JPH06230317A - Variable power optical system having vibration-proof function - Google Patents

Abstract

PURPOSE:To obtain the variable power optical system having the vibration-proof function which can correct an image blur due to vibration while holding optical performance excellent. CONSTITUTION:The variable power optical system having a power variation part closer to an object side than a stop SP is provided with a variable vertical angle prism KP nearby the stop SP and when the image blur of a photographed image which is generated when the variable power optical system slants, is corrected by varying the vertical angle of the variable vertical angle prism KP, a requirement 0.0005<d/fT<0.01 is satisfied, where (d) is the actual distance from the variable vertical angle prism KP to the stop SP and fT is the focal length of the variable power optical system at its telephoto end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable power optical system having a function of correcting image blur of a photographed image due to vibration, that is, a so-called anti-vibration function. The present invention relates to a variable power optical system having an image stabilizing function that corrects image blur by changing the apex angle of a prism in accordance with the vibration of the variable power optical system.

[0002]

2. Description of the Related Art When an image is captured from a moving object such as a car or an airplane in progress, vibration is transmitted to the image capturing system, and a large image blur occurs in a captured image particularly when the exposure time is long. These image blurs become more noticeable not only when shooting with a video camera or cine camera but also when shooting with a still camera, especially as the focal length increases.

In general, when a lens having a long focal length is attached to a camera for photographing, the camera is fixed to a tripod, but since the mobility is deteriorated, it is often used by hand, and in this case, due to image blurring. In many cases, good images could not be obtained.

In order to eliminate such image blur, a variable apex angle prism is provided in the lens system, and eccentric drive is performed so that the apex angle of the variable apex angle prism is changed. A variable power optical system having a function has been proposed in, for example, Japanese Patent Publication No. 56-21133.

[0005]

Generally, a variable apex angle prism is provided in a part of the photographing system, and when the photographing system vibrates, the prism apex angle of the variable apex angle prism is changed accordingly and the image blur of the photographed image is reduced. The correction method has a feature that a still image can be obtained relatively easily.

However, when the prism apex angle of the variable apex angle prism is changed, many decentering aberrations such as decentering coma and decentering astigmatism occur.

Particularly, in the variable power optical system, there is a problem that a large amount of eccentric magnification chromatic aberration occurs due to the prism action on the long focal length side (telephoto side).

According to the present invention, by appropriately disposing a variable apex angle prism having a predetermined shape in a part of the variable power optical system, the image blur of a photographed image generated when the variable power optical system is tilted due to vibration or the like is decentered. It is an object of the present invention to provide a variable power optical system having an image stabilizing function, which can correct aberrations while suppressing the amount of aberrations to be small and easily obtain high-quality still images.

[0009]

A variable-magnification optical system having a vibration-proof function according to the present invention is (a) a variable-magnification optical system having a variable-magnification section composed of a plurality of lens groups on the object side of an aperture. When a variable apex angle prism is provided in the vicinity of the diaphragm and the prism apex angle of the variable apex angle prism is changed to correct the image blur of the captured image that occurs when the variable magnification optical system is tilted, When the actual distance from the variable apex angle prism to the stop is d and the focal length at the telephoto end of the variable power optical system is fT, 0.0005 <d / fT <0.01 ... It is characterized in that the condition (1) is satisfied.

(B) The first refractive power first from the object side
Group, the second group of negative refractive power, the diaphragm, the third group of positive refractive power,
Further, it has four lens groups of the fourth group having a positive refractive power and a variable apex angle prism on the object side or the image plane side of the diaphragm, and the second group is moved to the image plane side from the wide angle end. A variable power optical system which performs zooming to the telephoto end, corrects an image plane variation due to zooming by moving the fourth group, and also moves the fourth group to perform focusing. When correcting the image blur of the captured image caused when the variable power optical system is tilted by changing the prism apex angle of the angle prism, the actual distance from the variable apex angle prism to the diaphragm is changed by d. When the focal length at the telephoto end of the doubling optical system is fT, the condition is 0.0005 <d / fT <0.01 (1) is satisfied.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of an optical system of Numerical Example 1 which will be described later.

In the figure, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, L3 is a third group having a positive refractive power, and L4 is a fourth group having a positive refractive power. . SP is an aperture stop, which is arranged in front of the third group 3.

KP is a variable apex angle prism.

11 and 12 are transparent glass plates, and 13
Is a bellows part made of a material such as polyethylene. A transparent liquid 14 made of, for example, silicon oil, is enclosed inside the glass plate and the bellows.

Each of these elements, 11, 12, 13, 14
Constitutes a part of the variable apex angle prism KP.

In FIG. 1, the two glass plates 11 and 12 are parallel to each other, and in this case, the incident angle and the outgoing angle of the light beam to the variable apex angle prism KP are equal.

At least one of the transparent members 11 and 12 is independently rotatable by an urging force from the outside. For example, the transparent member 11 is rotatable about the point 11a or the point 11b as a rotation axis. As a result, the two transparent members 11 and 12 form a variable prism having an arbitrary prism apex angle.

In this embodiment, the variable apex angle prism KP having such a structure is arranged in front of the diaphragm SP. When the variable-magnification optical system vibrates and an image blur occurs in a captured image, it is detected by a well-known blur detection means, and the well-known drive means according to the blur amount at that time, the well-known drive means, the prism apex angle of the prism KP. Is changed to deflect the passing light beam by a predetermined amount, thereby correcting the image blur.

In the variable power optical system of the present embodiment, the second lens unit L2 is moved to the image plane side as indicated by the arrow during zooming from the wide-angle end to the telephoto end, and the image plane variation caused by zooming is changed by the fourth lens unit. L4 is moved and corrected.

Further, a rear focus type in which focusing is performed by moving the fourth lens unit L4 on the optical axis is adopted. The solid curve 4a and the dotted curve 4b of the fourth group shown in the same figure represent image plane fluctuations due to zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and a near object, respectively. The movement locus for correction is shown. The first group L1 and the third group L3
Is fixed during zooming and focusing.

In the present embodiment, in the variable power optical system having the above-mentioned structure, the variable vertical angle prism KP is arranged at a predetermined position satisfying the conditional expression (1) in front of the diaphragm SP, and the variable power optical system vibrates. Image blur that sometimes occurs can be adjusted by a variable angle prism KP
It corrects by changing the prism apex angle.

At this time, each element is set so that the distance from the diaphragm-side surface of the variable apex angle prism KP to the diaphragm SP, the so-called actual distance d, satisfies the conditional expression (1).

As a result, the height of the light flux from the optical axis when passing through the variable apex angle prism is lowered to reduce the occurrence of eccentric aberrations such as eccentric coma and eccentric spherical aberration due to the prism action, and flare. Image blur is effectively corrected while preventing the occurrence of ghosts and ghosts.

Further, by disposing the variable apex angle prism KP close to the diaphragm SP so as to satisfy the conditional expression (1), the outer dimensions are reduced and the prism apex angle is changed at high speed.

When the variable apex angle prism KP is positioned farther than the stop SP beyond the upper limit of the conditional expression (1), the outer diameter of the variable apex angle prism becomes large and the prism apex angle is changed at high speed. Is difficult, and many decentering aberrations due to decentering occur, which is not good.

FIGS. 2A and 2B show longitudinal aberration diagrams at the telephoto end and the wide-angle end in Numerical Example 1.

FIGS. 3 and 4 are lateral aberration diagrams before and after decentering of the variable apex angle prism at the telephoto end in Numerical Example 1, and FIGS. 5 and 6 are graphs at Numerical Example 1 at the wide-angle end. FIG. 7 shows lateral aberration diagrams before and after decentering of the variable apex angle prism.

As is apparent from these aberration diagrams, it is understood that even if the prism apex angle is changed to decenter and the image blur is corrected, the decentering aberration is small.

FIG. 7 is a schematic view of the essential parts of an optical system according to Numerical Example 2 of the present invention, which will be described later.

In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

The present embodiment is different from the numerical embodiment 1 of FIG. 1 in that the variable apex angle prism KP is arranged on the image plane side of the aperture stop SP so as to satisfy the conditional expression (1). Have the same configuration.

In this embodiment, the variable apex angle prism KP is arranged on the image plane side of the diaphragm SP, and the same effect as that of the numerical embodiment 1 is obtained.

FIGS. 8A and 8B are longitudinal aberration diagrams at the telephoto end and the wide-angle end according to Numerical Example 2.

FIGS. 9 and 10 are transverse aberration diagrams before and after decentering of the variable apex angle prism at the telephoto end of Numerical Example 2, respectively.
11 and 12 show lateral aberration diagrams before and after decentering of the variable apex angle prism at the wide-angle end according to Numerical Example 2.

As is apparent from these aberration diagrams, it is understood that even if the prism apex angle is changed to decenter and the image blur is corrected, the decentering aberration is small.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side of the i-th lens. The refractive index of glass and the Abbe number.

In Numerical Examples 1 and 2, R13 to R1
Reference numeral 6 denotes a variable apex angle prism. Numerical Example 1 f = 9.45376 fno = 1: 1.9 2 ω = 5.9 to 52.0 r 1 = 10.858 d 1 = 1.58 n 1 = 1.51454 ν 1 = 54.7 r 2 = 170.490 d 2 = 0.02 r 3 = 9.024 d 3 = 0.15 n 2 = 1.80518 ν 2 = 25.4 r 4 = 6.281 d 4 = 0.33 r 5 = 6.982 d 5 = 1.31 n 3 = 1.51633 ν 3 = 64.2 r 6 = 17.690 d 6 = variable r 7 = 7.790 d 7 = 0.15 n 4 = 1.69680 ν 4 = 55.5 r 8 = 2.970 d 8 = 1.29 r 9 = 149.669 d 9 = 0.56 n 5 = 1.69680 ν 5 = 55.5 r10 = 2.899 d 10 = 0.30 r11 = 3.255 d 11 = 0.32 n 6 = 1.84666 ν 6 = 23.9 r12 = 5.808 d 12 = variable r13 = ∞ d 13 = 0.15 n 7 = 1.51633 ν 7 = 64.2 r14 = ∞ d 14 = variable n 8 = 1.41650 ν 8 = 52.2 r15 = ∞ d 15 = 0.15 n 9 = 1.51633 ν 9 = 64.2 r16 = ∞ d 16 = 0.05 r17 = ∞ (aperture) d 17 = 0.01 r18 = 8.199 d 18 = 0.27 n10 = 1.63854 ν10 = 55.4 r19 = -4.488 d 19 = 0.27 r20 = 3.074 d 20 = 0.23 n11 = 1.49782 ν11 = 66.8 r21 = -87.069 d 21 = 0.34 r22 = -3.602 d 22 = 0.15 n12 = 1.69895 ν12 = 30.1 r23 = 10.967 d 23 = variable r24 = 1130.885 d 24 = 0.70 n13 = 1.49700 ν13 = 81.6 r25 = -2.480 d 25 = 0.02 r26 = 2.255 d 26 = 0.30 n14 = 1.49700 ν14 = 81.6 r27 = -5.64 2 d 27 = 0.04 r28 = -4.075 d 28 = 0.15 n15 = 1.84666 ν15 = 23.9 r29 = -11.070 d / fT = 0.0053

[0038]

[Table 1] Numerical Example 2 f = 8.52 fno = 1: 1.9 to 2.0 2 ω = 7.0 to 55.0 r 1 = 14.467 d 1 = 2,38 n 1 = 1.51454 ν 1 = 54.7 r 2 = -138.895 d 2 = 0.09 r 3 = 9.640 d 3 = 0.17 n 2 = 1.80518 ν 2 = 25.4 r 4 = 6.883 d 4 = 0.46 r 5 = 7.514 d 5 = 1.59 n 3 = 1.51728 ν 3 = 69.6 r 6 = 17.055 d 6 = variable r 7 = 10.575 d 7 = 0.23 n 4 = 1.69680 ν 4 = 56.5 r 8 = 3.146 d 8 = 1.49 r 9 = 76.082 d 9 = 0.64 n 5 = 1.69680 ν 5 = 56.5 r10 = 3.231 d 10 = 0.29 r11 = 3.632 d 11 = 0.42 n 6 = 1.84666 ν 6 = 23.9 r12 = 6.955 d 12 = variable r13 = ∞ (aperture) d 13 = 0.01 r14 = ∞ d 14 = 0.16 n 7 = 1.51633 ν 7 = 64.2 r15 = ∞ d 15 = variable n 8 = 1.41650 ν 8 = 52.2 r16 = ∞ d 16 = 0.16 n 9 = 1.51633 ν 9 = 64.2 r17 = ∞ d 17 = 0.02 r18 = 7.836 d 18 = 0.30 n10 = 1.63854 ν10 = 55.4 r19 = -4.585 d 19 = 0.21 r20 = 3.550 d 20 = 0.29 n11 = 1.49782 ν11 = 66.8 r21 = -51.757 d 21 = 0.27 r22 = -3.725 d 22 = 0.28 n12 = 1.69895 ν12 = 30.1 r23 = 10.431 d 23 = variable r24 = -2617.105 d 24 = 0.55 n13 = 1.45600 ν13 = 90.3 r25 = -2.411 d 25 = 0.04 r26 = 1.996 d 26 = 0.49 n14 = 1.45600 ν14 = 90.3 r27 = -10.275 d 27 = 0.16 r28 = -4.378 d 28 = 0.33 n15 = 1.84666 ν15 = 23.9 r29 = -12.038 d / fT = 0.0012

[0039]

[Table 2]

[0040]

As described above, according to the present invention, when a variable apex angle prism having a predetermined shape is properly arranged in a part of the variable power optical system, the variable power optical system tilts due to vibration or the like. It is possible to achieve a variable-magnification optical system having an anti-vibration function that can satisfactorily correct the image blur of the captured image while suppressing the amount of eccentric aberration generated, and easily obtain a high-quality still image.

[Brief description of drawings]

FIG. 1 is a lens cross-sectional view of Numerical Example 1 of the present invention.

FIG. 2 is an aberration diagram at a telephoto end and a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 3 is an aberration diagram before decentering at the telephoto end according to Numerical Example 1 of the present invention.

FIG. 4 is an aberration diagram after decentering at the telephoto end according to Numerical Example 1 of the present invention.

FIG. 5 is an aberration diagram before decentering at the wide-angle end according to Numerical Example 1 of the present invention.

FIG. 6 is an aberration diagram after decentering at the wide-angle end according to Numerical Example 1 of the present invention.

FIG. 7 is a lens cross-sectional view of Numerical Example 2 of the present invention.

FIG. 8 is an aberration diagram at a telephoto end and a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 9 is an aberration diagram before decentering at the telephoto end according to Numerical Example 2 of the present invention.

FIG. 10 is an aberration diagram after decentering at the telephoto end according to Numerical Example 2 of the present invention.

FIG. 11 is an aberration diagram before decentering at the wide-angle end according to Numerical Example 2 of the present invention.

FIG. 12 is an aberration diagram after decentering at the wide-angle end according to Numerical Example 2 of the present invention.

[Explanation of symbols]

 L1 1st group L2 2nd group L3 3rd group L4 4th group KP variable apex angle prism SP diaphragm

Claims (2)

[Claims] 1. A variable power optical system having a variable power portion composed of a plurality of lens groups closer to the object side than a diaphragm, wherein a variable vertical angle prism is provided in the vicinity of the diaphragm, and the prism of the variable vertical angle prism is provided. When correcting the image blur of the photographed image caused when the variable power optical system is tilted by changing the vertical angle, the actual distance from the variable vertical angle prism to the diaphragm is d, A variable power optical system having an image stabilizing function, which satisfies the condition of 0.0005 <d / fT <0.01, where fT is the focal length at the telephoto end. 2. A first group having a positive refractive power, a second group having a negative refractive power, a diaphragm, a third group having a positive refractive power, and a fourth group having a positive refractive power are arranged in this order from the object side. A lens group and a variable apex angle prism on the object side or the image plane side of the diaphragm, and moving the second group to the image plane side to perform zooming from the wide-angle end to the telephoto end,
An image plane variation due to zooming is corrected by moving the fourth group, and a zooming optical system for moving the fourth group to perform focusing, and changing the prism apex angle of the variable apex angle prism. As a result, when correcting the image blur of the captured image that occurs when the variable power optical system is tilted, the actual distance from the variable apex angle prism to the diaphragm is d, and the focal length at the telephoto end of the variable power optical system is Where fT is defined as 0.005 <d / fT <0.01.