-angle end state. Since spherical aberration and curvature of field deteriorate, it is not preferable. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (2) to 0.55. On the other hand, if the lower limit of conditional expression (2) is not reached, the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (2) to 0.35.

  Conditional expression (3) is a conditional expression for defining the ratio between the focal length fw of the entire system in the wide-angle end state and the back focus BFw in the wide-angle end state. The present variable magnification optical system ZL can secure an effective back focus in the wide-angle end state with respect to a predetermined variable magnification by satisfying the conditional expression (3). Exceeding the upper limit value of conditional expression (3) is not preferable because the back focus at the wide-angle end becomes too short, spherical aberration deteriorates, and it becomes difficult to ensure effective back focus. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (3) to 0.77. On the other hand, if the lower limit of conditional expression (3) is not reached, the focal length in the wide-angle end state becomes too small, and it becomes difficult to correct field curvature and coma aberration in the wide-angle end state. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (3) to 0.47.

  In the variable magnification optical system ZL, it is desirable that at least a part of the second lens group G2 move on the optical axis when focusing from infinity to a short-distance object point. With such a configuration, it is possible to reduce the size of the lens barrel and to satisfactorily correct aberration fluctuations such as spherical aberration at the time of focusing and curvature of field.

  In addition, it is desirable that the present variable magnification optical system ZL satisfies the following conditional expression (4).

0.50 <(− f2) / fw <0.90 (4)

  Conditional expression (4) is a conditional expression for defining the ratio between the focal length f2 of the second lens group G2 and the focal length fw of the entire system in the wide-angle end state. The present zoom optical system ZL can achieve good optical performance and a predetermined zoom ratio by satisfying the conditional expression (4). If the upper limit of conditional expression (4) is exceeded, the refractive power of the second lens group G2 will be weakened, and the refractive power of the other groups will be strengthened in order to obtain a predetermined zoom ratio. Since surface curvature deteriorates, it is not preferable. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (4) to 0.85. On the other hand, if the lower limit of conditional expression (4) is not reached, the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 0.60.

  In the variable magnification optical system ZL, the rear group GR includes, in order from the object side, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a positive refractive power. And a fifth lens group G5. With this configuration, it is possible to ensure a predetermined zoom ratio while effectively correcting variations between spherical aberration and field curvature.

  Alternatively, in the variable magnification optical system ZL, the rear group GR may include, in order from the object side, a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power. desirable. With this configuration, it is possible to ensure a predetermined zoom ratio while effectively correcting variations between spherical aberration and field curvature.

  In the variable magnification optical system ZL, the most image side lens surface of the second lens group G2 is preferably aspheric. With this configuration, spherical aberration in the telephoto end state can be corrected well.

  In the zoom optical system ZL, it is desirable that the following conditional expression (5) is satisfied when the focal length of the first lens group G1 is f1 and the focal length of the fourth lens group G4 is f4. .

  2.00 <f1 / | f4 | <6.00 (5)

  Conditional expression (5) is a conditional expression for defining the focal length f4 of the fourth lens group G4 with respect to the focal length f1 of the first lens group G1. By satisfying the conditional expression (5), the present zoom optical system ZL can secure a predetermined zoom ratio while securing optical performance during image blur correction. If the upper limit of conditional expression (5) is exceeded, the refractive power of the fourth lens group G4 becomes strong, and it is difficult to simultaneously correct the fluctuations in the curvature of field and the fluctuations in decentering coma during the image blur correction. This is not preferable. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (5) to 5.54. On the other hand, if the lower limit of conditional expression (5) is not reached, the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct spherical aberration in the telephoto end state. Further, the deterioration of lateral chromatic aberration in the wide-angle end state becomes remarkable, which is not preferable. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (5) to 3.55.

  In the variable magnification optical system ZL, it is desirable that a part of the rear group GR moves so as to have a component in a direction substantially perpendicular to the optical axis. With this configuration, it is possible to simultaneously correct fluctuations in curvature of field during image blur correction and fluctuations in eccentric coma.

  In the zoom optical system ZL, it is preferable that at least a part of the fourth lens group G4 moves so as to have a component in a direction substantially perpendicular to the optical axis. With this configuration, it is possible to simultaneously correct the fluctuations in the curvature of field during the image blur correction and the fluctuations in the eccentric coma aberration while reducing the size of the lens barrel.

  In the variable magnification optical system ZL, it is desirable that the most object side lens surface of the second lens group G2 has an aspherical shape. With this configuration, it is possible to satisfactorily correct field curvature and distortion in the wide-angle end state.

  Further, when the zooming optical system ZL zooms from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the rear group It is desirable to reduce the distance from the GR. With this configuration, it is possible to ensure a predetermined zoom ratio while effectively correcting variations between spherical aberration and field curvature.

  FIG. 13 shows a schematic cross-sectional view of a digital single-lens reflex camera 1 (hereinafter simply referred to as a camera) as an optical apparatus including the above-described variable magnification optical system ZL. In this camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 (variable magnification optical system ZL) and imaged on the focusing screen 4 via the quick return mirror 3. The light imaged on the focusing screen 4 is reflected a plurality of times in the pentaprism 5 and guided to the eyepiece lens 6. Thus, the photographer can observe the object (subject) image as an erect image through the eyepiece 6.

  Further, when a release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light of an object (subject) (not shown) condensed by the photographing lens 2 is captured on the image sensor 7. Form an image. Thereby, the light from the object (subject) is captured by the image sensor 7 and recorded as an object (subject) image in a memory (not shown). In this way, the photographer can shoot an object (subject) with the camera 1. The camera 1 shown in FIG. 13 may hold the variable magnification optical system ZL in a detachable manner, or may be formed integrally with the variable magnification optical system ZL. The camera 1 may be a so-called single-lens reflex camera or a compact camera without a quick return mirror or the like.

  The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In the present embodiment, the variable magnification optical system ZL having a four-group or five-group configuration is shown, but the above-described configuration conditions and the like can be applied to other group configurations such as six groups. Further, a configuration in which a lens or a lens group is added to the most object side, or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group indicates a portion having at least one lens separated by an air interval that changes at the time of zooming.

  Alternatively, a single lens group or a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an infinite distance to a short-distance object point. In this case, the focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor). In particular, it is preferable that at least a part of the second lens group G2 is a focusing lens group.

  In addition, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or is rotated (swayed) in the in-plane direction including the optical axis to reduce image blur caused by camera shake. A vibration-proof lens group to be corrected may be used. In particular, it is preferable that at least a part of the third lens group G3 or at least a part of the fourth lens group G4 is an anti-vibration lens group.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. It is preferable that the lens surface is a spherical surface or a flat surface because lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in processing and assembly adjustment is prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  The aperture stop S is preferably arranged in the vicinity of the third lens group G3 or in the third lens group G3. However, the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop. .

  Further, each lens surface may be provided with an antireflection film having a high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

  The variable magnification optical system ZL of the present embodiment has a variable magnification ratio of about 3.5 to 15.

  In the variable magnification optical system ZL of the present embodiment, it is preferable that the first lens group G1 has two positive lens components. In the first lens group G1, it is preferable that lens components are arranged in order of positive and negative in order from the object side with an air gap interposed therebetween. Alternatively, the first lens group G1 preferably has two positive lens components and one negative lens component. In the first lens group G1, it is preferable to dispose the lens components in the order of negative positive / negative in order from the object side with an air gap interposed therebetween.

  In the variable magnification optical system ZL of the present embodiment, it is preferable that the second lens group G2 has one positive lens component and three negative lens components. In the second lens group G2, it is preferable to dispose the lens components in the order of negative, positive and negative in order from the object side with an air gap interposed therebetween. Alternatively, it is preferable that the second lens group G2 has one positive lens component and two negative lens components. In the second lens group G2, it is preferable to arrange the lens components in order of negative and positive in order from the object side with an air gap interposed therebetween.

  In the variable magnification optical system ZL of the present embodiment, it is preferable that the third lens group G3 has one positive lens component and one negative lens component. In the third lens group G3, it is preferable to arrange the lens components in order of positive and negative in order from the object side with an air gap interposed therebetween. Alternatively, it is preferable that the third lens group G3 has two positive lens components. In the third lens group G3, it is preferable that lens components are arranged in order of positive and negative in order from the object side with an air gap interposed therebetween.

  In the variable magnification optical system ZL of the present embodiment, it is preferable that the fourth lens group G4 has one negative lens component.

  In the variable magnification optical system ZL of the present embodiment, it is preferable that the fifth lens group G5 has two positive lens components. In the fifth lens group G5, it is preferable to arrange the lens components in order of positive and negative in order from the object side with an air gap interposed therebetween.

  In addition, in order to explain this application in an easy-to-understand manner, the configuration requirements of the embodiment have been described, but it goes without saying that the present application is not limited to this.

  Hereinafter, the outline of the manufacturing method of the variable magnification optical system ZL of this embodiment is demonstrated with reference to FIG. First, at least one positive lens and a negative lens adjacent to the object side of the positive lens having the largest refractive power among these positive lenses are arranged in the second lens group G2 (step S100).

  At this time, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the distance between the second lens group G2 and the rear group GR changes. (Step S200).

  The radius of curvature of the object side surface of the negative lens in the second lens group G2 is r1, the radius of curvature of the image side surface of the negative lens is r2, and the focal length of the entire system in the wide angle end state is fw. When the focal length of the second lens group G2 is f2 and the back focus in the wide-angle end state is BFw, the second lens group G2 is arranged so as to satisfy the following conditional expressions (1), (2), and (3) (step S300). ).

0.80 <(r2 + r1) / (r2-r1) <3.50 (1)
0.30 <(− f2) / BFw <0.60 (2)
0.45 <fw / BFw <0.80 (3)

  Hereinafter, each example of the present application will be described with reference to the drawings. 1, 4, 7, and 10 show the configuration and refractive power distribution of the photographic lenses SL (SL1 to SL4) according to each embodiment, and focusing from the infinitely focused state to the short-distance focused state. It is sectional drawing which shows the mode of the movement of each lens group in the change of a state. As shown in FIGS. 1, 4, and 7, the variable magnification optical systems ZL <b> 1 to ZL <b> 3 according to the first to third examples are, in order from the object side, the first lens group G <b> 1 having a positive refractive power, A second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power It is composed of When zooming from the wide-angle end state to the telephoto end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the air gap between the second lens group G2 and the third lens group G3 is increased. The distance between the lens groups changes so that the air distance between the third lens group G3 and the fourth lens group G4 increases and the air distance between the fourth lens group G4 and the fifth lens group G5 decreases. To do. As shown in FIG. 10, the variable magnification optical system ZL4 according to the fourth example includes, in order from the object side, a first lens group G1 having a positive refractive power and a second lens group having a negative refractive power. G2 includes a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power. When zooming from the wide-angle end state to the telephoto end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the air gap between the second lens group G2 and the third lens group G3 is increased. The distance between the lens groups is changed so that the air distance between the third lens group G3 and the fourth lens group G4 is decreased.

In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangential plane of the apex of each aspheric surface to each aspheric surface at height y. Is S (y), r is the radius of curvature of the reference sphere (paraxial radius of curvature), κ is the conic constant, and An is the nth-order aspheric coefficient, and is expressed by the following equation (a). . In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

S (y) = (y ² / r) / {1+ (1−κ × y ² / r ² ) ^1/2 }
^{+ A4 × y 4 + A6 ×} y 6 + A8 × y 8 + A10 × y 10 (a)

  In each embodiment, the secondary aspheric coefficient A2 is zero. In the table of each example, an aspherical surface is marked with * on the left side of the surface number.

[First embodiment]
FIG. 1 is a diagram showing a configuration of a variable magnification optical system ZL1 according to the first example of the present application. In the variable magnification optical system ZL1 of FIG. 1, the first lens group G1 includes, in order from the object side, a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and an object It is composed of a positive meniscus lens L13 having a convex surface facing the side. The second lens group G2, in order from the object side, has an aspheric negative meniscus lens L21 having a convex surface on the object side and an aspheric surface on the object side lens surface, a negative meniscus lens L22 having a concave surface on the object side, and a biconvex lens L23. , And an aspherical biconcave lens L24 having an aspherical surface on the image side lens surface. The third lens group G3 includes, in order from the object side, a biconvex lens L31, a cemented positive lens formed by cementing a negative meniscus lens L32 having a convex surface toward the object side, and a biconvex lens L33, and a biconvex lens L34. . The fourth lens group G4 includes, in order from the object side, a cemented negative lens formed by cementing a positive meniscus lens L41 having a concave surface directed toward the object side and a biconcave lens L42, and a negative meniscus lens L43 having a concave surface directed toward the object side. It is configured. The fifth lens group G5 includes, in order from the object side, a biconvex lens L51 having an aspheric surface on the object side, a positive meniscus lens L52 having a concave surface facing the object side, and a negative meniscus lens L53 having a concave surface facing the object side. This is composed of a cemented positive lens.

  The aperture stop S is located inside the third lens group G3, that is, between the biconvex lens L31 and the negative meniscus lens L32, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state. To do. Focusing from infinity to a short-distance object point is performed by moving the second lens group G2 in the object direction. Image blur correction (anti-vibration) is performed by moving the cemented negative lens of the fourth lens group G4 so as to have a component in a direction substantially perpendicular to the optical axis.

  Table 1 below lists values of specifications of the first embodiment. In Table 1, f represents the focal length, FNO represents the F number, 2ω represents the angle of view, and Bf represents the back focus. Furthermore, the surface number is the order of the lens surfaces from the object side along the direction of travel of the light beam, the surface interval is the distance on the optical axis from each optical surface to the next optical surface, and the refractive index and Abbe number are each The value for the d-line (λ = 587.6 nm) is shown. The total length represents the distance on the optical axis from the first surface of the lens surface to the image plane I when focusing on infinity. Here, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other length units listed in all the following specifications, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. The radius of curvature of 0.0000 indicates a plane, and the refractive index of air of 1.0000 is omitted. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1)
Wide angle end Intermediate focal length Telephoto end
f = 24.70 to 45.75 to 116.39
FNO = 4.12 to 4.13 to 4.14
2ω = 85.24 to 48.96 to 20.28
Image height = 21.6 to 21.6 to 21.6
Overall length = 146.351 to 158.339 to 190.957
Bf = 38.496 to 48.783 to 64.317

Surface number Curvature radius Surface spacing Abbe number Refractive index
1 207.8010 2.000 23.77 1.846660
2 84.2787 7.595 67.87 1.593189
3 -1502.5800 0.100
4 57.9483 5.600 52.29 1.755000
5 142.1986 (d1)
* 6 1030.3484 1.200 46.63 1.816000
7 15.8302 8.018
8 -31.9349 1.000 45.30 1.795000
9 -78.0281 0.100
10 60.0996 4.200 23.77 1.846660
11 -33.4080 0.537
12 -28.4260 1.000 40.94 1.806100
* 13 1638.3373 (d2)
14 51.6280 2.600 52.29 1.755000
15 -725.4606 1.400
16 0.0000 0.500 Aperture stop
17 30.6214 3.000 23.77 1.846660
18 17.0593 6.600 70.45 1.487490
19 -88.0490 0.100
20 42.1543 3.400 67.87 1.593189
21 -433.2258 (d3)
22 -54.3056 3.500 32.35 1.850 260
23 -17.0745 1.000 52.29 1.755000
24 85.6576 3.000
25 -54.2304 1.000 53.89 1.713000
26 -943.5177 (d4)
* 27 88.1343 5.734 61.18 1.589130
28 -24.2775 0.100
29 -207.7437 6.509 70.45 1.487490
30 -19.8055 1.000 32.35 1.850 260
31 -73.8800 (Bf)

[Focal length of each lens group]
Lens group Start surface Focal length G1 1 106.848
G2 6 -17.844
G3 14 25.331
G4 22 -30.712
G5 27 45.007

  In the first embodiment, the lens surfaces of the sixth surface, the thirteenth surface, and the twenty-seventh surface are formed in an aspherical shape. The following Table 2 shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 2)
κ A4 A6 A8 A10
6th surface 1.0000 1.31870E-05 -3.10490E-08 4.74440E-11 -3.43860E-14
13th surface 1.0000 -9.26690E-07 -2.12150E-08 8.52640E-12 -8.74630E-14
27th surface -30.0000 -7.12220E-06 -3.55240E-09 4.19740E-11 -1.12730E-13

  In the first embodiment, the axial air distance d1 between the first lens group G1 and the second lens group G2, the axial air distance d2 between the second lens group G2 and the third lens group G3, and the third lens group G3. The on-axis air gap d3 between the fourth lens group G4 and the on-axis air gap d4 between the fourth lens group G4 and the fifth lens group G5 changes during zooming. Table 3 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state at infinity and near-distance object points.

(Table 3)
Infinity Wide angle end Intermediate focal length Telephoto end
d1 2.899 17.248 44.501
d2 24.017 11.369 1.199
d3 1.779 5.564 8.842
d4 8.342 4.578 1.300

Short distance Wide angle end Intermediate focal length Telephoto end
d1 2.077 16.566 43.557
d2 24.840 12.051 2.143
d3 1.799 5.564 8.842
d4 8.342 4.578 1.300

  Table 4 below shows values corresponding to the conditional expressions in the first embodiment. In Table 4, r1 is the radius of curvature of the object side surface of the negative lens L22 in the second lens group G2, r2 is the radius of curvature of the image side surface of the negative lens L22, and fw is in the wide-angle end state. F1 represents the focal length of the first lens group G1, f2 represents the focal length of the second lens group G2, and f4 represents the focal length of the fourth lens group G4. Yes. The description of the above symbols is the same in the following embodiments.

(Table 4)
(1) (r2 + r1) / (r2-r1) = 2.386
(2) (−f2) /Bfw=0.464
(3) fw / BFw = 0.642
(4) (−f2) /fw=0.722
(5) f1 / | f4 | = 3.479

  FIG. 2A shows an aberration diagram in the infinite focus state in the wide-angle end state of the first embodiment, and FIG. 2B shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 2C shows an aberration diagram in the infinitely focused state in the telephoto end state. Further, FIG. 3A shows an aberration diagram in the short-distance focusing state in the wide-angle end state of the first embodiment, and FIG. 3B shows an aberration diagram in the short-distance focusing state in the intermediate focal length state. FIG. 3C shows an aberration diagram in the short-distance in-focus state in the telephoto end state. In each aberration diagram, FNO represents an F number, Y represents an image height, d represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.6 nm). In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. As is apparent from the respective aberration diagrams, in the first embodiment, it is understood that various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Second Embodiment]
FIG. 4 is a diagram showing a configuration of the variable magnification optical system ZL2 according to the second example of the present application. In the variable magnification optical system ZL2 of FIG. 4, the first lens group G1 includes, in order from the object side, a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and an object It is composed of a positive meniscus lens L13 having a convex surface facing the side. The second lens group G2, in order from the object side, has an aspheric negative meniscus lens L21 having a convex surface on the object side and an aspheric surface on the object side lens surface, a negative meniscus lens L22 having a convex surface on the image side, and a biconvex lens L23. And a biconcave lens L24. The third lens group G3 includes, in order from the object side, a biconvex lens L31, a cemented positive lens formed by cementing the biconvex lens L32 and a negative meniscus lens L33 having a concave surface on the object side, and a positive surface having a convex surface directed to the object side. It is composed of a cemented positive lens formed by cementing a meniscus lens L34 and a biconvex lens L35. The fourth lens group G4 includes, in order from the object side, a cemented negative lens formed by cementing a biconcave lens L41 and a positive meniscus lens L42 having a convex surface directed toward the object side, and a concave surface directed toward the object side toward the object side lens surface. It is composed of an aspheric negative meniscus lens L43 having an aspheric surface. The fifth lens group G5 includes, in order from the object side, a biconvex lens L51, a cemented positive lens formed by cementing the biconvex lens L52 and a negative meniscus lens L53 having a concave surface facing the object side, and a concave surface facing the object side. It is composed of an aspheric negative meniscus lens L54 having an aspheric surface on the side lens surface.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state. Focusing from infinity to a short-distance object point is performed by moving the second lens group G2 in the object direction. Image blur correction (anti-vibration) is performed by moving the cemented negative lens of the fourth lens group G4 so as to have a component in a direction substantially perpendicular to the optical axis.

  Table 5 below shows values of specifications of the second embodiment.

(Table 5)
Wide angle end Intermediate focal length Telephoto end
f = 28.79 to 100.00 to 292.00
FNO = 3.57 to 5.34 to 5.96
2ω = 76.52 to 23.32 to 8.16
Image height = 21.6 to 21.6 to 21.6
Total length = 159.888 to 205.193 to 232.653
Bf = 38.422 to 65.896 to 79.261

Surface number Curvature radius Surface spacing Abbe number Refractive index
1 125.8687 2.000 31.27 1.903660
2 68.2116 9.300 82.56 1.497820
3 -1478.5570 0.100
4 68.1452 6.700 65.47 1.603000
5 484.4905 (d1)
* 6 590.8560 1.300 46.73 1.765460
7 18.5437 7.000
8 -38.3401 1.000 46.58 1.804000
9 -310.1534 0.100
10 38.1237 4.850 23.78 1.846660
11 -44.8791 0.950
12 -29.4340 1.000 46.58 1.804000
* 13 99.9238 (d2)
14 0.0000 0.500 Aperture stop
15 53.3960 3.400 54.66 1.729160
16 -92.1030 0.100
17 39.7508 5.000 82.56 1.497820
18 -41.4651 1.000 23.78 1.846660
19 -356.7126 0.100
20 32.9053 1.400 46.63 1.816000
21 15.5333 6.600 58.89 1.518230
22 -67.2953 (d3)
23 -79.1792 1.000 49.61 1.772500
24 15.8779 3.000 32.34 1.850 260
25 51.8482 2.586
26 -23.4054 0.190 38.09 1.553890
* 27 -23.4054 1.200 54.66 1.729160
28 -47.5480 (d4)
29 83.9836 5.600 60.69 1.563840
30 -26.4280 0.300
31 59.3963 6.900 45.79 1.548140
32 -21.2296 1.100 31.27 1.903660
33 -43.5914 1.600
34 -28.9812 1.300 42.64 1.820800
* 35 -136.6351 (Bf)

[Focal length of each lens group]
Lens group Start surface Focal length G1 1 109.348
G2 6 -17.324
G3 14 25.755
G4 23 -25.979
G5 29 43.376

  In the second embodiment, the sixth, thirteenth, twenty-seventh and thirty-fifth lens surfaces are aspherical. Table 6 below shows the aspheric data, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 6)
κ A4 A6 A8 A10
6th surface -9.1146 6.35640E-06 -7.76870E-09 -2.54380E-11 1.93540E-13
Side 13 1.0000 1.00450E-06 -1.40860E-08 9.73830E-12 0.00000E + 00
27th surface -0.2178 1.55140E-06 2.93820E-08 1.09380E-10 0.00000E + 00
35th surface 1.0000 -8.52260E-06 1.10900E-08 -4.80970E-11 1.46300E-13

  In the second embodiment, the axial air distance d1 between the first lens group G1 and the second lens group G2, the axial air distance d2 between the second lens group G2 and the third lens group G3, and the third lens group G3. The on-axis air gap d3 between the fourth lens group G4 and the on-axis air gap d4 between the fourth lens group G4 and the fifth lens group G5 changes during zooming. Table 7 below shows variable intervals at the focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state at infinity and near-distance object points.

(Table 7)
Infinity Wide angle end Intermediate focal length Telephoto end
d1 2.534 37.442 63.214
d2 30.341 13.263 1.585
d3 2.961 6.701 7.803
d4 6.152 2.412 1.310

Short distance Wide angle end Intermediate focal length Telephoto end
d1 1.853 36.751 59.870
d2 31.022 13.954 4.929
d3 2.961 6.701 7.803
d4 6.152 2.412 1.310

  Table 8 below shows values corresponding to the conditional expressions in the second embodiment.

(Table 8)
(1) (r2 + r1) / (r2-r1) = 1.282
(2) (−f2) /Bfw=0.451
(3) fw / BFw = 0.750
(4) (−f2) /fw=0.601
(5) f1 / | f4 | = 4.209

  FIG. 5A shows an aberration diagram in the infinite focus state in the wide-angle end state of the second embodiment, and FIG. 5B shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 5C shows an aberration diagram in the infinitely focused state in the telephoto end state. Further, FIG. 6A shows an aberration diagram in the short distance focusing state in the wide-angle end state of the second embodiment, and FIG. 6B shows an aberration diagram in the short distance focusing state in the intermediate focal length state. FIG. 6C shows an aberration diagram in the short-distance in-focus state in the telephoto end state. As is apparent from the respective aberration diagrams, in the second example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Third embodiment]
FIG. 7 is a diagram showing the configuration of the variable magnification optical system ZL3 according to the third example of the present application. In the variable magnification optical system ZL3 of FIG. 7, the first lens group G1 includes, in order from the object side, a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and an object It is composed of a positive meniscus lens L13 having a convex surface facing the side. The second lens group G2, in order from the object side, has an aspheric negative meniscus lens L21 having a convex surface on the object side and an aspheric surface on the object side lens surface, a negative meniscus lens L22 having a convex surface on the image side, and both It is composed of a cemented positive lens formed by cementing a convex lens L23 and an aspherical biconcave lens L24 having an aspheric surface on the image side lens surface. The third lens group G3 is composed of, in order from the object side, a cemented positive lens formed by bonding a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex lens L32, and a biconvex lens L33 and a biconcave lens L34. It consists of a cemented positive lens. The fourth lens group G4 includes, in order from the object side, a cemented negative lens formed by cementing a biconcave lens L41 and a positive meniscus lens L42 having a convex surface directed toward the object side. The fifth lens group G5 includes, in order from the object side, a positive meniscus lens L51 having a convex surface facing the object side, and a cemented positive lens formed by cementing a biconvex lens L52 and a negative meniscus lens L53 having a convex surface facing the object side. It is configured.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state. The flare cut stop FS is located between the fourth lens group G4 and the fifth lens group G5. Focusing from infinity to a short-distance object point is performed by moving the second lens group G2 in the object direction. Image blur correction (anti-vibration) is performed by moving the fourth lens group G4 so as to have a component in a direction substantially perpendicular to the optical axis.

  Table 9 below shows values of specifications of the third embodiment.

(Table 9)
Wide angle end Intermediate focal length Telephoto end
f = 18.39 to 56.02 to 101.99
FNO = 3.63 to 5.21 to 5.84
2ω = 80.32 to 28.58 to 16.00
Image height = 14.5 to 14.5 to 14.5
Total length = 134.064 to 160.538 to 177.708
Bf = 39.008 to 57.868 to 66.008

Surface number Curvature radius Surface spacing Abbe number Refractive index
1 209.4337 1.800 23.78 1.846660
2 79.9301 6.400 60.68 1.603110
3 -294.0880 0.100
4 53.0478 4.200 53.89 1.713000
5 124.9384 (d1)
* 6 154.1371 0.200 38.09 1.553890
7 130.0000 1.200 42.72 1.834807
8 13.9274 6.800
9 -43.5879 1.000 42.72 1.834807
10 -519.1937 0.300
11 40.9980 5.000 23.78 1.846660
12 -26.4284 1.000 42.72 1.834810
* 13 68.0402 (d2)
14 0.0000 0.600 Aperture stop
15 64.4076 0.900 28.69 1.795040
16 34.1145 3.600 82.52 1.497820
17 -31.0643 0.100
18 25.1181 2.800 49.61 1.772500
19 -25.1181 0.800 32.35 1.850 260
20 120.6588 (d3)
21 -58.6499 0.800 54.66 1.729157
22 12.6352 2.400 32.35 1.850 260
23 34.1595 3.343
24 0.0000 (d4) Flare cut aperture stop
25 -1531.4175 3.600 64.10 1.516800
26 -24.8933 0.100
27 55.6770 6.000 64.12 1.516800
28 -17.1260 1.200 32.35 1.850 260
29 -64.8623 (Bf)

[Focal length of each lens group]
Lens group Start surface Focal length G1 1 91.398
G2 6 -14.923
G3 14 24.587
G4 21 -35.820
G5 25 41.672

  In the third embodiment, the sixth and thirteenth lens surfaces are aspherical. Table 10 below shows the data of the aspheric surface, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 10)
κ A4 A6 A8 A10
6th surface 93.3168 5.89740E-06 -7.29460E-08 2.86340E-10 -7.78550E-13
13th surface 1.0000 -6.55200E-06 -7.75620E-09 -1.44920E-10 0.00000E + 00

  In the third example, the axial air gap d1 between the first lens group G1 and the second lens group G2, the axial air gap d2 between the second lens group G2 and the third lens group G3, and the third lens group G3. The on-axis air gap d3 between the fourth lens group G4 and the on-axis air gap d4 between the fourth lens group G4 and the fifth lens group G5 changes during zooming. Table 11 below shows variable intervals at the focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state at infinity and near-distance object points.

(Table 11)
Infinity Wide angle end Intermediate focal length Telephoto end
d1 2.284 27.418 41.691
d2 25.740 8.221 2.978
d3 2.124 7.010 8.712
d4 10.662 5.776 4.074

Short distance Wide angle end Intermediate focal length Telephoto end
d1 1.518 26.731 40.680
d2 26.506 8.908 3.989
d3 2.124 7.010 8.712
d4 10.662 5.776 4.074

  Table 12 below shows values corresponding to the conditional expressions in the third embodiment.

(Table 12)
(1) (r2 + r1) / (r2-r1) = 1.181
(2) (−f2) /Bfw=0.383
(3) fw / BFw = 0.472
(4) (−f2) /fw=0.911
(5) f1 / | f4 | = 2.552

  FIG. 8A shows an aberration diagram in the infinite focus state in the wide-angle end state of this third embodiment, and FIG. 8B shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 8C shows an aberration diagram in the infinitely focused state in the telephoto end state. Further, FIG. 9A shows an aberration diagram in the short-distance focusing state in the wide-angle end state of the third embodiment, and FIG. 9B shows an aberration diagram in the short-distance focusing state in the intermediate focal length state. FIG. 9C shows an aberration diagram in the short-distance in-focus state in the telephoto end state. As is apparent from the respective aberration diagrams, in the third example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

[Fourth embodiment]
FIG. 10 is a diagram showing the configuration of the variable magnification optical system ZL4 according to the fourth example of the present application. In the variable magnification optical system ZL4 of FIG. 10, the first lens group G1 includes, in order from the object side, a cemented positive lens formed by cementing a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and an object It is composed of a positive meniscus lens L13 having a convex surface facing the side. The second lens group G2, in order from the object side, has an aspheric negative meniscus lens L21 having a convex surface on the object side and an aspheric surface on the object side lens surface, a biconcave lens L22, a biconvex lens L23, and an image side lens surface. It is composed of an aspherical biconcave lens L24 having an aspherical surface. The third lens group G3 includes, in order from the object side, a biconvex lens L31, a cemented positive lens formed by cementing the biconvex lens L32 and the biconcave lens L33, an aspheric biconcave lens L34 having an aspheric surface on the object side lens surface, and the object. It is composed of a cemented negative lens formed by cementing with a positive meniscus lens L35 having a convex surface on the side. The fourth lens group G4 has, in order from the object side, a biconvex lens L41 having an aspheric surface on the object side lens surface, a cemented negative lens formed by cementing the biconvex lens L42 and the biconcave lens L43, and a convex surface facing the object side. It is composed of a positive meniscus lens L44.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state. The flare cut stop FS is located between the third lens group G3 and the fourth lens group G4. Focusing from infinity to a short-distance object point is performed by moving the second lens group G2 in the object direction. Image blur correction (anti-vibration) is performed by moving the cemented negative lens of the third lens group G3 so as to have a component in a direction substantially perpendicular to the optical axis.

  Table 13 below lists values of specifications of the fourth embodiment.

(Table 13)
Wide angle end Intermediate focal length Telephoto end
f = 18.50 to 70.24 to 195.00
FNO = 3.58 to 5.11 to 5.89
2ω = 79.78-22.88-8.44
Image height = 14.5 to 14.5 to 14.5
Total length = 141.720 to 183.030 to 207.403
Bf = 38.000 to 67.280 to 80.450

Surface number Curvature radius Surface spacing Abbe number Refractive index
1 131.6264 2.000 32.35 1.850 260
2 64.5215 8.800 81.61 1.497000
3 -502.5306 0.100
4 60.4775 6.300 65.47 1.603000
5 295.9384 (d1)
* 6 757.8898 0.150 38.09 1.553890
7 150.0000 1.200 46.63 1.816000
8 14.7418 6.500
9 -37.4285 1.000 46.63 1.816000
10 855.9338 0.100
11 36.4002 4.800 23.78 1.846660
12 -38.2802 0.900
13 -25.9865 1.000 47.38 1.788000
* 14 250.1396 (d2)
15 0.0000 0.500 Aperture stop
16 39.9769 3.000 65.47 1.603000
17 -39.9769 0.100
18 27.0291 3.600 81.61 1.497000
19 -30.9025 1.000 32.35 1.850 260
20 15022.6378 3.000
* 21 -47.6472 0.100 38.09 1.553890
22 -54.8674 1.000 49.61 1.772500
23 28.9153 1.800 25.43 1.805180
24 77.8261 2.600
25 0.0000 (d3) Flare cut aperture stop
* 26 74.7506 4.400 54.52 1.676974
27 -32.8683 0.600
28 113.7229 4.000 70.24 1.487490
29 -31.3823 1.400 37.17 1.834000
30 57.5744 1.500
31 -127.9425 3.300 64.12 1.516800
32 -27.8519 (Bf)

[Focal length of each lens group]
Lens group Start surface Focal length G1 1 100.784
G2 6 -14.519
G3 15 49.281
G4 26 43.229

  In the fourth embodiment, the lens surfaces of the sixth surface, the fourteenth surface, the twenty-first surface, and the twenty-sixth surface are formed in an aspherical shape. Table 14 below shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 14)
κ A4 A6 A8 A10
6th surface 1.0000 1.85064E-05 -5.88122E-08 1.30157E-10 -1.19816E-13
14th surface 1.0000 6.90787E-07 -1.55867E-08 -1.21063E-10 7.07360E-13
Side 21 1.0000 8.67713E-06 2.45288E-09 0.00000E + 00 0.00000E + 00
26th surface 1.0000 -1.85346E-05 3.98364E-09 0.00000E + 00 0.00000E + 00

  In the fourth embodiment, the axial air distance d1 between the first lens group G1 and the second lens group G2, the axial air distance d2 between the second lens group G2 and the third lens group G3, and the third lens group G3. The on-axis air gap d3 between the first lens group G4 and the fourth lens group G4 changes upon zooming. Table 15 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state at infinity and near-distance object points.

(Table 15)
Infinity Wide angle end Intermediate focal length Telephoto end
d1 2.070 38.000 60.000
d2 29.400 11.000 1.800
d3 7.500 2.000 0.400

Short distance Wide angle end Intermediate focal length Telephoto end
d1 3.280 37.822 58.174
d2 28.189 11.177 3.625
d3 7.500 2.000 0.400

  Table 16 below shows values corresponding to the conditional expressions in the fourth embodiment.

(Table 16)
(1) (r2 + r1) / (r2-r1) = 0.916
(2) (−f2) /Bfw=0.390
(3) fw / BFw = 0.498
(4) (−f2) /fw=0.833
(5) f1 / | f4 | = 2.275

  FIG. 11A shows an aberration diagram in the infinite focus state in the wide-angle end state of the fourth embodiment, and FIG. 11B shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 11C shows an aberration diagram in the infinitely focused state in the telephoto end state. Further, FIG. 12A shows an aberration diagram in the short-distance focusing state in the wide-angle end state of the fourth embodiment, and FIG. 12B shows an aberration diagram in the short-distance focusing state in the intermediate focal length state. FIG. 12C shows an aberration diagram in the short-distance in-focus state in the telephoto end state. As is apparent from the respective aberration diagrams, in the fourth example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

ZL (ZL1 to ZL4) Variable magnification optical system G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group S Aperture stop 1 Digital single-lens reflex camera (optical apparatus)

Claims (13)

From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A rear group having a positive refractive power,
The second lens group includes at least one positive lens and a negative lens disposed adjacent to the object side of the positive lens having the largest refractive power among the positive lenses,
When zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the rear group changes,
The radius of curvature of the object side surface of the negative lens in the second lens group is r1, the radius of curvature of the image side surface of the negative lens is r2, and the focal length of the entire system in the wide-angle end state is fw. When the focal length of the second lens group is f2 and the back focus in the wide-angle end state is BFw, the following expression 0.80 <(r2 + r1) / (r2-r1) <3.50
0.30 <(− f2) / BFw <0.60
0.45 <fw / BFw <0.80
Variable magnification optical system that satisfies the above conditions.   2. The zoom optical system according to claim 1, wherein at least a part of the second lens unit moves on the optical axis when focusing from infinity to a short-distance object point. The following formula 0.50 <(− f2) / fw <0.90
The zoom optical system according to claim 1, wherein the zoom lens system satisfies the following condition. The rear group is
From the object side,
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A variable magnification optical system according to any one of claims 1 to 3, further comprising a fifth lens group having a positive refractive power. The rear group is
From the object side,
A third lens group having positive refractive power;
The zoom optical system according to claim 1, further comprising a fourth lens group having a positive refractive power.   The zoom lens system according to any one of claims 1 to 5, wherein a lens surface closest to the image side of the second lens group has an aspherical shape. When the focal length of the first lens group is f1, and the focal length of the fourth lens group is f4, the following formula 2.00 <f1 / | f4 |
The zoom optical system according to any one of claims 4 to 6, which satisfies the following condition.   The variable power optical system according to claim 1, wherein a part of the rear group moves so as to have a component in a direction substantially perpendicular to the optical axis.   9. The variable magnification optical system according to claim 4, wherein at least part of the fourth lens group moves so as to have a component in a direction substantially perpendicular to the optical axis.   The variable magnification optical system according to any one of claims 1 to 9, wherein a lens surface closest to the object side of the second lens group has an aspherical shape.   The distance between the first lens group and the second lens group increases and the distance between the second lens group and the rear group decreases when zooming from the wide-angle end state to the telephoto end state. The variable power optical system as described in any one of 10-10.   An optical apparatus having the variable magnification optical system according to any one of claims 1 to 11. A manufacturing method of a variable magnification optical system having, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group having a positive refractive power. And
Disposing at least one positive lens and a negative lens adjacent to the object side of the positive lens having the largest refractive power among the positive lenses in the second lens group;
When zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is changed, and the distance between the second lens group and the rear group is changed. And
The radius of curvature of the object side surface of the negative lens in the second lens group is r1, the radius of curvature of the image side surface of the negative lens is r2, and the focal length of the entire system in the wide-angle end state is fw. When the focal length of the second lens group is f2 and the back focus in the wide-angle end state is BFw, the following expression 0.80 <(r2 + r1) / (r2-r1) <3.50
0.30 <(− f2) / BFw <0.60
0.45 <fw / BFw <0.80
A method for manufacturing a variable magnification optical system arranged so as to satisfy the above condition.

Images