JP6119953B2 - Variable magnification optical system, optical apparatus having the variable magnification optical system, and method of manufacturing the variable magnification optical system - Google Patents

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-A-11-174329

  However, the conventional variable-power optical system has a problem that the aberration fluctuation at the time of zooming is large and that it cannot cope with the aberration fluctuation at the time of camera shake correction.

  The present invention has been made in view of such a problem, and a variable power optical system having an optical performance that is small in aberration fluctuation at the time of zooming and can cope with aberration fluctuation at the time of camera shake correction, and the variable power optical system It is an object of the present invention to provide an optical device having the above and a method for manufacturing a variable magnification optical system.

In order to solve the above problems, a variable magnification optical system according to the present invention includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a negative refractive power. a third lens group having made positive substantially four lens groups and the fourth lens group having a refractive power, upon zooming from the wide-angle end state to the telephoto end state, the first lens group The distance between the second lens group changes, the distance between the second lens group and the third lens group increases , the distance between the third lens group and the fourth lens group decreases , At least one single lens is an anti-vibration lens group that moves so as to include a component in a direction orthogonal to the optical axis, and has an opening in the second lens group or between the second lens group and the third lens group. an aperture stop, a third lens group includes only a single lens, the fourth lens group includes a positive lens nearest to the image side deflection It has a cemented lens formed by bonding a's, and satisfies the conditions of the following equation.
0.23 ≦ dSt / f4 ≦ 0.39
However,
dSt: spacing between the aperture stop and the third lens group in the telephoto end state f4: focal length of the fourth lens group

  The zoom optical system according to the present invention includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power. And a fourth lens group having a positive refractive power, 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 second lens group and the third lens group is increased, the distance between the third lens group and the fourth lens group is decreased, and at least one single lens in the second lens group is decreased. The lens is a vibration-proof lens group that moves so as to include a component in a direction orthogonal to the optical axis, and has an aperture stop in the second lens group or between the second lens group and the third lens group, The fourth lens group has a cemented lens in which a positive lens and a negative lens are bonded to the most image side, and satisfies the condition of the following expression. It is characterized in.
0.14 ≦ dSt / f4 <0.60
0.27 ≦ f2 / f2a ≦ 0.30
  However,
  dSt: Distance between the aperture stop and the third lens group in the telephoto end state
  f4: focal length of the fourth lens unit
  f2: Focal length of the second lens group
  f2a: Focal length of the anti-vibration lens group

  The zoom optical system according to the present invention includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power. And a fourth lens group having a positive refractive power, 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 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 at least one single lens in the second lens group is changed. The lens is a vibration-proof lens group that moves so as to include a component in a direction orthogonal to the optical axis, and has an aperture stop in the second lens group or between the second lens group and the third lens group, The third lens group has at least one single lens having an air gap on both sides, and the fourth lens group is the most image side. It has a positive lens and a negative lens and a cemented cemented lens, and satisfies the conditions of the following equation.
0.14 ≦ dSt / f4 <0.60
0.27 ≦ f2 / f2a ≦ 0.30
  However,
  dSt: Distance between the aperture stop and the third lens group in the telephoto end state
  f4: focal length of the fourth lens unit
  f2: Focal length of the second lens group
  f2a: Focal length of the anti-vibration lens group

  The 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 negative refractive power, a second lens group having a positive refractive power, and a negative refractive power. A variable magnification optical system manufacturing method comprising substantially four lens groups of a third lens group and a fourth lens group having a positive refractive power, the first lens group, the second lens group, When changing the magnification of the third lens group and the fourth lens group 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 lens group and the third lens group interval is increased, the interval between the third lens group and the fourth lens group arranged to reduce, at least one of the single lenses of the second lens group, a component in a direction perpendicular to the optical axis deployed as a vibration reduction lens group that moves to include the inside or the second lens group in the second lens group and the third lens group The aperture stop is disposed between, the third lens group, only one single lenses are arranged, a positive lens and a negative lens and a cemented cemented lens disposed on the most image side of the fourth lens group, the aperture The stop, the third lens group, and the fourth lens group are arranged so as to satisfy the following condition.
0.23 ≦ dSt / f4 ≦ 0.39
However,
dSt: distance between the aperture stop at the telephoto end state and the third lens group f4: the focal length of the fourth lens group

  When the present invention is configured as described above, a variable magnification optical system having an optical performance that is small in aberration variation at the time of zooming and can cope with aberration variation at the time of camera shake correction, an optical device having the variable magnification optical system, and A variable magnification optical system manufacturing method can be provided.

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example. FIG. 7A is a diagram illustrating various aberrations in the wide-angle end state of the variable magnification optical system according to the first example, where FIG. 9A is an aberration diagram in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 7 is a diagram illustrating various aberrations in the infinitely focused state in the intermediate focal length state of the variable magnification optical system according to the first example. FIG. 3A is a diagram illustrating various aberrations in the telephoto end state of the variable magnification optical system according to the first example, where FIG. 5A is an aberration diagram in an infinite focus state, and FIG. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. FIG. 6A is a diagram illustrating various aberrations in the wide-angle end state of the variable magnification optical system according to Example 2, wherein FIG. 5A is an aberration diagram in the infinite focus state, and FIG. 5B is an image blur correction in the infinite focus state. It is a coma aberration figure when performing. FIG. 10 is a diagram illustrating various aberrations in the infinitely focused state in the intermediate focal length state of the variable magnification optical system according to the second example. FIG. 7A is a diagram illustrating various aberrations in the telephoto end state of the variable magnification optical system according to Example 2, wherein FIG. 9A is an aberration diagram in the infinite focus state, and FIG. 9B is an image blur correction in the infinite focus state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 3rd Example. FIG. 6A is an aberration diagram in the wide-angle end state of the variable magnification optical system according to Example 3; FIG. 5A is an aberration diagram in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 12 is a diagram illustrating various aberrations in the infinitely focused state in the intermediate focal length state of the variable magnification optical system according to the third example. FIG. 7A is a diagram illustrating various aberrations in the telephoto end state of the variable magnification optical system according to the third example, where FIG. 9A is an aberration diagram in the infinite focus state, and FIG. 9B is an image blur correction in the infinite focus state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 4th Example. FIG. 6A is a diagram illustrating various aberrations in the wide-angle end state of the variable magnification optical system according to the fourth example, where FIG. 5A is an aberration diagram in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 11 is a diagram illustrating various aberrations in the infinitely focused state in the intermediate focal length state of the variable magnification optical system according to the fourth example. FIG. 9A is a diagram illustrating various aberrations of the zoom optical system according to Example 4 in the telephoto end state, where FIG. 9A is an aberration diagram in the infinite focus state, and FIG. It is a coma aberration figure when performing. A sectional view of a camera carrying the above-mentioned variable magnification optical system is shown. It is a flowchart for demonstrating the manufacturing method of the said variable magnification optical system.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG.
The zoom optical system ZL according to this embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a first lens group having a negative refractive power. The third lens group G3 includes a third lens group G3 and a fourth lens group G4 having a positive refractive power. In addition, 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 changes, and the second lens group G2 and the third lens group G3 change. The distance between the lens group G3 changes and the distance between the third lens group G3 and the fourth lens group G4 changes. In the variable magnification optical system ZL, at least one single lens (for example, the biconvex lens L21 in FIG. 1) of the second lens group G2 moves so as to include a component in a direction orthogonal to the optical axis. This is an anti-vibration lens group VL. When the zoom optical system ZL according to the present embodiment is configured in this manner, the coma aberration at the telephoto end and the field curvature aberration at the wide angle end at the time of zooming are effectively corrected, and the direction substantially orthogonal to the optical axis. A predetermined image plane movement amount can be ensured.

  Now, conditions for constructing such a variable magnification optical system ZL will be described. First, it is desirable that the variable magnification optical system ZL satisfies the following conditional expression (1).

0.40 <f1 / f3 <1.00 (1)
However,
f1: Focal length of the first lens group G1 f3: Focal length of the third lens group G3

  Conditional expression (1) is a conditional expression for defining the focal length of the first lens group G1 with respect to the focal length of the third lens group G3. Exceeding the upper limit of conditional expression (1) is not preferable because the refractive power of the third lens group G3 increases and it becomes difficult to correct spherical aberration at the wide-angle end. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (1) to 0.80. On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct field curvature aberration at the telephoto end, 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 (1) to 0.50.

  In the zoom optical system ZL, the first lens group G1 has a negative lens (for example, the negative meniscus lens L11 in FIG. 1) closest to the object side, and satisfies the following conditional expression (2). Is desirable.

−2.00 <(R2 + R1) / (R2−R1) <− 1.00 (2)
However,
R1: radius of curvature of the object side surface of the negative lens closest to the object side in the first lens group G1 R2: radius of curvature of the image side surface of the negative lens closest to the object side of the first lens group G1

Conditional expression (2) is a conditional expression for defining the shape of the negative lens arranged on the most object side of the first lens group G1. If the upper limit value of the conditional expression (2) is exceeded, the radius of curvature of the object side lens surface of the negative lens becomes small , or the radius of curvature of the image side lens surface becomes large, and it is difficult to correct spherical aberration at the telephoto end. Therefore, 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 -1.30. On the other hand, if the lower limit of conditional expression (2) is not reached, the radius of curvature of the image side lens surface of the negative lens becomes smaller, or the radius of curvature of the object side lens surface becomes smaller, and the field curvature aberration at the wide angle end becomes smaller . Since correction becomes difficult, it 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 −1.80.

  In this variable magnification optical system ZL, the third lens group G3 has at least one single lens (for example, a biconcave lens L31 in FIG. 1) having an air gap on both sides, and the following conditional expression ( It is desirable to satisfy 3).

3.00 <f4 / d3w <9.00 (3)
However,
f4: Focal length of the fourth lens group G4 d3w: Air distance between the third lens group G3 and the fourth lens group G4 in the wide-angle end state

  Conditional expression (3) is a conditional expression for defining the distance between the third lens group G3 and the fourth lens group G4 with respect to the focal length of the fourth lens group G4. If the upper limit of conditional expression (3) is exceeded, the air gap d3w between the third lens group G3 and the fourth lens group G4 becomes narrow, the zooming efficiency decreases, and it becomes difficult to correct spherical aberration at the wide-angle end. Therefore, 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 (3) to 7.00. On the other hand, if the lower limit of conditional expression (3) is not reached, the refractive power of the fourth lens group G4 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 application, it is preferable to set the lower limit of conditional expression (3) to 4.00.

  The variable magnification optical system ZL has an aperture stop S in or near the second lens group G2, and the fourth lens group G4 is a cemented lens in which a positive lens and a negative lens are bonded to the most image side. (For example, it is desirable to have a cemented lens including the positive meniscus lens L42 and the negative meniscus lens L42 in FIG. 1). By disposing a convex and concave cemented lens on the most image side lens in the fourth lens group G4, it is possible to satisfactorily correct chromatic coma at the wide angle end.

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

0.10 <dSt / f4 <0.60 (4)
However,
dSt: distance between the aperture stop S and the third lens group G3 in the telephoto end state f4: focal length of the fourth lens group G4

  Conditional expression (4) is a conditional expression for defining the position of the aperture stop S in the telephoto end state with respect to the focal length of the fourth lens group G4. Exceeding the upper limit value of conditional expression (4) is not preferable because the distance between the aperture stop S and the third lens group G3 becomes too wide and it becomes difficult to correct field curvature aberration at the telephoto end. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 0.50. On the other hand, if the lower limit value of conditional expression (4) is not reached, the distance between the aperture stop S and the third lens group G3 becomes too narrow, which makes it difficult to correct spherical aberration at the telephoto end, 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 (4) to 0.15.

  In the variable magnification optical system ZL, it is preferable that the most object side lens in the first lens group G1 has an aspherical surface (for example, the image side surface of the aspherical negative lens L11 in FIG. surface)). With this configuration, it is possible to effectively correct the field curvature aberration at the wide angle end and the spherical aberration at the telephoto end.

  In addition, it is desirable that the variable magnification optical system ZL satisfies the following conditional expression (5).

0.10 <f2 / f2a <0.55 (5)
However,
f2: focal length of the second lens group G2 f2a: focal length of the image stabilizing lens group VL

  Conditional expression (5) is a conditional expression for defining the focal length of the image stabilizing lens group VL with respect to the focal length of the second lens group G2. Exceeding the upper limit of conditional expression (5) is not preferable because the refractive power of the image stabilizing lens group VL becomes strong and it becomes difficult to correct field curvature aberration at the wide angle end. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (5) to 0.50. On the other hand, if the lower limit of conditional expression (5) is not reached, the refractive power of the image stabilizing lens group VL becomes weak, and it becomes difficult to correct coma at the telephoto end. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (5) to 0.20.

  In such a variable magnification optical system ZL, it is desirable that the third lens group G3 includes only a single lens. With this configuration, it is possible to effectively correct curvature of field aberration and coma at the telephoto end.

  In such a variable magnification optical system ZL, it is desirable that the single lenses constituting the third lens group G3 have a biconcave shape. Also with this configuration, it is possible to effectively correct field curvature aberration and coma at the telephoto end.

  In such a variable magnification optical system ZL, it is desirable that the fourth lens group G4 has at least one aspheric surface (for example, the seventeenth surface in FIG. 1). With this configuration, it is possible to effectively correct field curvature aberration and coma aberration at the wide angle end.

  In the variable magnification optical system ZL, a lens having an aspheric surface (for example, the aspheric positive lens L41 in FIG. 1) included in the fourth lens group G4 is located closest to the object side of the fourth lens group G4. Is preferred. With this configuration, it is possible to effectively correct curvature of field aberration and coma at the telephoto end.

  In the zoom optical system ZL, it is preferable that at least one of the cemented lenses included in the fourth lens group G4 has a cemented surface convex toward the image side (for example, the 19th surface in FIG. 1). ). With this configuration, chromatic coma at the wide-angle end can be effectively corrected.

  Further, in the zoom optical system ZL, when zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 and the fourth lens group G4 It is preferable that the distance from the lens group G4 is reduced. With this configuration, it is possible to ensure a predetermined zoom ratio while effectively correcting variations in spherical aberration and curvature of field.

  Next, a camera that is an optical device including the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG. This camera 1 is a so-called mirrorless camera of interchangeable lens provided with a variable magnification optical system ZL according to the present embodiment as a photographing lens 2. In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and is on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) (not shown). A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.

  Further, when a release button (not shown) is pressed by the photographer, an image photoelectrically converted by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1. In the present embodiment, an example of a mirrorless camera has been described. However, a variable power optical system ZL according to the present embodiment is applied to a single-lens reflex camera that has a quick return mirror in the camera body and observes a subject with a finder optical system. Even when the camera is mounted, the same effect as the camera 1 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 four-group configuration is shown, but the above-described configuration conditions and the like can be applied to other group configurations such as the fifth group and the sixth group. 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 first lens group G1 is a focusing lens group.

  Also, by moving the lens group or partial lens group so that it has a component in the direction perpendicular to the optical axis, or rotating (swinging) in the in-plane direction including the optical axis, image blur caused by camera shake is corrected. An anti-vibration lens group may be used. In particular, as described above, it is preferable that at least a part of the second lens group G2 is a vibration-proof 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 second lens group G2, but the role of the aperture stop S 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 2.0 to 5.0.

  Hereinafter, an outline of a method for manufacturing the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG. First, the lenses are arranged to prepare lens groups G1 to G4, respectively (step S100). 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, it arrange | positions so that the space | interval of the 3rd lens group G3 and the 4th lens group G4 may change (step S200). In addition, at least one single lens in the second lens group G2 is arranged as a vibration-proof lens group VL that moves so as to include a component in a direction orthogonal to the optical axis (step S300). In addition, an aperture stop S is disposed in or near the second lens group G2 (step S400). Further, a cemented lens in which a positive lens and a negative lens are bonded to each other is arranged closest to the image side of the fourth lens group G4 (step S500). Furthermore, the aperture stop S, the third lens group G3, and the fourth lens group G4 are arranged so as to satisfy the conditional expression (1) (step S600).

  Specifically, in the present embodiment, for example, as shown in FIG. 1, in order from the object side, a negative meniscus negative lens L11 having a negative meniscus lens shape with a convex surface facing the object side, and a negative meniscus with a convex surface facing the object side. A lens L12 and a positive meniscus lens L13 having a convex surface facing the object side are arranged as a first lens group G1, and in order from the object side, a biconvex lens L21 and a negative meniscus lens L22 having a convex surface facing the object side; A cemented lens with a biconvex lens L23 is arranged to form a second lens group G2, and a biconcave lens L31 is arranged to form a third lens group G3. A non-positive meniscus lens having a convex surface facing the object side in order from the object side. A spherical positive lens L41, and a cemented lens of a positive meniscus lens L42 having a concave surface facing the object side and a negative meniscus lens L43 having a concave surface facing the object side are arranged to form a fourth lens. And's group G4. The lens groups thus prepared are arranged according to the above-described procedure to manufacture the variable magnification optical system ZL.

  Hereinafter, each example of the present application will be described with reference to the drawings. 1, FIG. 5, FIG. 9 and FIG. 13 show the configuration and refractive power distribution of the variable magnification optical system ZL (ZL1 to ZL4) according to each example, and 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 focusing state. Further, in the lower part of the sectional views of these zoom optical systems ZL1 to ZL4, along the optical axes of the lens groups G1 to G4 when zooming from the wide-angle end state (W) to the telephoto end state (T) The direction of movement is indicated by an arrow. As shown in FIGS. 1, 5, 9, and 13, the variable magnification optical systems ZL1 to ZL4 according to the first to fourth examples are first lenses having negative refractive power in order from the object side. The lens unit includes a group G1, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power. Then, during 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 changes, and the air gap between the second lens group G2 and the third lens group G3 changes. The distance between the lens groups changes so that the air distance between the third lens group G3 and the fourth lens group G4 decreases and increases.

  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). .

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 right side of the surface number. In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

[First embodiment]
FIG. 1 is a diagram showing a configuration of a variable magnification optical system ZL1 according to the first example. In the variable magnification optical system ZL1 shown in FIG. 1, the first lens group G1 includes, in order from the object side, an aspheric negative lens L11 having a negative meniscus lens shape with a convex surface facing the object side, and a negative surface with a convex surface facing the object side. It comprises a meniscus lens L12 and a positive meniscus lens L13 having a convex surface facing the object side. Here, in the aspheric negative lens L11, a resin layer is provided on the glass lens surface (second surface) on the image side, and the image side surface (third surface) of the resin layer is formed in an aspheric shape. The second lens group G2 includes, in order from the object side, a biconvex lens L21 and a cemented lens of a negative meniscus lens L22 having a convex surface facing the object side and a biconvex lens L23. The third lens group G3 is composed of a biconcave lens L31. The fourth lens group G4 includes, in order from the object side, an aspheric positive lens L41 having a positive meniscus lens shape with a convex surface facing the object side, a positive meniscus lens L42 with a concave surface facing the object side, and a concave surface facing the object side. Further, it is composed of a cemented lens with a negative meniscus lens L43. Here, the image-side surface (the 17th surface) of the aspherical positive lens L41 is formed in an aspherical shape.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the second lens group G2 upon zooming from the wide-angle end state to the telephoto end state. Further, focusing from infinity to a close object is performed by extending (moving) the first lens group G1 in the object direction.

  In image blur correction (anti-shake), the biconvex lens L21 of the second lens group G2 is used as the anti-shake lens group VL, and the anti-shake lens group VL is moved so as to include a component in a direction perpendicular to the optical axis. To do.

  It is to be noted that the focal length of the entire system is f, and the image stabilization coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the image stabilization lens group VL in image blur correction) is K. Can be corrected by moving the image stabilizing lens group VL for blur correction by (f · tan θ) / K in the direction orthogonal to the optical axis (the same applies to the following embodiments). In the first embodiment, in the wide-angle end state, the image stabilization coefficient is 0.50 and the focal length is 18.50 (mm). Therefore, the image stabilization lens for correcting the rotation blur of 0.43 ° is used. The movement amount of the group VL is 0.28 (mm). Further, in the telephoto end state of the first embodiment, since the image stabilization coefficient is 0.83 and the focal length is 53.40 (mm), the anti-vibration for correcting the rotation blur of 0.26 °. The moving amount of the vibration lens group VL is 0.29 (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 TL represents the total length. Here, the total length TL represents the distance on the optical axis from the first surface of the lens surface to the image plane I when focusing on infinity. Further, the first column m of the lens data indicates the order (surface number) of the lens surfaces from the object side along the traveling direction of the light beam, the second column r indicates the curvature radius of each lens surface, and the third column. d is the distance on the optical axis from each optical surface to the next optical surface (surface interval). The fourth column νd and the fifth column nd are Abbe numbers and refractive indices for the d-line (λ = 587.6 nm). Is shown. The radius of curvature of 0.0000 indicates a plane, and the refractive index of air of 1.0000 is omitted. The surface numbers 1 to 20 shown in Table 1 correspond to the numbers 1 to 20 shown in FIG. The lens group focal length indicates the start surface and focal length of each of the first to fourth lens groups G1 to G4. Here, the focal length f, the radius of curvature r, the surface interval d, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or proportional. Since the same optical performance can be obtained even if the image is reduced, the present invention is not limited to this. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 18.50 to 45.00 to 53.40
FNO = 3.64 to 5.35 to 5.88
2ω = 78.1 to 35.0 to 29.7
TL = 122.38 to 119.93 to 124.96

[Lens data]
m r d νd nd
1 66.21 1.60 63.9 1.51680
2 15.70 0.17 38.1 1.55389
3 * 13.42 10.50
4 262.72 1.20 58.1 1.62299
5 21.53 1.10
6 21.37 4.40 28.4 1.72825
7 57.46 d7
8 1434.71 1.60 70.3 1.48749
9 -51.87 1.50
10 16.18 0.83 29.4 1.95000
11 11.88 4.50 63.9 1.51680
12 -162.43 1.50
13 0.00 d13 Aperture stop S
14 -60.18 1.50 52.77 1.74100
15 54.80 d15
16 135.21 1.50 56.2 1.52444
17 * 168.80 0.50
18 -337.52 3.50 59.4 1.58313
19 -14.39 0.80 35.3 1.74950
20 -21.48 Bf

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -27.23
Second lens group 8 28.21
Third lens group 14 -38.49
Fourth lens group 16 44.36

  In the first embodiment, the third and seventeenth lens surfaces are aspherical. 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
3rd surface -1.0 2.89951E-05 1.00217E-07 -2.55575E-10 1.58270E-12
17th surface -1.0 2.22627E-05 1.13930E-08 2.20954E-10 -3.78091E-12

  In this first example, the axial air distance d7 between the first lens group G1 and the second lens group G2, and the axial air distance d13 between the aperture stop S moving with the second lens group G2 and the third lens group G3. The on-axis air distance d15 between the third lens group G3 and the fourth lens group G4 and the back focus Bf change during zooming. Table 3 below shows the values of the variable interval and the back focus Bf at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on infinity. Note that the back focus Bf represents the distance on the optical axis from the most image side lens surface (the 20th surface in FIG. 1) to the image surface I. This description is the same in the following embodiments.

(Table 3)
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f 18.50 45.00 53.40
d7 35.325 5.896 3.068
d13 4.498 8.862 10.192
d15 7.548 2.891 1.561
Bf 38.600 65.580 73.437

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 (aspheric positive lens L11) closest to the object side of the first lens group G1, and R2 is the negative radius closest to the object side of the first lens group G1. The radius of curvature of the image side surface of the lens, f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f3 is the focal length of the third lens group G3, and f4 is the fourth lens. The focal length of the group G4, f2a is the focal length of the anti-vibration lens group VL in the second lens group G2, d3w is the air gap between the third lens group G3 and the fourth lens group G4 in the wide-angle end state, and dSt is The distance between the aperture stop S and the third lens group G3 in the telephoto end state is shown. The description of the above symbols is the same in the following embodiments.

(Table 4)
(1) dSt / f4 = 0.23
(2) (R2 + R1) / (R2-R1) = -1.62
(3) f4 / d3w = 5.88
(4) f1 / f3 = 0.71
(5) f2 / f2a = 0.27

  Thus, the variable magnification optical system ZL1 according to the first example satisfies all the conditional expressions (1) to (5).

  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. FIG. 2B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.28) is performed in the infinite focus state at the wide-angle end state in the first embodiment. FIG. 4B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.29) is performed in the infinitely focused state at the telephoto end 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. The explanation of this aberration diagram is the same in the following examples. As is apparent from the respective aberration diagrams, in the first embodiment, various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and aberration fluctuations at the time of camera shake correction are also excellent. It can be seen that the imaging performance is excellent.

[Second Embodiment]
FIG. 5 is a diagram showing a configuration of the variable magnification optical system ZL2 according to the second example. In the variable magnification optical system ZL2 shown in FIG. 5, the first lens group G1 includes, in order from the object side, a negative meniscus aspheric negative lens L11 having a convex surface facing the object side, a biconcave lens L12, and an object side. And a positive meniscus lens L13 having a convex surface. Here, in the aspheric negative lens L11, a resin layer is provided on the glass lens surface (second surface) on the image side, and the image side surface (third surface) of the resin layer is formed in an aspheric shape. The second lens group G2 includes, in order from the object side, a biconvex lens L21, and a cemented lens of a negative meniscus lens L22 having a convex surface facing the object side and a positive meniscus lens L23 having a convex surface facing the object side. . The third lens group G3 is composed of a biconcave lens L31. The fourth lens group G4 includes, in order from the object side, a biconvex aspherical positive lens L41, and a cemented lens of a biconvex lens L42 and a negative meniscus lens L43 having a concave surface facing the object. Here, the image-side surface (the 17th surface) of the aspherical positive lens L41 is formed in an aspherical shape.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the second lens group G2 upon zooming from the wide-angle end state to the telephoto end state. Further, focusing from infinity to a close object is performed by extending (moving) the first lens group G1 in the object direction.

  In image blur correction (anti-shake), the biconvex lens L21 of the second lens group G2 is used as the anti-shake lens group VL, and the anti-shake lens group VL is moved so as to include a component in a direction perpendicular to the optical axis. To do. In the second embodiment, in the wide-angle end state, the image stabilization coefficient is 0.80 and the focal length is 18.50 (mm). Therefore, the image stabilization lens for correcting the rotation blur of 0.45 ° is used. The movement amount of the group VL is 0.18 (mm). In the telephoto end state of the second embodiment, the image stabilization coefficient is 1.27 and the focal length is 53.40 (mm). The moving amount of the vibration lens group VL is 0.19 (mm).

  Table 5 below shows values of specifications of the second embodiment. The surface numbers 1 to 20 shown in Table 5 correspond to the numbers 1 to 20 shown in FIG.

(Table 5)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 18.50 to 45.00 to 53.40
FNO = 3.64 to 5.35 to 5.88
2ω = 78.1 to 35.5 to 29.7
TL = 120.79-114.99-121.16

[Lens data]
m r d νd nd
1 84.49 1.60 63.9 1.51680
2 15.40 0.17 38.2 1.55389
3 * 13.42 11.50
4 -137.54 1.20 58.1 1.62299
5 51.74 1.20
6 30.42 3.50 27.6 1.75520
7 77.73 d7
8 52.97 1.60 82.6 1.49782
9 -84.25 1.50
10 18.26 0.83 29.4 1.95000
11 13.53 4.50 70.3 1.48749
12 1657.95 1.50
13 0.00 d13 Aperture stop S
14 -92.69 1.50 52.2 1.51742
15 31.73 d15
16 374.19 1.50 56.4 1.52444
17 * -215.67 0.50
18 28.47 6.00 58.8 1.51823
19 -32.76 0.80 34.9 1.80 100
20 -103.60 Bf

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -29.64
Second lens group 8 30.11
Third lens group 14 -45.50
Fourth lens group 16 47.38

  In the second embodiment, the third and seventeenth 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
3rd surface -1.0 3.22810E-05 9.22930E-08 -2.01905E-10 1.43420E-12
17th surface -1.0 1.93725E-05 3.05794E-08 1.79558E-10 -2.62590E-13

  In the second embodiment, the axial air distance d7 between the first lens group G1 and the second lens group G2, and the axial air distance d13 between the aperture stop S moving with the second lens group G2 and the third lens group G3. The on-axis air distance d15 between the third lens group G3 and the fourth lens group G4 and the back focus Bf change during zooming. Table 7 below shows the values of the variable interval and the back focus Bf at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity.

(Table 7)
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f 18.50 45.0 53.4
d7 39.110 4.869 1.288
d13 13.462 15.786 15.803
d15 8.812 5.411 5.368
Bf 20.000 49.520 59.299

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

(Table 8)
(1) dSt / f4 = 0.33
(2) (R2 + R1) / (R2-R1) = -1.45
(3) f4 / d3w = 5.38
(4) f1 / f3 = 0.65
(5) f2 / f2a = 0.46

  Thus, the zoom optical system ZL2 according to the second example satisfies all the conditional expressions (1) to (5).

  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. FIG. 6B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.18) is performed in the infinite focus state at the wide-angle end state in the second embodiment. FIG. 8B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.19) is performed in the infinitely focused state at the telephoto end state. As is apparent from the respective aberration diagrams, in the second embodiment, various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and aberration fluctuations at the time of camera shake correction are also excellent. It can be seen that the imaging performance is excellent.

[Third embodiment]
FIG. 9 is a diagram illustrating a configuration of the variable magnification optical system ZL3 according to the third example. In the zoom optical system ZL3 shown in FIG. 9, the first lens group G1 includes, in order from the object side, a negative meniscus aspheric negative lens L11 having a convex surface facing the object side, a biconcave lens L12, and an object side. And a positive meniscus lens L13 having a convex surface. Here, in the aspheric negative lens L11, a resin layer is provided on the glass lens surface (second surface) on the image side, and the image side surface (third surface) of the resin layer is formed in an aspheric shape. The second lens group G2 includes, in order from the object side, a biconvex lens L21, and a cemented lens of a negative meniscus lens L22 having a convex surface facing the object side and a positive meniscus lens L23 having a convex surface facing the object side. . The third lens group G3 is composed of a biconcave lens L31. The fourth lens group G4 includes, in order from the object side, a positive meniscus aspheric lens L41 having a convex surface facing the object side, and a biconvex lens L42 and a negative meniscus lens L43 having a concave surface facing the object side. It consists of a lens. Here, the image-side surface (the 17th surface) of the aspherical positive lens L41 is formed in an aspherical shape.

  The aperture stop S is located between the biconvex lens L21 and the negative meniscus lens L22 of the second lens group G2, and moves together with the second lens group G2 upon zooming from the wide-angle end state to the telephoto end state. Further, focusing from infinity to a close object is performed by extending (moving) the first lens group G1 in the object direction.

  In image blur correction (anti-shake), the biconvex lens L21 of the second lens group G2 is used as the anti-shake lens group VL, and the anti-shake lens group VL is moved so as to include a component in a direction perpendicular to the optical axis. To do. In the third embodiment, in the wide-angle end state, the image stabilization coefficient is 0.56 and the focal length is 18.03 (mm). Therefore, the image stabilization lens for correcting the rotation blur of 0.45 ° is used. The movement amount of the group VL is 0.25 (mm). In the telephoto end state of the third embodiment, the image stabilization coefficient is 0.92, and the focal length is 53.63 (mm). The moving amount of the vibration lens group VL is 0.26 (mm).

  Table 9 below shows values of specifications of the third embodiment. The surface numbers 1 to 20 shown in Table 9 correspond to the surface numbers 1 to 20 shown in FIG.

(Table 9)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 18.03 to 43.66 to 53.63
FNO = 3.63 to 4.10 to 5.78
2ω = 79.4 to 63.3 to 29.7
TL = 127.57 to 125.30 to 132.98

[Lens data]
m r d νd nd
1 66.53 1.60 63.9 1.51680
2 15.30 0.17 38.2 1.55389
3 * 12.92 10.54
4 -4417.66 1.40 58.1 1.62299
5 27.61 2.07
6 26.72 3.05 28.4 1.72825
7 74.43 d7
8 86.65 2.30 63.9 1.51680
9 -105.78 1.01
10 0.00 0.18 Aperture stop S
11 19.59 2.61 25.4 1.80518
12 12.86 3.91 52.3 1.51742
13 -266.13 d13
14 -131.20 2.05 52.8 1.74100
15 47.96 d15
16 86.82 1.73 56.4 1.52444
17 * 298.28 1.07
18 1340.85 4.44 52.3 1.51742
19 -14.96 1.46 25.4 1.80518
20 -21.92 Bf

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -26.64
Second lens group 8 30.89
Third lens group 14 -47.17
Fourth lens group 16 45.15

  In the third embodiment, the third and seventeenth 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
3rd surface -1.0 3.11022E-05 7.96306E-08 -1.01842E-10 1.04228E-12
17th surface -1.0 1.59804E-05 -4.88413E-08 1.46203E-09 -1.17341E-11

  In the third embodiment, the axial air distance d7 between the first lens group G1 and the second lens group G2, the axial air distance d13 between the second lens group G2 and the third lens group G3, and the third lens group G3. The on-axis air distance d15 between the first lens group G4 and the fourth lens group G4 and the back focus Bf change during zooming. Table 11 below shows the values of the variable interval and the back focus at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on infinity.

(Table 11)
[Variable interval data]
Wide angle end Intermediate focal length Telephoto end f 18.03 43.66 53.63
d7 34.649 4.502 0.909
d13 4.001 10.088 10.893
d15 10.297 4.119 2.744
Bf 37.161 65.048 73.106

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

(Table 12)
(1) dSt / f4 = 0.39
(2) (R2 + R1) / (R2-R1) = -1.60
(3) f4 / d3w = 4.38
(4) f1 / f3 = 0.56
(5) f2 / f2a = 0.33

  Thus, the variable magnification optical system ZL3 according to the third example satisfies all the conditional expressions (1) to (5).

  FIG. 10A shows an aberration diagram in the infinite focus state in the wide-angle end state of the third embodiment, and FIG. 11 shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 12A shows an aberration diagram in the infinitely focused state in the state. FIG. 10B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.25) is performed in the infinite focus state at the wide-angle end state in the third example. FIG. 12B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.26) is performed in the infinitely focused state at the telephoto end state. As is apparent from the respective aberration diagrams, in the third example, various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and aberration fluctuations at the time of camera shake correction are also excellent. It can be seen that the imaging performance is excellent.

[Fourth embodiment]
FIG. 13 is a diagram showing a configuration of a variable magnification optical system ZL4 according to the fourth example of the present application. In the variable magnification optical system ZL4 in FIG. 13, the first lens group G1 includes, in order from the object side, a negative meniscus aspheric negative lens L11 having a convex surface facing the object side, a biconcave lens L12, and an object side. It is composed of a positive meniscus lens L13 having a convex surface. Here, in the aspheric negative lens L11, a resin layer is provided on the glass lens surface (second surface) on the image side, and the image side surface (third surface) of the resin layer is formed in an aspheric shape. The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a negative meniscus lens L22 having a convex surface facing the object side and a positive meniscus lens L23 having a convex surface facing the object side, and a convex surface facing the object side. Is formed from a positive meniscus lens L24. The third lens group G3 is composed of a biconcave lens L31. The fourth lens group G4 includes, in order from the object side, a biconcave lens-shaped aspheric negative lens L41 and a cemented lens of a biconvex lens L42 and a negative meniscus lens L43 having a concave surface facing the object. Here, the image-side surface (19th surface) of the aspheric negative lens L41 is formed in an aspheric shape.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the second lens group G2 upon zooming from the wide-angle end state to the telephoto end state. Further, focusing from infinity to a close object is performed by extending (moving) the first lens group G1 in the object direction.

  In image blur correction (anti-shake), the biconvex lens L21 of the second lens group G2 is used as the anti-shake lens group VL, and the anti-shake lens group VL is moved so as to include a component in a direction perpendicular to the optical axis. To do. In the fourth embodiment, in the wide-angle end state, the image stabilization coefficient is 0.54 and the focal length is 18.53 (mm). Therefore, the image stabilization lens for correcting the rotation blur of 0.44 ° is used. The movement amount of the group VL is 0.27 (mm). In the telephoto end state of the fourth embodiment, the image stabilization coefficient is 0.86 and the focal length is 53.71 (mm). The moving amount of the vibration lens group VL is 0.28 (mm).

  Table 13 below lists values of specifications of the fourth embodiment. The surface numbers 1 to 22 shown in Table 13 correspond to the numbers 1 to 22 shown in FIG.

(Table 13)
Wide-angle end state Intermediate focal length state Telephoto end state f = 18.53 to 43.38 to 53.71
FNO = 3.47 to 5.24 to 6.12
2ω = 78.0 to 36.4 to 29.7
TL = 127.58 to 127.55 to 135.41

[Lens data]
m r d νd nd
1 58.81 1.60 63.9 1.51680
2 15.85 0.17 38.2 1.55389
3 * 13.48 9.44
4 -180.66 1.39 58.1 1.62299
5 26.02 1.49
6 26.67 3.49 28.4 1.72825
7 94.09 d7
8 312.58 2.29 63.9 1.51680
9 -58.78 1.49
10 21.84 3.08 23.8 1.84666
11 14.16 2.73 52.2 1.51742
12 33.66 4.05
13 19.49 2.80 52.2 1.51742
14 316.42 1.03
15 0.00 d15 Aperture stop S
16 -6000.00 1.60 52.8 1.74100
17 29.14 d17
18 -81.46 1.39 56.4 1.52444
19 * 182.48 0.21
20 43.32 5.37 63.9 1.51680
21 -14.00 1.21 35.3 1.74950
22 -20.86 Bf

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -26.23
Second lens group 8 29.14
Third lens group 16 -39.13
Fourth lens group 18 44.82

  In the fourth embodiment, the third and nineteenth lens surfaces are aspherical. 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
3rd surface -1.0 2.74278E-05 7.96306E-08 -1.01842E-10 1.04228E-12
19th surface -1.0 2.60580E-05 3.23416E-09 1.06234E-09 -9.17414E-12

  In the fourth embodiment, the axial air distance d7 between the first lens group G1 and the second lens group G2, and the axial air distance d15 between the aperture stop S moving with the second lens group G2 and the third lens group G3. The on-axis air distance d17 between the third lens group G3 and the fourth lens group G4 and the back focus Bf change during zooming. Table 15 below shows the values of the variable interval and the back focus at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of focusing on infinity.

(Table 15)
Wide angle end Intermediate focal length Telephoto end f 18.53 43.38 53.71
d7 33.970 4.901 1.207
d15 2.413 5.616 6.346
d17 7.546 3.804 2.432
Bf 38.814 68.397 80.595

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

(Table 16)
(1) dSt / f4 = 0.14
(2) (R2 + R1) / (R2-R1) = -1.74
(3) f4 / d3w = 5.94
(4) f1 / f3 = 0.67
(5) f2 / f2a = 0.30

  Thus, the zoom optical system ZL4 according to the fourth example satisfies all the conditional expressions (1) to (5).

  FIG. 14A shows an aberration diagram in the infinite focus state in the wide-angle end state of the fourth embodiment, and FIG. 15 shows an aberration diagram in the infinite focus state in the intermediate focal length state. FIG. 16A shows an aberration diagram in the infinitely focused state in the state. FIG. 14B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens unit VL = 0.27) is performed in the infinitely focused state at the wide-angle end state in the fourth example. FIG. 16B shows a coma aberration diagram when image blur correction (shift amount of the image stabilizing lens group VL = 0.28) is performed in the infinitely focused state at the telephoto end state. As is apparent from the respective aberration diagrams, in the fourth example, various aberrations are satisfactorily corrected in each focal length state from the wide-angle end state to the telephoto end state, and aberration fluctuation at the time of camera shake correction is also excellent. It can be seen that the imaging performance is excellent.

ZL (ZL1 to ZL4) Variable magnification optical system G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group S Aperture stop 1 Camera (optical device)

Claims (13)

From the object side,
A first lens group having negative refractive power;
A second lens group having a positive refractive power;
A third lens group having negative refractive power;
Substantially consisting of four lens groups with a fourth lens group having positive refractive power,
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 increases . An interval between the third lens group and the fourth lens group is reduced ;
At least one single lens of the second lens group is an anti-vibration lens group that moves so as to include a component in a direction orthogonal to the optical axis,
An aperture stop in the second lens group or between the second lens group and the third lens group ;
The third lens group consists of only a single lens,
The fourth lens group includes a cemented lens in which a positive lens and a negative lens are bonded to the most image side,
A variable magnification optical system characterized by satisfying the following condition:
0.23 ≦ dSt / f4 ≦ 0.39
However,
dSt: distance between the aperture stop at the telephoto end state and the third lens group f4: the focal length of the fourth lens group From the object side,
A first lens group having negative refractive power;
A second lens group having a positive refractive power;
A third lens group having negative refractive power;
Substantially consisting of four lens groups with a fourth lens group having positive refractive power,
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 increases . An interval between the third lens group and the fourth lens group is reduced ;
At least one single lens of the second lens group is an anti-vibration lens group that moves so as to include a component in a direction orthogonal to the optical axis,
An aperture stop in the second lens group or between the second lens group and the third lens group ;
The fourth lens group includes a cemented lens in which a positive lens and a negative lens are bonded to the most image side,
A variable magnification optical system characterized by satisfying the following condition:
0.14 ≦ dSt / f4 <0.60
0.27 ≦ f2 / f2a ≦ 0.30
However,
dSt: distance between the aperture stop at the telephoto end state and the third lens group f4: the focal length of the fourth lens group
f2: Focal length of the second lens group
f2a: Focal length of the anti-vibration lens group From the object side,
A first lens group having negative refractive power;
A second lens group having a positive refractive power;
A third lens group having negative refractive power;
Substantially consisting of four lens groups with a fourth lens group having positive refractive power,
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,
At least one single lens of the second lens group is an anti-vibration lens group that moves so as to include a component in a direction orthogonal to the optical axis,
An aperture stop in the second lens group or between the second lens group and the third lens group ;
The third lens group has at least one single lens having an air gap on both sides,
The fourth lens group includes a cemented lens in which a positive lens and a negative lens are bonded to the most image side,
A variable magnification optical system characterized by satisfying the following condition:
0.14 ≦ dSt / f4 <0.60
0.27 ≦ f2 / f2a ≦ 0.30
However,
dSt: distance between the aperture stop at the telephoto end state and the third lens group f4: the focal length of the fourth lens group
f2: Focal length of the second lens group
f2a: Focal length of the image stabilizing lens group 2. The variable magnification optical system according to claim 1 , wherein a condition of the following formula is satisfied.
0.10 <f2 / f2a <0.55
However,
f2: focal length of the second lens group f2a: focal length of the anti-vibration lens group 3. The variable magnification optical system according to claim 2 , wherein the third lens group includes at least one single lens having an air gap on both sides. The variable power optical system according to claim 1 , wherein the single lens has a biconcave shape. The variable power optical system according to claim 1, wherein the first lens group includes a negative lens closest to the object side. The variable-power optical system according to claim 1, wherein a lens closest to the object side of the first lens group has an aspherical surface. The variable power optical system according to any one of claims 1 to 8, wherein the fourth lens group has at least one aspherical surface. 10. The variable magnification optical system according to claim 9 , wherein the lens having the aspheric surface included in the fourth lens group is positioned closest to the object side of the fourth lens group. The cemented lens included in the fourth lens group, at least one variable power optical system according to any one of claims 1 to 10, wherein the joint surfaces of which are convex inward in the image side .   An optical apparatus comprising the variable magnification optical system according to claim 1, wherein an object image is formed on a predetermined image plane. In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power A variable magnification optical system comprising substantially four lens groups with a group ,
When the first lens group, the second lens group, the third lens group, and the fourth lens group are zoomed from the wide-angle end state to the telephoto end state, the first lens group and the second lens group The distance between the second lens group and the third lens group is increased, and the distance between the third lens group and the fourth lens group is decreased ,
Arranging at least one single lens of the second lens group as an anti-vibration lens group that moves so as to include a component in a direction orthogonal to the optical axis,
An aperture stop is disposed in the second lens group or between the second lens group and the third lens group ,
Only one single lens is disposed in the third lens group,
A cemented lens in which a positive lens and a negative lens are bonded to the most image side of the fourth lens group;
A method of manufacturing a variable magnification optical system, wherein the aperture stop, the third lens group, and the fourth lens group are disposed so as to satisfy the following condition.
0.23 ≦ dSt / f4 ≦ 0.39
However,
dSt: distance between the aperture stop at the telephoto end state and the third lens group f4: the focal length of the fourth lens group

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