JP2010170062A - Zoom lens system, image capturing apparatus, and method of manufacturing the zoom lens system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens system or the like that includes a lens shifted to include a component in a direction perpendicular to an optical axis, and has a high variable power ratio and superior optical performance. <P>SOLUTION: The zoom lens system includes, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, and a fourth lens group G4 having positive refractive power. The third lens group G3 includes a cemented negative lens. When the zoom lens system varies power from a wide angle end state W to a telephoto end state T, spaces between the respective lens groups G1, G2, G3 and G4 change, and at least part of the third lens group G3 is shifted to include the component in the direction perpendicular to the optical axis, and the zoom lens system satisfies a prescribed conditional expression. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

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

JP-A-11-231220

  However, the conventional zooming optical system has a problem that the zooming ratio is small and the demand for high zooming cannot be fully satisfied.

  Therefore, the present invention has been made in view of the above problems, and has a lens that shifts to include a component in a direction orthogonal to the optical axis, and has a high zoom ratio and good optical performance. It is an object of the present invention to provide a manufacturing method of a system, an imaging device, and a variable magnification optical system.

In order to solve the above problems, the present invention
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power And having a group
The third lens group includes a cemented negative lens;
When zooming from the wide-angle end state to the telephoto end state, the distance between the lens groups changes,
Shifting so that at least a part of the third lens group includes a component in a direction orthogonal to the optical axis;
Provided is a variable magnification optical system characterized by satisfying the following conditional expressions (1) and (2).
(1) 0.60 <| f1 | / √ (fw · ft) <0.78
(2) 1.80 <f3 / f1 <2.50
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group fw: Focal length of the zooming optical system in the wide-angle end state ft: Focal length of the zooming optical system in the telephoto end state

The present invention also provides
An imaging apparatus comprising the variable magnification optical system is provided.

The present invention also provides
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power A variable magnification optical system having a group,
A cemented negative lens is disposed in the third lens group;
Each lens group of the variable magnification optical system satisfies the following conditional expressions (1) and (2),
When changing the magnification from the wide-angle end state to the telephoto end state, the interval between the lens groups can be changed.
Provided is a variable magnification optical system manufacturing method characterized in that at least a part of the third lens group can be shifted so as to include a component in a direction orthogonal to the optical axis.
(1) 0.60 <| f1 | / √ (fw · ft) <0.78
(2) 1.80 <f3 / f1 <2.50
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group fw: Focal length of the zooming optical system in the wide-angle end state ft: Focal length of the zooming optical system in the telephoto end state

  According to the present invention, a variable power optical system, an image pickup apparatus, and a variable power optical system having a lens that shifts so as to include a component in a direction orthogonal to the optical axis and having a high zoom ratio and good optical performance. A manufacturing method can be provided.

It is a lens sectional view in the wide angle end state of the variable magnification optical system concerning the 1st example of this application. (A) And (b) is the aberration diagram in the wide-angle end state of the variable magnification optical system which concerns on 1st Example of this application, and the coma aberration figure at the time of a shift. FIG. 6 is a diagram illustrating various aberrations in the intermediate focal length state of the variable magnification optical system according to the first example of the present application. (A) And (b) is the aberration diagram in the telephoto end state of the variable magnification optical system which concerns on 1st Example of this application, and the coma aberration figure at the time of a shift. It is a lens sectional view in the wide-angle end state of the variable magnification optical system concerning the 2nd example of this application. (A) And (b) is the various aberration figure in the wide angle end state of the variable magnification optical system which concerns on 2nd Example of this application, and the coma aberration figure at the time of a shift. It is an aberration diagram in the intermediate focal length state of the variable magnification optical system according to the second example of the present application. (A) And (b) is the aberration diagram in the telephoto end state of the variable magnification optical system which concerns on 2nd Example of this application, and the coma aberration figure at the time of a shift. It is a lens sectional view in the wide-angle end state of a variable magnification optical system concerning the 3rd example of this application. (A) And (b) is the aberration diagram in the wide-angle end state of the variable magnification optical system which concerns on 3rd Example of this application, and the coma aberration figure at the time of a shift. It is an aberration diagram in the intermediate focal length state of the variable magnification optical system according to the third example of the present application. (A) And (b) is the aberration diagram in the telephoto end state of the variable magnification optical system which concerns on 3rd Example of this application, and the coma aberration figure at the time of a shift. It is lens sectional drawing in the wide-angle end state of the variable magnification optical system which concerns on 4th Example of this application. (A) And (b) is the aberration diagram in the wide angle end state of the variable magnification optical system which concerns on 4th Example of this application, and the coma aberration figure at the time of a shift. It is various aberrational figures in the intermediate focal length state of the variable magnification optical system which concerns on 4th Example of this application. (A) And (b) is the various aberration figure in the telephoto end state of the variable magnification optical system which concerns on 4th Example of this application, and the coma aberration figure at the time of a shift. It is a figure which shows the structure of the camera provided with the variable magnification optical system of this application. It is a figure which shows the manufacturing method of the variable magnification optical system of this application.

Hereinafter, a variable magnification optical system, an imaging apparatus, and a method for manufacturing the variable magnification optical system of the present application will be described.
The variable magnification optical system of the present application includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, A fourth lens group having a refractive power of 5 mm, and the third lens group has a cemented negative lens, and when performing zooming from the wide-angle end state to the telephoto end state, the distance between the lens groups is Is changed, and at least a part of the third lens group is shifted to include a component in a direction orthogonal to the optical axis, and the following conditional expressions (1) and (2) are satisfied.
(1) 0.60 <| f1 | / √ (fw · ft) <0.78
(2) 1.80 <f3 / f1 <2.50
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group fw: Focal length of the zooming optical system in the wide-angle end state ft: Focal length of the zooming optical system in the telephoto end state

Conditional expression (1) sets the refractive power of the first lens group, and the variable power optical system of the present application can thereby maintain good optical performance.
If the lower limit value of conditional expression (1) is not reached, the refractive power of the first lens group becomes too large and spherical aberration cannot be corrected well. In addition, if the lower limit of conditional expression (1) is set to 0.65, the effect of the present invention can be exhibited more.
On the other hand, if the upper limit value of conditional expression (1) is exceeded, the refractive power of the first lens group becomes too small, and high zoom ratio cannot be realized. In addition, if the upper limit of conditional expression (1) is set to 0.76, the effect of this invention can be exhibited more.

Conditional expression (2) sets the refractive power of the first lens group and the third lens group. Accordingly, when the cemented negative lens in the third lens group is shifted so as to include a component in a direction orthogonal to the optical axis while effectively securing a predetermined zoom ratio and ensuring good optical performance ( Hereinafter, it is also simply referred to as “at the time of shift”), and good optical performance is realized.
If the lower limit value of conditional expression (2) is not reached, the refractive power of the first lens group becomes too large, and the spherical aberration fluctuation at the time of zooming cannot be corrected well. In addition, if the lower limit of conditional expression (2) is set to 1.82, the effect of the present invention can be exhibited more.

On the other hand, if the upper limit of conditional expression (2) is exceeded, the refractive power of the first lens group becomes too small, and a high zoom ratio cannot be realized. In addition, if the upper limit of conditional expression (2) is set to 2.20, the effect of this invention can be exhibited more.
In the variable magnification optical system of the present application, the third lens group has a cemented negative lens, so that the chromatic aberration at the time of shifting can be kept good.
Further, by shifting the cemented negative lens in the third lens group so as to include a component in a direction orthogonal to the optical axis, it is possible to perform image plane correction when image blur due to vibration occurs.
With the above configuration, a variable power optical system having a high variable power ratio and good optical performance can be realized.

In the variable magnification optical system of the present application, it is desirable that the first lens group has at least two lenses that satisfy the following conditional expression (3).
(3) 1.750 <n1 <2.500
However,
n1: Refractive index of the lens in the first lens group with respect to d-line (wavelength λ = 587.6 nm)

Conditional expression (3) sets the refracting power of the lenses in the first lens group, whereby the variable magnification optical system of the present application can maintain good optical performance.
If the lower limit of conditional expression (3) is not reached, the radius of curvature of each lens in the first lens group becomes small, and spherical aberration, field curvature aberration, and coma aberration cannot be corrected well. In addition, if the lower limit of conditional expression (3) is set to 1.770, the effect of the present invention can be exhibited more. Moreover, if the lower limit value of conditional expression (3) is set to 1.785, the effect of the present invention can be exhibited more.
On the other hand, if the value exceeds the upper limit value of conditional expression (3), the transmittance of short-wavelength light in the visible range is lowered and coloring is not preferable. In addition, if the upper limit of conditional expression (3) is set to 2.250, the effect of this invention can be exhibited more. Moreover, if the upper limit of conditional expression (3) is set to 2.150, the effect of this invention can be exhibited more. Furthermore, if the upper limit value of conditional expression (3) is set to 2.000, the effect of the present invention can be exhibited more.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (4).
(4) 0.50 <(Dt−Dw) / fw <1.50
However,
Dt: Distance on the optical axis from the most object side lens surface in the zoom optical system to the image plane in the telephoto end state Dw: Image from the lens surface closest to the object in the zoom optical system in the wide angle end state Distance fw on the optical axis to the surface: focal length of the variable magnification optical system in the wide-angle end state

Conditional expression (4) sets the distance from the lens surface closest to the object side to the image plane in the variable magnification optical system of the present application, thereby increasing the zoom ratio while ensuring good optical performance. Can be realized.
If the lower limit of conditional expression (4) is not reached, it becomes impossible to satisfactorily correct the field curvature aberration during zooming. In addition, if the lower limit of conditional expression (4) is set to 0.70, the effect of the present invention can be exhibited more.
On the other hand, if the upper limit of conditional expression (4) is exceeded, the total length of the variable magnification optical system of the present application in the telephoto end state becomes too large. In addition, if the upper limit of conditional expression (4) is set to 1.30, the effect of this invention can be exhibited more.

Further, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (5).
(5) 0.60 <(Dt−Dw) / Ymax <1.60
However,
Dt: Distance on the optical axis from the lens surface closest to the object side in the variable magnification optical system in the telephoto end state to the image plane Dw: Image from the lens surface closest to the object in the variable magnification optical system in the wide angle end state Distance on the optical axis to the surface Ymax: Maximum image height

Conditional expression (5) sets the distance from the lens surface closest to the object side to the image plane in the variable magnification optical system of the present application, thereby achieving a high zoom ratio while ensuring good optical performance. Can be realized.
If the lower limit value of conditional expression (5) is not reached, it becomes impossible to satisfactorily correct the field curvature aberration at the time of zooming. In addition, if the lower limit of conditional expression (5) is set to 0.80, the effect of the present invention can be exhibited more.
On the other hand, if the upper limit value of conditional expression (5) is exceeded, the total length of the variable magnification optical system of the present application in the telephoto end state becomes too large. In addition, if the upper limit of conditional expression (5) is set to 1.40, the effect of this invention can be exhibited more.

Further, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (6).
(6) 400 <| RA · f1 | <1300
However,
RA: radius of curvature of the lens surface closest to the object side in the variable magnification optical system f1: focal length of the first lens unit

Conditional expression (6) sets the radius of curvature of the lens surface closest to the object side in the variable magnification optical system of the present application and the focal length of the first lens group, thereby maintaining good optical performance. .
If the lower limit of conditional expression (6) is not reached, the radius of curvature of the lens surface closest to the object will be too small, or the refractive power of the first lens group will be too large, so that the field curvature fluctuation during zooming will be good. It will not be possible to correct it. In addition, if the lower limit of conditional expression (6) is set to 550, the effect of the present invention can be exhibited more.

  If the upper limit of conditional expression (6) is exceeded, the radius of curvature of the lens surface closest to the object side becomes too large, or the refractive power of the first lens group becomes too small, so that coma cannot be corrected well. Or, it becomes impossible to realize a high zoom ratio. In addition, if the upper limit of conditional expression (6) is set to 1100, the effect of this invention can be exhibited more.

In the variable magnification optical system of the present application, it is desirable that the first lens group has a negative lens closest to the object side and satisfies the following conditional expression (7).
(7) 1.40 <f11 / f1 <2.10
However,
f1: focal length of the first lens group f11: focal length of the negative lens in the first lens group

Conditional expression (7) sets the focal length of the negative lens closest to the object side in the first lens group and the focal length of the first lens group, thereby maintaining good optical performance.
If the lower limit value of conditional expression (7) is not reached, the refractive power of the most object-side negative lens in the first lens group becomes too large, so that coma cannot be corrected well. In addition, if the lower limit of conditional expression (7) is set to 1.50, the effect of this invention can be exhibited more.
If the upper limit of conditional expression (7) is exceeded, the refractive power of the most object-side negative lens in the first lens group becomes too small, and the lens outer diameter becomes large. In addition, the spherical aberration cannot be corrected satisfactorily. In addition, if the upper limit of conditional expression (7) is set to 2.00, the effect of this invention can be exhibited more.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (8).
(8) 1.00 <f4 / f2 <2.00
However,
f2: focal length of the second lens group f4: focal length of the fourth lens group

Conditional expression (8) sets the refractive powers of the second lens group and the fourth lens group, and this makes it possible to achieve good optical performance even during shifting while ensuring good optical performance. .
If the lower limit value of conditional expression (8) is not reached, the refractive power of the fourth lens group becomes too large, and the coma aberration at the time of shifting is deteriorated. In addition, if the lower limit of conditional expression (8) is set to 1.20, the effect of the present invention can be exhibited more.
On the other hand, if the upper limit value of conditional expression (8) is exceeded, the refractive power of the fourth lens group becomes too small, and the coma aberration during shifting deteriorates. In addition, if the upper limit of conditional expression (8) is set to 1.80, the effect of this invention can be exhibited more.

Further, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (9).
(9) 0.80 <f4 / (− f3) <1.30
However,
f3: focal length of the third lens group f4: focal length of the fourth lens group

Conditional expression (9) sets the refractive powers of the third lens group and the fourth lens group, and this makes it possible to achieve good optical performance even during shifting while ensuring good optical performance. .
If the lower limit value of conditional expression (9) is not reached, the refractive power of the fourth lens group becomes too large, and the coma aberration at the time of shifting deteriorates. In addition, if the lower limit of conditional expression (9) is set to 0.90, the effect of the present invention can be exhibited more.
On the other hand, if the upper limit value of conditional expression (9) is exceeded, the refractive power of the fourth lens group becomes too small and the coma aberration at the time of shifting deteriorates. In addition, if the upper limit of conditional expression (9) is set to 1.20, the effect of this invention can be exhibited more.

Further, it is desirable that the variable magnification optical system of the present application has an aperture stop between the second lens group and the fourth lens group.
With this configuration, the variable magnification optical system of the present application can correct coma aberration outside the optical axis at the time of zooming, and can realize good optical performance.

In the zoom optical system according to the present application, it is preferable that the first lens group includes at least two negative lenses and at least one positive lens.
With this configuration, the variable magnification optical system of the present application can satisfactorily correct variations in chromatic aberration outside the optical axis at the time of zooming.

In the variable magnification optical system of the present application, it is desirable that the first lens group has an aspheric lens.
With this configuration, distortion can be favorably corrected in the variable magnification optical system of the present application.

In the zoom optical system of the present application, it is desirable that the second lens group and the fourth lens group move together when zooming from the wide-angle end state to the telephoto end state.
With this configuration, it is possible to satisfactorily correct curvature of field aberration during zooming in the zooming optical system of the present application.

In the zoom optical system of the present application, when zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group and the third lens group is increased, and the third lens group and the third lens group are increased. It is desirable that the distance between the four lens groups is reduced.
With this configuration, in the variable magnification optical system of the present application, the diameter of the first lens group can be reduced, and a high zoom ratio can be easily achieved. In addition, spherical aberration can be corrected well in the telephoto end state.

The imaging apparatus of the present application includes the variable magnification optical system having the above-described configuration.
Thereby, it is possible to realize an imaging apparatus having a lens that shifts so as to include a component in a direction orthogonal to the optical axis and having a high zoom ratio and good optical performance.

Further, according to the manufacturing method of the variable magnification optical system of the present application, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power. And a fourth lens group having a positive refractive power, a variable magnification optical system, wherein a cemented negative lens is disposed in the third lens group, and each lens group of the variable magnification optical system includes: The following conditional expressions (1) and (2) are satisfied, and when changing magnification from the wide-angle end state to the telephoto end state, the interval between the lens groups can be changed, and at least the third lens group It is possible to shift so that a part includes a component in a direction orthogonal to the optical axis.
(1) 0.60 <| f1 | / √ (fw · ft) <0.78
(2) 1.80 <f3 / f1 <2.50
However,
f1: focal length of the first lens group f3: focal length of the third lens group fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state A zooming optical system having a lens that shifts so as to include a component in a direction orthogonal to the optical axis and having a high zooming ratio and good optical performance can be manufactured.

Hereinafter, a variable magnification optical system according to numerical examples of the present application will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a lens cross-sectional view in the wide-angle end state of the variable magnification optical system according to the first example of the present application.
The variable magnification optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens having a negative refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed by providing a resin layer on the glass lens surface on the image plane I side.
The second lens group G2 includes, in order from the object side, a cemented lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, and a positive meniscus lens L23 having a convex surface facing the object side. Become.

The third lens group G3 is composed of, in order from the object side, a cemented negative lens of a positive meniscus lens L31 having a concave surface directed toward the object side and a biconcave negative lens L32.
The fourth lens group G4 includes, in order from the object side, a planoconvex positive lens L41 having a convex surface directed toward the image plane I, a biconvex positive lens L42, and a negative meniscus lens having a convex surface directed toward the image plane I. It consists of a cemented lens with L43.

In the zoom optical system according to the present embodiment, an aperture stop S is disposed between the second lens group G2 and the third lens group G3, and the third lens is used for zooming from the wide-angle end state to the telephoto end state. Move together with the group G3.
In the zoom optical system according to the present embodiment, when zooming is performed from the wide-angle end state to the telephoto end state, the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 and The first lens group G1 is moved to the object side after moving to the image plane I side so that the distance from the fourth lens group G4 is reduced. The second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis along the optical axis. At this time, the second lens group G2 and the fourth lens group G4 move together.
In the variable magnification optical system according to this example, the cemented negative lens in the third lens group G3 is shifted so as to include a component in a direction orthogonal to the optical axis.

Table 1 below lists values of specifications of the variable magnification optical system according to the first example of the present application.
In Table 1, f indicates the focal length, and BF indicates the back focus.
In [Surface data], the surface number is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, nd is the refractive index with respect to the d-line (wavelength λ = 587.6 nm), νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm). Further, the object plane indicates the object plane, the variable indicates the variable plane spacing, the (aperture S) indicates the aperture stop S, and the image plane indicates the image plane I. Note that “∞” of the radius of curvature r indicates a plane, and the description of the refractive index of air nd = 1.0000 is omitted. When the lens surface is an aspheric surface, the surface number is marked with * and the paraxial radius of curvature is shown in the column of the radius of curvature r.

[Aspherical data] shows the aspherical coefficient when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
x = (h ² / r) / [1+ {1−K (h / r) ² } ^1/2 ]
+ A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰
Here, x is a distance (sag amount) along the optical axis direction from the tangent plane of each aspherical surface at a height h in the vertical direction from the optical axis, K is a conic constant, and A4, A6, A8, and A10 are non- The spherical coefficient r is defined as the radius of curvature of the reference spherical surface (paraxial radius of curvature). “E−n” (n: integer) represents “× 10 ⁻ⁿ ”, for example “1.234E-05” represents “1.234 × 10 ⁻⁵ ”.

  In [various data], FNO is the F number, 2ω is the angle of view, Y is the image height, TL is the total length of the optical system, and di (i: integer) is the variable surface interval of the i-th surface. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.

Here, “mm” is generally used as a unit of the focal length f, the radius of curvature r, and other lengths listed in Table 1. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.
In addition, the code | symbol of Table 1 described above shall be similarly used also in the table | surface of each Example mentioned later.

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞
1) 33.333 1.90 1.79500 45.30
2) 16.100 0.17 1.55389 38.09
* 3) 13.600 10.60
4) -102.031 1.50 1.72916 54.66
5) 27.621 2.30
6) 28.541 3.45 1.84666 23.78
7) 82.554 variable
8) 27.300 0.90 1.80518 25.43
9) 15.551 4.60 1.51823 58.89
10) -37.422 0.10
11) 25.246 2.45 1.51823 58.89
12) 55.309 Variable
13) (Aperture S) ∞ 2.90
14) -32.302 2.75 1.85026 32.35
15) -11.682 0.80 1.77250 49.61
16) 161.664 Variable
17) ∞ 3.00 1.51823 58.89
18) -23.681 0.10
19) 114.651 5.00 1.49782 82.56
20) -16.345 1.00 1.85026 32.35
21) -46.453 BF
Image plane ∞

[Aspherical data]
Third side K = 1
A4 = 2.54910E-05
A6 = 5.94080E-08
A8 = -1.06500E-10
A10 = 7.27750E-13

[Various data]
Zoom ratio 3.22
W M T
f 16.5 32.8 53.3
FNO 3.5 4.8 6.0
2ω 84.4 47.2 29.9
Y 14.25 14.25 14.25
TL 130.18 128.00 147.05
BF 38.29 57.79 84.31

d7 31.23 9.55 2.07
d12 1.61 7.22 11.15
d16 15.53 9.92 5.99

[Lens group data]
Group start surface f
1 1 -21.64
2 8 27.99
3 13 -40.96
4 17 43.13

[Conditional expression values]
(1) | f1 | / √ (fw · ft) = 0.729
(2) f3 / f1 = 1.89
(3) n1 = 1.79500, 1.84666
(4) (Dt−Dw) /fw=1.02
(5) (Dt−Dw) /Ymax=1.18
(6) | RA · f1 | = 721
(7) f11 / f1 = 1.52
(8) f4 / f2 = 1.54
(9) f4 / (− f3) = 1.05

  FIGS. 2A and 2B are diagrams showing various aberrations in the wide-angle end state of the zoom optical system according to the first example of the present application and a coma aberration diagram at the time of shift. FIG. 3 is a diagram illustrating various aberrations in the intermediate focal length state of the variable magnification optical system according to the first example of the present application. FIGS. 4A and 4B are graphs showing various aberrations in the telephoto end state of the variable magnification optical system according to Example 1 of the present application and coma aberration during shift.

2 to 4, FNO indicates an F number, and A indicates a half angle of view. The spherical aberration diagram shows the F-number value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum half field angle, and the coma diagram shows the half field value. D represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane.
Note that the same reference numerals as in this example are also used in the aberration diagrams of the examples shown below.

  2 to 4, the variable magnification optical system according to the present example has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent during shifting. It can be seen that it has imaging performance.

(Second embodiment)
FIG. 5 is a lens cross-sectional view in the wide-angle end state of the variable magnification optical system according to the second example of the present application.
The variable magnification optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens having a negative refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface directed toward the object side, a biconcave negative lens L12, a negative meniscus lens L13 having a convex surface directed toward the object side, and an object side. And a positive meniscus lens L14 having a convex surface. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed by providing a resin layer on the glass lens surface on the image plane I side.
The second lens group G2 includes, in order from the object side, a cemented lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, and a positive meniscus lens L23 having a convex surface facing the object side. Become.
The third lens group G3 is composed of, in order from the object side, a cemented negative lens of a positive meniscus lens L31 having a concave surface directed toward the object side and a biconcave negative lens L32.
The fourth lens group G4 includes, in order from the object side, a planoconvex positive lens L41 having a convex surface directed toward the image plane I, a biconvex positive lens L42, and a negative meniscus lens having a convex surface directed toward the image plane I. It consists of a cemented lens with L43.

In the zoom optical system according to the present embodiment, an aperture stop S is disposed between the second lens group G2 and the third lens group G3, and the third lens is used for zooming from the wide-angle end state to the telephoto end state. Move together with the group G3.
In the zoom optical system according to the present embodiment, when zooming is performed from the wide-angle end state to the telephoto end state, the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 and The first lens group G1 is moved to the object side after moving to the image plane I side so that the distance from the fourth lens group G4 is reduced. The second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis along the optical axis. At this time, the second lens group G2 and the fourth lens group G4 move together.
In the variable magnification optical system according to this example, the cemented negative lens in the third lens group G3 is shifted so as to include a component in a direction orthogonal to the optical axis.
Table 2 below lists values of specifications of the variable magnification optical system according to the second example of the present application.

(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞
1) 40.043 1.90 1.51680 64.12
2) 16.100 0.17 1.55389 38.09
* 3) 13.900 11.00
4) -114.885 1.40 1.80400 46.58
5) 32.203 3.00
6) 123.629 1.28 1.80400 46.58
7) 45.051 0.10
8) 32.378 3.50 1.80518 25.43
9) 838.071 variable
10) 31.539 0.90 1.75520 27.51
11) 16.577 4.30 1.51680 64.12
12) -44.059 2.16
13) 21.883 2.10 1.51823 58.89
14) 52.902 Variable
15) (Aperture S) ∞ 2.90
16) -36.742 2.75 1.85026 32.35
17) -12.426 0.80 1.77250 49.61
18) 104.520 variable
19) ∞ 2.75 1.48749 70.45
20) -23.444 0.10
21) 116.161 5.26 1.49782 82.56
22) -15.151 1.00 1.80 100 34.96
23) -41.509 BF
Image plane ∞

[Aspherical data]
Third side K = 1
A4 = 2.65560E-05
A6 = 5.94080E-08
A8 = -1.00010E-10
A10 = 9.63140E-13

[Various data]
Zoom ratio 3.24
W M T
f 16.5 32.6 53.3
FNO 3.7 4.8 5.9
2ω 84.6 47.4 29.9
Y 14.25 14.25 14.25
TL 130.85 128.70 148.00
BF 38.56 57.90 84.68

d9 29.65 8.16 0.69
d14 1.69 7.40 11.23
d18 13.58 7.87 4.04

[Lens group data]
Group start surface f
1 1 -21.90
2 10 29.17
3 15 -41.04
4 19 41.07

[Conditional expression values]
(1) | f1 | / √ (fw · ft) = 0.739
(2) f3 / f1 = 1.87
(3) n1 = 1.80400, 1.80400, 1.80518
(4) (Dt−Dw) /fw=1.04
(5) (Dt−Dw) /Ymax=1.20
(6) | RA · f1 | = 885
(7) f11 / f1 = 1.91
(8) f4 / f2 = 1.41
(9) f4 / (− f3) = 1.00

FIGS. 6A and 6B are graphs showing various aberrations in the wide-angle end state of the zoom optical system according to Example 2 of the present application and coma aberration during shift. FIG. 7 is a diagram of various aberrations in the intermediate focal length state of the variable magnification optical system according to the second example of the present application. FIGS. 8A and 8B are graphs showing various aberrations in the telephoto end state of the variable magnification optical system according to Example 2 of the present application, and coma aberration diagrams at the time of shifting.
6 to 8, the variable power optical system according to the present example has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent during shifting. It can be seen that it has imaging performance.

(Third embodiment)
FIG. 9 is a lens cross-sectional view in the wide-angle end state of the variable magnification optical system according to the third example of the present application.
The variable magnification optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens having a negative refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface directed toward the object side, a negative lens L12 having a biconcave shape, a negative meniscus lens L13 having a convex surface directed toward the object side, and a biconvex shape. Positive lens L14. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed by providing a resin layer on the glass lens surface on the image plane I side.
The second lens group G2 includes, in order from the object side, a cemented lens of a negative meniscus lens L21 having a convex surface directed toward the object side and a biconvex positive lens L22, and a biconvex positive lens L23.
The third lens group G3 is composed of, in order from the object side, a cemented negative lens of a positive meniscus lens L31 having a concave surface directed toward the object side and a biconcave negative lens L32.
The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L41 having a concave surface directed toward the object side, a cemented lens of a biconvex positive lens L42 and a negative meniscus lens L43 having a convex surface directed toward the image surface I. It consists of.

In the zoom optical system according to the present embodiment, an aperture stop S is disposed between the second lens group G2 and the third lens group G3, and the third lens is used for zooming from the wide-angle end state to the telephoto end state. Move together with the group G3.
In the zoom optical system according to the present embodiment, when zooming is performed from the wide-angle end state to the telephoto end state, the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 and The first lens group G1 is moved to the object side after moving to the image plane I side so that the distance from the fourth lens group G4 is reduced. The second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis along the optical axis. At this time, the second lens group G2 and the fourth lens group G4 move together.
In the variable magnification optical system according to this example, the cemented negative lens in the third lens group G3 is shifted so as to include a component in a direction orthogonal to the optical axis.
Table 3 below lists values of specifications of the variable magnification optical system according to the third example of the present application.

(Table 3) Third Example
[Surface data]
Surface number r d nd νd
Object ∞
1) 48.776 1.90 1.51680 64.12
2) 16.100 0.17 1.55389 38.09
* 3) 13.900 11.00
4) -114.885 1.40 1.80400 46.58
5) 28.378 3.20
6) 486.611 1.28 1.80400 46.58
7) 87.125 0.10
8) 36.548 3.50 1.80518 25.43
9) -893.698 variable
10) 31.539 0.90 1.80518 25.43
11) 17.844 2.89 1.51823 58.89
12) -80.458 4.24
13) 29.000 2.30 1.51823 58.89
14) -257.990 Variable
15) (Aperture S) ∞ 2.90
16) -42.033 2.75 1.85026 32.35
17) -14.348 0.80 1.77250 49.61
18) 92.894 Variable
19) -1000.000 2.75 1.48749 70.45
20) -23.091 0.10
21) 113.640 5.88 1.49782 82.56
22) -15.170 1.00 1.80 100 34.96
23) -45.654 BF
Image plane ∞

[Aspherical data]
Third side K = 1
A4 = 2.59080E-05
A6 = 5.94080E-08
A8 = -1.85780E-10
A10 = 9.08510E-13

[Various data]
Zoom ratio 3.12
W M T
f 16.0 31.2 49.9
FNO 3.6 4.8 5.9
2ω 87.6 49.7 31.9
Y 14.25 14.25 14.25
TL 132.45 130.09 147.53
BF 38.56 57.70 82.60

d9 29.65 8.16 0.69
d14 1.89 7.40 11.23
d18 10.88 5.37 1.54

[Lens group data]
Group start surface f
1 1 -20.95
2 10 29.66
3 15 -42.98
4 19 43.95

[Conditional expression values]
(1) | f1 | / √ (fw · ft) = 0.741
(2) f3 / f1 = 2.05
(3) n1 = 1.80400, 1.80400, 1.80518
(4) (Dt−Dw) /fw=1.04
(5) (Dt−Dw) /Ymax=1.21
(6) | RA · f1 | = 879
(7) f11 / f1 = 1.90
(8) f4 / f2 = 1.48
(9) f4 / (− f3) = 1.02

FIGS. 10A and 10B are diagrams showing various aberrations in the wide-angle end state of the zoom optical system according to the third example of the present application and coma aberration during shift. FIG. 11 is a diagram illustrating various aberrations in the intermediate focal length state of the variable magnification optical system according to the third example of the present application. 12 (a) and 12 (b) are graphs showing various aberrations in the telephoto end state of the zoom optical system according to the third example of the present application and coma aberration diagrams at the time of shift.
10 to 12, the variable magnification optical system according to the present example has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent during shifting. It can be seen that it has imaging performance.

(Fourth embodiment)
FIG. 13 is a lens cross-sectional view of the zoom optical system according to the fourth example of the present application in the wide-angle end state.
The variable magnification optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens having a negative refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface directed toward the object side, a biconcave negative lens L12, a negative meniscus lens L13 having a convex surface directed toward the object side, and an object side. And a positive meniscus lens L14 having a convex surface. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed by providing a resin layer on the glass lens surface on the image plane I side.
The second lens group G2 includes, in order from the object side, a cemented lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, and a positive meniscus lens L23 having a convex surface facing the object side. Become.
The third lens group G3 includes, in order from the object side, a cemented negative lens of a positive meniscus lens L31 having a concave surface directed toward the object side and a biconcave negative lens L32, and a plano-concave shape having a concave surface directed toward the image surface I. Negative lens L33.
The fourth lens group G4 includes, in order from the object side, a planoconvex positive lens L41 having a convex surface directed toward the image plane I, a biconvex positive lens L42, and a negative meniscus lens having a convex surface directed toward the image plane I. It consists of a cemented lens with L43.

In the zoom optical system according to the present embodiment, an aperture stop S is disposed between the second lens group G2 and the third lens group G3, and the third lens is used for zooming from the wide-angle end state to the telephoto end state. Move together with the group G3.
In the zoom optical system according to the present embodiment, when zooming is performed from the wide-angle end state to the telephoto end state, the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 and The first lens group G1 is moved to the object side after moving to the image plane I side so that the distance from the fourth lens group G4 is reduced. The second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis along the optical axis. At this time, the second lens group G2 and the fourth lens group G4 move together.
In the variable magnification optical system according to this example, the cemented negative lens in the third lens group G3 is shifted so as to include a component in a direction orthogonal to the optical axis.
Table 4 below lists values of specifications of the variable magnification optical system according to the fourth example of the present application.

(Table 4) Fourth Example
[Surface data]
Surface number r d nd νd
Object ∞
1) 40.043 1.90 1.51680 64.12
2) 16.100 0.17 1.55389 38.09
3) 13.900 11.00
4) -114.885 1.40 1.80400 46.58
5) 30.106 3.00
6) 120.351 1.28 1.80400 46.58
7) 50.332 0.10
8) 33.144 3.50 1.80518 25.43
9) 838.075 variable
10) 31.539 0.90 1.75520 27.51
11) 16.806 4.30 1.51680 64.12
12) -57.150 2.06
13) 24.603 2.10 1.51823 58.89
14) 107.987 Variable
15) (Aperture S) ∞ 2.90
16) -50.100 2.75 1.85026 32.35
17) -14.650 0.80 1.77250 49.61
18) 104.520 2.50
19) ∞ 1.20 1.51680 64.12
20) 100.452 variable
21) 0.000 2.75 1.48749 70.45
22) -24.078 0.10
23) 74.578 4.72 1.49782 82.56
24) -16.452 1.00 1.80 100 34.96
25) -49.260 BF
Image plane ∞

[Aspherical data]
Third side K = 1
A4 = 2.47620E-05
A6 = 5.94080E-08
A8 = -7.24100E-11
A10 = 6.81200E-13

[Various data]
Zoom ratio 3.24
W M T
f 16.5 32.5 53.3
FNO 3.6 4.9 5.9
2ω 84.6 47.4 29.8
Y 14.25 14.25 14.25
TL 131.41 129.27 148.63
BF 38.56 57.91 84.73

d9 29.65 8.16 0.69
d14 1.69 7.40 11.23
d20 11.08 5.37 1.54

[Lens group data]
Group start surface f
1 1 -21.94
2 10 29.55
3 15 -40.37
4 21 40.26

[Conditional expression values]
(1) | f1 | / √ (fw · ft) = 0.740
(2) f3 / f1 = 1.84
(3) n1 = 1.80400, 1.80400, 1.80518
(4) (Dt−Dw) /fw=0.94
(5) (Dt−Dw) /Ymax=1.06
(6) | RA · f1 | = 1022
(7) f11 / f1 = 1.81
(8) f4 / f2 = 1.36
(9) f4 / (− f3) = 1.00

FIGS. 14A and 14B are graphs showing various aberrations in the wide-angle end state of the zoom optical system according to the fourth example of the present application and coma aberration during shift. FIG. 15 is a diagram of various aberrations in the intermediate focal length state of the variable magnification optical system according to the fourth example of the present application. FIGS. 16A and 16B are graphs showing various aberrations in the telephoto end state of the zoom optical system according to the fourth example of the present application and coma aberration during shift.
14 to 16, the variable magnification optical system according to the present example has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent during shifting. It can be seen that it has imaging performance.

  According to each of the above embodiments, it is possible to realize a variable magnification optical system having a lens that shifts so as to include a component in a direction orthogonal to the optical axis and having a high variable magnification ratio and good optical performance. Here, each said Example has shown one specific example of this invention, and this invention is not limited to these.

In addition, the following content can be appropriately employed as long as the optical performance of the variable magnification optical system of the present application is not impaired.
Although a four-group configuration is shown as a numerical example of the variable magnification optical system of the present application, the present application is not limited to this, and a variable magnification optical system of another group configuration (for example, five groups) can also be configured. . Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image plane side of the variable magnification optical system of the present application may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during zooming.

In addition, the variable magnification optical system of the present application uses a part of a lens group, an entire lens group, or a plurality of lens groups as a focusing lens group for focusing from an object at infinity to an object at a short distance. It may be configured to move in the axial direction. In particular, it is preferable that at least a part of the first lens group or at least a part of the second lens group is a focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor.
In the zoom optical system of the present application, either the entire lens group or a part thereof is moved as an anti-vibration lens group so as to include a component perpendicular to the optical axis, or rotated in an in-plane direction including the optical axis. It can also be configured to correct image blur caused by camera shake by moving (swinging). In particular, in the variable magnification optical system of the present application, it is preferable that at least a part of the third lens group is an anti-vibration lens group.

  The lens surface of the lens constituting the variable magnification optical system of the present application may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspherical, any of aspherical surface by grinding, glass mold aspherical surface in which glass is molded into an aspherical shape, or composite aspherical surface in which resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In the variable magnification optical system of the present application, it is preferable that the aperture stop is disposed in or near the third lens group. However, a lens frame may be used instead of providing a member as the aperture stop.
Further, an antireflection film having a high transmittance in a wide wavelength range may be applied to the lens surface of the lens constituting the variable magnification optical system of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.

The variable magnification optical system of the present application has a variable magnification ratio of about 2 to 5 times.
In the variable power optical system of the present application, it is preferable that the first lens group has one positive lens component and two negative lens components, or one positive lens component and three negative lens components. . In the first lens group, it is preferable to dispose these lens components in the order of negative / negative / positive or negative / negative / positive from the object side with an air gap therebetween.
In the variable power optical system of the present application, it is preferable that the second lens group has two positive lens components, or two positive lens components and one negative lens component. In the latter case, it is preferable that the second lens group arranges these lens components in the order of negative positive / negative from the object side with an air gap interposed therebetween.

In the variable magnification optical system of the present application, it is preferable that the third lens group has one negative lens component or two negative lens components.
In the variable power optical system of the present application, it is preferable that the fourth lens group has two positive lens components, or two positive lens components and one negative lens component. In the latter case, it is preferable that the second lens group arranges these lens components in the order of positive and negative from the object side with an air gap therebetween.

Next, a camera provided with the variable magnification optical system of the present application will be described with reference to FIG.
FIG. 17 is a diagram illustrating a configuration of a camera including the variable magnification optical system of the present application.
This camera 1 is a digital single-lens reflex camera provided with the variable magnification optical system according to the first embodiment as the photographing lens 2 as shown in FIG.
In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and imaged on the focusing screen 4 through the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. Thereby, the light from the subject is picked up by the image pickup device 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.
With the above configuration, the present camera 1 equipped with the variable magnification optical system according to the first embodiment as the photographing lens 2 has a lens that shifts so as to include a component in a direction orthogonal to the optical axis, and has a high variable magnification. Ratio and good optical performance can be realized. Even if a camera equipped with the variable magnification optical system according to the second to fourth embodiments as the photographing lens 2 is configured, the same effect as the camera 1 can be obtained.

Hereinafter, the outline of the manufacturing method of the variable magnification optical system of this application is demonstrated based on FIG.
FIG. 18 is a diagram showing a manufacturing method of the variable magnification optical system of the present application.
The variable magnification optical system manufacturing method of the present application includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power. , And a fourth lens group having a positive refractive power, which includes steps S1 to S3 shown in FIG.

Step S1: A first lens group having a negative refractive power, a second lens group having a positive refractive power, and the third lens group so as to satisfy the following conditional expressions (1) and (2): And a fourth lens group having a positive refractive power are arranged from the object side in a cylindrical barrel.
(1) 0.60 <| f1 | / √ (fw · ft) <0.78
(2) 1.80 <f3 / f1 <2.50
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group fw: Focal length of the zooming optical system in the wide-angle end state ft: Focal length of the zooming optical system in the telephoto end state

Step S2: By providing a known moving mechanism in each lens group, the distance between the lens groups on the optical axis can be changed when zooming from the wide-angle end state to the telephoto end state.
Step S3: By providing a known moving mechanism in at least a part of the third lens group, it is possible to shift so that at least a part of the third lens group includes a component in a direction orthogonal to the optical axis. .

  According to such a variable magnification optical system manufacturing method of the present application, the variable magnification optical system has a lens that shifts so as to include a component in a direction orthogonal to the optical axis, and has a high zoom ratio and good optical performance. Can be manufactured.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group S Aperture stop I Image surface W Wide-angle end state T Telephoto end state

Claims (15)

In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power And having a group
The third lens group includes a cemented negative lens;
When zooming from the wide-angle end state to the telephoto end state, the distance between the lens groups changes,
Shifting so that at least a part of the third lens group includes a component in a direction orthogonal to the optical axis;
A zoom optical system characterized by satisfying the following conditional expression:
0.60 <| f1 | / √ (fw · ft) <0.78
1.80 <f3 / f1 <2.50
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group fw: Focal length of the zooming optical system in the wide-angle end state ft: Focal length of the zooming optical system in the telephoto end state 2. The variable magnification optical system according to claim 1, wherein the first lens group includes at least two lenses that satisfy the following conditional expression.
1.750 <n1 <2.500
However,
n1: Refractive index of the lens in the first lens group with respect to d-line (wavelength λ = 587.6 nm) The zoom lens system according to claim 1 or 2, wherein the following conditional expression is satisfied.
0.50 <(Dt−Dw) / fw <1.50
However,
Dt: Distance on the optical axis from the most object side lens surface in the zoom optical system to the image plane in the telephoto end state Dw: Image from the lens surface closest to the object in the zoom optical system in the wide angle end state Distance fw on the optical axis to the surface: focal length of the variable magnification optical system in the wide-angle end state The zoom lens system according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
0.60 <(Dt−Dw) / Ymax <1.60
However,
Dt: Distance on the optical axis from the lens surface closest to the object side in the variable magnification optical system in the telephoto end state to the image plane Dw: Image from the lens surface closest to the object in the variable magnification optical system in the wide angle end state Distance on the optical axis to the surface Ymax: Maximum image height The zoom lens system according to claim 1, wherein the following conditional expression is satisfied.
400 <| RA · f1 | <1300
However,
RA: radius of curvature of the lens surface closest to the object side in the variable magnification optical system f1: focal length of the first lens unit The first lens group has a negative lens closest to the object side,
The zoom lens system according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.
1.40 <f11 / f1 <2.10
However,
f1: focal length of the first lens group f11: focal length of the negative lens in the first lens group The zoom lens system according to any one of claims 1 to 6, wherein the following conditional expression is satisfied.
1.00 <f4 / f2 <2.00
However,
f2: focal length of the second lens group f4: focal length of the fourth lens group The zoom lens system according to any one of claims 1 to 7, wherein the following conditional expression is satisfied.
0.80 <f4 / (− f3) <1.30
However,
f3: focal length of the third lens group f4: focal length of the fourth lens group   The variable magnification optical system according to any one of claims 1 to 8, further comprising an aperture stop between the second lens group and the fourth lens group.   The variable power optical system according to any one of claims 1 to 9, wherein the first lens group includes at least two negative lenses and at least one positive lens. system.   The variable power optical system according to any one of claims 1 to 10, wherein the first lens group includes an aspherical lens.   The zoom lens according to any one of claims 1 to 11, wherein the second lens group and the fourth lens group move together when zooming from the wide-angle end state to the telephoto end state. The zoom optical system according to item.   When zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group and the third lens group increases and the distance between the third lens group and the fourth lens group decreases. The variable power optical system according to any one of claims 1 to 12, wherein   An imaging apparatus comprising the variable magnification optical system according to any one of claims 1 to 13. In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power A variable magnification optical system having a group,
A cemented negative lens is disposed in the third lens group;
Each lens group of the variable magnification optical system satisfies the following conditional expression,
When changing the magnification from the wide-angle end state to the telephoto end state, the interval between the lens groups can be changed.
A method for manufacturing a variable magnification optical system, wherein at least a part of the third lens group can be shifted so as to include a component in a direction orthogonal to the optical axis.
0.60 <| f1 | / √ (fw · ft) <0.78
1.80 <f3 / f1 <2.50
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group fw: Focal length of the zooming optical system in the wide-angle end state ft: Focal length of the zooming optical system in the telephoto end state

Images