JP2000171698A - Image pickup optical system and image pickup device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a video which can be easily corrected without making a device larger and which has high definition even when a focal distance or a subject distance is changed by providing a correction group constituted by combining positive and negative lenses and having an axial prism effect and moving it on a plane or a spherical surface where the normal of the lens surface of the correction group is aligned with the optical axis so that optical performance due to a production error may be corrected. SOLUTION: The correction group PA is moved on the plane or the spherical surface where the normal of the lens surface thereof is aligned with the optical axis so as to correct the optical performance due to the production error. Assuming that the radius of curvature of the lens surface nearest to the object side of the correction group PA is R1 and the radius of curvature of the lens surface nearest to an image surface side is RK, (1) when R1≈RK>0, a spherical surface with center at a point separate from the lens surface nearest to the image surface side by RK on the optical axis, (2) when R1≈RK<0, a spherical surface with center at a point separate from the lens surface nearest to the object side by R1 on the optical axis, (3) when R1≈RK≈∞, a plane perpendicular to the optical axis, (4) when R1≫RK or R1≪RK, a plane perpendicular to the optical axis are set as the plane or the spherical surface where the correction group PA is moved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup optical system such as a television camera, a video camera, and a film camera, and an image pickup apparatus using the same. The aberration is corrected by displacing a correction group forming a part of the imaging optical system, so that high optical performance can be maintained.

[0002]

2. Description of the Related Art Conventionally, television cameras, photographic cameras,
For a video camera or the like, a zoom lens having a large diameter, high zoom ratio, and high optical performance is required.

In addition to this, operability and mobility are emphasized especially in a color television camera for broadcasting, and in response to the demand, a small-sized CCD (solid-state image pickup device) has been used as an image pickup device.

[0004] In recent years, as image pickup means such as CCDs (solid state image pickup devices) have become more precise, there has been an increasing demand for higher definition images in image pickup optical systems. In particular, with regard to imaging optical systems for broadcasting, it is required not only to obtain high resolution but also to minimize color bleeding and distortion with the development of high-vision systems.

On the other hand, in a broadcast imaging optical system, the number of lenses is increased to improve the imaging performance of the lens system (photographing optical system). High resolution can be obtained by setting a plurality of channels by using three or more imaging units.

[0006]

In order to obtain a high resolution in an image pickup apparatus, there are methods for increasing the number of lenses of an image pickup optical system and increasing the number of image pickup means.

However, as the number of lenses and the number of imaging means increase, the total number of factors subject to manufacturing errors due to these members increases. For this reason, the imaging performance of the entire imaging optical system is likely to be degraded due to an inherent aberration or the like due to a manufacturing error.

In an imaging optical system for a television camera,
Among such imaging performances, one of the ones that degrades image quality and is difficult to correct is registration asymmetry.

Normally, when no influence is caused by a manufacturing error, the registration is performed at an arbitrary focal length and an object distance of the image pickup optical system (when a zoom lens is used) as shown in FIG.
G-ch (green light channel), B-ch
(Blue light channel).

When the focal length or the subject distance changes, the registration shifts symmetrically about the point C by the amount of the chromatic aberration of magnification of the zoom lens.

However, when affected by a manufacturing error, the registration shifts as shown in FIG. 15 without maintaining the symmetry of the B-ch with respect to the G-ch. For this reason, asymmetric color bleeding occurs over the entire screen.

An asymmetrical color bleeding at the center of the screen (on the axis), which should not be present, is present, which significantly reduces the image quality.

The causes of the asymmetry of the registration are as follows: (a-1) Color shift due to a prism effect caused by eccentricity of a lens element in a zoom lens; Deviation of the fixed position of B-ch and R-ch (red light channel) with respect to -ch.

Further, regarding the cause (A-1), when the decentered lens element belongs to the moving group in zooming or focusing, the asymmetry changes depending on the focal length and the value of the object distance depending on the moving structure. .

[0015] For this reason, the tolerance at the time of manufacturing the lens element must be set to a very strict one, which is a factor that makes the manufacturing difficult. Therefore, it has become urgent to consider a relatively simple adjustment method.

Conventionally, several proposals have been made as an optical system for correcting an on-axis prism effect. For example,
Japanese Patent Application Laid-Open No. 61-223819 has a function of arranging a refraction-type variable apex prism closest to a subject in an image pickup optical system and deflecting an image in accordance with the shake of the apparatus.

In this optical system, a chromatic aberration (magnitude on the axis) proportional to the focal length of the imaging optical system and the degree of dispersion of the prism, which is generated due to the existence of the chromatic dispersion effect in the prism material, is corrected. I have.

When the imaging optical system has an in-focus function for adjusting the focus according to the subject distance or an optical system having a zooming function, a portion where a manufacturing error occurs is a lens group which moves during focusing or zooming.

In addition, due to the mechanical structure, in an image pickup optical system that moves back and forth while rotating with the optical axis as a symmetric axis, the amount of asymmetric color blur and the direction in which it occurs vary depending on the subject distance and focal length. Would.

For this reason, it is desired that the correction can be made without depending on the individual difference of the manufacturing error of the lens, the subject distance and the focal length.

According to the present invention, an axial prism effect (registration asymmetry) due to a manufacturing error of each element of the lens system can be easily corrected without increasing the size of the entire apparatus, and the focal length and the object distance can be corrected. It is an object of the present invention to provide an image pickup optical system capable of easily obtaining a high-definition image even if the image changes, and an image pickup apparatus using the same.

[0022]

According to the present invention, there is provided an imaging optical system comprising:
(1-1) An imaging optical system that forms an object image on a predetermined surface, wherein the imaging optical system has an on-axis prism effect constituted by a combination of at least one positive lens and negative lens. The correction group is characterized in that the correction group corrects the optical performance due to a manufacturing error by moving on a plane or a spherical surface whose normal to the lens surface coincides with the optical axis.

The image pickup apparatus of the present invention has a (2-1) configuration (1)
-2) an imaging optical system, at least one imaging unit that converts an object image formed by the imaging optical system into an electric signal, and a detection unit that detects at least two color channel information using the imaging unit. , Calculating means for calculating the difference between the respective color channel information, and driving means for driving the correction group based on the difference value.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. FIG. 1 is a sectional view of an imaging optical system including a correction group having an on-axis prism effect for correcting a manufacturing error.

In FIG. 1, L1 is a focus group (front lens group) having a positive refractive power as a first group. L2 is a variator having a negative refractive power for zooming as a second unit, and zooms from the wide-angle end (wide) to the telephoto end (tele) by monotonously moving on the optical axis to the image plane side. It is carried out. L3 is a compensator having a negative refractive power as a third lens unit, and moves non-linearly on the optical axis in order to correct an image plane variation accompanying zooming. Note that the third lens unit L3 may be configured with a positive refractive power. Variator L2 and compensator L
3 constitutes a variable power system.

SP is a stop, and L4 is a fixed relay group having a positive refractive power as a fourth group. PR denotes a color separation prism or an optical filter, and is shown as a glass block in FIG. IP is an image plane.

PA in the fourth lens unit L4 is a correction lens unit having an on-axis prism effect. However, in FIG. 1, the imaging optical system is in an ideal state that does not include a manufacturing error. FIG. 2 shows the lateral aberration at the telephoto end in this case.

In each lateral aberration diagram, d is the d line, g is the g line,
c indicates the c-line, F indicates the F-line, and S indicates the lateral aberration on the sagittal plane.

In the present invention, aberrations (optical performance) due to manufacturing errors are corrected using a correction group having an on-axis prism effect. The correction group includes at least one combination of a positive lens and a negative lens in the imaging optical system, and has an on-axis prism effect. The lens group having the correction unit is moved on a plane or a spherical surface whose normal line coincides with the optical axis.

A plane or a spherical surface on which a correction group having an on-axis prism effect for correcting optical performance due to the manufacturing error moves has a radius of curvature of a lens surface closest to the object side of the correction group of R1, and a most image plane. (1) When R1 側 RK> 0, a spherical surface centered on a point RK on the optical axis away from the lens surface closest to the image plane (A-2) R1 ≒ RK < When 0, a spherical surface centered on a point away from the lens surface closest to the object side by R1 on the optical axis. (A-3) When R1 垂直 RK ≒ ∞, a plane perpendicular to the optical axis. (A-4) R1≫RK or Rl When ≪RK, the plane is perpendicular to the optical axis.

The Abbe number of the material of the positive lens is νd1,
When the Abbe number of the material of the negative lens is νd2 and the combined power of the correction group having the prism effect in a predetermined reference wavelength region is φ, φ ≒ 0 ‥‥‥ (1) | νd1-νd2 | ≧ 25 (2) is satisfied.

The image pickup optical system of the present invention has a detecting means for detecting a focal length or a subject distance, and a driving mechanism for driving the prism effect correction group based on an evaluation value from the detecting means.

The image pickup optical system has at least one image pickup means, a detection means for detecting at least two pieces of color channel information using the image pickup means, and a calculation means for calculating a difference between each color channel information. And the prism effect correction group is driven by the difference value.

According to the above equation (1), the power of the correction group having the on-axis prism effect is set to almost 0, and the change of the optical axis when the correction group is moved perpendicularly to the optical axis is almost equal. 0
I am trying to be.

According to the equation (2), the chromatic aberration of magnification is generated asymmetrically when the correction group is moved perpendicularly to the optical axis by providing a dispersion difference in the lens elements constituting the correction group. ing.

When the correction group having the on-axis prism effect is moved perpendicularly to the optical axis according to the method and the conditional expression of the present invention, the change in the optical axis is suppressed to almost zero, and the on-axis prism is changed. The effects are fully corrected. At this time, an inherent aberration due to the eccentricity of the correction group occurs, and the imaging performance of the imaging optical system may be significantly reduced.

This is because the correction group having the on-axis prism effect is moved (eccentric) perpendicularly to the optical axis, so that it does not normally exist on the axis of the optical system rotationally symmetric with respect to the optical axis. This is due to the occurrence of on-axis coma and the like.

In such a case, the axis is moved perpendicularly to the optical axis of the correction group so that the movement of one glass plate perpendicularly to the optical axis does not affect the imaging performance at all. In order to suppress the occurrence of the above coma, the shape of the correction group is made as close as possible to a parallel flat plate, and the difference in the refractive index at the interface between the positive lens and the negative lens of the correction group is reduced. .

In the case where the above-described restriction is added to the correction group having the on-axis prism effect, the correction group cannot have a role of correcting aberration for improving the imaging performance of the original imaging optical system. Since the optical system is provided as an attachment in an arbitrary space of the imaging optical system, the size of the optical system may be increased.

In the Abbe number difference near the lower limit of the equation (2), if a correction group having an on-axis prism effect is formed by a cemented lens, a sufficient correction effect can be obtained by using a positive lens. The absolute value of the radius of curvature of the boundary surface between the lens and the negative lens becomes extremely small.

At this time, when considering the lens diameter of the correction group in which the amount of movement with respect to the optical axis is added to the normal beam effective diameter, the radius of curvature of the lens surface on the object side of the positive lens and the curvature of the lens surface on the image surface side In order to allow the intersection of the radii to escape outside the lens diameter of the correction group, it is necessary to increase the center thickness of the positive lens.

For this reason, especially in a broadcast zoom lens that requires a long back focus to dispose the color separation optical system immediately after the image forming optical system, the size of the optical system is increased.

On the other hand, in order to reduce the center thickness of the correction group, the absolute value of the radius of curvature of the boundary lens surface between the positive lens and the negative lens of the correction group may be increased.

However, when the radius of curvature of the boundary lens surface is reduced, the correction effect per unit length in the vertical direction of the correction group with respect to the optical axis decreases. In other words, in order to obtain a sufficient correction effect, the amount of correction of the prism effect must be increased, so that the size of the correction device increases.

Therefore, in the present invention, by specifying each element as described above, the individual difference of the manufacturing error of the lens system is favorably corrected without depending on the change of the subject distance and the focal length.

FIG. 3 is a lens cross-sectional view when the image pickup optical system shown in FIG. 1 has an eccentricity in a part L1a of the first lens unit L1 and a part L2b of the second lens unit as a manufacturing error.

In the first lens unit L1, the lens surface R1 to the lens surface R4 are integrally eccentric parallel to the ideal optical axis La by Δh, and the lens surface R13 to the lens surface R15 of the second lens unit L2. Are inclined by an angle △ θ with respect to the ideal optical axis La about the intersection of the lens surface R13 and the optical axis La. FIG. 4 shows a lateral aberration diagram at the telephoto end in this state.

FIG. 5 is an optical path diagram when the correction group PA having an on-axis prism effect is driven and deflected (parallel eccentricity) with respect to the manufacturing error shown in FIG. 3, and FIG. It is a transverse aberration figure. In FIG. 5, △ a represents the adjustment amount of the correction group PA having the on-axis prism effect.

In the imaging optical system according to the present embodiment, as an example of a manufacturing error, the lens surfaces R1 to R4 of the first lens unit are integrated and parallel eccentric from the ideal optical axis La, and From the lens surface R13 to the lens surface R
The chromatic aberration of magnification caused by tilting up to 17 with respect to the ideal optical axis La is reduced by an on-axis prism effect composed of a positive lens and a negative lens arranged in the fourth group in the entire imaging optical system. The correction is performed by moving the normal line of one lens surface of the correction group PA on the plane or the spherical surface that coincides with the optical axis.

The state shown in FIGS. 1, 3 and 5 is a case where each lens group is adjusted to the telephoto end in the image pickup optical system as described above. In the image pickup optical system shown in FIG. Amount Δh = + 0.4 mm, tilt eccentricity Δθ = + 60
As shown in FIG. 5, for a manufacturing error of 1 minute (= 1 °),
A correction group PA having an on-axis prism effect is placed on a lens surface R
Since 35 = ∞, chromatic aberration is corrected by moving the correction amount △ a = −0.8 mm on a plane perpendicular to the optical axis.

At this time, comparing the lateral aberration diagrams of FIGS. 2, 4, and 6, it is found that the correction group PA having the on-axis prism effect is provided.
It can be seen that when the above-described movement for correction is performed, only the chromatic aberration of the magnification mainly on the axis is satisfactorily corrected, and the inherent aberration associated with other movements is hardly generated. .

FIG. 7 is a schematic view of a main part of a second embodiment of the present invention. FIG. 1 is a cross-sectional view of an imaging optical system including a correction group having an on-axis prism effect for correcting a manufacturing error.

The imaging optical system shown in FIG. 7 has, in order from the object side, a first lens unit L1 having a positive refractive power and a focusing effect, and a second lens unit L1 having a negative refractive power and a zooming effect. The zoom lens includes a lens unit L2, a third lens unit L3 for correcting a change in image point due to a zooming effect, and a fourth lens unit L4 having an imaging effect.

SP is a stop, PR is a glass block equivalent to a color separation optical system, and PA in the fourth group is a correction group having an on-axis prism effect. However, in FIG. 7, the imaging optical system is in an ideal state that does not include a manufacturing error. FIG. 8 shows the lateral aberration at the telephoto end in this case.

FIG. 9 is a cross-sectional view of the imaging optical system shown in FIG. 7 when a part L1a of the first lens unit L1 and a part L2b of the second lens unit have an eccentricity as a manufacturing error. Of the first group L1,
The lens surfaces R1 to R4 are integral and decentered parallel to the ideal optical axis La by Δh, and the second group lens surfaces R1, 3 to the lens surface R15 have the ideal optical axis La.
△ θ centered on the intersection CR between the lens surface R13 and the optical axis.
Just leaning. FIG. 10 shows a lateral aberration diagram at the telephoto end in this state.

FIG. 11 is an optical path diagram when a correction group having an on-axis prism effect is driven and deflected against the manufacturing error shown in FIG. 9, and FIG. 12 is a lateral aberration at the telephoto end in that state. FIG. Δa represents the adjustment amount of the correction group having the on-axis prism effect.

In the imaging optical system of this embodiment, as an example of a manufacturing error, the group L1a of the first lens unit L1 from the lens surface R1 to the lens surface R4 is integrally decentered parallel to the ideal optical axis La, and The chromatic aberration of magnification caused by the inclination of the lens surfaces R13 to R15 of the second group with respect to the ideal optical axis is corrected by correcting the chromatic aberration of magnification, which is arranged in the fourth group, in the entire imaging optical system. The correction group PA having an on-axis prism effect composed of a lens and a negative lens is corrected by moving on a plane or spherical surface whose normal to the lens surface coincides with the optical axis.

In the imaging optical system of the second embodiment, the same manufacturing error as in the first embodiment, that is, the parallel eccentricity .DELTA.h = + 0.4 mm and the tilt eccentricity .DELTA..theta. = + 60 minutes (= 1.degree.), The correction group PA having the above prism effect is moved to the lens surface R3.
From the intersection of 0 and the optical axis is -77.46127 (= R30)
Correction amount on a curved surface centered on a point CR separated by
Chromatic aberration is corrected by rotating by a = −40 minutes.

At this time, comparing the lateral aberration diagrams of FIG. 8, FIG. 10, and FIG. 12, as in the first embodiment, the correction group PA having the on-axis prism effect It can be seen that when the lens is moved, only the chromatic aberration of magnification mainly on the axis is satisfactorily corrected, and almost no inherent aberrations due to other movements are generated.

As can be seen from the comparison between the first embodiment and the second embodiment, the shape and aberration coefficient of the lens element for satisfactorily correcting only such an on-axis prism effect can be understood.
There are various solutions depending on the location to be corrected and the degree of refraction of light rays.

FIG. 13 is a schematic diagram of a main part of an image pickup apparatus according to a third embodiment of the present invention. As in Embodiments 1 and 2, the imaging optical system illustrated in FIG. 13 has, in order from the object side, a first lens unit L1 having a positive refractive power and a focusing action, and a negative refractive power. The zoom lens includes a second lens unit L2 having a zooming action, a third lens unit L3 for correcting a change in image point due to the zooming action, and a fourth lens unit L4 having an imaging action. SP is a stop, PR is a glass block equivalent to a color separation optical system, and PA in the fourth group is
Denotes a correction group having an on-axis prism effect.

ID is an image pickup means, OD is a subject distance detecting means, and FD is a focal length detecting means.

Further, a color channel information detecting means GI of a wavelength range serving as a reference from the imaging means ID and a color channel information detecting means BI of another arbitrary wavelength range are arranged.

Now, when an image of a certain subject is formed on the image pickup means ID by the image pickup optical system, based on the evaluation value regarding the asymmetric color shift on the axis of the color channel information of the reference wavelength region and the other color channel information. The correction amount is calculated by the calculation device CL so that the asymmetric color shift on the axis is minimized,
Drive unit DR for correction group PA having on-axis prism effect
Chromatic aberration is corrected by moving the correction group.

The same effect can be obtained by providing such a function not in the imaging optical system but in an adjustment tool at the time of manufacturing.

The driving device DR includes a recording device M.
S is connected, for example, to record a correction amount at a typical subject distance and a focal length at the time of manufacture, and to correct the other subject distances and focal lengths by function approximation based on the recorded information. The amounts are calculated and interpolated, and in actual use, the current subject distance and the focal length are detected based on signals from the subject distance detecting means OD and the focal length detecting means FD, and correction corresponding to both information is executed. This dynamically corrects the asymmetric color shift on the axis.

In each of the above embodiments, another lens group in the fourth group or all of the fourth group may be used as the correction group having the on-axis prism effect.

The magnification change of the correction group may be performed by parallel eccentricity, rotational eccentricity, or a combination thereof.

The present invention can be applied to imaging devices such as video cameras, still cameras, film cameras, etc., in addition to TV zoom lenses.

Next, numerical examples of the present invention will be described. In the numerical examples, Ri is the radius of curvature of the ith lens surface in order from the object side, Di is the ith lens thickness and air spacing in order from the object side, and Ni and νi are the ith lens in order from the object side. Are the refractive index and Abbe number of the glass.

For the aspherical coefficient, the radius of curvature at the center of the lens surface is R, the direction of the optical axis (the traveling direction of light) is the X axis,
When the direction perpendicular to the optical axis is the Y axis and B, C, D, and E are aspherical coefficients, respectively,

[0072]

This is expressed by the following equation. “DX” is “× 10
^-X ".

[0073]

[Outside 1]

[0074]

[Outside 2]

[0075]

According to the present invention, by setting each element as described above, an on-axis prism effect (asymmetry of registration) due to a manufacturing error of each element of the lens system.
Optical system and an imaging apparatus using the same, which can easily correct the image without increasing the size of the entire apparatus, and can easily obtain a high-definition image even if the focal length or the subject distance changes. can do.

In particular, the imaging optical system according to the present invention has a sufficient use range and compensation range by correcting inherent aberrations caused by manufacturing errors, and has a small and inexpensive imaging performance with good imaging performance. Optics can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ideal state at a telephoto end according to a first embodiment of the present invention.

FIG. 2 is a lateral aberration diagram of an ideal state at a telephoto end according to the first embodiment of the present invention.

FIG. 3 is an optical path diagram when receiving a manufacturing error at the telephoto end according to the first embodiment of the present invention;

FIG. 4 is a lateral aberration diagram when a manufacturing error is received at the telephoto end according to the first embodiment of the present invention.

FIG. 5 is an optical path diagram when a manufacturing error at the telephoto end is adjusted according to the first embodiment of the present invention.

FIG. 6 is a lateral aberration diagram when a manufacturing error at the telephoto end is adjusted according to the first embodiment of the present invention.

FIG. 7 is a sectional view of an ideal state at a telephoto end according to a second embodiment of the present invention.

FIG. 8 is a lateral aberration diagram in an ideal state at a telephoto end according to a second embodiment of the present invention.

FIG. 9 is an optical path diagram when a manufacturing error is received at the telephoto end according to the second embodiment of the present invention.

FIG. 10 is a lateral aberration diagram when a manufacturing error is received at the telephoto end according to the second embodiment of the present invention.

FIG. 11 is an optical path diagram when a manufacturing error at the telephoto end is adjusted according to the second embodiment of the present invention.

FIG. 12 is a lateral aberration diagram when a manufacturing error at the telephoto end is adjusted according to the second embodiment of the present invention.

FIG. 13 is a configuration diagram of a second embodiment of the present invention.

FIG. 14: Registration when there is no asymmetric component

FIG. 15 Registration when there is an asymmetric component

[Explanation of symbols]

 L1 First group (focus group) L2 Second group (variator) L3 Third group (compensator) L4 Fourth group (relay lens) SP Aperture PR Glass block equivalent to color separation optical system PA Prism effect correction group on axis ID imaging means OD subject distance detecting means FD focal length detecting means GI reference wavelength band color channel information detecting means BI other wavelength band color channel information detecting means CL arithmetic unit DR driving device MS recording device d d line g g line c c line FF line S Sagittal La Optical axis

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA02 KA03 MA12 NA09 PA15 PA16 PB20 QA02 QA07 QA17 QA21 QA25 QA34 QA42 QA45 RA05 RA12 RA13 RA32 RA41 RA43 SA23 SA27 SA30 SA32 SA63 SA64 SA72 SA75 SB05 SB15 BB23 SB31 9BB01 BB06 GZ04 GZ14 HZ31 KK16 KK42

Claims (5)

[Claims] 1. An imaging optical system for forming an object image on a predetermined surface, wherein the imaging optical system has an on-axis prism effect constituted by a combination of at least one positive lens and negative lens. An imaging optical system, wherein the correction group corrects optical performance due to a manufacturing error by moving on a plane or a spherical surface whose normal to a lens surface coincides with the optical axis. . 2. A plane or a sphere on which the correction group moves has a radius of curvature of a lens surface of the correction object which is the most object example.
1. When the radius of curvature of the lens surface closest to the image plane is RK, (1) When R1 ≒ RK> 0, a spherical surface centered at a point RK away from the lens surface closest to the image plane on the optical axis. ) When R1 ≒ RK <0, a spherical surface centered on a point away from the lens surface closest to the object side by R1 on the optical axis. (3) When R1 ≒ RK ≒ ∞, a plane perpendicular to the optical axis. (4) R1≫RK or 2. The imaging optical system according to claim 1, wherein when R1≪RK, the plane is perpendicular to the optical axis. 3. The Abbe number of the material of the positive lens is νd.
1. When the Abbe number of the material of the negative lens is νd2 and the combined power of the correction group in a predetermined reference wavelength region is φ, φ ≒ 0│νd1-νd2│ ≧ 25 is satisfied. 3. The imaging optical system according to claim 1, wherein: 4. An image pickup optical system according to claim 1, 2, or 3, detection means for detecting a focal length or a subject distance of the image pickup optical system, and driving for driving the correction group based on an evaluation value from the detection means. An imaging device having a mechanism. 5. An image pickup optical system according to claim 1, 2 or 3, at least one image pickup means for converting an object image formed by the image pickup optical system into an electric signal, and at least two image pickup means using the image pickup means. An image pickup apparatus comprising: a detection unit that detects color channel information; a calculation unit that calculates a difference between each color channel information; and a driving unit that drives the correction group based on the difference value.