US20200049961A1

US20200049961A1 - Variable magnification optical system, optical apparatus, and method for manufacturing variable magnification optical system

Info

Publication number: US20200049961A1
Application number: US16/660,747
Authority: US
Inventors: Hiroki Harada
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 2015-01-30
Filing date: 2019-10-22
Publication date: 2020-02-13
Also published as: JP6406360B2; US20180180858A1; EP3252518A4; EP3252518A1; JPWO2016121945A1; JP2019008320A; CN107407794B; JP6673420B2; WO2016121945A1; US10473901B2; JP2020106860A; CN107407794A

Abstract

A variable magnification optical system includes: a first lens group (G1) having a negative refractive power; a second lens group (G2) having a positive refractive power; an intermediate group (Gn) disposed closer to an image side than the second lens group (G2); and a vibration-reduction lens group (VR) disposed closer to the image side than the intermediate group (Gn) and configured to be movable so as to have a component in a direction orthogonal to an optical axis. The system performs varying magnification by changing at least the distance between the first lens group (G1) and the second lens group (G2) and the distance between the second lens group (G2) and the intermediate group (Gn), and the system satisfies Conditional Expression (1).

1.500<β(Gn)t<100.000 (1)

- where
- β(Gn)t: an imaging magnification of the intermediate group (Gn) in a telephoto end state

Description

TECHNICAL FIELD

The present invention relates to a variable magnification optical system, an optical apparatus, and a method for manufacturing the variable magnification optical system.
Priority is claimed on Japanese Patent Application No. 2015-017917, filed Jan. 30, 2015, the content of which is incorporated herein by reference.

TECHNICAL BACKGROUND

Conventionally, a variable magnification optical system having a wide angle of view including a camera shake compensation mechanism has been proposed (for example, see Patent Document 1).

RELATED ART DOCUMENTS

Patent Document

Patent Document 1:

Japanese Patent Application, Publication No. H11-231220

SUMMARY OF INVENTION

Technical Problem

In recent years, there has been increasing demand for a variable magnification optical system which has a satisfactory optical performance and has a brighter F-value.

Solution to Problem

According to an aspect of the present invention, there is provided a variable magnification optical system including: a first lens group having a negative refractive power; a second lens group having a positive refractive power; an intermediate group disposed closer to an image side than the second lens group; and a vibration-reduction lens group disposed closer to the image side than the intermediate group and configured to be movable so as to have a component in a direction orthogonal to an optical axis, wherein the system performs varying magnification by changing at least the distance between the first lens group and the second lens group and the distance between the second lens group and the intermediate group, and the system satisfies the following conditional expression.
1.500<β(Gn)t<100.000
where
β(Gn)t: an imaging magnification of the n-th lens group in a telephoto end state
According to another aspect of the present invention, there is provided a variable magnification optical system including, in order from an object: a first lens group having a negative refractive power; a second lens group having a positive refractive power, the first and second lens groups; an n-th lens group which is disposed closer to the image side than the second lens group, of which the position in the direction orthogonal to an optical axis is fixed, and which has negative refractive power; and a vibration-reduction lens group disposed closer to the image side than the n-th lens group and configured to be movable so as to have a component in the direction orthogonal to the optical axis, wherein the system performs varying magnification by changing at least the distance between the first lens group and the second lens group and the distance between the second lens group and the n-th lens group, and the system satisfies the following conditional expression.
1.500<β(Gn)t<100.000
where
β(Gn)t: an imaging magnification of the intermediate group in a telephoto end state
According to another aspect of the present invention, there is provided an optical apparatus having the above-described variable magnification optical system mounted thereon.
According to another aspect of the present invention, there is provided a method for manufacturing a variable magnification optical system, wherein the variable magnification optical system includes: a first lens group having a negative refractive power; a second lens group having a positive refractive power; an intermediate group disposed closer to an image side than the second lens group; and a vibration-reduction lens group disposed closer to the image side than the intermediate group and configured to be movable so as to have a component in a direction orthogonal to an optical axis, wherein the system performs varying magnification by changing at least the distance between the first lens group and the second lens group and the distance between the second lens group and the intermediate group, and wherein the method includes arranging the respective lenses in a lens barrel so as to satisfy the following conditional expression.
1.500<β(Gn)t<100.000
where
β(Gn)t: an imaging magnification of the intermediate group in a telephoto end state
According to another aspect of the present invention, there is provided a method for manufacturing a variable magnification optical system, wherein the variable magnification optical system includes, in order from an object: a first lens group having a negative refractive power; a second lens group having a positive refractive power, the first and second lens groups; an n-th lens group which is disposed closer to the image side than the second lens group, of which the position in the direction orthogonal to an optical axis is fixed, and which has negative refractive power; and a vibration-reduction lens group disposed closer to the image side than the n-th lens group and configured to be movable so as to have a component in the direction orthogonal to the optical axis, wherein the system performs varying magnification by changing at least the distance between the first lens group and the second lens group and the distance between the second lens group and the n-th lens group, and wherein the method includes arranging the respective lens groups in a lens barrel so as to satisfy the following conditional expression.
1.500<β(Gn)t<100.000
where
β(Gn)t: an imaging magnification of the intermediate group in a telephoto end state

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a variable magnification optical system according to Example 1, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 2 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 1 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 3 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 1 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 4 is a cross-sectional view of a variable magnification optical system according to Example 2, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 5 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 2 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 6 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 2 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 7 is a cross-sectional view of a variable magnification optical system according to Example 3, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 8 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 3 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 9 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 3 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 10 is a cross-sectional view of a variable magnification optical system according to Example 4, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 11 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 4 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 12 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 4 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 13 is a cross-sectional view of a variable magnification optical system according to Example 5, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 14 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 5 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 15 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 5 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 16 is a cross-sectional view of a variable magnification optical system according to Example 6, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 17 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 6 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 18 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 6 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 19 is a cross-sectional view of a variable magnification optical system according to Example 7, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 20 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 7 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 21 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 7 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 22 is a cross-sectional view of a variable magnification optical system according to Example 8, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 23 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 8 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 24 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 8 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 25 is a cross-sectional view of a variable magnification optical system according to Example 9, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 26 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 9 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 27 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 9 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 28 is a cross-sectional view of a variable magnification optical system according to Example 10, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 29 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 10 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 30 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 10 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 31 is a cross-sectional views of a variable magnification optical system according to Example 11, wherein parts (W), (M), and (T) are in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 32 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 11 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 33 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 11 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 34 is a cross-sectional view of a variable magnification optical system according to Example 12 in a wide-angle end state, an intermediate focal length state, and a telephoto end state, respectively.

FIG. 35 shows graphs illustrating various aberrations of the variable magnification optical system according to Example 12 upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 36 shows graphs illustrating lateral aberrations of the variable magnification optical system according to Example 12 after image blur correction was performed upon focusing on infinity, wherein parts (a), (b), and (c) are in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

FIG. 37 is a diagram illustrating an example of a configuration of a camera having a variable magnification optical system mounted thereon.

FIG. 38 is a diagram illustrating an outline of an example of a method for manufacturing a variable magnification optical system.

DESCRIPTION OF EMBODIMENTS

An embodiment will now be described with reference to the drawings. FIG. 1 illustrates an example of a configuration of a variable magnification optical system (variable power optical system) ZL. In other examples, the number of lens groups, a lens configuration of each lens group, and the like can be changed appropriately.
In an embodiment, a variable magnification optical system ZL includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and an intermediate group (an n-th lens group) disposed closer to an image side than the second lens group G2, the system including a vibration-reduction lens group VR disposed closer to the image side than the intermediate group Gn and configured to be moveable so as to have component in a direction orthogonal to an optical axis, the system performing varying magnification (varying power) by changing at least the distance between the first lens group G1 and the second lens group G2 and the distance between the second lens group G2 and the intermediate group Gn. In an example, the position of the intermediate group Gn in the direction orthogonal to the optical axis is immovable, and the intermediate group Gn has a negative refractive power.
In Example 1 illustrated in FIG. 1, the intermediate group Gn of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and the vibration-reduction lens group VR disposed at an image-side of the intermediate group correspond to a 31st lens group G31 and a 32nd lens group G32, respectively. In Examples 2, 3, 5, and 7 to 11 to be described later, the intermediate group Gn and the vibration-reduction lens group VR disposed at an image-side of the intermediate group correspond to a 31st lens group G31 and a 32nd lens group G32, respectively. In Examples 4, 6, and 12, the intermediate group Gn and the vibration-reduction lens group VR disposed at an image-side of the intermediate group correspond to a fourth lens group G4 and a fifth lens group G5.
The vibration-reduction lens group VR preferably has negative refractive power.
As described above, the variable magnification optical system ZL has lens groups having negative, positive, negative, and positive refractive power or negative, positive, negative, positive, and positive refractive power and changes at least the distances between these lens groups. Therefore, it is possible to implement a variable magnification optical system having a wide angle of view. Moreover, the variable magnification optical system ZL includes the intermediate group Gn having a negative refractive power and the vibration-reduction lens group VR (having a negative refractive power) disposed at an image-side of the intermediate group, and the vibration-reduction lens group VR is moved so as to have a component in the direction orthogonal to the optical axis to perform image blur correction. Therefore, it is possible to suppress the occurrence of eccentric coma aberration (decentering coma aberration) and one-sided blur during image blur correction and to obtain satisfactory imaging performance.
The variable magnification optical system ZL satisfies Conditional Expression (1) below.
1.500<β(Gn)t<100.000 (1)
where
β(Gn)t: an imaging magnification of the intermediate group Gn in the telephoto end state
Conditional Expression (1) is a conditional expression for restoring incident light converged by the first lens group G1 and the second lens group G2 to light (approximately afocal light) substantially parallel to the optical axis using the intermediate group Gn and guiding the light toward the vibration-reduction lens group VR to thereby improve a vibration-reduction performance. When Conditional Expression (1) is satisfied, it is possible to secure a bright F-value of approximately F2.8 to F3.5 and to correct aberrations including spherical aberration satisfactorily.
If the imaging magnification exceeds the upper limit value of Conditional Expression (1), the power of the intermediate group Gn is too large, the correction of aberrations such as spherical aberration by the intermediate group Gn is insufficient, and it is difficult to obtain a variable magnification ratio (variable power ratio) of approximately 3 or higher
In order to obtain the effect reliably, it is preferable that the upper limit value of Conditional Expression (1) is set to 50.000. In order to obtain the effect more reliably, it is preferable that the upper limit value of Conditional Expression (1) is set to 25.000.
If the imaging magnification is smaller than the lower limit value of Conditional Expression (1), strong convergent light enters the vibration-reduction lens group VR, and it is difficult to suppress the occurrence of eccentric coma aberration in the telephoto end state during image blur correction and the occurrence of one-sided blur in the wide-angle end state. As a result, it is difficult to set the F-value to be as bright as approximately F2.8 to F3.5. In some cases, the occurrence of spherical aberration becomes severe, and it may be difficult to obtain a satisfactory imaging performance.
In order to obtain the effect reliably, it is preferable that the lower limit value of Conditional Expression (1) is set to 2.000. In order to obtain the effect more reliably, it is preferable that the lower limit value of Conditional Expression (1) is set to 2.500.
Preferably, the variable magnification optical system ZL satisfies Conditional Expression (2) below.
1.360<−f(Gn˜G(VR))w/fw<5.000 (2)
where
f(Gn˜G(VR))w: a composite focal length from the intermediate group Gn to the vibration-reduction lens group VR in the wide-angle end state
fw: a focal length of the entire system in the wide-angle end state
Conditional Expression (2) is a conditional expression for obtaining a variable magnification ratio of approximately 3 and a satisfactory optical performance by appropriately setting the composite focal length in the wide-angle end state, of the intermediate group Gn and the vibration-reduction lens group VR. When Conditional Expression (2) is satisfied, it is possible to secure a bright F-value of approximately F2.8 to F3.5 and to correct aberrations including spherical aberration satisfactorily.
If the focal length ratio exceeds the upper limit value of Conditional Expression (2), a composite refractive power of the intermediate group Gn and the vibration-reduction lens group VR becomes too small and it is difficult to secure a variable magnification ratio of approximately 3 in the entire system. As a result, it is necessary for the second lens group G2 or other groups to perform varying magnification, and consequently, correction of spherical aberration or coma aberration is insufficient.
In order to obtain the effect reliably, it is preferable that the upper limit value of Conditional Expression (2) is set to 4.000. In order to obtain the effect more reliably, it is preferable that the upper limit value of Conditional Expression (2) is set to 3.000.
If the focal length ratio is smaller than the lower limit value of Conditional Expression (2), the composite refractive power of the intermediate group Gn and the vibration-reduction lens group VR is too large and it is difficult to correct spherical aberration and coma aberration. As a result, it is difficult to obtain a satisfactory imaging performance while obtaining a bright F-value of approximately F2.8 to F3.5.
In order to obtain the effect reliably, it is preferable that the lower limit value of Conditional Expression (2) is set to 1.400. In order to obtain the effect more reliably, it is preferable that the lower limit value of Conditional Expression (2) is set to 1.450.
Preferably, the variable magnification optical system ZL includes an image-side lens group RP having the strongest positive refractive power among the lens groups having a positive refractive power disposed closer to the image side than the vibration-reduction lens group VR, the distance between the image-side lens group RP and the vibration-reduction lens group VR changes upon varying magnification, and preferably, Conditional Expression (3) below is satisfied.
0.400<f(RP)/f(FP)<2.000 (3)
where
f(RP): a focal length of the image-side lens group RP
f(FP): a composite focal length in the wide-angle end state, of lenses disposed closer to the image plane side than the first lens group G1 and disposed closer to the object side than the intermediate group Gn
Conditional Expression (3) is a conditional expression for obtaining a variable magnification ratio of approximately 3 and a satisfactory optical performance by appropriately setting the refractive power of the image-side lens group RP. When Conditional Expression (3) is satisfied, it is possible to secure a bright F-value of approximately F2.8 to F3.5 and to correct aberrations including spherical aberration satisfactorily.
When the focal length ratio exceeds the upper limit value of Conditional Expression (3), varying magnification by the image-side lens group RP is insufficient and it is difficult to secure a variable magnification ratio of approximately 3 in the entire system. As a result, it is necessary to cause the second lens group G2 or other groups to perform varying magnification, and consequently, correction of spherical aberration or coma aberration is insufficient.
In order to obtain the effect reliably, it is preferable that the upper limit value of Conditional Expression (3) is set to 1.800. In order to obtain the effect more reliably, it is preferable that the upper limit value of Conditional Expression (3) is set to 1.700.
If the focal length ratio is smaller than the lower limit value of Conditional Expression (3), the refractive power of the image-side lens group RP is too large and it is difficult to correct spherical aberration and coma aberration. As a result, it is difficult to obtain a satisfactory imaging performance while obtaining a bright F-value of approximately F2.8 to F3.5.
In order to obtain the effect reliably, it is preferable that the lower limit value of Conditional Expression (3) is set to 0.500. In order to obtain the effect more reliably, it is preferable that the lower limit value of Conditional Expression (3) is set to 0.600.
In the variable magnification optical system ZL, it is preferable that the intermediate group Gn has one or more positive lens components and one or more negative lens components.
The “lens component” refers to a single lens or a cemented lens.
Due to this configuration, it is possible to satisfactorily correct the spherical aberration and the coma aberration using the intermediate group Gn and to improve a vibration-reduction performance. When the intermediate group Gn includes any one of the lens components, correction of spherical aberration and coma aberration by the intermediate group Gn is insufficient, and it is necessary to cause the vibration-reduction lens group VR to correct these aberrations. As a result, the occurrence of eccentric coma aberration or one-sided blur occurring during image blur correction is greater, and it is difficult to maintain a satisfactory imaging performance during image blur correction.
In order to obtain the effect reliably, it is more preferable that the intermediate group Gn has at least two negative lens components and one or more positive lens components.
In the variable magnification optical system ZL, it is preferable that the second lens group G2 has at least four lens components.
Due to this configuration, it is possible to satisfactorily correct spherical aberration and coma aberration using the second lens group G2 and to improve a vibration-reduction performance. When the second lens group G2 has three or fewer lens components, since correction of spherical aberration and coma aberration by the second lens group G2 is insufficient, it is necessary to cause the intermediate group Gn to correct these aberrations. As a result, the occurrence of eccentric coma aberration or one-sided blur occurring during image blur correction is greater, and it is difficult to maintain a satisfactory imaging performance during image blur correction.
In order to obtain the effect reliably, it is preferable that the second lens group G2 has five or more lens components.
In the variable magnification optical system ZL, it is preferable that the second lens group G2 is constituted by, in order from the object, a 21st lens group G21 having a positive refractive power and a 22nd lens group G22 having a positive refractive power, and preferably, focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 to the image side as a focusing lens group.
Due to this configuration, it is possible to decrease the size and the weight of the lens group that moves upon focusing and to decrease the size of an entire lens system and accelerate the focusing speed during autofocus.
The variable magnification optical system ZL preferably satisfies Conditional Expression (4) below.
10.00°<ωt<30.00° (4)
where
ωt: a half-angle of view in the telephoto end state
Conditional Expression (4) is a condition that determines the value of a half-angle of view in the telephoto end state. When Conditional Expression (4) is satisfied, it is possible to obtain a desired angle of view and to satisfactorily correct coma aberration, distortion, and a curvature of field.
In order to obtain the effect reliably, it is preferable that the upper limit value of Conditional Expression (4) is set to 27.00°. In order to obtain the effect more reliably, it is preferable that the upper limit value of Conditional Expression (4) is set to 24.00°.
In order to obtain the effect reliably, it is preferable that the lower limit value of Conditional Expression (4) is set to 11.00°. In order to obtain the effect more reliably, it is preferable that the lower limit value of Conditional Expression (4) is set to 12.00°.
The variable magnification optical system ZL preferably satisfies Conditional Expression (5) below.
30.00°<ωw<50.00° (5)
where
ωw: a half-angle of view in the wide-angle end state
Conditional Expression (5) is a condition that specifies the value of a half-angle of view in the wide-angle end state. When Conditional Expression (5) is satisfied, it is possible to obtain a desired angle of view and to satisfactorily correct coma aberration, distortion, and a curvature of field.
In order to obtain the effect reliably, it is preferable that the upper limit value of Conditional Expression (5) is set to 48.00°. In order to obtain the effect more reliably, it is preferable that the upper limit value of Conditional Expression (5) is set to 45.00°.
In order to obtain the effect reliably, it is preferable that the lower limit value of Conditional Expression (5) is set to 32.00°. In order to obtain the effect more reliably, it is preferable that the lower limit value of Conditional Expression (5) is set to 34.00°.
In the variable magnification optical system ZL, the distance between the 21st lens group G21 and the 22nd lens group G22 may be fixed or variable upon varying magnification.
In the variable magnification optical system ZL, the distance between the intermediate group Gn and the vibration-reduction lens group VR may be fixed or variable upon varying magnification. When the distance is fixed, it is preferable that the composite refractive power of the intermediate group Gn and the vibration-reduction lens group VR is negative.
In the variable magnification optical system ZL, it is preferable that an optical system constituted by lenses disposed closer to the image side than the vibration-reduction lens group VR has a positive refractive power.
The variable magnification optical system ZL preferably has at least one lens group having a positive refractive power on a side closer to the image side than the vibration-reduction lens group VR.
The variable magnification optical system ZL preferably has an aperture stop between the second lens group G2 and the intermediate group Gn.
In this way, it is possible to implement a variable magnification optical system ZL which has a bright F-value and a wide angle of view and in which aberrations are corrected satisfactorily.
Next, a camera (an optical apparatus) having the above-described variable magnification optical system ZL will be described with reference to the drawings. FIG. 37 illustrates an example of a configuration of a camera having a variable magnification optical system mounted thereon.
As illustrated in FIG. 37, a camera 1 is an interchangeable lens camera (so-called a mirrorless camera) having the above-described variable magnification optical system ZL as an image capturing lens 2. In this camera 1, light from an object (a subject) which is not illustrated is collected by the image capturing lens 2 and forms a subject image on an image plane of the imaging unit 3 via an optical low-pass filter (OLPF) which is not illustrated. The subject image is photoelectrically converted by a photoelectric conversion element provided in the imaging unit 3, whereby the image of the object is generated. This image is displayed on an electronic viewfinder (EVF) 4 provided in the camera 1. In this way, a photographer can view the subject via the EVF 4. Moreover, when a release button (not illustrated) is pressed by the photographer, the image of the subject generated by the imaging unit 3 is stored in a memory (not illustrated). In this way, the photographer can capture the image of the subject using the camera 1.
As can be understood from respective examples to be described later, the variable magnification optical system ZL mounted on the camera 1 as the image capturing lens 2 has a bright F-value and a wide angle of view and has a satisfactory optical performance such that aberrations are corrected satisfactorily due to its characteristic lens configuration. Therefore, according to the camera 1, it is possible to implement an optical apparatus which has a bright F-value and a wide angle of view and has a satisfactory optical performance such that aberrations are corrected satisfactorily.
Although a mirrorless camera has been described as an example of the camera 1, the camera is not limited to this. For example, the same effect as the camera 1 can be obtained even when the above-described variable magnification optical system ZL is mounted on a single-lens reflex camera which has a quick return mirror on a camera body and views a subject using a finder optical system.
Next, an example of a method for manufacturing the above-described variable magnification optical system ZL will be described. FIG. 38 illustrate an example of a method for manufacturing the variable magnification optical system ZL.
First, respective lenses are arranged in a lens barrel so as to include a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power (step ST10). Respective lenses are arranged so as to have an intermediate group Gn disposed closer to an image side than the second lens group G2 (step ST20). Respective lenses are arranged so as to have a vibration-reduction lens group VR disposed closer to the image side than the intermediate group Gn and configured to be movable so as to have a component in the direction orthogonal to the optical axis (step ST30) Respective lenses are arranged so that varying magnification is performed by changing at least the distance between the first lens group G1 and the second lens group G2 and the distance between the second lens group G2 and the intermediate group Gn (step ST40). The respective lenses are arranged so as to satisfy Conditional Expression (1) below (step ST50).
1.500<β(Gn)t<100.000 (1)
where
β(Gn)t: an imaging magnification of the intermediate group Gn in the telephoto end state
According to an example of a lens arrangement, as illustrated in FIG. 1, a negative meniscus lens L11 having a concave surface oriented toward an image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side are arranged, in order from the object, to form the first lens group G1. A biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25 are arranged, in order from the object, to form the 21st lens group G21. A biconvex lens L26 is arranged to form the 22nd lens group G22. A biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33 are arranged, in order from the object, to form the 31st lens group G31. A biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side are arranged, in order from the object, to form the 32nd lens group G32. A biconvex lens L41, a cemented lens including a negative meniscus lens L42 having a concave surface oriented toward the image side and a biconvex lens L43, and a cemented lens including a biconvex lens L44, a biconcave lens L45, and a positive meniscus lens L46 having a convex surface oriented toward the object side are, in order from the object, to form the fourth lens group G4. The respective lens groups prepared in this manner are arranged in the above-described order to manufacture the variable magnification optical system ZL.
According to the above-described manufacturing method, it is possible to manufacture the variable magnification optical system ZL which has a bright F-value and a wide angle of view and in which aberrations are corrected satisfactorily.

EXAMPLES

Hereinafter, respective examples will be described with reference to the drawings.
FIGS. 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, and 34 are cross-sectional views illustrating the configuration and the refractive power allocation of variable magnification optical systems ZL (ZL1 to ZL12) according to respective examples. In the lower part of the cross-sectional views of the variable magnification optical systems ZL1 to ZL12, the moving directions along the optical axis of each lens group upon varying magnification from the wide-angle end state (W) to the telephoto end state (T) via the intermediate focal length state (M) are indicated by arrows. In the upper part of the cross-sectional views of the variable magnification optical systems ZL1 to ZL13, the moving direction of the focusing lens group upon focusing from an object at infinity to an object at a close distance is indicated by an arrow and the state of the vibration-reduction lens group VR when correcting image blur is also illustrated.
Respective reference signs in FIG. 1 associated with Example 1 are used independently in respective examples in order to avoid complication of description due to an increased number of reference sign characters. Therefore, even when components in diagrams associated with other examples are denoted by the same reference signs as used in FIG. 1, these components do not necessarily have the same configuration as those of other examples.
Tables 1 to 12 illustrated below are tables of respective specifications of Examples 1 to 12.
In the respective examples, the d-line (wavelength: 587.562 nm) and the g-line (wavelength: 435.835 nm) are selected as an aberration characteristics calculation target.
In [Lens Specification] in tables, a surface number indicates a sequence number of an optical surface from an object side along a traveling direction of light, R indicates a radius of curvature of each optical surface, D indicates a surface distance which is the distance on the optical axis from each optical surface to the next optical surface (or an image plane), nd indicates a refractive index for the d-line, of a material of an optical member, νd indicates the Abbe number for the d-line, of a material of an optical member, and Aperture stop indicates an aperture stop S. When the radius of curvature is “0.00000,” this indicates a flat surface for a lens surface and indicates an aperture or a diaphragm surface for an aperture stop. When the optical surface is an aspherical surface, a mark “*” is assigned to the surface number and a paraxial radius of curvature is shown in the radius of curvature column R.
In [Aspheric Data] in tables, the shape of an aspherical surface shown in [Lens Specification] is expressed by Equation (a) below. X(y) indicates the distance along the optical axis direction from a tangential plane at the vertex of an aspherical surface to a position on the aspherical surface at a height y, R indicates a radius of curvature (a paraxial radius of curvature) of a reference spherical surface, κ indicates a conic constant, and Ai indicates an aspheric coefficient at degree i. “E-n” indicates “×10⁻ⁿ”. For example, 1.234E-05=1.234×10⁻⁵. An aspheric coefficient A2 at degree 2 is 0 and is not illustrated.
X(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 [Various Data] in tables, f indicates a focal length of an entire lens system, FNo indicates the F-number, ω indicates a half-angle of view (unit: °), Y indicates the maximum image height, TL indicates the distance from the frontmost lens surface to the last lens surface on the optical axis upon focusing on infinity, BF indicates the distance from the last lens surface to the image plane I on the optical axis upon focusing on infinity, and BF (air-conversion length) indicates the distance (an air-conversion length) from the last lens surface to the image plane I on the optical axis upon focusing on infinity.
In [Variable Distance Data] in tables, DO indicates an axial air distance between an object plane and a lens surface closest to an object, of the first lens group G1, Di indicates a surface distance (i=1, 2, 3, . . . ) between an i-th surface and an (i+1)th surface, and f indicates the focal length of an entire lens system.
In [Lens Group Data] in tables, a starting surface and a focal length of each lens group are illustrated.
In [Focusing Data] in tables, a lens moving distance and an imaging distance upon focusing are illustrated.
In [Conditional Expression Correspondence Values] in tables, values corresponding to Conditional Expressions (1) to (5) are illustrated.
Hereinafter, “mm” is generally used as the unit of the focal length f, the radius of curvature R, the surface distance D, and other lengths and the like described in all specification values unless particularly stated otherwise. However, the unit is not limited to this since an equivalent optical performance is obtained even when the optical system is proportionally expanded or reduced. Moreover, the unit is not limited to “mm” and other appropriate units may be used.
The above description of tables is common to all examples, and description thereof will not be provided below.

Example 1

Example 1 will be described with reference to FIGS. 1 to 3 and Table 1. As illustrated in FIG. 1, a variable magnification optical system ZL (ZL1) according to Example 1 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, 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.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25 The 22nd lens group G22 is constituted by a biconvex lens L26.
The third lens group G3 is constituted by, in order from the object, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a cemented lens including a negative meniscus lens L42 having a concave surface oriented toward the image side and a biconvex lens L43, and a cemented lens including a biconvex lens L44, a biconcave lens L45, and a positive meniscus lens L46 having a convex surface oriented toward the object side. The biconvex lens L41 has an aspherical object-side surface. The positive meniscus lens L46 has an aspherical image-side surface.
A first flare-cut diaphragm FC1 and an aperture stop S arranged in that order from the object are disposed between the second lens group G2 and the third lens group G3. A second flare-cut diaphragm FC2 is disposed between the fourth lens group G4 and the image plane I.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the image side and then moving the same toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The first flare-cut diaphragm FC1, the aperture stop S, and the second flare-cut diaphragm FC2 are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is κ, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 1, in the wide-angle end state, since the vibration reduction coefficient is −0.45 and the focal length is 24.80 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.29 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.51 and the focal length is 50.01 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.51 mm. In the telephoto end state, since the vibration reduction coefficient is −0.58 and the focal length is 67.85 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.61 mm.
Table 1 illustrates the values of respective specifications of Example 1. Surface numbers 1 to 40 in Table 1 correspond to optical surfaces of m1 to m40 illustrated in FIG. 1.

TABLE 1

[Lens Specification]

Surface number	R	D	n(d)	νd

1	121.85638	2.900	1.74389	49.5
*2	29.63670	15.360	1.00000
*3	−197.50816	0.200	1.56093	36.6
4	−169.39125	2.100	1.80400	46.6
5	60.51496	0.150	1.00000
6	52.85097	5.600	2.00100	29.1
7	146.47986	D7	1.00000
8	148.41161	3.000	1.59349	67.0
9	−517.10678	0.100	1.00000
10	49.87002	3.500	1.59349	67.0
11	157.35190	4.762	1.00000
12	87.49334	4.800	1.59349	67.0
13	−132.22400	1.500	1.90366	31.3
14	45.76622	1.640	1.00000
15	78.93526	4.450	1.77250	49.6
16	−176.75459	D16	1.00000
17	57.14809	5.300	1.81600	46.6
18	−583.40702	D18	1.00000
19	0.00000	1.200	1.00000
20	(Aperture stop)	D20	1.00000
21	−141.85186	1.200	1.80400	46.6
22	33.20059	4.360	1.00000
23	−33.72704	1.200	1.60300	65.4
24	−60.09530	0.100	1.00000
25	65.48868	3.150	1.84666	23.8
26	−127.25009	D26	1.00000
27	−119.24441	1.100	1.59349	67.0
28	67.70394	1.150	1.00000
29	62.36800	2.100	1.80518	25.5
30	107.42000	D30	1.00000
*31	119.87584	4.700	1.55332	71.7
32	−115.00129	0.100	1.00000
33	71.95116	1.400	1.83481	42.7
34	38.48800	6.800	1.59319	67.9
35	−237.01429	0.280	1.00000
36	43.00799	9.500	1.49782	82.6
37	−42.99900	1.400	1.80518	25.5
38	98.94100	4.600	1.69350	53.3
*39	462.40647	D39	1.00000
40	0.00000	D40	1.00000

[Aspheric Data]

	2nd surface
	κ = 0.00000e+00
	A4 = 2.21510e−06
	A6 = 2.57690e−09
	A8 = −6.01500e−12
	A10 = 1.09200e−14
	A12 = −7.29000e−18
	3rd surface
	κ = 1.00000e+00
	A4 = −3.83430e−07
	A6 = 7.93340e−10
	A8 = −3.53630e−12
	A10 = 5.08120e−15
	A12 = −3.43370e−18
	31st surface
	κ = 1.00000e+00
	A4 = 4.80890e−06
	A6 = 5.06980e−l0
	A8 = −2.73140e−12
	A10 = −7.78150e−16
	A12 = 0.00000e+00
	39th surface
	κ = 1.00000e+00
	A4 = 7.56540e−06
	A6 = −9.88600e−10
	A8 = 5.61740e−12
	A10 = −8.07750e−15
	A12 = 0.00000e+00

[Various Data]

	W	M	T

f	24.80	50.01	67.85
FNo	2.92	2.92	2.92
ω	42.5	22.7	17.2
Y	21.60	21.60	21.60
TL	220.251	198.419	200.827
BF	41.035	48.522	55.686
BF (air-conversion length)	41.035	48.522	55.686

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.80	50.01	67.85
D7	48.945	10.930	1.902
D16	7.735	7.735	7.735
D18	1.802	17.931	29.439
D20	2.088	4.668	3.620
D26	1.250	1.250	1.250
D30	17.692	7.680	1.492
D39	2.530	10.000	17.180
D40	38.505	38.522	38.506

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.47
2nd lens group	8	42.49
21st lens group	8	78.58
22nd lens group	17	64.02
3rd lens group	21	−39.26
31st lens group	21	−65.76
32nd lens group	27	−121.07
4th lens group	31	48.95

[Focusing Data]

	W	M	T

Lens moving distance	6.735	6.735	6.735
Imaging distance (m)	0.4183	0.3810	0.3966

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 12.080
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.583
	Conditional Expression (3)	f(RP)/f(FP) = 1.152
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.5

It can be understood from Table 1 that the variable magnification optical system ZL1 according to Example 1 satisfies Conditional Expressions (1) to (5).
FIG. 2 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration (lateral chromatic aberration), and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL1 according to Example 1, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 3 shows graphs illustrating lateral aberration of the variable magnification optical system ZL1 according to Example 1 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 3.
In the graphs illustrating respective aberrations, FNO indicates the F-number and Y indicates an image height. d indicates aberration at the d-line and g indicates aberration at the g-line. Moreover, aberrations without these characters indicate aberrations at the d-line. In the graphs illustrating the spherical aberration upon focusing on infinity, the F-number values corresponding to the maximum aperture are illustrated. In the graphs illustrating the astigmatism, a solid line indicates the sagittal image plane and a broken line indicates the meridional image plane. The same reference symbols as in this example are used in the aberration graphs of respective examples to be described later.
As is obvious from respective aberration graphs, it can be understood that the variable magnification optical system ZL1 according to Example 1 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it can be understood that the variable magnification optical system ZL1 has an excellent imaging performance upon image blur correction.

Example 2

Example 2 will be described with reference to FIGS. 4 to 6 and Table 2. As illustrated in FIG. 4, a variable magnification optical system ZL (ZL2) according to Example 2 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, 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.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25. The 22nd lens group G22 is constituted by a biconvex lens L26.
The third lens group G3 is constituted by, in order from the object, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side. The biconcave lens L34 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a cemented lens including a negative meniscus lens L42 having a concave surface oriented toward the image side and a biconvex lens L43, and a cemented lens including a biconvex lens L44, a biconcave lens L45, and a positive meniscus lens L46 having a convex surface oriented toward the object side. The biconvex lens L41 has an aspherical object-side surface. The positive meniscus lens L46 has an aspherical image-side surface.
An aperture stop S is disposed between the second lens group G2 and the third lens group G3. A flare-cut diaphragm FC is disposed between the fourth lens group G4 and the image plane I.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the image side and then moving the same toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The aperture stop S and the flare-cut diaphragm FC are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 2, in the wide-angle end state, since the vibration reduction coefficient is −0.44 and the focal length is 24.80 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.30 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.50 and the focal length is 47.76 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.50 mm. In the telephoto end state, since the vibration reduction coefficient is −0.58 and the focal length is 67.85 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.62 mm.
Table 2 illustrates the values of respective specifications of Example 2. Surface numbers 1 to 39 in Table 2 correspond to optical surfaces of m1 to m39 illustrated in FIG. 4.

TABLE 2

[Lens Specification]

Surface number	R	D	n(d)	νd

1	123.86834	2.900	1.74389	49.5
*2	29.53373	15.066	1.00000
*3	−163.51331	0.300	1.56093	36.6
4	−139.86223	2.100	1.80400	46.6
5	65.45825	0.150	1.00000
6	56.53091	5.625	2.00100	29.1
7	182.99126	D7	1.00000
8	143.07855	3.200	1.59349	67.0
9	−394.38588	0.200	1.00000
10	55.12400	3.500	1.59349	67.0
11	197.46867	3.900	1.00000
12	77.75166	4.842	1.59349	67.0
13	−158.02225	1.500	1.90366	31.3
14	46.02834	1.844	1.00000
15	83.85157	3.848	1.77250	49.6
16	−277.24360	D16	1.00000
17	59.19194	5.400	1.80400	46.6
18	−354.91781	D18	1.00000
19	(Aperture stop)	D19	1.00000
20	−140.00000	1.178	1.77250	49.6
21	33.57372	4.337	1.00000
22	−36.69329	1.200	1.59349	67.0
23	−63.63544	0.100	1.00000
24	61.90037	3.102	1.84666	23.8
25	−187.23382	D25	1.00000
*26	−120.15188	1.100	1.61000	65.0
27	78.56667	0.966	1.00000
28	66.22584	1.921	1.80518	25.5
29	108.00000	D29	1.00000
*30	96.36461	5.000	1.55332	71.7
31	−132.37171	0.200	1.00000
32	103.35532	1.300	1.80518	25.5
33	49.66548	6.742	1.59319	67.9
34	−101.36549	0.188	1.00000
35	55.76221	9.450	1.49782	82.6
36	−36.89155	1.400	1.75000	31.4
37	97.48202	4.003	1.69350	53.2
*38	442.81061	D38	1.00000
39	0.00000	D39	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	1.48700e−01	1.33488e−06	1.45328e−09	−6.97898e−13	5.22062e−16
3	4.31460e+00	−4.66997e−07	4.80176e−10	−1.05569e−12	3.62706e−16
26	−2.40000e+01	−1.76198e−06	1.30497e−09	0.00000e+00	0.00000e+00
30	3.97310e+00	3.04836e−06	−6.62447e−10	0.00000e+00	0.00000e+00
38	3.71000e+02	4.89412e−06	1.67774e−10	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.80	47.76	67.85
FNo	2.92	2.92	2.92
ω	42.5	23.7	17.2
Y	21.60	21.60	21.60
TL	219.362	198.056	201.131
BF	41.459	48.894	57.632
BF (air-conversion length)	41.459	48.894	57.632

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.80	47.76	67.85
D7	48.978	12.578	1.835
D16	7.750	7.750	7.750
D18	3.000	18.144	31.911
D19	2.000	4.200	2.500
D25	1.440	1.440	1.440
D29	18.172	8.487	1.500
D38	1.139	8.574	17.251
D39	40.319	40.320	40.381

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.77
2nd lens group	8	42.97
21st lens group	8	81.61
22nd lens group	17	63.47
3rd lens group	20	−40.68
31st lens group	20	−68.40
32nd lens group	26	−123.54
4th lens group	30	49.36

[Focusing Data]

	W	M	T

Lens moving distance	6.75	6.75	6.75
Imaging distance (m)	0.4124	0.3853	0.4059

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 13.824
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.640
	Conditional Expression (3)	f(RP)/f(FP) = 1.149
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.5

It is understood from Table 2 that the variable magnification optical system ZL2 according to Example 2 satisfies Conditional Expressions (1) to (5).
FIG. 5 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL2 according to Example 2, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 6 shows graphs illustrating lateral aberration of the variable magnification optical system ZL2 according to Example 2 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 6.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL2 according to Example 2 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL2 has an excellent imaging performance upon image blur correction.

Example 3

Example 3 will be described with reference to FIGS. 7 to 9 and Table 3. As illustrated in FIG. 7, a variable magnification optical system ZL (ZL3) according to Example 3 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25. The 22nd lens group G22 is constituted by a biconvex lens L26.
The third lens group G3 is constituted by, in order from the object, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side. The biconcave lens L34 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a cemented lens including a negative meniscus lens L42 having a concave surface oriented toward the image side and a biconvex lens L43, and a cemented lens including a biconvex lens L44 and a biconcave lens L45. The biconvex lens L41 has an aspherical object-side surface. The biconcave lens L45 has an aspherical image-side surface.
The fifth lens group G5 is constituted by a cemented lens including, in order from an object, a positive meniscus lens L51 having a convex surface oriented toward the object side and a negative meniscus lens L52 having a concave surface oriented toward the image side.
An aperture stop S is disposed between the second lens group G2 and the third lens group G3.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the image side and then moving the same toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The fifth lens group G5 and the aperture stop S are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 3, in the wide-angle end state, since the vibration reduction coefficient is −0.45 and the focal length is 24.82 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.29 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.50 and the focal length is 47.49 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.49 mm. In the telephoto end state, since the vibration reduction coefficient is −0.58 and the focal length is 67.84 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.62 mm.
Table 3 illustrates the values of respective specifications of Example 3. Surface numbers 1 to 40 in Table 3 correspond to optical surfaces of m1 to m40 illustrated in FIG. 7.

TABLE 3

[Lens Specification]

Surface number	R	D	n(d)	νd

1	134.61434	2.900	1.74389	49.5
*2	30.98121	14.105	1.00000
*3	−271.55507	0.300	1.56093	36.6
4	−224.01871	2.100	1.80400	46.6
5	65.07720	0.200	1.00000
6	53.84066	5.401	2.00100	29.1
7	113.70514	D7	1.00000
8	259.91458	3.000	1.59349	67.0
9	−443.80327	0.243	1.00000
10	71.84029	3.500	1.69680	55.5
11	238.64880	4.057	1.00000
12	66.72188	5.288	1.59349	67.0
13	−145.97738	1.500	1.90366	31.3
14	49.38387	1.625	1.00000
15	83.91292	4.117	1.77250	49.6
16	−207.54373	D16	1.00000
17	59.58569	5.400	1.80400	46.6
18	−338.02309	D18	1.00000
19	(Aperture stop)	D19	1.00000
20	−140.00000	1.178	1.77250	49.6
21	34.70000	4.110	1.00000
22	−37.39824	1.200	1.59349	67.0
23	−64.12090	0.100	1.00000
24	62.46432	2.941	1.90200	25.3
25	−277.86426	D25	1.00000
*26	−157.84803	1.100	1.77250	49.6
27	61.66083	1.232	1.00000
28	63.26230	2.386	1.84666	23.8
29	198.11149	D29	1.00000
*30	74.15506	5.000	1.55332	71.7
31	−190.85228	0.100	1.00000
32	414.99863	1.300	1.84666	23.8
33	79.29491	6.640	1.59319	67.9
34	−59.47223	0.188	1.00000
35	77.14715	8.284	1.49700	81.6
36	−39.12349	1.400	1.70600	30.9
*37	467.32553	D37	1.00000
38	74.86867	2.769	1.49700	81.6
39	177.01793	1.400	1.79504	28.7
40	100.00000	D40	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−8.40000e−03	1.76676e−06	1.42633e−09	−6.16355e−13	3.36393e−16
3	5.89560e+00	−4.29758e−07	9.43230e−10	−1.79782e−12	8.72339e−16
26	−2.40000e+01	−5.18855e−07	4.69601e−10	0.00000e+00	0.00000e+00
30	7.93900e−01	2.20229e−06	−7.31449e−10	0.00000e+00	0.00000e+00
37	4.51000e+02	4.05983e−06	9.42292e−10	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.82	47.49	67.84
FNo	2.91	2.91	2.92
ω	42.3	23.8	17.2
Y	21.60	21.60	21.60
TL	220.442	198.936	201.965
BF	42.289	42.290	42.353
BF (air-conversion length)	42.289	42.290	42.353

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.82	47.49	67.84
D7	49.018	12.832	1.835
D16	7.750	7.750	7.750
D18	3.000	17.679	31.753
D19	2.000	3.989	2.000
D25	1.412	1.412	1.412
D29	18.411	8.690	1.500
D37	1.500	9.233	18.301
D40	42.289	42.290	42.353

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.85
2nd lens group	8	42.32
21st lens group	8	82.21
22nd lens group	17	63.39
3rd lens group	20	−41.39
31st lens group	20	−69.44
32nd lens group	26	−122.74
4th lens group	30	52.58
5th lens group	38	2000.09

[Focusing Data]

	W	M	T

Lens moving distance	6.75	6.75	6.75
Imaging distance (m)	0.4144	0.3857	0.4059

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 9.843
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.668
	Conditional Expression (3)	f(RP)/f(FP) = 1.242
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.3

It is understood from Table 3 that the variable magnification optical system ZL3 according to Example 3 satisfies Conditional Expressions (1) to (5).
FIG. 8 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL3 according to Example 3, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 9 shows graphs illustrating lateral aberration of the variable magnification optical system ZL3 according to Example 3 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 9.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL3 according to Example 3 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL3 has an excellent imaging performance upon image blur correction.

Example 4

Example 4 will be described with reference to FIGS. 10 to 12 and Table 4. As illustrated in FIG. 10, a variable magnification optical system ZL (ZL4) according to Example 4 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a negative refractive power, a sixth lens group G6 having a positive refractive power, and a seventh lens group G7 having a negative refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 (a focusing lens group) is constituted by a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25.
The third lens group G3 is constituted by a biconvex lens L31.
The fourth lens group G4 (an intermediate group) is constituted by, in order from the object, a biconcave lens L41, a negative meniscus lens L42 having a concave surface oriented toward the object side, and a biconvex lens L43, of which the positions in the direction orthogonal to the optical axis are immovable.
The fifth lens group G5 (a vibration-reduction lens group) is constituted by, in order from the object, a biconcave lens L51 and a positive meniscus lens L52 having a convex surface oriented toward the object side. The biconcave lens L51 has an aspherical object-side surface.
The sixth lens group G6 is constituted by, in order from the object, a biconvex lens L61, a cemented lens including a negative meniscus lens L62 having a concave surface oriented toward the image side and a biconvex lens L63, and a cemented lens including a biconvex lens L64 and a biconcave lens L65. The biconvex lens L61 has an aspherical object-side surface. The biconcave lens L65 has an aspherical image-side surface.
The seventh lens group G7 is constituted by a cemented lens including, in order from an object, a positive meniscus lens L71 having a convex surface oriented toward the object side and a negative meniscus lens L72 having a concave surface oriented toward the image side.
An aperture stop S is disposed between the third lens group G3 and the fourth lens group G4.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the object side, moving the fourth lens group G4 toward the image side and then moving the same toward the object side, moving the fifth lens group G5 toward the image side and then moving the same toward the object side, and moving the sixth lens group G6 toward the object side such that the distances between the respective lens groups are changed. The seventh lens group G7 and the aperture stop S are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the second lens group G2 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the fifth lens group G5 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 4, in the wide-angle end state, since the vibration reduction coefficient is −0.46 and the focal length is 25.49 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.29 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.53 and the focal length is 48.81 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.49 mm. In the telephoto end state, since the vibration reduction coefficient is −0.61 and the focal length is 69.45 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.59 mm.
Table 4 illustrates the values of respective specifications of Example 4. Surface numbers 1 to 40 in Table 4 correspond to optical surfaces of m1 to m40 illustrated in FIG. 10.

TABLE 4

[Lens Specification]

Surface number	R	D	n(d)	νd

1	134.61434	2.900	1.74389	49.5
*2	30.98121	14.105	1.00000
*3	−271.55507	0.300	1.56093	36.6
4	−224.01871	2.100	1.80400	46.6
5	65.07720	0.200	1.00000
6	53.84066	5.401	2.00100	29.1
7	113.70514	D7	1.00000
8	259.91458	3.000	1.59349	67.0
9	−443.80327	0.243	1.00000
10	71.84029	3.500	1.69680	55.5
11	238.64880	4.057	1.00000
12	66.72188	5.288	1.59349	67.0
13	−145.97738	1.500	1.90366	31.3
14	49.38387	1.625	1.00000
15	83.91292	4.117	1.77250	49.6
16	−207.54373	D16	1.00000
17	59.58569	5.400	1.80400	46.6
18	−338.02309	D18	1.00000
19	(Aperture stop)	D19	1.00000
20	−140.00000	1.178	1.77250	49.6
21	34.70000	4.110	1.00000
22	−37.39824	1.200	1.59349	67.0
23	−64.12090	0.100	1.00000
24	62.46432	2.941	1.90200	25.3
25	−277.86426	D25	1.00000
*26	−157.84803	1.100	1.77250	49.6
27	61.66083	1.232	1.00000
28	63.26230	2.386	1.84666	23.8
29	198.11149	D29	1.00000
*30	74.15506	5.000	1.55332	71.7
31	−190.85228	0.100	1.00000
32	414.99863	1.300	1.84666	23.8
33	79.29491	6.640	1.59319	67.9
34	−59.47223	0.188	1.00000
35	77.14715	8.284	1.49700	81.6
36	−39.50000	1.400	1.70600	30.9
*37	467.32553	D37	1.00000
38	74.86867	2.769	1.48749	70.3
39	300.00000	1.400	1.79504	28.7
40	100.00000	D40	1.00000

[Aspheric Data]

[Various Data]

	W	M	T

f	25.49	48.81	69.45
FNo	2.92	2.92	2.92
ω	41.6	23.3	16.8
Y	21.60	21.60	21.60
TL	222.079	204.772	203.978
BF	44.388	45.157	44.803
BF (air-conversion length)	44.388	45.157	44.803

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	25.49	48.81	69.45
D7	49.018	12.832	1.900
D16	7.750	12.000	8.300
D18	2.500	16.500	30.700
D19	2.000	3.989	2.000
D25	1.412	3.000	1.412
D29	18.450	7.000	1.500
D37	1.500	9.233	18.301
D40	44.388	45.157	44.803

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.85
2nd lens group	8	82.21
3rd lens group	17	63.39
4th lens group	20	−69.44
5th lens group	26	−122.74
6th lens group	30	52.47
7th lens group	38	−3528.86

[Focusing Data]

	W	M	T

Lens moving distance	6.75	11.00	7.30
Imaging distance (m)	0.4160	0.3019	0.3889

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 11.069
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.624
	Conditional Expression (3)	f(RP)/f(FP) = 1.240
	Conditional Expression (4)	ωt = 16.8
	Conditional Expression (5)	ωw = 41.6

It is understood from Table 4 that the variable magnification optical system ZL4 according to Example 4 satisfies Conditional Expressions (1) to (5).
FIG. 11 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL4 according to Example 4, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 12 shows graphs illustrating lateral aberration of the variable magnification optical system ZL4 according to Example 4 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 12.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL4 according to Example 4 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL4 has an excellent imaging performance upon image blur correction.

Example 5

Example 5 will be described with reference to FIGS. 13 to 15 and Table 5. As illustrated in FIG. 13, a variable magnification optical system ZL (ZL5) according to Example 5 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25. The 22nd lens group G22 is constituted by a biconvex lens L26.
The third lens group G3 is constituted by, in order from the object, an aperture stop S, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side. The biconcave lens L34 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a cemented lens including a negative meniscus lens L42 having a concave surface oriented toward the image side and a biconvex lens L43, and a cemented lens including a biconvex lens L44 and a biconcave lens L45. The biconvex lens L41 has an aspherical object-side surface. The biconcave lens L45 has an aspherical image-side surface.
The fifth lens group G5 is constituted by a cemented lens including a biconvex lens L51 and a biconcave lens L52 arranged in that order from the object.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The third lens group G3 and the fifth lens group G5 are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 5, in the wide-angle end state, since the vibration reduction coefficient is −0.46 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.28 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.52 and the focal length is 47.50 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.48 mm. In the telephoto end state, since the vibration reduction coefficient is −0.58 and the focal length is 67.85 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.62 mm.
Table 5 illustrates the values of respective specifications of Example 5. Surface numbers 1 to 40 in Table 5 correspond to optical surfaces of m1 to m40 illustrated in FIG. 13.

TABLE 5

[Lens Specification]

Surface number	R	D	n(d)	νd

1	144.94817	2.900	1.74389	49.5
*2	29.83529	14.301	1.00000
*3	−322.90228	0.300	1.56093	36.6
4	−228.59270	2.100	1.80400	46.6
5	65.19707	0.200	1.00000
6	54.96083	5.379	2.00100	29.1
7	130.46571	D7	1.00000
8	127.91888	3.200	1.59349	67.0
9	−2245.90430	1.780	1.00000
10	81.17716	3.500	1.69680	55.5
11	679.72724	2.453	1.00000
12	61.05134	5.724	1.59349	67.0
13	−130.20006	1.500	1.90366	31.3
14	46.24112	1.694	1.00000
15	77.95470	3.722	1.77250	49.6
16	−564.05655	D16	1.00000
17	60.46759	5.400	1.80400	46.6
18	−263.45861	D18	1.00000
19	(Aperture stop)	2.000	1.00000
20	−140.00000	1.178	1.77250	49.6
21	35.60000	4.059	1.00000
22	−35.16240	1.200	1.72916	54.6
23	−51.36153	0.100	1.00000
24	69.55169	2.879	1.90200	25.3
25	−209.71368	D25	1.00000
*26	−118.85935	1.100	1.77250	49.6
27	54.49135	1.415	1.00000
28	60.78441	2.635	1.90200	25.3
29	331.09581	D29	1.00000
*30	118.81221	4.686	1.55332	71.7
31	−102.83315	0.100	1.00000
32	152.27830	1.300	1.72000	28.0
33	85.35751	6.402	1.59319	67.9
34	−54.69093	0.188	1.00000
35	959.47501	7.222	1.49700	81.6
36	−30.23774	1.400	1.70600	29.0
*37	1029.85760	D37	1.00000
38	53.49812	4.770	1.55332	71.7
39	−6970.92580	1.400	1.90366	31.3
40	100.00000	D40	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−1.01100e−01	1.43852e−06	1.71179e−09	−1.42870e−12	1.05723e−15
3	2.81381e+01	−7.54473e−07	4.14335e−10	−5.77466e−13	3.16668e−16
26	−1.90000e+01	−9.14707e−07	9.49568e−10	0.00000e+00	0.00000e+00
30	−1.43460e+00	2.27762e−06	−5.51593e−10	0.00000e+00	0.00000e+00
37	2.44600e+03	4.05698e−06	0.00000e+00	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.77	47.50	67.85
FNo	2.90	2.90	2.91
ω	42.4	23.8	17.2
Y	21.60	21.60	21.60
TL	218.725	198.522	200.695
BF	41.843	41.843	41.903
BF (air-conversion length)	41.843	41.843	41.903

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.50	67.85
D7	49.003	12.690	1.835
D16	7.750	7.750	7.750
D18	1.450	17.610	30.588
D25	1.473	1.473	1.473
D29	17.519	8.681	1.500
D37	1.500	10.288	17.459
D40	41.843	41.843	41.903

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.88
2nd lens group	8	42.16
21st lens group	8	80.98
22nd lens group	17	61.63
3rd lens group	19	−42.05
31st lens group	19	−71.15
32nd lens group	26	−121.45
4th lens group	30	56.98
5th lens group	38	619.99

[Focusing Data]

	W	M	T

Lens moving distance	6.75	6.75	6.75
Imaging distance (m)	0.4148	0.3865	0.4059

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 6.597
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.698
	Conditional Expression (3)	f(RP)/f(FP) = 1.352
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.4

It is understood from Table 5 that the variable magnification optical system ZL5 according to Example 5 satisfies Conditional Expressions (1) to (5).
FIG. 14 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL5 according to Example 5, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 15 shows graphs illustrating lateral aberration of the variable magnification optical system ZL5 according to Example 5 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 15.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL5 according to Example 5 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL5 has an excellent imaging performance upon image blur correction.

Example 6

Example 6 will be described with reference to FIGS. 16 to 18 and Table 6. As illustrated in FIG. 16, a variable magnification optical system ZL (ZL6) according to Example 6 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a negative refractive power, a sixth lens group G6 having a positive refractive power, and a seventh lens group G7 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 (a focusing lens group) is constituted by a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25.
The third lens group G3 is constituted by a biconvex lens L31.
The fourth lens group G4 (an intermediate group) is constituted by, in order from the object, an aperture stop S, a biconcave lens L41, a negative meniscus lens L42 having a concave surface oriented toward the object side, and a biconvex lens L43, of which the positions in the direction orthogonal to the optical axis are immovable.
The fifth lens group G5 (a vibration-reduction lens group) is constituted by, in order from the object, a biconcave lens L51 and a positive meniscus lens L52 having a convex surface oriented toward the object side. The biconcave lens L51 has an aspherical object-side surface.
The sixth lens group G6 is constituted by, in order from the object, a biconvex lens L61, a cemented lens including a negative meniscus lens L62 having a concave surface oriented toward the image side and a biconvex lens L63, and a cemented lens including a biconvex lens L64 and a biconcave lens L65. The biconvex lens L61 has an aspherical object-side surface. The biconcave lens L65 has an aspherical image-side surface.
The seventh lens group G7 is constituted by a cemented lens including a biconvex lens L71 and a biconcave lens L72 arranged in that order from the object.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the object side, moving the fourth lens group G4 toward the image side, moving the fifth lens group G5 toward the image side and then moving the same toward the object side, and moving the sixth lens group G6 toward the object side such that the distances between the respective lens groups are changed. The seventh lens group G7 is immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the second lens group G2 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the fifth lens group G5 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 6, in the wide-angle end state, since the vibration reduction coefficient is −0.46 and the focal length is 24.73 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.28 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.53 and the focal length is 47.48 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.48 mm. In the telephoto end state, since the vibration reduction coefficient is −0.58 and the focal length is 67.41 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.61 mm.
Table 6 illustrates the values of respective specifications of Example 6. Surface numbers 1 to 40 in Table 6 correspond to optical surfaces of m1 to m40 illustrated in FIG. 16.

TABLE 6

[Lens Specification]

[Aspheric Data]

[Various Data]

	W	M	T

f	24.73	47.48	67.41
FNo	2.90	2.90	2.93
ω	42.5	23.9	17.3
Y	21.60	21.60	21.60
TL	218.388	200.467	201.434
BF	41.880	42.603	42.530
BF (air-conversion length)	41.880	42.603	42.530

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.73	47.48	67.41
D7	49.003	12.690	1.835
D16	7.750	9.500	8.500
D18	1.450	17.000	30.000
D25	1.100	2.500	1.473
D29	17.519	7.700	1.450
D37	1.500	10.288	17.459
D40	41.880	42.603	42.530

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.88
2nd lens group	8	80.98
3rd lens group	17	61.63
4th lens group	19	−71.15
5th lens group	26	−121.45
6th lens group	30	56.98
7th lens group	38	619.99

[Focusing Data]

	W	M	T

Lens moving distance	6.75	8.50	7.50
Imaging distance (m)	0.4145	0.3406	0.3816

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 6.868
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.704
	Conditional Expression (3)	f(RP)/f(FP) = 1.352
	Conditional Expression (4)	ωt = 17.3
	Conditional Expression (5)	ωw = 42.5

It is understood from Table 6 that the variable magnification optical system ZL6 according to Example 6 satisfies Conditional Expressions (1) to (5).
FIG. 17 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL6 according to Example 6, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 18 shows graphs illustrating lateral aberration of the variable magnification optical system ZL6 according to Example 6 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 18.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL6 according to Example 6 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL6 has an excellent imaging performance upon image blur correction.

Example 7

Example 7 will be described with reference to FIGS. 19 to 21 and Table 7. As illustrated in FIG. 19, a variable magnification optical system ZL (ZL7) according to Example 7 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a positive meniscus lens L21 having a convex surface oriented toward the object side, a biconvex lens L22, a biconcave lens L23, and a biconvex lens L24. The 22nd lens group G22 is constituted by a biconvex lens L25.
The third lens group G3 is constituted by, in order from the object, an aperture stop S, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side. The biconcave lens L34 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a biconvex lens L42, and a cemented lens including a biconvex lens L43 and a biconcave lens L44. The biconvex lens L41 has an aspherical object-side surface.
The fifth lens group G5 is constituted by a cemented lens including, in order from an object, a negative meniscus lens L51 having a concave surface oriented toward the image side and a positive meniscus lens L52 having a convex surface oriented toward the object side.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The third lens group G3 and the fifth lens group G5 are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 7, in the wide-angle end state, since the vibration reduction coefficient is −0.46 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.29 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.52 and the focal length is 47.50 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.48 mm. In the telephoto end state, since the vibration reduction coefficient is −0.58 and the focal length is 67.86 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.62 mm.
Table 7 illustrates the values of respective specifications of Example 7. Surface numbers 1 to 38 in Table 7 correspond to optical surfaces of m1 to m38 illustrated in FIG. 19.

TABLE 7

[Lens Specification]

Surface number	R	D	n(d)	νd

1	155.89691	2.900	1.74389	49.5
*2	29.88191	12.307	1.00000
*3	−998.95016	0.380	1.56093	36.6
4	−380.00000	2.100	1.75500	52.3
5	54.41504	0.200	1.00000
6	48.25639	5.777	1.90200	25.3
7	111.71017	D7	1.00000
8	75.52522	4.500	1.75000	53.0
9	599.23665	3.427	1.00000
10	65.44832	4.500	1.75500	52.3
11	−536.13486	0.864	1.00000
12	−161.64034	1.550	1.90200	25.3
13	48.60000	1.455	1.00000
14	77.92408	4.650	1.77250	49.6
15	−199.82321	D15	1.00000
16	59.54554	5.676	1.81600	46.6
17	−305.53264	D17	1.00000
18	(Aperture stop)	2.000	1.00000
19	−140.00000	1.200	1.77250	49.6
20	34.07853	4.022	1.00000
21	−34.00000	1.200	1.72916	54.6
22	−47.36695	0.100	1.00000
23	60.05931	3.182	1.84666	23.8
24	−160.47286	D24	1.00000
*25	−266.90180	1.100	1.77250	49.6
26	80.68524	0.780	1.00000
27	68.16544	1.736	1.84666	23.8
28	100.00000	D28	1.00000
*29	300.52804	4.082	1.55332	71.7
30	−61.39111	0.100	1.00000
31	178.14990	4.513	1.60300	65.4
32	−65.35343	0.200	1.00000
33	142.59265	7.934	1.65160	58.6
34	−28.88978	1.400	1.90200	29.1
35	300.00000	D35	1.00000
36	137.03160	1.400	1.83000	37.0
37	64.66324	3.650	1.59319	67.9
38	735.00000	D38	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−9.54700e−01	5.69885e−06	−1.82979e−09	8.49633e−13	0.00000e+00
3	−1.40000e+01	−6.77491e−07	−2.49807e−10	0.00000e+00	0.00000e+00
25	−1.90000e+01	3.06942e−07	−6.70956e−10	0.00000e+00	0.00000e+00
29	5.86950e+00	−6.89526e−07	2.25877e−09	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.77	47.50	67.86
FNo	2.90	2.90	2.90
ω	42.4	23.9	17.2
Y	21.60	21.60	21.60
TL	210.992	190.994	193.977
BF	39.982	39.983	40.044
BF (air-conversion length)	39.982	39.983	40.044

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.50	67.86
D7	49.068	12.647	1.800
D15	7.785	7.785	7.785
D17	3.346	19.816	33.635
D24	0.999	0.999	0.999
D28	19.428	10.413	3.291
D35	1.500	10.465	17.538
D38	39.982	39.983	40.044

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−38.96
2nd lens group	8	42.92
21st lens group	8	85.00
22nd lens group	16	61.50
3rd lens group	18	−45.09
31st lens group	18	−84.08
32nd lens group	25	−117.85
4th lens group	29	56.15
5th lens group	36	620.00

[Focusing Data]

	W	M	T

Lens moving distance	6.785	6.785	6.785
Imaging distance (m)	0.3997	0.3832	0.4060

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 4.299
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.820
	Conditional Expression (3)	f(RP)/f(FP) = 1.308
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.4

It is understood from Table 7 that the variable magnification optical system ZL7 according to Example 7 satisfies Conditional Expressions (1) to (5).
FIG. 20 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL7 according to Example 7, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 21 shows graphs illustrating lateral aberration of the variable magnification optical system ZL7 according to Example 7 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 21.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL7 according to Example 7 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL7 has an excellent imaging performance upon image blur correction.

Example 8

Example 8 will be described with reference to FIGS. 22 to 24 and Table 8. As illustrated in FIG. 22, a variable magnification optical system ZL (ZL8) according to Example 8 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface. The biconcave lens L12 is a composite aspherical lens obtained by forming a resin layer formed on a glass surface on the object side into an aspherical surface.
The second lens group G2 is constituted by, in order from the object, a flare-cut diaphragm FC, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a positive meniscus lens L21 having a convex surface oriented toward the object side, a biconvex lens L22, a biconcave lens L23, and a biconvex lens L24. The 22nd lens group G22 is constituted by a biconvex lens L25.
The third lens group G3 is constituted by, in order from the object, an aperture stop S, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a biconvex lens L33. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a positive meniscus lens L35 having a convex surface oriented toward the object side. The biconcave lens L34 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a positive meniscus lens L41 having a convex surface oriented toward the image side, a biconvex lens L42, and a cemented lens including a biconvex lens L43 and a biconcave lens L44. The positive meniscus lens L41 has an aspherical object-side surface.
The fifth lens group G5 is constituted by a cemented lens including, in order from an object, a negative meniscus lens L51 having a concave surface oriented toward the image side and a positive meniscus lens L52 having a convex surface oriented toward the object side.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The third lens group G3 and the fifth lens group G5 are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 8, in the wide-angle end state, since the vibration reduction coefficient is −0.50 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.26 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.58 and the focal length is 47.50 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.43 mm. In the telephoto end state, since the vibration reduction coefficient is −0.66 and the focal length is 67.85 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.54 mm.
Table 8 illustrates the values of respective specifications of Example 8. Surface numbers 1 to 39 in Table 8 correspond to optical surfaces of m1 to m39 illustrated in FIG. 22.

TABLE 8

[Lens Specification]

Surface number	R	D	n(d)	νd

1	171.22378	2.900	1.74389	49.5
*2	29.77139	12.208	1.00000
*3	−2272.73400	0.380	1.56093	36.6
4	−400.00000	2.100	1.75500	52.3
5	59.96509	0.200	1.00000
6	50.35816	7.000	1.90200	25.3
7	111.56759	D7	1.00000
8	0.00000	0.200	1.00000
9	82.35931	3.100	1.75000	51.0
10	869.55661	3.243	1.00000
11	65.70660	4.150	1.77250	49.6
12	−400.15117	0.889	1.00000
13	−142.76803	1.550	1.90200	25.3
14	49.72103	1.379	1.00000
15	78.21406	4.000	1.77250	49.6
16	−195.63433	D16	1.00000
17	58.26284	5.676	1.81600	46.6
18	−346.07444	D18	1.00000
19	(Aperture stop)	2.000	1.00000
20	−140.00000	1.200	1.77250	49.6
21	36.40792	4.110	1.00000
22	−39.80791	1.200	1.72916	54.7
23	−59.45079	0.100	1.00000
24	69.32659	3.085	1.84666	23.8
25	−134.48153	D25	1.00000
*26	−251.99331	1.100	1.77250	49.6
27	63.18500	0.868	1.00000
28	59.71324	2.131	1.86000	24.2
29	100.00000	D29	1.00000
*30	−900.00000	3.663	1.55332	71.7
31	−54.18440	0.100	1.00000
32	84.94639	5.806	1.60300	65.5
33	−60.43832	0.200	1.00000
34	278.20778	6.810	1.65160	58.5
35	−32.56689	1.400	1.90200	28.5
36	191.68646	D36	1.00000
37	132.64391	1.400	1.83000	34.0
38	61.28313	3.734	1.59319	67.9
39	735.00000	D39	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−3.84000e−01	2.66465e−06	−1.34312e−10	−5.72743e−14	0.00000e+00
3	3.50000e+00	−9.48227e−07	−3.38888e−10	0.00000e+00	0.00000e+00
26	−2.80000e+01	3.11252e−07	−7.78416e−10	0.00000e+00	0.00000e+00
30	−6.00000e+00	−1.99894e−06	1.27933e−09	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.77	47.50	67.85
FNo	2.90	2.90	2.90
ω	42.4	24.0	17.2
Y	21.60	21.60	21.60
TL	209.253	187.862	189.544
BF	40.016	40.020	40.085
BF (air-conversion length)	40.016	40.020	40.085

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.50	67.85
D7	49.018	12.518	1.800
D16	7.835	7.835	7.835
D18	3.200	18.355	30.700
D25	0.930	0.930	0.930
D29	18.873	9.373	1.900
D36	1.500	10.950	18.413
D39	40.016	40.020	40.085

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−39.60
2nd lens group	8	41.35
21st lens group	8	84.99
22nd lens group	17	61.50
3rd lens group	19	−43.44
31st lens group	19	−85.70
32nd lens group	26	−106.03
4th lens group	30	54.89
5th lens group	37	619.95

[Focusing Data]

	W	M	T

Lens moving distance	6.835	6.835	6.835
Imaging distance (m)	0.4055	0.3839	0.4040

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 3.949
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.754
	Conditional Expression (3)	f(RP)/f(FP) = 1.327
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.4

It is understood from Table 8 that the variable magnification optical system ZL8 according to Example 8 satisfies Conditional Expressions (1) to (5).
FIG. 23 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL8 according to Example 8, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 24 shows graphs illustrating lateral aberration of the variable magnification optical system ZL8 according to Example 8 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 24.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL8 according to Example 8 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL8 has an excellent imaging performance upon image blur correction.

Example 9

Example 9 will be described with reference to FIGS. 25 to 27 and Table 9. As illustrated in FIG. 25, a variable magnification optical system ZL (ZL9) according to Example 9 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a biconvex lens L21, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25. The 22nd lens group G22 is constituted by a cemented lens including, in order from an object, a biconvex lens L26 and a negative meniscus lens L27 having a concave surface oriented toward the object side.
The third lens group G3 is constituted by, in order from the object, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31, a negative meniscus lens L32 having a concave surface oriented toward the object side, and a positive meniscus lens L33 having a convex surface oriented toward the image side. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L34 and a biconvex lens L35. The biconcave lens L34 has an aspherical surface on both sides thereof.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a biconvex lens L42, and a cemented lens including a biconvex lens L43 and a biconcave lens L44. The biconvex lens L41 has an aspherical object-side surface. The biconcave lens L44 has an aspherical image-side surface.
The fifth lens group G5 is constituted by a cemented lens including a biconvex lens L51 and a biconcave lens L52 arranged in that order from the object.
An aperture stop S is disposed between the second lens group G2 and the third lens group G3.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the image side and then moving the same toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The fifth lens group G5 and the aperture stop S are immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 9, in the wide-angle end state, since the vibration reduction coefficient is −0.51 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.25 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.57 and the focal length is 47.50 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.43 mm. In the telephoto end state, since the vibration reduction coefficient is −0.66 and the focal length is 67.85 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.54 mm.
Table 9 illustrates the values of respective specifications of Example 9. Surface numbers 1 to 39 in Table 9 correspond to optical surfaces of m1 to m39 illustrated in FIG. 25.

TABLE 9

[Lens Specification]

Surface number	R	D	n(d)	νd

1	180.28031	2.900	1.74389	49.5
*2	30.43353	15.281	1.00000
3	−400.00000	2.100	1.80400	46.6
4	61.64102	0.200	1.00000
5	52.74108	5.413	2.00100	29.1
6	127.21255	D6	1.00000
7	250.61095	3.650	1.48749	70.3
8	−249.39202	0.258	1.00000
9	60.71776	3.347	1.69680	55.5
10	223.73133	2.543	1.00000
11	88.72642	4.052	1.59349	67.0
12	−200.28776	1.450	1.90366	31.3
13	46.94856	1.456	1.00000
14	71.21863	4.324	1.77250	49.6
15	−259.88006	D15	1.00000
16	64.61643	5.373	1.80400	46.6
17	−171.33576	1.500	1.85026	32.4
18	−427.99181	D18	1.00000
19	(Aperture stop)	D19	1.00000
20	−140.00000	1.200	1.77250	49.6
21	98.73269	2.349	1.00000
22	−46.53449	1.200	1.76000	50.0
23	−88.62573	0.100	1.00000
24	−227.14142	2.169	1.90200	25.3
25	−65.70168	D25	1.00000
*26	−82.31022	1.100	1.77250	49.6
*27	41.14809	1.433	1.00000
28	50.51593	3.020	1.90200	25.3
29	−7587.28970	D29	1.00000
*30	445.83969	3.966	1.55332	71.7
31	−73.29859	0.100	1.00000
32	153.51046	3.949	1.60300	65.4
33	−101.27922	0.200	1.00000
34	86.09865	7.212	1.59319	67.9
35	−40.79305	1.200	1.79000	26.0
*36	180.00000	D36	1.00000
37	69.32616	4.432	1.61800	63.3
38	−225.96343	1.200	1.90366	31.3
39	140.29946	D39	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−1.14500e−01	2.30934e−06	4.18972e−10	6.24631e−13	0.00000e+00
26	−4.22870e+00	4.95698e−23	1.31315e−09	0.00000e+00	0.00000e+00
27	5.80700e−01	3.38518e−07	0.00000e+00	0.00000e+00	0.00000e+00
30	1.94200e−01	3.81661e−06	−2.35375e−09	0.00000e+00	0.00000e+00
36	1.00000e+00	4.12000e−06	0.00000e+00	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.77	47.50	67.85
FNo	2.90	2.90	2.92
ω	42.3	23.9	17.2
Y	21.60	21.60	21.60
TL	214.110	194.068	198.548
BF	40.318	40.318	40.378
BF (air-conversion length)	40.318	40.318	40.378

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.50	67.85
D6	49.013	12.596	1.845
D15	7.840	7.840	7.840
D18	3.000	19.375	34.606
D19	2.000	3.243	2.000
D25	0.930	0.930	0.930
D29	20.833	9.633	1.900
D36	1.500	11.458	20.373
D39	40.318	40.318	40.378

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−39.13
2nd lens group	7	43.78
21st lens group	7	80.97
22nd lens group	16	71.04
3rd lens group	20	−48.53
31st lens group	20	−95.21
32nd lens group	26	−105.72
4th lens group	30	57.82
5th lens group	37	700.00

[Focusing Data]

	W	M	T

Lens moving distance	6.840	6.840	6.840
Imaging distance (m)	0.4165	0.3788	0.3972

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 3.341
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.959
	Conditional Expression (3)	f(RP)/f(FP) = 1.321
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.3

It is understood from Table 9 that the variable magnification optical system ZL9 according to Example 9 satisfies Conditional Expressions (1) to (5).
FIG. 26 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL9 according to Example 9, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 27 shows graphs illustrating lateral aberration of the variable magnification optical system ZL9 according to Example 9 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 27.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL9 according to Example 9 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL9 has an excellent imaging performance upon image blur correction.

Example 10

Example 10 will be described with reference to FIGS. 28 to 30 and Table 10. As illustrated in FIG. 28, a variable magnification optical system ZL (ZL10) according to Example 10 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a cemented lens including a positive meniscus lens L12 having a convex surface oriented toward the object side and a biconcave lens L13, and a positive meniscus lens L14 having a convex surface oriented toward the object side. The negative meniscus lens L11 has an aspherical image-side surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a positive meniscus lens L21 having a convex surface oriented toward the object side, a positive meniscus lens L22 having a convex surface oriented toward the object side, a cemented lens including a biconvex lens L23 and a biconcave lens L24, and a biconvex lens L25. The 22nd lens group G22 is constituted by a biconvex lens L26. The positive meniscus lens L22 has an aspherical object-side surface.
The third lens group G3 is constituted by, in order from the object, an aperture stop S, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31 and a positive meniscus lens L32 having a convex surface oriented toward the object side. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L33 and a positive meniscus lens L34 having a convex surface oriented toward the object side. The biconcave lens L33 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a cemented lens including a negative meniscus lens L42 having a concave surface oriented toward the image side and a biconvex lens L43, and a cemented lens including a biconvex lens L44 and a biconcave lens L45. The biconvex lens L41 has an aspherical object-side surface. The biconcave lens L45 has an aspherical image-side surface.
The fifth lens group G5 is constituted by a cemented lens including, in order from an object, a positive meniscus lens L51 having a convex surface oriented toward the object side and a negative meniscus lens L52 having a concave surface oriented toward the image side arranged.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the image side and then moving the same toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The fifth lens group G5 is immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 10, in the wide-angle end state, since the vibration reduction coefficient is −0.50 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.26 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.57 and the focal length is 47.50 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.44 mm. In the telephoto end state, since the vibration reduction coefficient is −0.66 and the focal length is 67.84 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.54 mm.
Table 10 illustrates the values of respective specifications of Example 10. Surface numbers 1 to 38 in Table 10 correspond to optical surfaces of m1 to m38 illustrated in FIG. 28.

TABLE 10

[Lens Specification]

Surface number	R	D	n(d)	νd

1	179.73529	2.880	1.74389	49.5
*2	28.00000	13.314	1.00000
3	−709.59863	2.295	1.80518	25.4
4	−228.05154	2.100	1.76500	49.5
5	90.21469	0.200	1.00000
6	56.00020	4.396	2.00100	29.1
7	96.29881	D7	1.00000
8	96.54068	2.840	1.60300	65.4
9	715.47283	0.200	1.00000
*10	57.08059	3.395	1.69680	55.5
11	181.18928	5.604	1.00000
12	98.04986	3.261	1.59319	67.9
13	−796.91447	1.450	1.76182	26.6
14	41.75300	1.983	1.00000
15	73.03256	3.630	1.74100	52.8
16	−3863.66610	D16	1.00000
17	58.79270	5.010	1.80400	46.6
18	−393.67543	D18	1.00000
19	(Aperture stop)	1.540	1.00000
20	−142.34068	1.200	1.81600	46.6
21	35.05467	1.301	1.00000
22	38.87328	2.715	1.90200	25.3
23	117.88926	D23	1.00000
*24	−118.17706	1.200	1.73231	53.2
25	44.69744	1.030	1.00000
26	52.10387	2.485	1.90200	25.3
27	195.76461	D27	1.00000
*28	71.27465	4.998	1.49782	82.6
29	−102.88416	0.100	1.00000
30	91.68269	1.200	1.90366	31.3
31	52.62629	6.605	1.60300	65.4
32	−69.88439	0.200	1.00000
33	3314.77510	4.235	1.59319	67.9
34	−54.08421	1.200	1.78500	26.2
*35	216.08233	D35	1.00000
36	56.19817	3.548	1.61800	63.3
37	210.95097	1.200	1.83400	37.2
38	84.00000	D38	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−6.73000e−02	2.59588e−06	7.45638e−10	−2.10470e−14	3.51745e−16
10	1.00000e+00	−4.00000e−07	0.00000e+00	0.00000e+00	0.00000e+00
24	−4.10880e+00	5.35515e−07	2.05353e−09	0.00000e+00	0.00000e+00
28	−1.10460e+00	3.84373e−06	−4.29919e−09	3.81283e−12	0.00000e+00
35	1.00000e+00	5.16409e−06	2.00000e−09	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.77	47.50	67.84
FNo	2.90	2.90	2.90
ω	42.2	23.9	17.2
Y	21.60	21.60	21.60
TL	208.124	187.432	190.017
BF	40.315	40.322	40.381
BF (air-conversion length)	40.315	40.322	40.381

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.50	67.84
D7	48.968	12.510	1.800
D16	7.185	7.185	7.185
D18	1.300	17.853	29.355
D23	2.232	2.232	2.232
D27	19.311	9.731	1.900
D35	1.500	10.287	19.851
D38	40.315	40.322	40.381

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−39.97
2nd lens group	8	43.09
21st lens group	8	80.97
22nd lens group	17	63.94
3rd lens group	19	−42.99
31st lens group	19	−77.20
32nd lens group	24	−103.89
4th lens group	28	56.10
5th lens group	36	419.32

[Focusing Data]

	W	M	T

Lens moving distance	6.185	6.185	6.185
Imaging distance (m)	0.4444	0.4101	0.4308

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 4.359
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.736
	Conditional Expression (3)	f(RP)/f(FP) = 1.302
	Conditional Expression (4)	ωt = 17.2
	Conditional Expression (5)	ωw = 42.2

It is understood from Table 10 that the variable magnification optical system ZL10 according to Example 10 satisfies Conditional Expressions (1) to (5).
FIG. 29 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL10 according to Example 10, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 30 shows graphs illustrating lateral aberration of the variable magnification optical system ZL10 according to Example 10 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 30.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL10 according to Example 10 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL10 has an excellent imaging performance upon image blur correction.

Example 11

Example 11 will be described with reference to FIGS. 31 to 33 and Table 11. As illustrated in FIG. 31, a variable magnification optical system ZL (ZL11) according to Example 11 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a cemented lens including a positive meniscus lens L13 having a convex surface oriented toward the object side and a negative meniscus lens L14 having a concave surface oriented toward the image side. The negative meniscus lens L11 has an aspherical image-side surface.
The second lens group G2 is constituted by, in order from the object, a 21st lens group G21 (a focusing lens group) having a positive refractive power and a 22nd lens group G22 having a positive refractive power.
The 21st lens group G21 is constituted by, in order from the object, a positive meniscus lens L21 having a convex surface oriented toward the object side, a positive meniscus lens L22 having a convex surface oriented toward the object side, a negative meniscus lens L23 having a concave surface oriented toward the image side, and a biconvex lens L24. The 22nd lens group G22 is constituted by a cemented lens including, in order from an object, a negative meniscus lens L25 having a concave surface oriented toward the image side and a biconvex lens L26. The positive meniscus lens L22 has an aspherical object-side surface.
The third lens group G3 is constituted by, in order from the object, an aperture stop S, a 31st lens group G31 (an intermediate group) of which the position in the direction orthogonal to the optical axis is immovable and which has negative refractive power and a 32nd lens group G32 (a vibration-reduction lens group) having a negative refractive power.
The 31st lens group G31 is constituted by, in order from the object, a biconcave lens L31 and a positive meniscus lens L32 having a convex surface oriented toward the object side. The 32nd lens group G32 is constituted by, in order from the object, a biconcave lens L33 and a positive meniscus lens L34 having a convex surface oriented toward the object side. The biconcave lens L33 has an aspherical object-side surface.
The fourth lens group G4 is constituted by, in order from the object, a biconvex lens L41, a positive meniscus lens L42 having a convex surface oriented toward the image side, and a cemented lens including a negative meniscus lens L43 having a concave surface oriented toward the image side and a biconvex lens L44. The biconvex lens L44 has an aspherical image-side surface.
The fifth lens group G5 is constituted by a cemented lens including, in order from an object, a positive meniscus lens L51 having a convex surface oriented toward the object side and a negative meniscus lens L52 having a concave surface oriented toward the image side.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the image side and then moving the same toward the object side, and moving the fourth lens group G4 toward the object side such that the distances between the respective lens groups are changed. The fifth lens group G5 is immovable upon varying magnification.
Focusing from an object at infinity to an object at a close distance is performed by moving the 21st lens group G21 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the 32nd lens group G32 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 11, in the wide-angle end state, since the vibration reduction coefficient is −0.54 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.24 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.61 and the focal length is 47.53 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.41 mm. In the telephoto end state, since the vibration reduction coefficient is −0.70 and the focal length is 67.85 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.51 mm.
Table 11 illustrates the values of respective specifications of Example 11. Surface numbers 1 to 37 in Table 11 correspond to optical surfaces of m1 to m37 illustrated in FIG. 31.

TABLE 11

[Lens Specification]

Surface number	R	D	n(d)	νd

1	169.82392	2.880	1.74389	49.5
*2	28.00000	13.823	1.00000
3	−277.92141	2.100	1.69680	55.5
4	89.48130	0.972	1.00000
5	57.53130	5.977	1.90366	31.3
6	288.24720	2.000	1.60311	60.7
7	89.16103	D7	1.00000
8	97.98839	2.906	1.62041	60.3
9	988.16122	0.870	1.00000
*10	52.75776	3.799	1.69680	55.5
11	185.81817	3.941	1.00000
12	244.48174	1.450	1.74077	27.7
13	42.81836	2.225	1.00000
14	81.99098	3.910	1.74100	52.8
15	−359.52152	D15	1.00000
16	56.22525	1.450	1.85000	25.5
17	41.20061	6.609	1.75500	52.3
18	−333.94984	D18	1.00000
19	(Aperture stop)	1.488	1.00000
20	−133.09742	1.200	1.81600	46.6
21	40.80390	0.998	1.00000
22	48.84393	2.545	1.90200	25.3
23	197.19167	D23	1.00000
*24	−159.18908	1.200	1.70000	55.0
25	46.35402	0.845	1.00000
26	47.53111	2.169	1.90200	25.3
27	92.34748	D27	1.00000
28	59.48521	4.431	1.59319	67.9
29	−192.71174	0.100	1.00000
30	−6013.33410	3.364	1.59319	67.9
31	−71.43167	0.200	1.00000
32	5300.14030	1.404	1.90366	31.3
33	31.44019	7.197	1.59319	67.9
*34	−117.32485	D34	1.00000
35	57.67894	3.814	1.70000	56.0
36	263.45851	0.763	1.77250	49.6
37	84.00000	D37	1.00000

[Aspheric Data]

Surface	κ	A4	A6	A8	A10

2	−5.97000e−02	2.62042e−06	7.82559e−10	9.78767e−14	4.33213e−16
10	5.28200e−01	6.32647e−08	1.88164e−10	0.00000e+00	0.00000e+00
24	−6.74850e+00	4.82591e−07	2.86667e−10	0.00000e+00	0.00000e+00
34	−1.67545e+01	1.36811e−06	3.39381e−09	0.00000e+00	0.00000e+00

[Various Data]

	W	M	T

f	24.77	47.53	67.85
FNo	2.90	2.90	2.91
ω	42.2	23.9	17.3
Y	21.60	21.60	21.60
TL	210.949	190.232	192.480
BF	43.417	43.503	43.670
BF (air-conversion length)	43.417	43.503	43.670

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.53	67.85
D7	48.868	12.444	1.800
D15	7.185	7.185	7.185
D18	0.800	16.872	28.207
D23	1.827	1.827	1.827
D27	20.646	10.368	1.900
D34	1.574	11.401	21.260
D37	43.417	43.503	43.670

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−39.52
2nd lens group	8	42.67
21st lens group	8	81.00
22nd lens group	16	66.83
3rd lens group	19	−43.84
31st lens group	19	−83.74
32nd lens group	24	−98.45
4th lens group	28	61.94
5th lens group	35	285.15

[Focusing Data]

	W	M	T

Lens moving distance	6.185	6.185	6.185
Imaging distance (m)	0.4485	0.4038	0.4202

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 3.303
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.771
	Conditional Expression (3)	f(RP)/f(FP) = 1.452
	Conditional Expression (4)	ωt = 17.3
	Conditional Expression (5)	ωw = 42.2

It is understood from Table 11 that the variable magnification optical system ZL11 according to Example 11 satisfies Conditional Expressions (1) to (5).
FIG. 32 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL11 according to Example 11, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 33 shows graphs illustrating lateral aberration of the variable magnification optical system ZL11 according to Example 11 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±15.10 about the image height y=0.0 as illustrated in FIG. 33.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL11 according to Example 11 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL11 has an excellent imaging performance upon image blur correction.

Example 12

Example 12 will be described with reference to FIGS. 34 to 36 and Table 12. As illustrated in FIG. 34, a variable magnification optical system ZL (ZL12) according to Example 12 is constituted by, in order from an object, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a negative refractive power, a sixth lens group G6 having a positive refractive power, and a seventh lens group G7 having a positive refractive power.
The first lens group G1 is constituted by, in order from the object, a negative meniscus lens L11 having a concave surface oriented toward the image side, a biconcave lens L12, and a cemented lens including a positive meniscus lens L13 having a convex surface oriented toward the object side and a negative meniscus lens L14 having a concave surface oriented toward the image side. The negative meniscus lens L11 has an aspherical image-side surface.
The second lens group G2 (focusing lens group) is constituted by a positive meniscus lens L21 having a convex surface oriented toward the object side, a positive meniscus lens L22 having a convex surface oriented toward the object side, a negative meniscus lens L23 having a concave surface oriented toward the image side, and a biconvex lens L24. The positive meniscus lens L22 has an aspherical object-side surface.
The third lens group G3 is constituted by a cemented lens including, in order from an object, a negative meniscus lens L31 having a concave surface oriented toward the image side and a biconvex lens L32.
The fourth lens group G4 (intermediate group) is constituted by, in order from the object, an aperture stop S, a biconcave lens L41, and a positive meniscus lens L42 having a convex surface oriented toward the object side of which the positions in the direction orthogonal to the optical axis are immovable.
The fifth lens group G5 (a vibration-reduction lens group) is constituted by, in order from the object, a biconcave lens L51 and a positive meniscus lens L52 having a convex surface oriented toward the object side. The biconcave lens L51 has an aspherical object-side surface.
The sixth lens group G6 is constituted by, in order from the object, a biconvex lens L61, a positive meniscus lens L62 having a concave surface oriented toward the image side, and a cemented lens including and a negative meniscus lens L63 having a concave surface oriented toward the image side and a biconvex lens L64. The biconcave lens L64 has an aspherical image-side surface.
The seventh lens group G7 is constituted by a cemented lens including, in order from an object, a positive meniscus lens L71 having a convex surface oriented toward the object side and a negative meniscus lens L72 having a concave surface oriented toward the image side.
Varying magnification from the wide-angle end state to the telephoto end state is performed by moving the first lens group G1 toward the image side and then moving the first lens group G1 toward the object side, moving the second lens group G2 toward the object side, moving the third lens group G3 toward the object side, moving the fourth lens group G4 toward the image side and then moving the same toward the object side, moving the fifth lens group G5 toward the image side and then moving the same toward the object side, moving the sixth lens group G6 toward the object side, and moving the seventh lens group G7 toward the object side such that the distances between the respective lens groups are changed.
Focusing from an object at infinity to an object at a close distance is performed by moving the second lens group G2 as a focusing lens group toward the image side.
When image blur occurs, image blur correction (vibration reduction) on the image plane I is performed by moving the fifth lens group G5 as the vibration-reduction lens group VR so as to have a component in the direction orthogonal to the optical axis. In an image capturing lens in which the focal length of an entire system is f and a vibration reduction coefficient (the ratio of an image moving distance on an imaging plane to a moving distance of a moving lens group during blur correction) is K, in order to correct rotation blur of angle θ, the vibration-reduction lens group VR (a moving lens group) for image blur correction may be moved in the direction orthogonal to the optical axis by (f×tan θ)/K.
In Example 12, in the wide-angle end state, since the vibration reduction coefficient is −0.54 and the focal length is 24.77 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.24 mm. In the intermediate focal length state, since the vibration reduction coefficient is −0.61 and the focal length is 47.33 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.41 mm. In the telephoto end state, since the vibration reduction coefficient is −0.72 and the focal length is 67.34 mm, the moving distance of the vibration-reduction lens group VR for correcting the rotation blur of 0.30° is −0.50 mm.
Table 12 illustrates the values of respective specifications of Example 12. Surface numbers 1 to 37 in Table 12 correspond to optical surfaces of m1 to m37 illustrated in FIG. 34.

TABLE 12

[Lens Specification]

[Aspheric Data]

[Various Data]

	W	M	T

f	24.77	47.33	67.34
FNo	2.90	2.90	2.91
ω	42.2	24.0	17.4
Y	21.60	21.60	21.60
TL	210.949	193.610	195.380
BF	43.417	43.433	45.688
BF (air-conversion length)	43.417	43.433	45.688

[Variable Distance Data]

Focusing on infinity

	W	M	T

D0	∞	∞	∞
Magnification	—	—	—
f	24.77	47.33	67.34
D7	48.868	12.444	1.600
D15	7.185	12.000	9.500
D18	0.800	16.872	26.900
D23	1.827	1.827	2.000
D27	20.646	9.000	1.800
D34	1.574	11.401	21.260
D37	43.417	43.433	45.688

[Lens Group Data]

Lens group	Starting surface	Focal length

1st lens group	1	−39.52
2nd lens group	8	81.00
3rd lens group	16	66.83
4th lens group	19	−83.74
5th lens group	24	−98.45
6th lens group	28	61.94
7th lens group	35	285.15

[Focusing Data]

	W	M	T

Lens moving distance	6.185	11.000	8.500
Imaging distance (m)	0.4485	0.2946	0.3494

[Conditional Expression Correspondence Values]

	Conditional Expression (1)	β(Gn)t = 3.516
	Conditional Expression (2)	−f(Gn~G(VR))w/fw = 1.770
	Conditional Expression (3)	f(RP)/f(FP) = 1.452
	Conditional Expression (4)	ωt = 17.4
	Conditional Expression (5)	ωw = 42.2

It is understood from Table 12 that the variable magnification optical system ZL12 according to Example 12 satisfies Conditional Expressions (1) to (5).
FIG. 35 shows graphs illustrating various aberrations (spherical aberration, astigmatism, distortion, magnification chromatic aberration, and lateral aberration) upon focusing on infinity, of the variable magnification optical system ZL12 according to Example 12, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. FIG. 36 shows graphs illustrating lateral aberration of the variable magnification optical system ZL12 according to Example 12 when image blur correction is performed upon focusing on infinity, in which part (a) illustrates the wide-angle end state, part (b) illustrates the intermediate focal length state, and part (c) illustrates the telephoto end state. In this example, the optical performance during vibration reduction is illustrated as a lateral aberration graph corresponding to an image height of ±27.10 about the image height y=0.0 as illustrated in FIG. 36.
As is obvious from respective aberration graphs, it is understood that the variable magnification optical system ZL12 according to Example 12 has a satisfactory optical performance such that aberrations are satisfactorily corrected in states ranging from the wide-angle end state to the telephoto end state. Moreover, it is understood that the variable magnification optical system ZL12 has an excellent imaging performance upon image blur correction.
According to the above-described examples, it is possible to implement a variable magnification optical system which has a F-value as bright as approximately F2.8 to F3.5 and a wide angle of view of approximately 50° or more in terms of a half-angle of view, and in which aberrations are corrected satisfactorily.
While the present invention has been described by assigning reference numerals to elements of the embodiment for better understanding of the present invention, the aspect of the present invention is not limited to this. The following content can be appropriately employed within a range where the optical performance of the variable magnification optical system is not diminished.
Although the numbered examples of a four-group configuration, a five-group configuration, and a seven-group configuration have been illustrated as numbered examples of the variable magnification optical system ZL, the present invention is not limited to these and can be applied to other group configurations (for example, a six-group configuration, an eight-group configuration, or the like). Specifically, a configuration in which a lens or a lens group is added at a side closest to the object and a configuration in which a lens or a lens group is added at a side closest to the image may be employed. A lens group having positive or negative refractive power may be added between the first lens group and the second lens group. Furthermore, a lens group which has negative or positive refractive power and of which the position in the direction orthogonal to the optical axis is immovable may be added at an image-plane-side of the vibration-reduction lens group VR (in this case, the distance between the vibration-reduction lens group VR and the lens group which has negative or positive refractive power and of which the position in the direction orthogonal to the optical axis is immovable may be changed or not) upon varying magnification. Moreover, although the fourth lens group G4 in Examples 1 to 3, 5, and 7 to 11 and the sixth lens group G6 in Examples 4, 6, and 12 have been illustrated as an example of the image-side lens group RP having the strongest positive refractive power among the lens groups having a positive refractive power arranged closer to the image side than the vibration-reduction lens group VR, the present invention is not limited to this. The distance between lenses included in the image-side lens group RP may be fixed upon varying magnification. A lens group refers to a portion having at least one lens isolated by air space which changes upon varying magnification or focusing.
The intermediate group is a lens group which is disposed closer to the image side than the second lens group and is disposed at an object-side of the vibration-reduction lens group at a position to face the vibration-reduction lens group. The aperture stop may be disposed at an object-side of the intermediate group at a position to face the intermediate group.
Moreover, as for lenses that form the intermediate group, the positions in the optical axis direction upon varying magnification may be changed integrally, and the lenses may be grouped into two or more lens groups, and the distance between the lens groups may be changed upon varying magnification.
At least a portion of the lenses of the intermediate group may be moved (or fixed) in the optical axis direction integrally with the vibration-reduction lens group upon varying magnification.
In the variable magnification optical system ZL, a portion of a lens group, an entire lens group, or a plurality of lens groups may be moved in the optical axis direction as a focusing lens group in order to perform focusing from an object at infinity to an object at a close distance. Moreover, such a focusing lens group can be applied to autofocus and is also suitable for driving based on an autofocus motor (for example, an ultrasonic motor or the like). Particularly, it is preferable to use at least a portion of the second lens group G2 as the focusing lens group described above.
In the variable magnification optical system ZL, an entire arbitrary lens group or a partial lens group may be moved so as to have a component in the direction vertical to the optical axis or may be rotated (oscillated) in an in-plane direction including the optical axis so as to function as a vibration-reduction lens group VR that corrects image blur occurring due to camera shake or the like. Particularly, it is preferable that at least a portion of an optical system disposed closer to the image side than the intermediate group Gn which is disposed closer to the image side than the aperture stop S and has negative refractive power is used as the vibration-reduction lens group VR. Moreover, in the case of a four- or five-group configuration, it is preferable that at least a portion of the third lens group G3 is used as the vibration-reduction lens group VR. Moreover, in the case of a seven-group configuration, it is preferable that at least a portion of the fifth lens group G5 is used as the vibration-reduction lens group VR. Furthermore, a lens of which the position in the direction orthogonal to the optical axis is fixed may be disposed at an image-side of the vibration-reduction lens group VR, and the lens may be moved or fixed upon varying magnification integrally with the vibration-reduction lens group VR.
In the variable magnification optical system ZL, the lens surface may be formed as a spherical surface or a flat surface and may be formed as an aspherical surface. When the lens surface is a spherical surface or a flat surface, it is possible to facilitate lens processing, assembly, and adjustment and to prevent deterioration of optical performance resulting from errors in the processing, assembly and adjustment. Moreover, deterioration of the rendering performance is little even when the image plane is shifted. When the lens surface is an aspherical surface, the aspherical surface may be an aspherical surface obtained by grinding, a glass-molded aspherical surface obtained by molding glass into an aspherical surface, or a composite aspherical surface obtained by forming a resin on the surface of glass into an aspherical shape. Moreover, the lens surface may be a diffraction surface and may be a refractive index distributed lens (a GRIN lens) or a plastic lens.
In the variable magnification optical system ZL, it is preferable that an aspherical surface is formed on a lens formed of a medium in which the refractive index nd for the d-line is smaller than 70. The lens formed of a medium in which the refractive index nd for the d-line is smaller than 70 is preferably disposed in a lens group having the strongest positive refractive power among the lens groups disposed closer to the image side than the vibration-reduction lens group VR. Moreover, the lens formed of a medium in which the refractive index nd for the d-line is smaller than 70 is more preferably disposed in a lens component disposed closest or the next closest to an object, of the lens group having the strongest positive refractive power among the lens groups disposed closer to the image side than the vibration-reduction lens group VR. Furthermore, an aspherical surface of the lens formed of a medium in which the refractive index nd for the d-line is smaller than 70 is more preferably a surface located closest to the object plane, of the lens group having the strongest positive refractive power among the lens groups disposed closer to the image side than the vibration-reduction lens group VR.
In the variable magnification optical system ZL, it is preferable that the aperture stop S is disposed between the second lens group and the intermediate group Gn as described above. However, the role of the aperture stop may be substituted by the frame of a lens without providing a separate member as the aperture stop.
In the variable magnification optical system ZL, each lens surface may be coated with an anti-reflection film which has high transmittance in a wide wavelength region in order to decrease flare and ghosting and achieve satisfactory optical performance with high contrast.
The variable magnification ratio of the variable magnification optical system ZL is approximately between 2.0 and 3.5.

EXPLANATION OF NUMERALS AND CHARACTERS

- ZL (ZL1 to ZL13) Variable magnification optical system
- G1 First lens group
- G2 Second lens group
- G3 Third lens group
- G4 Fourth lens group
- VR Vibration-reduction lens group
- S Aperture stop
- I Image plane
- 1 Camera (Optical apparatus)

Claims

1-9. (canceled)

10. A variable magnification optical system comprising:

a first lens group having a negative refractive power;

a second lens group having a positive refractive power and disposed closer to an image side than the first lens group; and

an intermediate lens group and an image side lens group, both disposed closer to the image side than the second lens group,

wherein the system performs varying magnification by changing at least a distance between the first lens group and the second lens group and a distance between the second lens group and the intermediate lens group, and

the system satisfies the following conditional expression:

1.500<β(Gn)t<100.000

where

β(Gn)t: an imaging magnification of the intermediate lens group in a telephoto end state.

11. The variable magnification optical system according to claim 10, wherein

the image side lens group has a positive refractive power.

12. The variable magnification optical system according to claim 10, wherein

the image side lens group has the strongest positive refractive power among lens groups which are disposed closer to the image side than the intermediate lens group and have positive refractive power.

13. The variable magnification optical system according to claim 10, wherein

the system satisfies the following conditional expression:

0.400<f(RP)/f(FP)<2.000

where

f(RP): a focal length of the image-side lens group, and

f(FP): a composite focal length in a wide-angle end state, of lenses disposed closer to an image plane than the first lens group and disposed closer to an object side than the intermediate lens group.

14. The variable magnification optical system according to claim 10, wherein

the intermediate lens group has negative refractive power, and a position of the intermediate lens group in a direction orthogonal to an optical axis is fixed.

15. The variable magnification optical system according to claim 10, wherein

the intermediate lens group has one or more positive lens components and one or more negative lens components.

16. The variable magnification optical system according to claim 10, wherein

the second lens group includes at least four lens components.

17. The variable magnification optical system according to claim 10, wherein

the second lens group is constituted by, in order from an object side, a 2-1st lens group having a positive refractive power and a 2-2nd lens group having a positive refractive power, and

the 2-1st lens group is moved toward the image side as a focusing lens group to perform focusing from an object at infinity to an object at a close distance.

18. The variable magnification optical system according to claim 10, including:

a third lens group disposed adjacent to an image side of the second lens group and having a negative refractive power, wherein

upon varying magnification, a distance between the second lens group and the third lens group is changed.

19. The variable magnification optical system according to claim 18, wherein

the intermediate lens group is disposed closest to an object side in the third lens group.

20. The variable magnification optical system according to claim 18, wherein

an aperture stop is disposed between the second lens group and the third lens group.

21. The variable magnification optical system according to claim 10, including:

a third lens group disposed between the second lens group and the intermediate lens group and having a positive refractive power.

22. The variable magnification optical system according to claim 21, wherein

third lens group has only one lens component.

23. The variable magnification optical system according to claim 21, wherein

an aperture stop is disposed between the third lens group and the intermediate lens group.

24. The variable magnification optical system according to claim 10, including:

a vibration-reduction lens group disposed closer to the image side than the intermediate lens group and configured to be movable so as to have a movement component in a direction orthogonal to an optical axis, wherein

the system satisfies the following conditional expression:

1.360<−f(Gn˜G(VR))w/fw<5.000

where

f(Gn˜G(VR))w: a composite focal length from the intermediate lens group to the vibration-reduction lens group in a wide-angle end state, and

fw: a focal length of the system in the wide-angle end state.

25. An optical apparatus having the variable magnification optical system of claim 10 mounted thereon.

26. A method for manufacturing a variable magnification optical system,

the variable magnification optical system comprising:

a first lens group having a negative refractive power;

an intermediate lens group and an image side lens group both disposed closer to the image side than the second lens group, and

the method comprising:

arranging the lens groups in a lens barrel such that the system performs varying magnification by changing at least a distance between the first lens group and the second lens group and a distance between the second lens group and the intermediate lens group, and

satisfying the following conditional expression:

1.500<β(Gn)t<100.000

where