JPH0772372A - Rear focus type zoom lens - Google Patents

Abstract

PURPOSE:To excellently correct focusing movement by zooming all over the focal distance and subject distance by driving a focusing lens by using a position signal and information concerning the correction amount of out-of-focus amount stored in a storage means. CONSTITUTION:This zoom lens is provided with a 1st focusing correction means 5 and a 2nd focusing correction means; and the 2nd focusing correction means is provided with a focusing lens absolute position detection means 3 detecting the position of the focusing lens 4b on an optical axis, a zoom absolute position detection means 8 detecting the position of a variable power lens, and the storage means 11 storing the correction amount of the out-of-focus amount as a matrix consisting of plurally divided zoom areas and plurally divided subject distance areas. The focusing lens 4b is driven by a focusing lens driving means 7 by using the position signals from the detection means 3 and 8 and the information concerning the correction amount of the out-of-focus amount stored in the storage means 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear focus type zoom lens, and particularly to a compact, high-power zoom lens for zooming over the entire range from an infinitely distant subject having a short closest distance (focal length) to a very close subject. The present invention relates to a rear focus type zoom lens having a focus correction mechanism which is excellent in correction of the focus movement, and which is suitable for, for example, a 35 mm single-lens reflex camera, a video camera and an electronic still camera.

[0002]

2. Description of the Related Art Conventionally, in a zoom lens for focusing by moving a front lens group or a part of the front lens group on an optical axis, a focus lens for focusing on a certain object distance (object distance) The feeding amount of
It is almost constant regardless of the focal length. Therefore, focusing can be performed without requiring a complicated moving mechanism.

However, when the close-up shooting distance is set to be short, particularly in a zoom lens including a wide angle of view in which the focal length on the short focus side (wide angle side) is shorter than the diagonal line of the screen,
There is a problem that the diameter of the front lens becomes large in order to obtain a desired peripheral light amount ratio. For this reason, in the autofocus camera which has become popular in recent years, the load on the driving means for driving the focus lens becomes large,
There was a problem that quick autofocus could not be done.

In order to solve this problem, various conventional zoom lenses of the rear focus type have been proposed in which focusing is performed by a lens group behind the front lens group or a part thereof. .

In the case of this rear focus type zoom lens, the effective diameter of the first group becomes smaller than that of the zoom lens in which the front lens group is moved for focusing.
The overall lens diameter can be easily reduced, and close-up photography, especially very close-up photography, becomes easier. Furthermore, since the relatively small and lightweight lens group is moved, the driving force of the lens group can be small and quick focusing is possible. It has features such as matching.

However, the rear focus type zoom lens has a problem that the amount of extension of the focus lens for focusing on a certain subject distance differs depending on the focal length.

Therefore, in order to perform zooming while maintaining the in-focus state, a focus correction mechanism that corrects the position of the focus lens in association with the zooming is required.

Therefore, in the conventional rear focus type zoom lens, as a typical correction method therefor, there are a correction by an autofocus, a correction by an electronic cam, and a correction by a mechanical cam.

[0009] Regarding, for example, Japanese Patent Publication No. 56-475
In Japanese Patent Laid-Open No. 4-184405 and Japanese Patent Laid-Open No. 64-33512, for example, Japanese Laid-Open Patent Publication No. 52-114321 is proposed. Etc. have been proposed respectively.

In the first correction method by autofocus (Japanese Patent Publication No. 56-47533), the focus lens moved by the change of the focal length is moved to the focus lens based on the information from the focus detection means for autofocus. It is driven so that the focus surface is corrected so as not to move from a predetermined position.

In a correction method using an electronic cam (Japanese Patent Laid-Open No. 52-114321), the positional relationship between the variator (optical slide element) and the focus lens (optical slide element) on the optical axis during zooming is as follows. The object distance and the position of the variator are stored in the storage means, and during the zoom operation after focusing, the focus drive is performed based on the data read from the storage means, thereby preventing the focus movement. ing.

One of the correction methods using a mechanical cam (Japanese Patent Application Laid-Open No. 4-184405) is also a method used in an embodiment of the present invention described later. In this correction method, a focus lens at each focal length is used. The approximate focus curve, which is the movement locus for focusing from the infinity subject to the close-up subject, is superimposed by shifting the origin so that the focus error is minimized at all focal lengths and subject distances. A curved focus zoom / combined cam is used, and its use area is moved by zooming (zooming), and at the same time, the focus zoom / combined cam ring itself is moved in the optical axis direction to correct the focus movement.

In another correction method using a mechanical cam (Japanese Patent Laid-Open No. 64-33512), movement of the cam in the circumferential direction represents movement of the focus lens due to focusing, and movement in the radial direction results from zooming. By using a 3D cam that represents the movement of the focus lens, and tracing on the surface of the 3D cam with a pin that moves in the radial direction by zooming, the position on the optical axis of the focus lens that corresponds to the zoom position is obtained and the focus is moved. Is being corrected.

[0014]

The above-described conventional autofocus correction method has the merit of simplifying the mechanical structure, but the focus correction greatly depends on the capability of the focus detection means. In the case of an object that is not suitable for the means, there is a problem in that the focus cannot be corrected sufficiently and the focus detection tends to be delayed, so that a comfortable shooting environment cannot be obtained. Further, since the actuator (generally a motor) as the driving means is always driven, there is a problem that the load on the power source becomes large.

Unlike the above-described correction method using the auto focus, the correction method using the electronic cam has the advantage that it is not affected by the capability of the focus detection means, but the focus drive is always performed during focus correction. There are still points, and since the focus movement amount caused by the drive error of the focus driving means is large, precise control by the focus driving means is required. There is also a problem that a storage means having a relatively large storage capacity is required.

In the former correction method using a mechanical cam, unlike the above-described correction method, the focus driving means is not used during the zoom operation, so that power is not consumed for focus correction. It has the advantage of being able to fully support manual zoom. Moreover, since the system is completed inside the lens barrel, there is also an advantage that the system on the camera side does not matter.

However, in a power arrangement having a focus extension curve that sharply bends, it may not be possible to approximate a focus / zoom cam well, and thus a large focus movement may occur depending on the subject distance.

Although the latter correction method using a mechanical cam has the same merit as the former correction method, it is necessary to use a pin sufficiently smaller than the size of the three-dimensional cam in order to obtain a correct lens position. However, there is a problem in that it is difficult to make the lens barrel compact because the three-dimensional cam cannot have a cylindrical configuration that covers the outside of the optical system.

The present invention solves the problems of each of the conventional correction methods by appropriately configuring the focus correction mechanism for correcting the focus movement during zooming, and achieves a high magnification and a close range (focal length). It is an object of the present invention to provide a rear focus type zoom lens which has a relatively easy configuration as a total system for a short and compact zoom lens.

[0020]

A rear-focus type zoom lens according to the present invention has (1-1) a zoom function, and the amount of movement of the focus lens when focusing on the same object differs depending on the zoom position. In a focus type zoom lens, during zooming after focusing, within a first object distance range, a first focus correcting unit that mechanically maintains a predetermined focus state in association with the first object distance range, and the first focus correcting unit. In the second object distance range in which the out-of-focus amount after the operation of the out-of-focus correction means exceeds the predetermined focus state, the out-of-focus amount is electronically linked based on the information about the correction amount of the out-of-focus amount. And a second focus correction means for compensating the focus of the focus lens on the optical axis of the focus lens. Focus lens absolute position detecting means for detecting the position, zoom absolute position detecting means for detecting the position of the variable magnification lens, and a zoom area obtained by dividing the correction amount of the out-of-focus amount into a plurality of areas and a subject distance area divided into a plurality of areas. Using the storage means for storing as a matrix, the position signals from the focus lens absolute position detection means and the zoom absolute position detection means, and the information regarding the correction amount of the out-of-focus amount stored in the storage means. It is characterized by having a focus lens driving means for driving the lens.

In particular, the position signal detected by the focus lens absolute position detection means and the information regarding the correction amount of the out-of-focus amount stored in the storage means are based on the rotation angle of the focus rotation member. .

(1-2) In a rear focus type zoom lens in which the amount of extension for focusing of the focus lens changes according to the change of the focal length due to zooming, at least one operation is performed within at least one predetermined subject distance range. And at the time of zooming after focusing on any object point within at least the predetermined subject distance range, a first focus correcting means that mechanically maintains a predetermined focused state in association with the zooming. If the defocus amount after the first focus correction means is activated exceeds the predetermined in-focus state, at least one object distance range is activated, and based on the information regarding the correction amount of the defocus amount. Second focus correction means for electronically compensating for the out-of-focus amount, and the second focus correction means detects the position of the focus lens. Focus lens absolute angle detection means, zoom absolute position detection means for detecting the position of the lens relating to zooming, storage means for storing information regarding the correction amount of the out-of-focus amount, and focus lens absolute angle detection means. Focus lens driving means for driving the focus lens based on the information regarding the correction amount of the out-of-focus amount called from the storage means based on the position signal from the zoom absolute position detection means, and the focus lens driving means. The information about the correction amount of the deviation amount is characterized in that it is stored in the storage means in a matrix composed of a plurality of divided zoom areas and a plurality of divided object distance areas.

In particular, the information detected by the focus lens absolute angle detection means and the information regarding the correction amount of the out-of-focus amount stored in the storage means are represented by using the rotation angle of the focus rotation member. Is characterized by.

[0024]

Embodiment 1 FIG. 1 is a block diagram of essential parts showing a system configuration of Embodiment 1 of the present invention.

In the figure, 1 is a lens system, 2 is a camera system (camera main body), and 3 is a focus absolute angle detection means, which detects a rotation angle of a focus rotation member (not shown) and detects a focus lens 4b which will be described later. The position on the optical axis is detected and the position information is sent to the CPU 10. 4a,
4c is a lens (variable magnification lens group) related to the variable magnification operation,
Reference numeral 4b denotes a focus lens (focus lens group) which corrects an image plane variation due to zooming and performs focusing.

Reference numeral 5 denotes a first focus correction means, which operates at least within at least one predetermined subject distance range (first subject distance range) and at least any object point within the predetermined subject distance range. In contrast, during zooming after focusing, a predetermined focused state is mechanically maintained in association with the zooming.

A zooming cam mechanism 6 and a focus lens driving means 7 drive the focus lens 4b based on a signal from the CPU 10. Reference numeral 8 denotes a zoom absolute position detection means, which detects the positions of the lenses 4a and 4c on the optical axis and sends the position information to the CPU 10. Reference numeral 9 is a data search means, and RO as a storage means.
Information stored in M (storage element) 11 is stored in CPU 1
It searches based on the signal from 0. Reference numeral 10 is a CPU of the lens system 1.

The ROM 11 stores information about the correction amount of the out-of-focus amount, and the information is composed of a matrix of a plurality of divided zoom areas and a plurality of divided object distance areas. It is expressed using the rotation angle of the member.

Reference numerals 12 and 13 denote switches, which are CPUs.
A command signal is sent to 10. 14 is a mirror.

Defocusing amount detecting means 15 detects the focus state of the lens system 1. 16 is a camera system C
A PU is used to calculate and control the amount of movement of the focus lens 4b on the optical axis using the signal from the defocus amount detecting means 15.

The focus lens absolute angle detecting means 3
Each element of the zoom absolute position detecting means 8, the storage means 11, and the focus lens driving means 7 constitutes one element of the second focus correcting means.

Next, the focusing operation of this embodiment will be described with reference to the flow chart shown in FIG.

In this embodiment, the information on the focus state of the subject image guided from the lens system 1 is sent to the defocus amount detecting means 17 of the camera system 2.

First, when SW1 is turned on in step 201, the defocus amount detecting means 17 detects the defocus amount def in step 202. Next, in step 203, this defocus amount def is compared with a preset threshold value, and if the defocus amount def is large, step 2
In 04, the CPU 18 calculates the calculation coefficients Sn, An, B determined by the zoom position of the lens system 1, the focus lens position, etc.
Read Pn, etc.

Next, at step 205, each calculation coefficient Sn,
The movement amount x of the focus lens 4b on the optical axis is calculated from An and BPn and the defocus amount def, and then step 2
At 06, the calculation result is sent to the CPU 12 of the lens system 1.

Next, at step 207, the CPU 12 sends a control command to the focus lens driving means 7 so that the movement amount of the focus lens 4b becomes x, and moves the focus lens 4b on the optical axis.

When the above operation is completed, the process returns to step 202 and the defocus amount detecting means 17 detects the defocus amount def again, and then at step 203, the defocus amount def becomes smaller than the threshold value as described above. The operation (from step 202 to step 207) is repeated.

On the other hand, in step 203, the defocus amount d
When ef becomes equal to or less than the threshold value, the CPU 18 determines that focusing has been performed, waits for a release command from the user through SW2 in step 208, and releases in step 209 to end the focusing operation.

Depending on the camera system, the release may be prioritized when the SW2 is turned on even in a non-focused state.

Next, the first focus correcting means 5 according to this embodiment will be described.

FIG. 3 is an explanatory view for explaining the shape of the focus / zoom cam used in the first focus correcting means 5.

In the figure, the vertical axis represents the sum of the focus angle and the zoom parameter (hereinafter referred to as "ZP") which is a parameter for design convenience. This zoom parameter corresponds to the rotation angle of the manual zoom ring, and normally has a certain reference focal length state as 0, and the other focal length states have values proportional to the rotation angle of the zoom cam ring from the reference focal length state. In FIG. 4 described later, the wide-angle end is 0 and the telephoto end is 1.

The focus angle corresponds to the rotation angle of the manual focus ring, and its origin is determined by the subject at infinity, but the maximum value is determined by the shape of the focus / zoom cam. The focus angle will be described in detail later.

The horizontal axis represents the amount of displacement in the optical axis direction on the focus cam ring, and in this embodiment, the position of the focus lens that focuses on the infinitely distant object at the wide-angle end is the origin.

In FIG. 3, a curve 3a is a cam for focusing and zooming, and the focus extension curve for each focal length of each curve 3b, 3c, 3d is set so that the focus error is minimized at all focal lengths and object distances. It is a representative curve which is superposed and approximated.

For example, the curve 3b shows the extension of the focus lens when focusing from an object at infinity to a near object at the wide-angle end.

FIG. 4 is an explanatory view showing an operation for obtaining a focus extension amount for focusing on an arbitrary focal length and an arbitrary subject distance by using the cam for focus zoom.

The focus zoom / combined cam moves in the vertical axis direction represented by the zoom parameter according to the zoom operation. In the figure, the rotation of the focus zoom / combined cam ring interlocked with the rotation of the zoom cam ring is expanded on a plane. And illustrated.

As will be described later, the focus-zoom cam ring itself moves in the optical axis direction by the zoom operation.
It doesn't show it. Therefore, in the figure, only the focus extension amount is shown, not the position on the optical axis of the focus lens.

The area of the focus / zoom cam used for focusing in this embodiment is the portion surrounded by the straight lines 4e and 4f in the figure, and is moved by the zoom operation as shown in the figure. To do.

That is, at the wide-angle end, the upper end of the focus / zoom cam moves downward as it moves to the telephoto end, and becomes the lowest end region at the telephoto end. Then, the desired follow-out amount is obtained by rotating the cam follower interlocking with the focus lens within the moved region.

Further, as described above, the zoom operation is performed while the focus angle (rotation angle) is fixed to a value corresponding to a certain object distance at a certain focal length by specifying the shape of the focus / zoom cam. , The focus extension amount corresponding to the focal length after zooming can be approximately obtained.

Incidentally, wmod, mmod, tmod in the figure
Indicates the focus extension amounts at the wide-angle end, the middle, and the telephoto end, respectively, at the closest subject distance.

Further, it is shown that focusing from the object at infinity to the object at the closest distance can be performed with the same focus angle regardless of the zoom position.

By the way, there is a power arrangement of the lens system in which both the movement locus of the focus lens by the zoom operation and the movement locus of the focus lens by the focusing operation can be represented by almost one curve. The degree of freedom is limited, which is not preferable.

Therefore, in this embodiment, the focus zoom and cam ring itself is configured to be movable in the optical axis direction in conjunction with the zoom operation, so that the rotation amount of the focus angle for focusing with respect to the zoom rotation angle. Also, the rotation direction can be set freely.

FIG. 5 is an explanatory view showing, as an example, the zoom movement locus of the focus lens with respect to the closest object. As shown in the figure, the focus lens position (position on the optical axis of the focus lens) is the amount of movement of the focus zoom / combined cam ring in the optical axis direction (moved from the origin 0 in the figure) and the amount of focus extension. Curve a by the sum of
Is changing like.

Now, the focus angle will be described.

As described above, the focus extension amount for focusing of the focus lens is obtained by rotating the cam follower interlocking with the focus lens and inscribed in the cam for focus zoom with the focus rotating member along the cam. . The rotation angle for focusing the focus rotation member is the focus angle described above. By configuring this focus angle as described above, when focusing on the same subject, it is possible to suppress the change in focus movement due to the focal length to be small.

FIG. 6 shows a change in focus angle due to a zoom operation when a focus zoom / combined cam which is considered to be optimal is designed for a zoom lens having a zoom ratio of about 4 times.

As a result, when zooming from the telephoto end to the wide-angle side as shown in the figure, even if the focus angle is fixed at the telephoto end, the focus angle is the focus angle at another focal length during zooming. Since the difference between and is small, the amount of focus movement that occurs is small, and an object point within the object distance range excluding a part on the closest object side can be included in the depth of field.

That is, once the focusing operation is performed at the telephoto end to obtain the focus angle, it is not necessary to perform the focus drive again, and the in-focus state can be maintained at all focal lengths.

Further, FIG. 7 shows a change in the focus angle due to the zoom operation when the focus-zoom cam is designed for the zoom lens in which the zoom ratio is increased to about 7 times while achieving the compactness and the close-up distance reduction. .

In this case, as shown in the figure, the focus angle is determined at the telephoto end with respect to an object point within the object distance range from the infinite object to the object distance of about 2.2 m (first object distance range). The amount of focus movement due to subsequent zooming is ±
It can be 0.3 mm or less. This is within the allowable range.

That is, the focus movement amount can be corrected by the first focus correction means. However, from the subject distance of 2.2 m to 0.5 m (second subject distance range), the focus movement amount cannot be corrected with the same focus angle, and the amount is out of the allowable range. In this embodiment, at this time, the focus movement amount is corrected by the second focus correction means.

Next, the overall focus correction operation in this embodiment will be described with reference to the flowchart of FIG.

First, when SW1 is turned on in step 801, a focusing operation is started based on the flowchart shown in FIG. 2 in step 802, and after completion, step 803.
Then, the CPU 10 in the lens system 1 reads the focus angle information FPo from the focus absolute angle detection means 3 and the zoom position information ZPo from the zoom absolute position detection means 8. This focus angle information FPo is expressed using the rotation angle of the focus rotation member.

In the ROM 11 as a storage means, a zoom position / zoom region representative value correspondence table which stores the zoom position into a plurality of regions and each zoom region is represented using a representative value is stored. The CPU 10 uses the correspondence table in the ROM 11 via the data search means 9,
Representative value Z of the zoom area corresponding to the zoom position information ZPo
Po ′ is obtained, and at the same time, the representative value ZP is calculated in step 805.
Let o ′ be the initial value ZPtump ′.

Next, at step 806, the representative value ZP on the matrix relating to the correction amount of the defocus amount in the ROM 11
The data stored in the o'row is searched for the value FPo 'closest to the focus angle information FPo.

Next, in step 807, by recognizing which column in the matrix to which the value FPo 'belongs,
A subject distance area S corresponding to the subject is obtained.

Next, at step 808, the subject distance area S
Determines whether it is the area in which the focus correction is performed only by the first focus correction means described above or the area in which the focus correction is performed by the second focus correction means described later. As a result, if the subject distance area S is an area in which only the first focus correcting means is used, the CPU finishes the processing, and if not, executes the operation of the second focus correcting means after step 809.

In step 809, the CPU 10 reads the zoom position information ZP again, and then in step 810, R
Using the correspondence table in the OM 11, the representative value ZP 'of the zoom area to which the zoom position information ZP belongs is obtained.

Next, at step 811, the representative value ZP 'of the zoom area is compared with the initial value ZPtump', and if it is determined that these values are different and correction driving is necessary during zooming, step 812. Then, the value of the data FP ′ in the representative value ZP ′ row of the zoom region in the column of the subject distance region S is read on the matrix regarding the correction amount of the out-of-focus amount.

Next, in step 813, the control pulse Pk for the focus lens driving means 7 is calculated by the following equation: Pk = (FP'-FPo ') / B (B is a conversion coefficient), and in step 814 the control pulse for the focus lens driving means 7 is calculated. Pk is sent, and the focus lens 4b is driven in step 815.

Next, at step 816, the representative value ZP 'is set as a new initial value ZPtump' and FP 'is set as a new FPo.
Then, the value of the zoom position information ZP is read again, a representative value ZP ′ of the zoom area to which the zoom position information ZP belongs is obtained using the correspondence table in the ROM 11, and the representative value ZP is stored. 'And initial value ZPtum
p ′ is compared, and the above-described operation (from step 809 to step 816) is repeated every time when both values are different, and the focus position is corrected and driven.

On the other hand, in step 811, the representative value ZP '
And it is determined that the initial value ZPtump 'is equal, it is determined that the CPU 10 is not zooming or correction driving is not necessary, and then in step 817, S
Determines the W1 state (ON / OFF), and SW1 is OFF
If so, the CPU ends the process, and if not, returns to step 809 again to perform the operation described above (step 80).
9 to step 816) is repeated.

In this embodiment, by performing the focus correction according to the procedure described above, it is possible to drive the focus lens to a proper focus angle even during the zoom operation, thereby performing the zoom operation. The amount of focus movement at is suppressed to be small, and the in-focus state is maintained in a good condition.

Note that, during any of the above-mentioned operations, when the user turns on the SW2, the focusing operation is performed or the shutter is released without performing the focusing operation.

Further, in this embodiment, as described above, the object distance range using only the first focus correction means,
The focus movement during zooming was corrected by dividing it into a subject distance range to be electronically controlled by U, but electronic correction may be added in all subject distance ranges. The focus movement amount can be further reduced in the entire object distance range to maintain the in-focus state in a good condition.

The present invention can be applied to a rear focus type zoom lens other than the lens structure shown in FIG. 1 in the same manner as the above-mentioned embodiment.

[0081]

As described above, according to the present invention, the focus driving means includes the first focus correcting means constituted by the cam mechanism, though the structure is relatively easy to complete in the lens system as described above. The focus movement amount is small with respect to the drive error of the main subject, and the manual zoom is possible at the main subject distance, and the focus drive means is not always driven so that the power supply is not burdened. Since the area is obtained and the correction drive is performed, the storage capacity can be reduced, and the focus angle is directly used as the data, so that all the focal lengths and the subject distances can be calculated without the CPU performing complicated and highly accurate calculation. Achieve a rear focus type zoom lens that can satisfactorily correct focus movement due to zooming Door can be.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts showing a system configuration of a first embodiment of the present invention.

FIG. 2 is a flowchart showing a focusing operation according to the first embodiment of the present invention.

FIG. 3 is an explanatory view showing the shape of a focus / zoom cam.

FIG. 4 is an explanatory diagram showing the principle for obtaining the amount of extension by using a cam that also serves as a focus zoom.

FIG. 5 is an explanatory diagram showing a zoom movement locus of the focus lens with respect to a close-up subject.

FIG. 6 is an explanatory diagram showing a change in focus angle due to zooming when the first focus correcting means is applied to a zoom lens having a zoom ratio of about 4 times.

FIG. 7 is an explanatory diagram showing a change in focus angle due to zooming when the first focus correcting means is applied to a zoom lens having a zoom ratio of about 7 times.

FIG. 8 is a flowchart showing a focus correction operation according to the first embodiment of the present invention.

[Explanation of symbols]

 1 lens system 2 camera system 3 focus lens absolute angle detection means 4a lens group 4b focus lens group 4c lens group 5 first focus correction means 6 zooming cam mechanism 7 focus lens drive means 8 zoom absolute position detection means 9 data search means 10 CPU 11 storage means (ROM) 12 SW1 13 SW2 14 mirror 15 defocus amount detection means 16 CPU

Claims (4)

[Claims] 1. A rear-focus type zoom lens having a zoom function, wherein the amount of movement of the focus lens when focusing on the same object varies depending on the zoom position, and within the first object distance range during zooming after focusing. Then, a first focus correction means that mechanically maintains a predetermined focus state in conjunction therewith, and a first focus correction means after the operation of the first focus correction means exceeds the predetermined focus state. In the second object distance range, there is provided a second focus correcting means which is adapted to electronically compensate the out-of-focus amount based on the information regarding the correction amount of the out-of-focus amount in association with the range. The focus correction unit 2 includes a focus lens absolute position detection unit that detects the position of the focus lens on the optical axis, and a position of the variable power lens. Zoom absolute position detecting means, storage means for storing the correction amount of the out-of-focus amount as a matrix composed of a plurality of divided zoom areas and a plurality of divided object distance areas, and the focus lens absolute position detecting means and the And a focus lens driving means for driving the focus lens by using a position signal from the zoom absolute position detecting means and information on the correction amount of the out-of-focus amount stored in the storage means. Rear focus type zoom lens. 2. The position signal detected by the focus lens absolute position detection means and the information regarding the correction amount of the out-of-focus amount stored in the storage means are based on the rotation angle of the focus rotation member. The rear focus type zoom lens according to claim 1. 3. A rear focus type zoom lens in which a moving amount for focusing of a focus lens changes in accordance with a change in focal length due to zooming, at least one working within a predetermined object distance range, and A first focus correction means for mechanically maintaining a predetermined focus state in association with the zooming during zooming after focusing on at least any object point within the predetermined subject distance range; When the out-of-focus amount after the operation of the first focus correcting means exceeds the predetermined in-focus state, the first out-of-focus amount operates at least in one object distance range, and based on the information regarding the correction amount of the out-of-focus amount, A second focus correction means for electronically compensating for an out-of-focus amount, and the second focus correction means detects a position of the focus lens. Focus lens absolute angle detection means, zoom absolute position detection means for detecting the position of the lens relating to zooming, storage means for storing information regarding the correction amount of the out-of-focus amount, focus lens absolute angle detection means, and And a focus lens driving unit that drives the focus lens based on information about the correction amount of the out-of-focus amount that is called from the storage unit based on a position signal from the absolute zoom position detection unit. The rear-focus type zoom characterized in that the information regarding the correction amount of the amount is stored in the storage means in a matrix composed of a plurality of divided zoom areas and a plurality of divided object distance areas. lens. 4. The information detected by the focus lens absolute angle detection means and the information regarding the correction amount of the out-of-focus amount stored in the storage means are expressed by using the rotation angle of the focus rotation member. 4. The method according to claim 3, wherein
Rear focus type zoom lens.