JP3278783B2 - Variable power optical system with anti-vibration function - Google Patents

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 blurring of a photographed image due to vibration, that is, a so-called image stabilizing 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 an angular prism according to vibration of a variable power optical system.

[0002]

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

In general, when a camera having a long focal length is attached to a camera for photographing, the camera is fixed on a tripod. However, the camera is often used by hand because of poor mobility. In many cases, good images could not be obtained.

In order to eliminate such image blur, a lens system has a variable apex angle prism, and an eccentric drive is performed so as to change the apex angle of the variable apex angle prism. 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 a photographing system, and when the photographing system vibrates, the prism apex angle of the variable apex angle prism is changed in accordance with the vibration to reduce image blur of a photographed image. The correction method has a feature that a still image can be obtained relatively easily.

However, when the apex angle of the variable apex angle prism is changed, there is a problem that many eccentric aberrations such as eccentric coma and eccentric astigmatism are generated.

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

According to the present invention, by appropriately disposing a variable apex prism having a predetermined shape in a part of a variable power optical system, an image blur of a photographed image caused 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 capable of easily obtaining a high-quality still image by appropriately correcting the amount of aberration while keeping the amount small.

[0009]

According to the present invention, there is provided a variable power optical system having an image stabilizing function comprising: (a) a variable power optical system having a variable power unit including a plurality of lens groups on the object side of the stop. A variable apex prism is provided in the vicinity of the stop, and a prism apex angle of the variable apex prism is changed to prevent image blurring of a captured image caused when the variable power optical system is tilted. A variable power optical system having a vibration function, wherein the actual distance from the variable apex angle prism to the aperture is d, and the focal length at the telephoto end of the variable power optical system is fT. 0.0005 <d / It is characterized by satisfying the condition of fT <0.01 ‥‥‥ (1).

(B) First positive refractive power in order from the object side
Group, second group of negative refractive power, aperture, third group of positive refractive power,
A fourth lens group having a positive refractive power and a variable apex angle prism disposed on the object side or the image plane side of the diaphragm; and moving the second group to the image plane side. A zoom optical system that performs zooming from a wide-angle end to a telephoto end, corrects an image plane variation caused by zooming by moving the fourth unit, and performs focusing by moving the fourth unit. By changing the prism apex angle of the variable apex angle prism, when correcting image blurring of a photographed image caused when the variable power optical system is tilted, the actual distance from the variable apex angle prism to the diaphragm is d. When the focal length at the telephoto end of the variable power optical system is fT, the following condition is satisfied: 0.0005 <d / fT <0.01 ‥‥‥ (1)

[0011]

FIG. 1 is a schematic view of a main part of an optical system according to a first numerical embodiment of the present invention.

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 denotes an aperture stop, which is arranged in front of the third lens unit 3.

KP is a variable angle prism.

11 and 12 are transparent glass plates, and 13
Is a bellows portion made of a material such as polyethylene. A transparent liquid 14 of, for example, silicon oil or the like is sealed in the interior surrounded by the glass plate and the bellows.

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

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

At least one of the transparent members 11 and 12 is independently rotatable by an external biasing force. For example, the transparent member 11 is rotatable around the point 11a or the point 11b as a rotation axis. Thereby, a variable prism having an arbitrary prism apex angle is formed by the two transparent members 11 and 12.

In this embodiment, the variable apex angle prism KP having such a configuration is disposed in front of the stop SP. Then, when the variable magnification optical system vibrates and an image blur occurs in the photographed image, the blur is detected by a known blur detecting means, and the prism apex angle of the variable apex prism KP is determined by a known driving means according to the amount of blur at that time. Is changed to deflect the passing light beam by a predetermined amount, thereby correcting image blurring.

In the variable power optical system according to the present embodiment, the second lens unit L2 is moved to the image plane side as indicated by an arrow at the time of zooming from the wide angle end to the telephoto end, and the image plane fluctuation due to the zooming is changed to the fourth lens unit. L4 is moved for correction.

Also, a rear focus system is employed in which the fourth unit L4 is moved on the optical axis to perform focusing. A solid line curve 4a and a dotted line curve 4b of the fourth lens group shown in the same figure show the image plane fluctuation caused by zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at a short distance, respectively. The movement locus for correction is shown. Note that the first lens unit L1 and the third lens unit L3
Is fixed during zooming and focusing.

In this embodiment, in the variable power optical system having the above-described configuration, the variable power angle optical system vibrates by disposing the variable apex angle prism KP at a predetermined position satisfying the conditional expression (1) in front of the stop SP. Variable image angle prism KP
Is corrected by changing the prism apex angle.

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

With this arrangement, the height of the light beam from the optical axis when passing through the variable apex angle prism is reduced, so that the occurrence of eccentric aberrations such as eccentric coma and eccentric spherical aberration due to the prism action is reduced. Image blur is effectively corrected while preventing the occurrence of ghosts and the like.

Further, by arranging the variable apex angle prism KP close to the stop SP so as to satisfy the conditional expression (1), the external dimensions are reduced, and the change of the prism apex angle is made faster.

If the variable apex angle prism KP is located farther than the stop SP beyond the upper limit value of the conditional expression (1), the outer diameter of the variable apex angle prism increases, and the prism apex angle is changed at high speed. Is difficult, and a large amount of eccentric aberration due to eccentricity is generated.

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

FIGS. 3 and 4 show lateral aberration diagrams before and after decentering of the variable apex angle prism at the telephoto end in Numerical Embodiment 1, and FIGS. FIG. 3 shows lateral aberration diagrams before and after decentering of a variable apex angle prism.

As is apparent from these aberration diagrams, even when the prism is decentered by changing the vertex angle and the image blur is corrected, the decentering aberration is small.

FIG. 7 is a schematic view of a main part of an optical system according to a second numerical example of the present invention described later.

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

The present embodiment differs from Numerical Embodiment 1 of FIG. 1 in that the variable apex angle prism KP is arranged on the image plane side of the stop SP so as to satisfy the conditional expression (1). Is the same.

In this embodiment, the variable apex angle prism KP is arranged closer to the image plane side than the stop SP, and the same effects as those of the first embodiment are obtained.

FIGS. 8A and 8B show longitudinal aberration diagrams at the telephoto end and the wide-angle end in Numerical Embodiment 2. FIGS.

9 and 10 are lateral aberration diagrams before and after decentering of the variable apex angle prism at the telephoto end in Numerical Embodiment 2, respectively.
11 and 12 show lateral aberration diagrams before and after decentering of the variable apex angle prism at the wide angle end in Numerical Embodiment 2. FIG.

As is apparent from these aberration diagrams, even when the prism is decentered by changing the vertex angle and the image blur is corrected, the decentering aberration is small.

Next, numerical examples of the present invention will be described. 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 spacing from the object side, and Ni and νi are the i-th lens surfaces in order from the object side. The refractive index and Abbe number of glass.

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: 1.92ω = 5.9〜52.0 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 ~ 2.0 2ω = 7.0 ~ 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]

According to the present invention, as described above, by appropriately disposing a variable apex angle prism having a predetermined shape in a part of a variable power optical system, the variable power optical system is generated when the variable power optical system is tilted due to vibration or the like. It is possible to satisfactorily correct image blurring of a photographed image while suppressing the amount of eccentric aberration to be small, and to achieve a variable power optical system having an image stabilizing function that can easily obtain a high-quality still image.

[Brief description of the drawings]

FIG. 1 is a sectional view of a lens according to a 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 Embodiment 1 of the present invention.

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

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

FIG. 5 is an aberration diagram before decentering at the wide angle end in Numerical Embodiment 1 of the present invention.

FIG. 6 is an aberration diagram after decentering at the wide angle end in Numerical Embodiment 1 of the present invention.

FIG. 7 is a sectional view of a lens according to a 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 Embodiment 2 of the present invention.

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

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

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

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

[Explanation of symbols]

 L1 First group L2 Second group L3 Third group L4 Fourth group KP Variable vertex angle prism SP Stop

Claims (2)

(57) [Claims] 1. A variable power optical system having a variable power unit including a plurality of lens groups on the object side of a stop, wherein a variable vertex angle prism is provided near the stop, and the variable vertex angle prism is provided. By changing the apex angle, an anti- shake function to correct image blurring of a captured image caused when the variable power optical system is tilted is provided.
Wherein 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 A variable power optical system having an anti-vibration function, satisfying the following condition: 2. A first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a stop, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power are arranged in order from the object side. Having a lens group and a variable apex angle prism arranged on the object side or the image plane side of the stop,
The second lens unit is moved to the image plane side to change the magnification from the wide-angle end to the telephoto end, and the image plane fluctuation caused by zooming is corrected by moving the fourth lens unit, and the fourth lens unit is moved. A variable power optical system that performs focusing by changing the prism apex angle of the variable apex angle prism to correct the image blur of a captured image caused when the variable power optical system is tilted. When the actual distance from the apex angle prism to the stop is d and the focal length at the telephoto end of the variable power optical system is fT, the condition of 0.0005 <d / fT <0.01 is satisfied. Variable power optical system with anti-vibration function.