JP2012042548A - Variable power optical system, optical apparatus having the same and method for manufacturing variable power optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable power optical system or the like having excellent optical performance which can correct camera shake, and F-number of which is bright while having high power variation.SOLUTION: The variable power optical system ZL mounted in a digital single-lens reflex camera 1 or the like includes a first lens group G1 having 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 in order from an object side. At least a part of any lens group out of these lens groups is moved so as to have a component in a perpendicular direction to an optical axis. When power is varied from a wide angle end state to a telephoto end state, a space between the first lens group G1 and the second lens group G2 changes, a space between the second lens group G2 and the third lens group G3 changes, a space between the third lens group G3 and the fourth lens group G4 changes, and a space between the fourth lens group G4 and the fifth lens group G5 changes.

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 2008-3511 A

  However, a variable magnification optical system having a camera shake correction function has a large number of lenses constituting the optical system, and a mechanism for correcting camera shake must be incorporated in the lens barrel. However, the compactness tends to be impaired. In addition, if the zoom ratio is increased while having the camera shake correction function, the optical performance is significantly deteriorated. In addition to the zoom ratio of 4.5 times or more, a lens having a bright F value can satisfy the optical performance now. There was an unprecedented problem.

  The present invention has been made in view of such a problem. A high-performance variable magnification optical system having a bright F value while having a high F / F, which enables image stabilization by an image shiftable optical system. It is an object of the present invention to provide an optical apparatus having a magnifying optical system and a method of manufacturing a magnifying optical system.

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. A third lens group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, and at least one of any of these lens groups. The unit moves so as to have a component in a direction orthogonal to the optical axis, and 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 second The distance between the lens group and the third lens group changes, the distance between the third lens group and the fourth lens group changes, the distance between the fourth lens group and the fifth lens group changes, and the third lens group From the wide-angle end state of the fifth lens group, where f3 is the focal length and the amount of movement from the image side to the object side is positive. When the amount of movement on the optical axis to the far end state is x5, the focal length of the fourth lens group is f4, and the focal length of the second lens group is f2, the following formula 0.75 <f3 / x5 <1 .00
0.53 <(− f2) / (− f4) <0.70
Satisfy the conditions.

Further, such a variable magnification optical system has the amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the first lens group G1 when the amount of movement from the image side to the object side is positive x1. Then, the following formula 1.70 <x1 / x5 <2.10
It is preferable to satisfy the following conditions.

  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 orthogonal to the optical axis.

  In such a variable magnification optical system, it is preferable that the fourth lens group includes a cemented negative lens of a positive lens and a negative lens and a negative lens in order from the object side.

Further, in such a variable magnification optical system, when the focal length of the fifth lens group is f5 and the focal length of the third lens group is f3, the following expression 0.70 <f5 / f3 <1.50
It is preferable to satisfy the following conditions.

Further, in such a variable magnification optical system, when the focal length of the fifth lens group is f5 and the focal length of the second lens group is f2, the following formula 1.60 <f5 / (− f2) <2. 40
It is preferable to satisfy the following conditions.

  In such a variable magnification optical system, it is preferable that the first lens unit moves from the image side to the object side when changing magnification from the wide-angle end state to the telephoto end state.

  In such a variable power optical system, it is preferable that the fifth lens unit moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state.

  In such a variable magnification optical system, it is preferable to perform focusing on a short-distance object point by moving at least a part of the second lens group along the optical axis.

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

  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 method of manufacturing a variable magnification optical system having a third lens group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, At least a part of any one of the lens groups is arranged to move so as to have a component in a direction perpendicular to the optical axis, and when zooming from the wide-angle end state to the telephoto end state, the first lens group and the second lens group The distance between the lens group is changed, the distance between the second lens group and the third lens group is changed, the distance between the third lens group and the fourth lens group is changed, and the fourth lens group and the fifth lens group are changed. The focal length of the third lens group is f3, and the distance from the image side to the object side is changed. When the amount is positive, the amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the fifth lens group is x5, the focal length of the fourth lens group is f4, and the focal length of the second lens group Where f2 is the following formula: 0.75 <f3 / x5 <1.00
0.53 <(− f2) / (− f4) <0.70
Arrange to satisfy the conditions.

  When the variable power optical system according to the present invention, the optical apparatus having the variable power optical system, and the manufacturing method of the variable power optical system are configured as described above, image stabilization is enabled by an optical system capable of image shift. It is possible to have a good optical performance with a bright F value while being variable in magnification.

It is sectional drawing which shows the structure of the variable magnification optical system by 1st Example. FIG. 4A is a diagram illustrating various aberrations in the infinitely focused state in the wide-angle end state according to the first embodiment, FIG. 5A is an aberration diagram in the infinitely focused state in the wide-angle end state, and FIG. FIG. 6 is a coma aberration diagram when blur correction is performed with respect to a rotational blur of 1.02 ° in an infinite photographing state. FIG. 6 is an aberration diagram in an infinitely focused state at an intermediate focal length state in the first example. FIG. 6 is a diagram illustrating various aberrations in the infinitely focused state in the telephoto end state according to the first embodiment, (a) is an aberration diagram in the infinitely focused state in the telephoto end state, and (b) is the telephoto end state. FIG. 7 is a coma aberration diagram when blur correction is performed for 0.28 ° rotational blur in the infinite distance shooting state. It is sectional drawing which shows the structure of the variable magnification optical system by 2nd Example. FIG. 7A is a diagram illustrating various aberrations in the infinitely focused state in the wide-angle end state according to the second embodiment, FIG. 9A is an aberration diagram in the infinitely focused state in the wide-angle end state, and FIG. FIG. 7 is a coma aberration diagram when blur correction is performed with respect to 0.76 ° rotational blur in the infinity shooting state. It is an aberration diagram of the infinite focus state in the intermediate focal length state of the second embodiment. FIG. 7A is a diagram illustrating various aberrations in the infinitely focused state in the telephoto end state according to the second embodiment, FIG. 9A is an aberration diagram in the infinitely focused state in the telephoto end state, and FIG. FIG. 6 is a coma aberration diagram when blur correction is performed for a rotational shake of 0.25 ° in an infinite photographing 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 this embodiment.

  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. A third lens group G3 having a negative refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. The variable magnification optical system ZL moves at least a part of any one of these lens groups so as to have a component in a direction orthogonal to the optical axis. Further, in the variable magnification optical system ZL, when changing the magnification 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 second lens group G2 and the third lens group G3. The distance between the lens group G3 changes, the distance between the third lens group G3 and the fourth lens group G4 changes, and the distance between the fourth lens group G4 and the fifth lens group G5 changes.

  Now, conditions for constructing such a variable magnification optical system ZL will be described. First, the variable magnification optical system ZL has a telephoto end from the wide-angle end state of the fifth lens group G5 when the focal length of the third lens group G3 is f3 and the amount of movement from the image side to the object side is positive. When the amount of movement on the optical axis to the state is x5, it is desirable to satisfy the following conditional expression (1).

0.75 <f3 / x5 <1.00 (1)

  Conditional expression (1) is a conditional expression for defining the amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the fifth lens group G5 with respect to the focal length of the third lens group G3. This zoom optical system ZL can satisfy the conditional expression (1) to realize good optical performance and to secure a predetermined zoom ratio. When the upper limit of conditional expression (1) is exceeded, the amount of movement of the fifth lens group G5 becomes small, the refractive power of the second lens group G2 becomes strong in order to ensure a predetermined zoom ratio, and the spherical surface at the telephoto end. Since it is difficult to correct aberrations, it is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (1) to 0.98. By satisfying this condition, the amount of movement of the fifth lens group G5 is appropriately set. And spherical aberration at the telephoto end can be reduced. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.95. On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the third lens group G3 becomes strong and it becomes difficult to correct coma at the telephoto end, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (1) to 0.80. By satisfying this condition, the refractive power of the third lens group G3 is appropriately set. The coma aberration at the telephoto end can be reduced. Furthermore, in order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.85.

  Further, it is desirable that the zoom optical system ZL satisfies the following conditional expression (2) when the focal length of the fourth lens group G4 is f4 and the focal length of the second lens group G2 is f2. .

0.53 <(− f2) / (− f4) <0.70 (2)

  Conditional expression (2) is a conditional expression for defining the focal length of the second lens group G2 with respect to the focal length of the fourth lens group G4. The zooming optical system ZL satisfies this conditional expression (2), thereby realizing good optical performance and ensuring a predetermined zooming ratio. 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 at the telephoto end, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (2) to 0.55. By satisfying this condition, the refractive power of the second lens group G2 is appropriately set. And spherical aberration at the telephoto end can be reduced. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.57. On the other hand, if the value exceeds the upper limit of conditional expression (2), the refractive power of the fourth lens group G4 becomes strong, and it becomes difficult to correct coma at the telephoto end, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (2) to 0.65. By satisfying this condition, the refractive power of the fourth lens group G4 is appropriately set. The coma aberration at the telephoto end can be reduced. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.63.

  Further, in the zoom optical system ZL, when the amount of movement from the image side to the object side is positive, the amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the first lens group G1 is x1. When the amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the fifth lens group G5 is x5, it is desirable to satisfy the following conditional expression (3).

1.70 <x1 / x5 <2.10 (3)

  Conditional expression (3) indicates that the movement amount on the optical axis from the wide-angle end state to the telephoto end state of the fifth lens group G5 with respect to the movement amount on the optical axis from the wide-angle end state to the telephoto end state of the first lens group G1. Is a conditional expression for prescribing. This zoom optical system ZL can satisfy the conditional expression (3) to realize good optical performance and to ensure a predetermined zoom ratio. If the upper limit value of conditional expression (3) is exceeded, the amount of movement of the fifth lens group G5 becomes smaller, the refractive power of the second lens group G2 becomes stronger in order to ensure a predetermined zoom ratio, and the spherical surface at the telephoto end. Since it is difficult to correct aberrations, it is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (3) to 2.00. By satisfying this condition, the amount of movement of the fifth lens group G5 is appropriately set. And spherical aberration at the telephoto end can be reduced. Furthermore, in order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 1.90. On the other hand, if the lower limit value of conditional expression (3) is not reached, the moving amount of the first lens group G1 becomes small, the refractive power of the first lens group G1 becomes strong to secure a predetermined zoom ratio, and the telephoto This is not preferable because it is difficult to correct field curvature at the edge. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (3) to 1.75. By satisfying this condition, the amount of movement of the first lens group G1 is appropriately set. Therefore, the field curvature aberration at the telephoto end can be reduced. Furthermore, in order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 1.80.

  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 orthogonal to the optical axis. With this configuration, it is possible to ensure a predetermined amount of image plane movement in a direction orthogonal to the optical axis while effectively correcting coma aberration at the telephoto end and field curvature aberration at the wide-angle end during such movement. .

  Further, in the present variable magnification optical system ZL, the fourth lens group G4 includes a cemented negative lens of a positive lens and a negative lens in order from the object side (for example, a cemented lens of the positive meniscus lens L41 and the biconcave lens L42 in FIG. 1). And a negative lens (for example, the negative meniscus lens L43 in FIG. 1). With this configuration, spherical aberration at the telephoto end and field curvature aberration at the wide-angle end can be corrected simultaneously.

  In the zoom optical system ZL, it is desirable that the following conditional expression (4) is satisfied when the focal length of the fifth lens group G5 is f5 and the focal length of the third lens group G3 is f3. .

0.70 <f5 / f3 <1.50 (4)

  Conditional expression (4) is a conditional expression for defining the focal length of the third lens group G3 with respect to the focal length of the fifth lens group G5. This zoom optical system ZL can satisfy the conditional expression (4) to realize good optical performance and to secure a predetermined zoom ratio. Exceeding the upper limit of conditional expression (4) is not preferable because the refractive power of the third lens group G3 becomes strong and it becomes difficult to correct coma at the telephoto end. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (4) to 1.40. By satisfying this condition, the refractive power of the third lens group G3 is appropriately set. The coma aberration at the telephoto end can be reduced. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 1.30. On the other hand, if the lower limit of conditional expression (4) is not reached, the refractive power of the fifth lens group G5 becomes strong, and it becomes difficult to correct field curvature aberration at the wide angle end, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.80. By satisfying this condition, the refractive power of the fifth lens group G5 is appropriately set. Therefore, the field curvature aberration at the wide angle end can be reduced. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.90.

  Further, such a variable magnification optical system ZL satisfies the following conditional expression (5) when the focal length of the fifth lens group G5 is f5 and the focal length of the second lens group G2 is f2. Is desirable.

1.60 <f5 / (− f2) <2.40 (5)

  Conditional expression (5) is a conditional expression for defining the focal length of the second lens group G2 with respect to the focal length of the fifth lens group G5. This zoom optical system ZL can satisfy the conditional expression (5) to realize good optical performance and to secure a predetermined zoom ratio. Exceeding the upper limit of conditional expression (5) is not preferable because the refractive power of the second lens group G2 becomes strong and it becomes difficult to correct spherical aberration at the telephoto end. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (5) to 2.30. By satisfying this condition, the refractive power of the second lens group G2 is appropriately set. And spherical aberration at the telephoto end can be reduced. In order to further secure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 2.20. On the other hand, if the lower limit of conditional expression (5) is not reached, the refractive power of the fifth lens group G5 becomes strong, and it becomes difficult to correct field curvature aberration at the wide-angle end, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (5) to 1.70. By satisfying this condition, the refractive power of the fifth lens group G5 is appropriately set. Therefore, the field curvature aberration at the wide angle end can be reduced. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 1.80.

  In the variable power optical system ZL, it is desirable that the first lens group G1 moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. With this configuration, it is possible to ensure a predetermined zoom ratio while effectively correcting variations between spherical aberration and field curvature.

  In such a zoom optical system ZL, it is desirable that the fifth lens group G5 moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. With this configuration, it is possible to ensure a predetermined zoom ratio while effectively correcting variations between spherical aberration and field curvature.

  Further, it is desirable that the variable magnification optical system ZL performs focusing on a short-distance object point by moving at least a part of the second lens group G2 along the optical axis. With this configuration, it is possible to effectively correct aberration fluctuations such as spherical aberration and field curvature during focusing.

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

  FIG. 9 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. Note that the camera 1 shown in FIG. 9 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. In addition, a camera that does not include the quick return mirror may be used, and the same effects as the camera can be obtained.

  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 the 5th and 6th group configuration is shown, but the above configuration conditions and the like can be applied to other group configurations such as the 7th group configuration. 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 refers to a portion having at least one lens separated by an air interval that changes during zooming.

  Alternatively, a single lens group, 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 object at infinity to a near object. 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, as described above, 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, as described above, it is preferable that 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 disposed in or near 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 3.0 to 10.0.

  In the present embodiment, it is preferable that the first lens group G1 has two positive lens components. The second lens group G2 preferably 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.

  In the present embodiment, it is preferable that the third lens group G3 has three positive lens components. Further, it is preferable that the fourth lens group G4 has two negative lens components. The fifth lens group G5 preferably has two positive lens components.

  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, an outline of a manufacturing method of the variable magnification optical system ZL of the present embodiment will be described with reference to FIG. First, each lens is arranged and a lens group is prepared (step S100). Specifically, in this embodiment, for example, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a positive meniscus lens L13 having a convex surface facing the object side are provided. The first lens group G1 is arranged, and in order from the object side, a biconcave lens L21, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side are arranged to form a second lens group G2. In order from the object side, a positive meniscus lens L31 having a convex surface facing the image side, a cemented lens of a negative meniscus lens L32 having a convex surface facing the object side and a biconvex lens L33, and a positive meniscus lens having a convex surface facing the image side L34 is arranged to form a third lens group G3, and in order from the object side, a cemented lens of a positive meniscus lens L41 having a convex surface directed to the image side and a biconcave lens L42. A negative meniscus lens L43 having a concave surface facing the object side is arranged as a fourth lens group G4, and in order from the object side, the biconvex lens L51, the biconvex lens L52 and the negative meniscus having a concave surface facing the object side A cemented lens with the lens L53 is arranged to form a fifth lens group G5. The variable power optical system ZL is manufactured by arranging the lens groups thus prepared.

  At this time, at least a part of any one of the first lens group G1 to the fifth lens group G5 is arranged to move so as to have a component in a direction orthogonal to the optical axis (step S200). . Further, 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 third lens group G3 changes. Then, the distance between the third lens group G3 and the fourth lens group G4 is changed, and the distance between the fourth lens group G4 and the fifth lens group G5 is changed (Step S300).

  Then, the movement of the fifth lens group G5 on the optical axis from the wide-angle end state to the telephoto end state when the focal length of the third lens group G3 is f3 and the amount of movement from the image side to the object side is positive. When the quantity is x5, the focal length of the fourth lens group G4 is f4, and the focal length of the second lens group G2 is f2, the arrangement is made so as to satisfy the conditional expressions (1) and (2) described above (step). S400).

  Hereinafter, each example of the present application will be described with reference to the drawings. FIGS. 1 and 5 show the configuration and refractive power distribution of the variable magnification optical system ZL (ZL1 to ZL2) according to each example, and the change of the in-focus state from the infinite focus state to the short-range focus state. It is sectional drawing which shows the mode of a movement of each lens group. As shown in FIGS. 1 and 5, the variable magnification optical systems ZL1 to ZL2 according to the first to second examples include a first lens group G1 having a positive refractive power and a negative refractive power in order from the object side. A second lens group G2 having positive 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. ing. 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.

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 + A12 × y ¹² (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 lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a convex surface facing the object side. It is composed of a positive meniscus lens L13 directed to it. The second lens group G2 includes, in order from the object side, a biconcave lens L21, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side, and is the most object side of the second lens group G2. The biconcave lens L21 located at is an aspherical lens in which an aspheric surface is formed on the object side glass lens surface, and the biconcave lens L24 located on the most image side is an aspherical surface in which an aspheric surface is formed on the image side glass lens surface. It is a spherical lens. The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed to the image side, a cemented lens of a negative meniscus lens L32 having a convex surface directed to the object side and a biconvex lens L33, and a convex surface facing the image side. Is formed from a positive meniscus lens L34. The fourth lens group G4 includes, in order from the object side, a cemented lens of a positive meniscus lens L41 having a convex surface facing the image side and a biconcave lens L42, and a negative meniscus lens L43 having a concave surface facing the object side. . The fifth lens group G5 includes, in order from the object side, a biconvex lens L51, and a cemented lens of the biconvex lens L52 and a negative meniscus lens L53 having a concave surface directed toward the object side. The biconvex lens L51 located closest to the object side. Is an aspherical lens in which an aspherical surface is formed on the glass lens surface on the object side.

  The aperture stop S is located adjacent to the image side of the most object side positive lens (biconvex lens L31) of the third lens group G3, and the third lens group during zooming from the wide-angle end state to the telephoto end state. Move with G3. 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 lens of the fourth lens group G4 so as to have a component in a direction orthogonal to the optical axis.

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the first embodiment, in the wide-angle end state, the image stabilization coefficient is 0.97, and the focal length is 16.4 (mm). Therefore, the fourth lens group for correcting the rotation blur of 1.02 °. The amount of movement of G4 is 0.3 (mm). In the telephoto end state of the first embodiment, the image stabilization coefficient is 1.41 and the focal length is 86.4 (mm). Therefore, the fourth lens group for correcting rotational shake of 0.28 °. The moving amount of G4 is 0.30 (mm).

  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 = 16.4 to 35.3 to 86.4
F.NO = 4.3 to 4.6 to 4.7
2ω = 85.5 to 45.8 to 20.4
Total length = 110.0 to 122.9 to 140.9
Bf = 38.0 to 50.5 to 55.1

Surface number Curvature radius Surface spacing Abbe number Refractive index
1 140.9452 1.315 23.78 1.84666
2 61.4142 4.907 67.87 1.59319
3 -450.4988 0.066
4 42.5013 3.471 52.31 1.75500
5 113.2924 (d1)
* 6 -162.5207 0.888 42.72 1.83481
7 13.0765 4.931
8 -25.0265 0.658 42.72 1.83481
9 103.8110 0.066
10 25.2250 3.123 23.78 1.84666
11 -25.9859 0.334
12 -22.0584 0.658 40.94 1.80610
* 13 -121.7103 (d2)
14 -170.3530 1.682 52.31 1.75500
15 -67.9362 0.921
16 0.0000 0.329 Aperture stop S
17 21.4023 1.315 23.78 1.84666
18 12.8613 4.767 70.40 1.48749
19 -123.1092 0.066
20 20.7295 1.775 67.87 1.59319
21 100.2147 (d3)
22 -36.6911 2.190 32.35 1.85026
23 -11.0488 0.658 52.31 1.75500
24 61.0256 1.805
25 -29.8383 0.658 52.31 1.75500
26 -87.7936 (d4)
* 27 129.9963 3.616 61.16 1.58913
28 -16.7894 0.066
29 110.9228 3.945 70.40 1.48749
30 -13.5088 0.789 32.35 1.85026
31 -36.6170 (Bf)

[Lens focal length]
Lens group Start surface Focal length separation First lens group 1 69.20
Second lens group 6 -13.40
Third lens group 14 23.00
Fourth lens group 22 -22.20
5th lens group 27 24.86

  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 the aspheric surface, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A12.

(Table 2)
κ A4 A6 A8 A10 A12
6th surface 1.00000 5.05259E-05 -1.59011E-07 6.33033E-10 -2.47712E-12 7.47330E-15
13th surface 10.00000 3.78646E-05 6.68301E-08 -7.34358E-10 4.35580E-13 0.00000E + 00
27th surface-30.00000 -1.17677E-05 3.68016E-08 1.27392E-10 -1.15092E-12 0.00000E + 00

  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 distance d3 between the fourth lens group G4 and the on-axis air distance 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)
Wide angle end Intermediate focal length Telephoto end
d1 1.90 13.20 32.92
d2 18.00 7.10 0.79
d3 1.70 4.30 6.00
d4 5.40 2.80 1.10

  Table 4 below shows values corresponding to the conditional expressions in the first embodiment. In Table 4, f3 is the focal length of the third lens group G3, and x5 is the distance from the wide-angle end state to the telephoto end state when the amount of movement from the image side to the object side is positive. The amount of movement on the optical axis, f4 is the focal length of the fourth lens group G4, f2 is the focal length of the second lens group G2, and x1 is the amount of movement from the image side to the object side. The amount of movement of the first lens group G1 on the optical axis from the wide-angle end state to the telephoto end state, and f5 represents the focal length of the fifth lens group G5. The description of the above symbols is the same in the following embodiments.

(Table 4)
(1) f3 / x5 = 0.92
(2) (−f2) / (− f4) = 0.60
(3) x1 / x5 = 1.81
(4) f5 / f3 = 1.08
(5) f5 / (− f2) = 1.85

  FIG. 2A shows an aberration diagram in the infinite focus state in the wide-angle end state of the first embodiment, and FIG. 3 shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 4A shows an aberration diagram in the infinitely focused state in the state. Further, FIG. 2B shows a coma aberration diagram when the shake correction is performed with respect to the rotational shake of 1.02 ° in the infinite distance photographing state in the first embodiment at the wide angle end state, and infinite in the telephoto end state. FIG. 4B shows a coma aberration diagram when blur correction is performed for 0.28 ° rotational blur in the far-field state. In each aberration diagram, FNO is an F number, Y is an image height with respect to a half angle of view, d is a d-line (λ = 587.6 nm), and g is a g-line (λ = 435.6 nm). Yes. 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. 5 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. 5, the first lens group G1 includes, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a convex surface facing the object side. It is composed of a positive meniscus lens L13 directed to it. The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface directed toward the image side, a biconcave lens L22, a biconvex lens L23, and a biconcave lens L24, and is the most object side of the second lens group G2. The negative meniscus lens L21 located at is an aspherical lens in which an aspheric surface is formed on the glass lens surface on the object side, and the biconcave lens L24 located on the most image side has an aspherical surface on the glass lens surface on the image side. It is an aspheric lens. The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a cemented lens of a negative meniscus lens L32 having a convex surface directed toward the object side and a biconvex lens L33, and a biconvex lens L34. It is configured. The fourth lens group G4 includes, in order from the object side, a cemented lens of a positive meniscus lens L41 having a convex surface facing the image side and a biconcave lens L42, and a negative meniscus lens L43 having a concave surface facing the object side. . The fifth lens group G5 includes, in order from the object side, a biconvex lens L51, and a cemented lens of 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. The biconvex lens L51 located on the object side is an aspheric lens in which an aspheric surface is formed on the glass lens surface on the object side.

  The aperture stop S is located adjacent to the object side of the most object side positive lens (biconvex lens L31) of the third lens group G3, and the third lens group upon zooming from the wide-angle end state to the telephoto end state. Move with G3. 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 lens of the fourth lens group G4 so as to have a component in a direction orthogonal to the optical axis.

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the wide-angle end state of the second embodiment, the image stabilization coefficient is 1.43 and the focal length is 16.3 (mm). Therefore, the fourth lens group for correcting a rotational shake of 0.76 °. The moving amount of G4 is 0.15 (mm). In the telephoto end state of the second embodiment, since the image stabilization coefficient is 2.22 and the focal length is 76.0 (mm), the fourth lens group for correcting a rotational blur of 0.25 °. The moving amount of G4 is 0.15 (mm).

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

(Table 5)
Wide angle end Intermediate focal length Telephoto end f = 16.3 to 34.3 to 76.0
F.NO = 4.1 to 4.3 to 4.9
2ω = 84.8 to 43.8 to 20.3
Total length = 108.7 to 124.5 to 146.9
Bf = 39.9 to 64.5 to 84.0

Surface number Curvature radius Surface spacing Abbe number Refractive index
1 291.6677 1.314 23.77 1.84666
2 70.2017 5.058 67.87 1.59319
3 -231.4519 0.066
4 43.3965 3.599 46.63 1.81600
5 112.4283 (d1)
* 6 165.0442 0.066 38.09 1.55389
7 97.8093 0.985 46.63 1.81600
8 10.5655 5.255
9 -25.1119 0.657 42.72 1.83481
10 281.8606 0.066
11 31.8673 2.956 23.77 1.84666
12 -21.5510 0.353
13 -21.2561 0.788 40.94 1.80610
* 14 1001.3221 (d2)
15 0.0000 0.985 Aperture stop S
16 50.3117 1.081 52.29 1.75500
17 59.3546 0.200
18 18.7646 3.784 23.77 1.84666
19 11.6712 3.410 70.45 1.48749
20 -244.9230 0.200
21 21.8515 2.350 67.87 1.59319
22 -116.3328 (d3)
23 -22.6980 1.983 32.35 1.85026
24 -11.1317 0.657 52.29 1.75500
25 67.4378 0.832
26 -55.7972 0.657 55.52 1.69680
27 -155.7618 (d4)
* 28 61.0746 3.635 61.18 1.58913
29 -15.7646 0.200
30 -108.8687 3.331 70.45 1.48749
31 -14.5167 1.000 32.35 1.85026
32 -34.0970 (Bf)

[Lens focal length]
Lens group Start surface Focal length separation 1st lens group 1 72.96
Second lens group 6 -12.14
Third lens group 16 20.76
Fourth lens group 23 -20.44
5th lens group 28 24.07

  In the second embodiment, the lens surfaces of the sixth surface, the fourteenth surface, and the twenty-eighth surface are formed in an aspherical shape. 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 A12.

(Table 6)
κ A4 A6 A8 A10 A12
6th surface -13.15270 4.50740E-05 -2.06890E-07 4.69270E-10 -1.59140E-12 0.00000E + 00
14th surface 0.00000 1.44570E-05 -1.90290E-07 4.71900E-10 0.00000E + 00 0.00000E + 00
28th surface 15.27350 -4.58100E-05 -1.07530E-07 2.74810E-09 -1.86780E-11 0.00000E + 00

  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 distance d3 between the fourth lens group G4 and the on-axis air distance 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)
Wide angle end Intermediate focal length Telephoto end
d1 2.00 13.56 30.93
d2 15.74 7.02 2.35
d3 1.47 4.58 7.70
d4 4.17 1.81 0.20

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

(Table 8)
(1) f3 / x5 = 0.86
(2) (−f2) / (− f4) = 0.59
(3) x1 / x5 = 1.87
(4) f5 / f3 = 1.16
(5) f5 / (− f2) = 1.98

  FIG. 6A shows an aberration diagram in the infinite focus state in the wide-angle end state of this second embodiment, and FIG. 7 shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 8A shows an aberration diagram in the infinitely focused state in the state. Further, FIG. 6B shows a coma aberration diagram when performing blur correction for 0.76 ° rotational blur in the infinity photographing state in the wide-angle end state of the second embodiment, and the infinite in the telephoto end state. FIG. 8B shows a coma aberration diagram when blur correction is performed with respect to a rotational blur of 0.25 ° in the far shooting 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.

ZL (ZL1 to ZL2) 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 (12)

From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having a positive refractive power,
At least a part of any one of the lens groups moves so as to have a component in a direction perpendicular to the optical axis,
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 third lens group changes, The distance between the third lens group and the fourth lens group changes, and the distance between the fourth lens group and the fifth lens group changes,
The amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the fifth lens group when the focal length of the third lens group is f3 and the amount of movement from the image side to the object side is positive. Assuming x5, the focal length of the fourth lens group is f4, and the focal length of the second lens group is f2, the following expression 0.75 <f3 / x5 <1.00
0.53 <(− f2) / (− f4) <0.70
A variable power optical system characterized by satisfying the following conditions. When the amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the first lens group when the amount of movement from the image side to the object side is positive is x1, the following expression 1.70 <x1 /X5<2.10
The zoom lens system according to claim 1, wherein the following condition is satisfied.   3. The variable magnification optical system according to claim 1, wherein at least a part of the fourth lens group moves so as to have a component in a direction orthogonal to the optical axis.   4. The zoom lens according to claim 1, wherein the fourth lens group includes a negative lens and a cemented negative lens of a positive lens and a negative lens in order from the object side. Optical system. When the focal length of the fifth lens group is f5 and the focal length of the third lens group is f3, the following expression 0.70 <f5 / f3 <1.50
The zoom lens system according to any one of claims 1 to 4, wherein the following condition is satisfied. When the focal length of the fifth lens group is f5 and the focal length of the second lens group is f2, the following formula 1.60 <f5 / (− f2) <2.40
The zoom lens system according to any one of claims 1 to 5, which satisfies the following condition.   The zoom optical system according to any one of claims 1 to 6, wherein the first lens unit moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. .   The zoom optical system according to any one of claims 1 to 7, wherein the fifth lens unit moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. .   The zooming according to any one of claims 1 to 8, wherein focusing on a short-distance object point is performed by moving at least a part of the second lens group along an optical axis. Optical system.   The variable magnification optical system according to claim 1, wherein the second lens group has an aspherical lens surface.   An optical apparatus comprising the variable magnification optical system according to claim 1. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a negative refractive power A variable magnification optical system having a group and a fifth lens group having a positive refractive power,
At least a part of any one of the lens groups is arranged to move so as to have a component in a direction orthogonal to the optical axis,
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 third lens group changes, The distance between the third lens group and the fourth lens group is changed, and the distance between the fourth lens group and the fifth lens group is changed.
The amount of movement on the optical axis from the wide-angle end state to the telephoto end state of the fifth lens group when the focal length of the third lens group is f3 and the amount of movement from the image side to the object side is positive. Assuming x5, the focal length of the fourth lens group is f4, and the focal length of the second lens group is f2, the following expression 0.75 <f3 / x5 <1.00
0.53 <(− f2) / (− f4) <0.70
A method of manufacturing a variable magnification optical system, wherein the zoom lens system is arranged so as to satisfy the above condition.

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