JP4764524B2 - Variable magnification optical system and camera having the same - Google Patents

Description

  The present invention relates to a variable magnification optical system and a camera having the same, and takes a picture when the variable magnification optical system vibrates (tilts) by moving a part of the lens group of the variable magnification optical system in a direction perpendicular to the optical axis. This is to optically correct image blurring. In particular, the present invention is suitable for a video camera, a silver halide photographic camera, an electronic still camera, a digital camera, and the like that obtain a still image and thereby stabilize a photographed image.

  If an attempt is made to shoot from a moving object such as an ongoing car or aircraft, vibrations are transmitted to the photographic system, causing camera shake and blurring of the captured image.

  Conventionally, various anti-vibration optical systems having a function of preventing blurring of captured images have been proposed (Patent Documents 1 to 7).

  For example, in Patent Document 1, the image is stabilized by moving some optical members in a direction that cancels the vibrational displacement of the image due to the vibration in accordance with an output signal from a detection unit that detects a vibration state in the optical device. I am trying. In Patent Document 2, in an imaging system in which a variable apex angle prism is arranged on the most object side, the apex angle of the variable apex angle prism is changed in accordance with the vibration of the imaging system to stabilize the image.

  In Patent Document 3 and Patent Document 4, vibration of the photographing system is detected using an acceleration sensor or the like, and a part of the lens group of the photographing system is vibrated in a direction perpendicular to the optical axis according to a signal obtained at this time. A still image is obtained.

  In Patent Document 5, in order from the object side, when zooming and focusing, a first group of fixed positive refractive power, a second group of negative refractive power having a zooming function, an aperture stop, a positive refractive power It has a third group. Further, the zoom lens system includes a fourth lens unit having a positive refractive power and a fourth lens unit having both a correction function for correcting an image plane fluctuating due to zooming and a focusing function. The third group is composed of two lens groups, a negative refractive power group 31 and a positive refractive power group 32, and the zoom lens is moved by moving the 32nd group in a direction perpendicular to the optical axis. Corrects the blurring of the captured image when the system vibrates.

  In Patent Document 6, the entire third group of the variable power optical system having a four-group configuration of positive, negative, positive, and positive refractive power is vibrated to prevent vibration.

  On the other hand, in Patent Document 7, in a zoom lens having a four-group configuration including positive, negative, positive, and positive refractive power lens groups, zooming is performed by the second and third lens groups, and the first lens group is a positive single lens. We have proposed a zoom lens that is designed to improve performance while shortening the overall lens length.

JP 56-21133 A JP-A-61-223819 JP-A-1-116619 Japanese Patent Laid-Open No. 2-124521 Japanese Patent Laid-Open No. 7-128619 JP-A-7-199124 JP-A-10-62687

  In general, a method for obtaining a still image by arranging a vibration-proof optical system in front of the photographing system, vibrating a part of the operating lens group of the vibration-proof optical system to eliminate a blur of the photographed image, There is a problem that a moving mechanism for moving the operating lens group becomes complicated.

  In an optical system that performs vibration isolation using a variable apex angle prism, there is a problem in that the amount of decentered chromatic aberration generated increases during image stabilization, particularly on the long focal length side.

  On the other hand, an optical system that performs vibration isolation by decentering a part of the lenses of the photographing system in the direction perpendicular to the optical axis has an advantage that no extra optical system is required for image stabilization. However, there is a problem in that it requires a space for the lens to be moved, and the amount of decentration aberrations generated during image stabilization increases.

  In addition, when the entire third lens unit of the variable power optical system having a four-group configuration including positive, negative, positive, and positive refractive power lens units is moved in the direction perpendicular to the optical axis, Problems arise. That is, when the third lens unit is configured with a telephoto type of a positive lens and a meniscus negative lens in order to shorten the entire length, decentration aberrations such as decentration coma and decentration field curvature occur and image quality deteriorates.

  Furthermore, although the zoom lens of the conventional example described above having a zoom ratio of 8 times or more can be used for a video camera or the like, it is inconvenient in terms of aberration correction when used for an electronic still camera having an image sensor equivalent to 1 million pixels. It was enough.

  The present invention corrects image blurring when the zoom optical system vibrates (tilts) by moving a relatively small and lightweight lens group constituting a part of the zoom optical system in a direction perpendicular to the optical axis. In addition, the configuration of the lens group for correcting blur is appropriate. As a result, it is possible to reduce the size of the entire apparatus, simplify the mechanism, and reduce the load on the driving means. In addition, the zoom lens system has an anti-vibration function that satisfactorily corrects decentration aberrations when the lens group is decentered, and has a variable power optical system that can sufficiently handle, for example, an electronic still camera having an image sensor with 1 million pixels or more. The purpose is to provide a camera.

The zoom optical system according to the first aspect of the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, A variable power optical system that includes a fourth lens group having a positive refractive power and performs zooming by moving the first lens group, the second lens group, and the third lens group, and the fourth lens The group is composed of a single positive lens, and the fourth lens group is moved on the optical axis for focusing, and the entire third lens group is moved in the direction perpendicular to the optical axis to change the variable magnification optical system. Can correct the shake of the photographed image when the lens vibrates, and the amount of movement of the first lens group and the third lens group in zooming from the wide-angle end to the telephoto end is M1, M3 , and the third lens, respectively. When the focal length of the group is f3 and the focal length of the entire system at the wide angle end is fw ,
0.2 <M1 / M3 <1.5
1.5 <f3 / fw <3.0
It satisfies the following conditional expression.

  According to a second aspect of the present invention, there is provided a camera having the variable magnification optical system according to the first aspect.

  According to the present invention, as described above, when the relatively small and light lens group constituting a part of the variable magnification optical system is moved in the direction perpendicular to the optical axis, the variable magnification optical system vibrates (tilts). It is configured to correct the image blurring. Along with that, the configuration of the lens group for correcting blur is made appropriate. As a result, it is possible to reduce the size of the entire apparatus, simplify the mechanism, and reduce the load on the driving means. Furthermore, to achieve a variable magnification optical system that has an anti-vibration function that satisfactorily corrects decentration aberrations when the lens group is decentered, and is sufficiently compatible with, for example, an electronic still camera having an image sensor with 1 million pixels or more. I can do it.

Schematic diagram of paraxial refractive power arrangement of variable magnification optical system in Reference Example 1 Explanatory drawing of optical principle of vibration isolation system in the present invention Cross-sectional view of the lens at the wide angle end of Numerical Example 1 of Reference Example 1 Schematic diagram of paraxial refractive power arrangement of variable magnification optical system in Reference Example 2 Schematic of paraxial refractive power arrangement of the variable magnification optical system in Embodiment 1 Cross-sectional view of the lens at the wide angle end according to Numerical Example 3 of Embodiment 1 Aberration diagram at the wide angle end in Numerical Example 1 of Reference Example 1. Intermediate aberration diagram of Numerical Example 1 of Reference Example 1 Aberration diagram at telephoto end of Numerical Example 1 of Reference Example 1 Aberration diagram at wide-angle end in Numerical example 2 of Reference example 2 Intermediate aberration diagram of Numerical Example 2 of Reference Example 2 Aberration diagram at telephoto end of Numerical Example 2 of Reference Example 2 Aberration diagram at wide-angle end in Numerical example 3 according to Embodiment 1 Intermediate aberration diagram of Numerical Example 3 of Embodiment 1 Aberration diagram at telephoto end in Numerical Example 3 according to Embodiment 1 Lens sectional view at the wide-angle end of Numerical Example 2 of Reference Example 2

  FIG. 1 is a schematic diagram showing the paraxial refractive power arrangement of Reference Example 1 of the present invention. In FIG. 1, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a fourth lens group having a positive refractive power. It is.

  In this reference example, by moving the third lens group in the direction perpendicular to the optical axis, blurring of the captured image (image blurring) when the entire optical system vibrates (tilts) is corrected. SP is an aperture stop, which is located in front of the third lens unit L3.

  In this reference example, the second lens group and the third lens group are moved on the optical axis as indicated by arrows when zooming from the wide-angle end to the telephoto end. Further, a rear focus type is employed in which the fourth lens group is moved on the optical axis to perform focusing. The first lens group is fixed during zooming and focusing.

  When zooming from the wide-angle end to the telephoto end, the third lens group moves to the object side, and the second lens group first moves to the image plane side and from the middle to the object side. The aperture stop SP moves to the object side integrally with the third lens group, but may move independently as necessary.

  In this reference example, for example, when focusing from an object at infinity to an object at a short distance, the fourth lens group is moved forward as shown in FIG.

  In this reference example, image blur when the entire optical system vibrates is corrected by moving the third lens unit L3 in the direction perpendicular to the optical axis for image stabilization. As a result, image stabilization is performed without adding an optical member such as a variable apex angle prism or a lens group for image stabilization.

  Next, the optical principle of the image stabilization system for correcting the shake of the photographed image by moving the lens group in the direction perpendicular to the optical axis in the variable magnification optical system according to the present invention will be described with reference to FIG.

  As shown in FIG. 2A, the optical system is composed of three parts, a fixed group Y1, an eccentric group Y2, and a fixed group Y3, and an object point P on the optical axis sufficiently separated from the lens is an imaging surface IP. It is assumed that an image is formed as an image point p at the center of the image. Assuming that the entire optical system including the imaging surface IP is instantaneously tilted due to camera shake as shown in FIG. 2B, the object point P is also instantaneously moved to the image point P ′, resulting in a blurred image. .

  On the other hand, when the eccentric group Y2 is moved in the direction perpendicular to the optical axis, the image point p moves to p "as shown in FIG. 2C, and the amount and direction of movement depend on the refractive power arrangement, and the lens group. 2B, the image point p ′ shifted due to camera shake in FIG. 2B is moved by an appropriate amount in the direction perpendicular to the optical axis by moving the eccentric group Y2 to the original imaging position p. By returning to the position, as shown in FIG. 2D, camera shake correction, that is, image stabilization is performed.

  Now, Δ is given by the following equation, where Δ is the amount of shift lens group movement required to correct the optical axis by θ °, f is the focal length of the entire optical system, and TS is the eccentricity sensitivity of the shift group Y2. .

Δ = f · tan (θ) / TS
Now, if the eccentricity sensitivity TS of the shift group is too large, Δ becomes a small value and the shift group movement amount necessary for image stabilization can be reduced, but control for performing image stabilization becomes difficult, and the remaining correction remains. It will occur.

  Particularly in video cameras and digital still cameras, the image size of an image sensor such as a CCD is smaller than that of a silver halide film, and the focal length for the same angle of view is short. Therefore, the shift amount Δ of the shift lens group for correcting the same angle is small. Get smaller. Therefore, if the accuracy of the mechanism is approximately the same, the remaining correction on the screen becomes relatively large.

  On the other hand, if the eccentricity sensitivity TS is too small, the amount of movement of the shift lens group necessary for control becomes large, and the driving means such as an actuator for driving the shift lens group also becomes large.

  In this reference example, the decentration sensitivity TS of the third lens group is set to an appropriate value by setting the refractive power arrangement of each lens group to an appropriate value, and there is little residual vibration correction due to mechanical control errors, and actuators, etc. This achieves an optical system with a small load on the driving means.

  Specifically, the entire third lens group is moved in the direction perpendicular to the optical axis to correct the shake of the captured image when the variable magnification optical system vibrates, and at least the second lens group and the third lens group are moved. Move to scale. The first lens group is composed of a positive single lens or one positive lens and one negative lens.

  FIG. 3 shows a cross-sectional view of the optical system of Numerical Example 1 of Reference Example 1.

  In this reference example, the first lens group is composed of a positive single lens. Further, the second lens group is composed of a meniscus negative lens having a strong concave surface facing the image surface side in order from the object side, a negative lens, and a positive lens having a strong convex surface facing the object side. Here, “strong on the image plane side” means “the lens surface on the image plane side is stronger (larger) than the object side on the absolute value of refractive power”. The third lens group includes, in order from the object side, a positive lens 31, a positive lens and a negative lens cemented lens 32 having a strong concave surface on the image plane side, and a positive lens 33. The positive lens 31 has an aspheric lens surface on the object side.

  By providing a meniscus negative lens having a strong concave surface on the image surface side in the third lens group, the entire third lens group is made into a telephoto configuration, and the principal point interval between the second lens group and the third lens group is shortened. The overall length of the lens has been shortened.

  In this reference example, the positive lens 33 is arranged on the image plane side of the meniscus negative lens 32 to maintain a certain telephoto configuration, while correcting distortion in the third lens group and shifting the third lens group. As a result, the occurrence of decentration distortion that occurs when performing vibration isolation is reduced. In this reference example, the positive lens 31 is provided with an aspherical surface, so that the third lens group suppresses spherical aberration and reduces decentration coma that occurs during image stabilization.

  In addition, the load of the focus actuator is reduced by configuring the fourth lens group with one positive lens.

  Although the fourth lens group is composed of a single positive lens, if a negative lens is added here, fluctuations in chromatic aberration during focusing can be further reduced.

  In the present reference example, by setting the lens configuration as described above, high optical performance is obtained over the entire zoom range and over the entire object distance in the reference state and the image stabilization state.

  In the variable magnification optical system having the image stabilization function of this reference example, in order to obtain further excellent optical performance, it is preferable to satisfy at least one of the following conditions.

(A-1) When the magnifications at the telephoto end of the third lens group and the lens group arranged on the image side from the third lens group are B3t and Brt, respectively, 0.5 <| (1-B3t) · Brt | <3 ... (1)
The following conditional expression is satisfied.

The decentering sensitivity TS3 at the telephoto end of the third lens group is B3t when the magnification of the third lens group at the telephoto end is B3t, and the magnification of the lens group closer to the image plane than the third lens group is TS3 = (1-B3t ) ・ Brt
Given in.

In this reference example, this absolute value is set to 0.5 <| (1-B3t) · Brt | <3 (1)
The eccentricity sensitivity is set to an appropriate range so as to satisfy the following conditions.

If the lower limit of conditional expression (1) is exceeded, the amount of movement of the third lens group during image stabilization becomes too large.
On the other hand, if the upper limit is exceeded, the sensitivity becomes too high, and it becomes difficult to control the image stabilization.

In order to further improve the controllability and reduce the movement amount, the numerical range of the conditional expression (1) is changed to 0.6 <| (1-B3t) · Brt | <2 (1a)
It is desirable to satisfy the following conditions.

(A-2) When the focal length of the third lens group is f3, and the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively. 1.5 <f3 / fw <3.0 (2)
2.0 <ft / fw (3)
It is good to satisfy the following conditional expression.

  If the lower limit of conditional expression (2) is exceeded and the refractive power of the third lens group becomes too strong, it is advantageous for shortening the overall length, but the Petzval sum becomes too large in the positive direction, making it difficult to correct field curvature. So not good. On the other hand, if the upper limit is exceeded, the amount of movement of the third lens group required for zooming becomes too large.

  If the conditional expression (3) is exceeded, a predetermined zoom ratio cannot be obtained.

  FIG. 4 is a schematic diagram showing the paraxial refractive power arrangement of Reference Example 2 of the present invention. In FIG. 4, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a fourth lens group having a positive refractive power. It is. By moving the entire second lens group in the direction perpendicular to the optical axis, the shake of the captured image when the entire optical system vibrates (tilts) is corrected.

  Also in this reference example, zooming is performed by moving the second lens unit and the third lens unit on the optical axis as indicated by arrows when zooming from the wide-angle end to the telephoto end. Further, a rear focus type is employed in which the fourth lens group is moved on the optical axis to perform focusing.

  By performing image stabilization with the second lens group, it is disadvantageous compared to the invention in Reference Example 1 in terms of the size of the lens diameter, but the change in the amount of peripheral light during image stabilization is further reduced. The optical action in image stabilization is the same as in Reference Example 1 shown in FIG. FIG. 16 is a lens cross-sectional view at the wide-angle end of Numerical Example 2 of Reference Example 2.

  Reference Example 2 of the present invention is characterized in that the first lens group is composed of a single positive lens or one positive lens and one negative lens. The lens configurations of the first lens group and the third lens group are the same as in Reference Example 1.

  In Reference Example 2 of the present invention, the following conditional expression should be satisfied in order to obtain good optical performance in both the reference state and the image stabilization state.

(A-1) In the reference example 2 of the present invention, the sensitivity TS2 at the time of image stabilization of the second lens group is the magnification at the telephoto end of the second lens group and the lens group disposed on the image side from the second lens group. Where B2t and Brt are TS2 = (1-B2t) · Brt
Given in.

In Reference Example 2 of the present invention, this absolute value is 0.5 <| (1-B2t) · Brt | <3 (4)
It is desirable to satisfy the following conditional expression.

  If the sensitivity of the second lens group becomes smaller than the lower limit of the conditional expression, the amount of movement of the second lens group at the time of image stabilization increases, which is not good. On the other hand, if the sensitivity exceeds the upper limit and becomes too high, control becomes difficult, which is not good.

  In the present invention, it is preferable to satisfy at least one of the following conditions in order to maintain good optical performance in the reference state and the image stabilization state.

  (C-1) The second lens group includes, in order from the object side, a meniscus negative lens having a strong concave surface facing the image surface side, a negative lens, and a positive lens having a strong convex surface facing the object side. .

(C-2) The first lens unit is composed of a single positive lens, and when the radiuses of curvature of the object-side and image-side lens surfaces are R1 and R2, and the Abbe number of the material is ν1, −3 < (R1 + R2) / (R1-R2) <0 (5)
55 <ν1 (6)
It is desirable to satisfy the following conditions.

  If the lower limit of conditional expression (5) is exceeded, spherical aberration will increase in the negative direction too much at the telephoto end, and conversely if it exceeds the upper limit, it will be difficult to correct coma aberration.

  On the other hand, if the lower limit of the expression (6) is exceeded, it will be difficult to correct on-axis and chromatic aberrations of magnification accompanying zooming.

  FIG. 5 is a schematic diagram showing a paraxial refractive power arrangement according to the first embodiment of the present invention. In FIG. 5, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a fourth lens group having a positive refractive power. It is.

  In this embodiment, the entire third lens group is moved in the direction perpendicular to the optical axis, thereby correcting blurring of the captured image when the entire optical system vibrates (tilts). SP is an aperture stop, which is located in front of the third lens unit L3.

  In the present embodiment, zooming is performed by moving the first lens group, the second lens group, and the third lens group on the optical axis as indicated by arrows when zooming from the wide-angle end to the telephoto end. Further, a rear focus type is employed in which the fourth lens group is moved on the optical axis to perform focusing.

  When zooming from the wide-angle end to the telephoto end, the first lens group and the third lens group move to the object side, and the second lens group first moves to the image plane side and then moves from the middle to the object side.

  By moving the first lens unit L1 to the object side, the movement amount of the third lens unit L3 required for zooming is reduced, and the total lens length at the wide angle end can be shortened. The aperture stop SP moves to the object side integrally with the third lens group, but may move independently as necessary.

  In the present embodiment, for example, when focusing from an infinitely distant object to a close object at the telephoto end, the fourth lens group is moved forward as shown in FIG.

In the first embodiment, in order to sufficiently obtain the effect of shortening the total lens length at the wide angle end, the movement amount of the first lens group required for zooming from the wide angle end to the telephoto end is M1, and the movement amount of the third lens group is M3. When doing 0.2 <M1 / M3 <1.5 (7)
It is good to satisfy the condition.

  If the amount of movement of the first lens unit becomes small beyond the lower limit, the effect of shortening the total lens length cannot be obtained sufficiently. On the other hand, if the amount of movement of the first lens unit becomes too large beyond the upper limit, the mechanical mechanism for extending the first lens unit becomes complicated, which is not good.

  FIG. 6 shows a lens cross-sectional view at the wide angle end according to Numerical Example 3 of Embodiment 1. In this embodiment, the first lens group is composed of two positive and negative lenses, so that axial chromatic aberration and axial chromatic aberration caused by zooming are reduced. The fluctuation is improved.

  In the first embodiment as well, the second lens group may be composed of a meniscus negative lens having a strong concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side.

  Next, numerical examples of Embodiment 1 of the present invention and Reference Examples 1 and 2 are shown. In each numerical example, Ri is the radius of curvature of the i-th surface in order from the object side, Di is the distance between the i-th surface and the (i + 1) -th surface in order from the object side, and Ni and νi are from the object side, respectively. It is the refractive index and Abbe number of the glass of the i-th optical member in order. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, and K, B, C, D and E are the aspheric coefficients. When

It is expressed by the following formula.

Numerical example 1
f = 1 ~ 2.97 Fno = 2.43 ~ 3.60 2ω = 64.2 ° ~ 23.9 °
R 1 = 3.333 D 1 = 0.60 N 1 = 1.516330 ν 1 = 64.1
R 2 = 19.183 D 2 = variable
R 3 = 5.356 D 3 = 0.13 N 2 = 1.834000 ν 2 = 37.2
R 4 = 1.141 D 4 = 0.63
R 5 = -13.107 (Aspherical) D 5 = 0.17 N 3 = 1.658441 ν 3 = 50.9
R 6 = 1.939 D 6 = 0.07
R 7 = 1.838 D 7 = 0.42 N 4 = 1.846660 ν 4 = 23.8
R 8 = 9.362 D 8 = variable
R 9 = Aperture D 9 = 0.28
R10 = 1.422 (Aspherical) D10 = 0.33 N 5 = 1.834807 ν 5 = 42.7
R11 = -7.256 D11 = 0.03
R12 = 2.836 D12 = 0.40 N 6 = 1.834000 ν 6 = 37.2
R13 = -1.997 D13 = 0.12 N 7 = 1.846660 ν 7 = 23.8
R14 = 0.936 D14 = 0.37
R15 = -263.842 D15 = 0.37 N 8 = 1.772499 ν 8 = 49.6
R16 = -4.052 D16 = variable
R17 = 1.447 (Aspherical) D17 = 0.36 N 9 = 1.806100 ν 9 = 40.7
R18 = -74.627 D18 = 0.29
R19 = ∞ D19 = 0.45 N10 = 1.516330 ν10 = 64.1
R20 = ∞

Focal length 1.00 2.65 2.97
Variable interval
D 2 0.09 1.19 1.07
D 8 2.88 0.54 0.30
D16 0.49 1.73 2.07

Aspheric coefficient
R 5 k = -3.23868e + 02 B = 4.34086e-03 C = -3.26552e-03 D = 1.45007e-02
R10 k = -8.21638e-01 B = -2.15746e-02 C = 1.56862e-03 D = -9.29549e-03
R17 k = -2.11938e-01 B = -3.62716e-02 C = -8.77965e-03 D = 0.00000e + 00

Numerical example 2
f = 1〜2.97 Fno = 2.48〜3.60 2ω = 64.2 ° 〜23.9 °
R 1 = 2.816 D 1 = 0.60 N 1 = 1.516330 ν 1 = 64.1
R 2 = 11.896 D 2 = variable
R 3 = 6.390 D 3 = 0.13 N 2 = 1.834000 ν 2 = 37.2
R 4 = 1.119 (Aspherical) D 4 = 0.63
R 5 = -4.480 D 5 = 0.16 N 3 = 1.650158 ν 3 = 39.4
R 6 = 2.331 D 6 = 0.04
R 7 = 2.117 D 7 = 0.42 N 4 = 1.846660 ν 4 = 23.8
R 8 = -18.814 D 8 = variable
R 9 = Aperture D 9 = 0.39
R10 = 1.416 (Aspherical) D10 = 0.33 N 5 = 1.834807 ν 5 = 42.7
R11 = -10.288 D11 = 0.03
R12 = 2.667 D12 = 0.40 N 6 = 1.834000 ν 6 = 37.2
R13 = -1.997 D13 = 0.12 N 7 = 1.846660 ν 7 = 23.8
R14 = 0.935 D14 = 0.37
R15 = -263.842 D15 = 0.30 N 8 = 1.603112 ν 8 = 60.6
R16 = -4.052 D16 = variable
R17 = 1.881 (Aspherical) D17 = 0.36 N 9 = 1.806100 ν 9 = 40.7
R18 = -74.627 D18 = 0.29
R19 = ∞ D19 = 0.45 N10 = 1.516330 ν10 = 64.1
R20 = ∞

Focal length 1.00 2.65 2.97
Variable interval
D 2 0.09 2.42 1.39
D 8 2.84 0.54 0.30
D16 0.22 1.26 1.56

Aspheric coefficient
R 4 k = -1.09438e-01 B = -1.68564e-02 C = 2.08890e-02 D = -2.52790e-02
R10 k = -6.69154e-01 B = -2.13385e-02 C = 4.37738e-03 D = -1.63567e-02
R17 k = -1.09618e-01 B = -2.44913e-02 C = 2.08869e-03 D = 0.00000e + 00

Numerical Example 3
f = 1 ~ 4.00 Fno = 2.24 ~ 3.60 2ω = 64.2 ° 〜17.8 °
R 1 = 3.588 D 1 = 0.16 N 1 = 1.834000 ν 1 = 37.2
R 2 = 2.680 D 2 = 0.72 N 2 = 1.603112 ν 2 = 60.6
R 3 = 28.984 D 3 = variable
R 4 = 4.182 D 4 = 0.13 N 3 = 1.834000 ν 3 = 37.2
R 5 = 1.207 D 5 = 0.66
R 6 = -5.965 D 6 = 0.15 N 4 = 1.583126 ν 4 = 59.4
R 7 = 1.819 D 7 = 0.07
R 8 = 1.769 D 8 = 0.42 N 5 = 1.846660 ν 5 = 23.8
R 9 = 6.817 D 9 = variable
R10 = Aperture D10 = 0.45
R11 = 1.364 D11 = 0.33 N 6 = 1.834807 ν 6 = 42.7
R12 = -10.154 D12 = 0.03
R13 = 2.330 D13 = 0.40 N 7 = 1.834000 ν 7 = 37.2
R14 = -1.997 D14 = 0.12 N 8 = 1.846660 ν 8 = 23.8
R15 = 0.844 D15 = 0.37
R16 = -9.752 D16 = 0.37 N 9 = 1.772499 ν 9 = 49.6
R17 = -4.788 D17 = variable
R18 = 2.027 (Aspherical) D18 = 0.36 N10 = 1.806100 ν10 = 40.7
R19 = -74.627 D19 = 0.29
R20 = ∞ D20 = 0.45 N11 = 1.516330 ν11 = 64.1
R21 = ∞

Focal length 1.00 3.36 4.00
Variable interval
D 3 0.09 1.95 2.06
D 9 2.96 0.60 0.36
D17 0.45 1.99 2.43

Aspheric coefficient
R 6 k = 1.76310e + 01 B = 1.81049e-02 C = -4.77367e-03 D = 4.50945e-03
R11 k = -8.70146e-01 B = -1.25504e-02 C = 4.92439e-03 D = -1.44314e-02
R18 k = -1.10607e-02 B = 4.79091e-03 C = -5.01469e-04 D = 0.00000e + 00

L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group d d line g g line ΔM meridional image plane ΔS sagittal image plane SP aperture IP image plane

Claims (2)

In order from the object side to the image side, the lens unit includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. , A variable power optical system that performs zooming by moving the first lens group, the second lens group, and the third lens group, and the fourth lens group is constituted by a single positive lens, The fourth lens group is moved on the optical axis to perform focusing, and the entire third lens group is moved in the direction perpendicular to the optical axis to correct the shake of the photographed image when the variable magnification optical system vibrates. The amount of movement of the first lens unit and the third lens unit in zooming from the wide-angle end to the telephoto end is respectively M1, M3 , the focal length of the third lens unit is f3, and the entire system at the wide-angle end When the focal length of is fw ,
0.2 <M1 / M3 <1.5
1.5 <f3 / fw <3.0
A variable magnification optical system characterized by satisfying the following conditional expression: A camera comprising the variable magnification optical system according to claim 1.