JPH07168135A - Additional optical system for vibration-isolator - Google Patents

Abstract

PURPOSE:To correct the blurring of an image caused by vibration while keeping optical performance by moving a part of lens group out of plural lens groups attachably/ detachably mounted in a direction perpendicular to an optical axis and compensating the blurring of a taken picture caused when all the system is vibrated. CONSTITUTION:This system is constituted of plural lens groups B11, B21 and B31 attachably/detachably mounted on the image surface side of an image-formation system ML. That is, the additional optical system AL1 is constituted of a 1st group B11 of positive refractive power consisting of a stuck lens obtained by bonding a positive lens and a negative lens, a 2nd group B21 of negative refractive power having two stuck lenses obtained by bonding the positive lens and the negative lens, and a 3rd group B31 of positive refractive power having the stuck lens obtained by bonding the positive lens and the negative lens and the positive lens in order from an object side. The refractive power of the entire optical system AL1 is a converter of unmagnification proximate to about zero. By such constitution, the blurring of the taken picture when a photographing system is vibrated is corrected by displacing the 2nd group B21 as a movable lens group in the direction perpendicular to the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adds a vibration proof (for vibration compensation) that is detachably attached to the image plane side of an image forming system in order to correct the blurring of a photographed image that occurs when the photographic system vibrates. Regarding the optical system, in particular, the movable lens group for image stabilization is moved, for example, in the direction orthogonal to the optical axis to exert the image stabilization effect while preventing the deterioration of the optical performance during image stabilization.

[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 the captured image is blurred.

The magnitude of the blur of the photographed image at this time depends on the tilt angle and the focal length of the photographing system. Therefore, there is a problem that the shooting time must be sufficiently short in order to prevent the deterioration of the image quality in the still image shooting device, and it is difficult to set and maintain the composition in the moving image shooting device. There is a problem that

Conventionally, an anti-vibration optical system having a function of preventing the blur of a photographed image caused when the photographing system vibrates has been disclosed in, for example, Japanese Patent Application Laid-Open No. 50-80147 and Japanese Patent Publication No. 56-21.
133, JP-A-61-223819, and the like.

In Japanese Patent Application Laid-Open No. 50-80147, in a zoom lens having two afocal variable power systems, the angular magnification of the first variable power system is M ₁ and the angular power of the second variable power system is M.
_Then , the zooming is performed in each zooming system so as to have a relation of M ₁ = 1-1 / M ₂ when _2, and the _second zooming system is spatially fixed to correct the blurring of the image. We are trying to stabilize the image.

According to Japanese Patent Publication No. 56-21133, some optical members are moved in a direction of canceling the vibrational displacement of an image due to vibration in accordance with an output signal from a detecting means for detecting a vibrational state of an optical device. To stabilize the image.

In Japanese Patent Laid-Open No. 61-223819, in a photographing system in which a refracting variable apex angle prism is arranged closest to the subject, the apex angle of the refracting variable apex prism is changed according to the vibration of the photographing system. The image is deflected to stabilize the image.

In addition to this, vibration of the photographing system is detected using an acceleration sensor, and a part of the lens group of the photographing system is vibrated in a direction orthogonal to the optical axis in accordance with a signal obtained at this time to obtain a still image. There is also a way to get.

[0009]

Generally, a vibration reduction mechanism for obtaining a still image by displacing a part of a lens group of a photographing system to obtain a still image does not deteriorate the image quality at the time of the vibration reduction. Is large, and the lens group (movable lens group) vibrating for shake correction in order to reduce the size and weight of the entire device is small, and the displacement amount such as the movement amount and the rotation amount is small. Is requested.

A vibration-proof optical system having an optical member which is spatially fixed against vibration has a problem that it is difficult to support the optical member and it is difficult to downsize the optical system. .

Further, the vibration-proof optical system in which the variable apex angle prism is arranged at the most object side of the image forming system has an advantage that various aberrations other than decentration chromatic aberration are hardly generated at the time of vibration compensation.

However, there is a problem that the driving member becomes large and it is difficult to satisfactorily correct the eccentric chromatic aberration with a simple structure.

In addition, in a vibration-proof optical system that decenters a part of the lens group (movable lens group) of the image forming system, a relatively small device can be realized by appropriately selecting and arranging the decentering movable lens group. be able to.

However, since the vibration compensation mechanism is incorporated,
There is a problem that the entire device becomes large. For this reason, there is a problem in that it is particularly troublesome in the case of shooting that does not require a vibration compensation mechanism, such as when using a tripod or the like.

According to the present invention, an optical device for image stabilization is detachably attached to the image side of the image capturing system so that the image capturing function can be performed only when the image capturing system needs to perform image stabilization. It is an object of the present invention to provide an additional optical system for image stabilization, in which the overall size of the apparatus is reduced, image quality is prevented from being degraded during image stabilization, and good optical performance is easily obtained even during image stabilization.

[0016]

An additional optical system for image stabilization according to the present invention comprises (1-1) a plurality of lens groups detachably mounted on the image plane side of an image forming system. It is characterized in that some of the lens groups are moved in a direction perpendicular to the optical axis to compensate for blurring of a captured image that occurs when the entire system vibrates.

In particular, (1-1-1) each of the plurality of lens groups includes, in order from the object side, a first group having negative refracting power, a second group having positive refracting power, and a third group having negative refracting power. The second lens group is composed of two lens groups, and the second lens group is moved in the direction perpendicular to the optical axis to compensate for the blurring of the captured image that occurs when the entire system vibrates, and the refraction of the second and third lens groups. It is characterized by satisfying the condition 1.0 <| φ ₂₁ / φ ₃₁ | <2.5 (1) when the forces are φ ₂₁ and φ ₃₁ .

(1-1-2) The plurality of lens groups are, in order from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the third lens group having a positive refractive power. A second lens group, and moving the second lens group in a direction perpendicular to the optical axis to compensate for blurring of a captured image that occurs when the entire system vibrates; and refracting the second lens group and the third lens group. is set to <satisfies the 3.5 ..... (2) the condition | force phi _22, 1.5 <when the _{φ 32 | φ 22 / φ 32} .

[0019]

1 and 2 are sectional views of lenses of Examples 1 and 2 in which an additional optical system for image stabilization (vibration compensation) according to the present invention is mounted on the image side of a known image forming system. Is.

In the figure, ML is a known imaging system, AL1 and AL2.
Is an additional optical system for image stabilization. The image forming system ML is a telephoto lens proposed by the present applicant in Japanese Patent Application No. 5-48609 with a focal length of 300 mm and an F number of 5.6 for a 35 mm film.

The additional optical system AL1 of the first embodiment shown in FIG. 1 has a first lens unit B11 having a positive refractive power composed of a cemented lens in which a positive lens and a negative lens are cemented in order from the object side, and a positive lens and a negative lens are cemented. It is composed of three lens groups, that is, a second lens unit B21 having a negative refractive power having two cemented lenses, a cemented lens having a positive lens and a negative lens cemented to each other, and a third lens unit B31 having a positive refractive power having a positive lens. ing.

The refracting power of the entire additional optical system is a unity-magnification converter which is approximately zero. Therefore, the focal length 30 having substantially the same specifications as the imaging system ML as the entire imaging system in FIG.
The optical system is 0 mm and has an F number of about 5.6.

In this embodiment, the blurring of the photographed image when the photographing system vibrates is corrected by displacing the second lens group B21 as a movable lens group in the direction perpendicular to the optical axis.

The additional optical system of the present embodiment has a lens structure of a positive lens group, a negative lens group, and a positive lens group in order from the object side. Further, by making each lens group an appropriate lens shape, a vibration compensation state is obtained. Sensitivity for good compensation of various aberrations including vibration compensation (the amount of movement of the movable lens group that moves in the direction perpendicular to the optical axis and the amount of movement of the subject image on the image plane during vibration compensation) Ratio) is sufficiently large.

3 and 4 show the movable lens group B when the additional optical system of the first embodiment is mounted on the image plane side of the above-mentioned image forming system ML.
21 is a lateral aberration diagram when the object distance is infinity in a normal state in which 21 is not displaced and in a vibration compensation state when the imaging system vibrates by 1 °.

As shown in the figure, in Example 1 of the present invention, various aberrations including eccentric aberration are well corrected.

The additional optical system AL2 of the second embodiment shown in FIG. 2 is composed of a cemented lens in which a positive lens and a negative lens are cemented in order from the object side, and a negative lens having a negative refractive power of three lenses in two groups. The second group B22 having a positive refractive power, which is composed of a group B12, a cemented lens in which a negative lens and a positive lens are cemented, a positive lens, and a cemented lens in which three lenses are cemented with a positive lens and a negative lens. , A negative lens, a negative lens, and a positive lens, and the third lens unit B32 has a negative refractive power and includes three lenses. The entire additional optical system is constructed so as to have a weak negative refractive power.

Therefore, in the optical system of FIG. 2 in which the additional optical system AL2 of the present embodiment is mounted on the image plane side of the image forming system ML, the focal length of the image forming system ML is 300 mm and the F number of 5.6 is about 5.6, respectively. It is an optical system that is 1.1 times larger, has a focal length of 330 mm, and an F number of about 6.2.

In this embodiment, the blurring of the photographed image when the photographing system vibrates is corrected by displacing the second lens group B22 as a movable lens group in the direction perpendicular to the optical axis.

The additional optical system of this embodiment has a lens structure of a negative lens group, a positive lens group, and a negative lens group in order from the object side. Further, by making each lens group an appropriate lens shape, a vibration compensation state is obtained. In addition, various aberrations are properly corrected and the sensitivity for vibration compensation is sufficiently increased.

5 and 6, the movable lens group B when the additional optical system of the second embodiment is mounted on the image plane side of the above-described image forming system ML.
22 is a lateral aberration diagram when the object distance is infinity in a normal state in which 22 is not displaced and in a vibration compensation state when the imaging system vibrates by 1 °.

As shown in the figure, in the second embodiment of the present invention, various aberrations including decentration aberrations are satisfactorily corrected.

In the first and second embodiments, the blurring of the photographed image is sufficient because the amount of decentration aberration can be corrected well by simply decentering the second lens group in parallel.
If the group is rotationally decentered, it is possible to further reduce the occurrence of decentration aberrations and maintain good optical performance.

Next, the optical characteristics of the additional optical system for image stabilization of the present invention will be described.

In general, when an attempt is made to correct image blur by decentering a part of lens groups of an optical system in parallel, defocusing aberrations occur and the imaging performance deteriorates. Therefore, next, at the 23rd Applied Physics Lecture, from the standpoint of aberration theory, the occurrence of eccentric aberration when the movable lens group is moved in the direction orthogonal to the optical axis in an arbitrary refractive power arrangement to correct image blur I will explain based on the method presented by Matsui at the meeting (1962).

When the lens group P of a part of the optical system is decentered in parallel by E, the aberration amount ΔY1 of the entire system is the aberration amount ΔY before decentering and the decentering aberration amount Δ caused by decentering as shown in equation (a).
It is the sum of Y (E). Here, the aberration amount ΔY is represented by spherical aberration (I), coma aberration (II), astigmatism (III), Petzval sum (P), and distortion aberration (Y). Also decentering aberration Δ
Y (E) is the first-order decentering coma aberration (I
IE), first-order eccentric astigmatism (IIIE), first-order eccentric field curvature (PE), first-order eccentric distortion (VE1), first-order eccentric distortion-added aberration (VE2), and 1 It is represented by the next origin movement (ΔE).

From equation (d), equations (i) to (ΔE) to (V)
The incident angle alpha _P of the ray aberration up E2) is the lens group P in the optical system for parallel decentering lens group P, the aberration coefficients of the lens unit P when the _{αa P I P, II P,} III P, P
_P , V _P, and similarly, the aberration coefficients when the lens unit arranged on the image plane side of the lens unit P is one q-th lens unit as a whole, I _q , II _q , III _q , P _q , V _Represented using _q .

[0038]

[Equation 1] _{(VE1) = α 'P V} q - α P (V P + V q) - αa P' III q + αa P (III P + III q) = h P φ P V q - α P V P - (ha _{P φ P III q -αa P III} P) ‥‥‥ (h) (VE2) = αa P P q - αa P (P P + P q) = ha P φ P P q - αa P P P ‥‥‥ (i) In order to reduce the occurrence of eccentric aberration from the above formula, the aberration coefficients I _P , II _P , III _P , P _P , and V _P of the lens group P are set to small values, or the formula (a) is used. It is necessary to set the various aberration coefficients in a well-balanced manner so as to cancel each other as shown in the formula (i).

Next, the optical function of the additional optical system for image stabilization of the present invention is displaced by eccentrically driving a part of the lens group of the photographic optical system shown in FIG. 7 in the direction orthogonal to the optical axis. A model assuming an anti-vibration optical system that corrects is explained.

First, in order to realize a sufficiently large displacement correction with a sufficiently small eccentric drive amount, the primary origin movement (Δ
E) needs to be sufficiently large. Based on this, the condition for correcting the primary eccentric field curvature (PE) will be considered. FIG. 7 shows the photographic optical system in order from the object side.
It is composed of three lens groups of a group and a q-th group, of which the p-th group is moved in parallel in a direction orthogonal to the optical axis to correct the image blur.

Here, the refracting powers of the o-th group, the p-th group, and the q-th group are φ _o , φ _p , and φ _q , respectively, and the incident angle of the paraxial on-axis ray and the off-axis ray to each lens group is α , Αa, the incident heights of paraxial on-axis rays and off-axis rays to h, ha, and the same s
Notated with uffix. It is also assumed that each lens group is composed of a small number of lenses, and that each aberration coefficient shows a tendency of undercorrection.

Under these assumptions, focusing on the Petzval sum of each lens group, the Petzval sum P of each lens group
_o , P _p , and P _q are the refractive powers φ _o , φ _p , and φ _q of each lens group.
And satisfy the relation of approximately P _o = Cφ _o P _p = Cφ _p P _q = Cφ _q (where C is a constant). Therefore, the primary eccentric field curvature (PE) that occurs when the p-th group is decentered in parallel can be rearranged as follows by substituting the above equation.

(PE) = Cφ _p (h _p φ _q −α _p ) Therefore, in order to correct the eccentric field curvature (PE), φ _p =
It is necessary to set 0 or φ _q = α _p / h _p . However, if φ _p = 0, the primary origin movement (ΔE) becomes 0 and the displacement cannot be corrected. Therefore, a solution satisfying φ _q = α _p / h _p must be obtained. That is, since h _p > 0, at least α _p and φ _q need to have the same sign.

(A) When α _p > 0, φ _q > 0 for correction of eccentric field curvature, and inevitably φ _o >.
It becomes 0. Further, if φ _p > 0 at this time, 0 <α _p <
α ′ _p <1, the primary origin movement (ΔE) is as follows.

(ΔE) =-2 (α _p ′ −α _p )> − 2 That is, the eccentricity sensitivity (the ratio of the displacement amount of the blur of the photographed image to the unit displacement amount of the eccentric lens group) becomes smaller than 1. Further, as described above, the eccentricity sensitivity becomes 0 when φ _p = 0. Therefore, in such a case, φ _p <0 must be set.

(B) When α _p <0, φ _q <0 and inevitably φ _o <0, and therefore inevitably φ _p > 0 due to correction of the eccentric field curvature (PE).

From the above, the refracting power arrangement of the optical system which makes it possible to correct the primary eccentric field curvature (PE) while sufficiently increasing the primary origin movement (ΔE) is as follows. Is suitable.

[0048]

[Table 1] FIG. 8 (A) and FIG. 8 (B) respectively show a lens configuration having such a refractive power arrangement.

The anti-vibration additional optical system of the present invention is constructed on the basis of the above concept, and is detachably attached to the image plane side of the image forming system.

In the present invention, when the additional optical system is composed of a positive lens group, a negative lens group, and a positive lens group in order from the object side as shown in FIG. 1, the refractive powers of the second and third groups are φ. _{When 21} and φ ₃₁ , 1.0 <| φ ₂₁ / φ ₃₁ | <2.5 (1) The following condition must be satisfied.

As shown in FIG. 2, when the negative lens group, the positive lens group and the negative lens group are arranged in this order from the object side, the refracting powers of the second and third groups are φ ₂₂ and φ ₃₂ . are to meet <3.5 ..... (2) the condition | 1.5 <when | φ ₂₂ / φ _32.

Thus, while simplifying the lens structure of the additional optical system, the eccentricity sensitivity of the movable lens group driven for vibration compensation is sufficiently increased, and the eccentric field curvature is satisfactorily corrected. .

If the refractive power arrangement exceeds the conditional expression (1) or (2), it has a sufficiently large decentering sensitivity with a simple lens structure, and it becomes difficult to satisfactorily correct the decentered field curvature.

Next, numerical examples of the additional optical systems AL1 and AL2 and the image forming system ML shown in FIGS. 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.

[0055]

[Outer 1]

[0056]

[Outside 2]

[0057]

[Outside 3]

[0058]

As described above, according to the present invention, by attaching the anti-vibration optical means to the image side of the image taking system in a detachable manner, the image taking action can be performed only when the image taking system needs the image taking action. Achieves an additional optical system for image stabilization that achieves the function to reduce the size of the entire image capturing device, prevents deterioration of image quality during image stabilization, and easily obtains good optical performance during image stabilization can do.

[Brief description of drawings]

FIG. 1 is a lens cross-sectional view of a first embodiment in which an additional optical system for image stabilization according to the present invention is mounted on the image side of a known imaging system.

FIG. 2 is a lens cross-sectional view of a second embodiment in which an additional optical system for image stabilization according to the present invention is mounted on the image plane side of a known imaging system.

FIG. 3 is an aberration diagram when the movable lens unit B21 is fixed in FIG.

FIG. 4 is an aberration diagram when the movable lens group B21 is displaced in FIG.

FIG. 5 is an aberration diagram when the movable lens group B22 is fixed in FIG.

FIG. 6 is an aberration diagram when the movable lens group B22 is displaced in FIG.

FIG. 7 is an explanatory view of the refractive power arrangement of the additional optical system of the present invention.

FIG. 8 is an explanatory view of the refractive power arrangement of the additional optical system of the present invention.

[Explanation of symbols]

 AL1, AL2 Additional optical system B11, B12 First group B21, B22 Second group B31, B32 Third group ML Imaging system h Image height d d line g g line

Claims (5)

[Claims] 1. A plurality of lens groups detachably attached to the image plane side of an image forming system, a part of the plurality of lens groups is moved in a direction perpendicular to the optical axis, and the whole lens group is moved. An additional optical system for image stabilization, which compensates for blurring of a captured image that occurs when the system vibrates. 2. The plurality of lens groups comprises, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, 2. The blur of a photographed image, which occurs when the entire system vibrates by moving the second group in a direction perpendicular to the optical axis, to compensate.
Anti-vibration additional optical system. 3. The refracting powers of the second group and the third group are φ ₂₁ ,
1.0 <When the _{φ 31 | φ 21 / φ 31} | < additional optical system for vibration isolation as claimed in claim 2, characterized by satisfying 2.5 following condition. 4. The plurality of lens groups have, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, The second group is moved in a direction perpendicular to the optical axis to compensate for a blur of a captured image that occurs when the entire system vibrates.
Anti-vibration additional optical system. 5. The refracting powers of the second group and the third group are φ ₂₂ ,
1.5 <When the _{φ 32 | φ 22 / φ 32} | < additional optical system for vibration isolation as claimed in claim 4, characterized by satisfying the 3.5 following condition.