JPH103030A - Autofocus device and interchangeable zoom lens - Google Patents

Abstract

(57) [Problem] To provide an automatic focusing device that does not erroneously perform tracking determination even with a zoom lens in which a focal point moves due to zooming. SOLUTION: An automatic operation having a first driving mode for detecting a movement of an object in an optical axis direction and correcting a lens driving amount according to the movement of the object, and a second driving mode for not correcting a lens driving amount is performed. Output means (117, 217, 317) for outputting a focus shift signal indicating that a focus shift due to the zooming operation occurs in a region where a focus shift due to the zooming operation of the photographing lens occurs in the focusing device.
And prohibiting means (123, 223, 323) for prohibiting driving in the first driving mode in response to the focus movement signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device and an interchangeable zoom lens most suitable for a camera for photographing.

[0002]

2. Description of the Related Art In an automatic focusing camera which performs an automatic focusing operation while repeatedly performing focus detection, a movement of a subject in an optical axis direction is detected from a change in a focus detection state and a driving state of a focusing lens. 2. Description of the Related Art There is known an apparatus which performs drive control such as tracking drive or moving object predictive drive, which performs drive control so that an in-focus state is continuously obtained for an object moving in an axial direction. For example, JP-A-63-148218 discloses a specific operation principle.

As an optical system used for an automatic focusing camera, there are a single focus lens and a zoom lens capable of changing a focal length. A zoom lens originally does not move the focal point due to the zooming operation, that is, the image plane position does not move in the optical axis direction due to the zooming operation, but in recent years the optical system has been downsized and the zoom ratio has been increased. Due to restrictions in optical design, zoom lenses in which a focal point shift occurs due to a zooming operation are being commercialized. In particular, when the focal point shifts in the entire photographing area, it may be called a varifocal lens to distinguish it from a zoom lens.

[0004]

In the automatic focusing apparatus that performs the tracking drive as described above, the movement of the image plane is detected and the tracking determination is performed. In the case of the combination, there is a problem that the movement of the imaging plane due to the zooming operation is erroneously recognized as the movement of the imaging plane due to the movement of the subject. In other words, despite shooting a still subject, the camera enters tracking mode by performing a zooming operation, and excessive correction of the lens drive amount due to the tracking mode takes place. It takes a long time. In the prior art, there was no one that appropriately addressed this problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide an automatic focusing apparatus that does not erroneously perform tracking determination even with a zoom lens in which a focus shift occurs due to a zooming operation. .

[0006]

In order to achieve this object, in the automatic focusing apparatus according to the first aspect of the present invention, the movement of the subject in the optical axis direction is detected, and the amount of lens drive is corrected in accordance with the movement of the subject. In an automatic focusing apparatus having a first drive mode and a second drive mode in which correction of a lens drive amount is not performed, in an area where a focus movement by a zooming operation of a photographing lens occurs, a focus movement by a zooming operation occurs. Output means (11) for outputting a focus shift signal
7, 217, 317) and prohibiting means (123, 123) for prohibiting driving in the first driving mode in accordance with the focal point movement signal.
223, 323).

In the interchangeable zoom lens according to the second aspect of the present invention, a first drive mode in which the movement of the subject in the optical axis direction is detected and the drive amount of the lens is corrected in accordance with the movement of the subject, and the drive amount of the lens is corrected. Output means (7) for outputting to the autofocus camera a focus shift signal indicating that a focus shift occurs due to a zooming operation of the taking lens in an interchangeable lens that can be mounted on the autofocus camera having no second drive mode. And restricts driving in the first driving mode according to the focal point movement signal.

In the interchangeable zoom lens according to the third aspect of the present invention, the first drive mode in which the movement of the object in the optical axis direction is detected and the lens drive amount is corrected in accordance with the movement of the object, and the lens drive amount is corrected. In an interchangeable lens that can be attached to an autofocus camera having no second drive mode, a focus movement signal indicating that a focus movement due to the zooming operation occurs in an area where the focus movement due to the zooming operation of the photographing lens occurs. An output unit (7) for outputting to the camera is provided, and the driving in the first driving mode is restricted according to the focal point movement signal.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 6 show an embodiment of the present invention, taking the case of an interchangeable lens system as an example.

First, the overall system will be described with reference to FIG. The interchangeable lens 1 is mounted on the camera body 2. The light beam transmitted through the photographing optical systems L1 and L2 is transmitted through a half mirror L3 in the camera body 2, and is further guided to a focus detection unit 3 by a submirror L4. At the time of photographing, the light beam forms an image on the film surface F. The defocus amount, that is, the shift amount of the actual image plane position with respect to the planned image formation plane is obtained by the focus detection unit 3 and transmitted to the control unit 5. The control unit 5 converts the defocus amount into a drive amount using the information transmitted from the lens information generation unit 7 and controls the lens drive unit 9. At this time, the lens position control is performed by feeding back the driving amount by the monitor unit 11. The driving force of the lens driving means 9 is transmitted to the lens driving transmitting means 1 in the lens 1 via a connecting member (not shown) of the mounting portion.
3, and the focusing drive of the focusing lens unit L2 is performed. The position of the focusing lens unit L2 is detected as an absolute position by the focus position detection unit 15 and transmitted to the lens information generation unit 7.
The focusing lens unit L2 includes a distance operation ring 17
It can be moved by manual operation, and manual focusing is possible. When the zoom operation ring 19 is operated, the zooming lens unit L1 moves to perform a zooming operation. The position of the zooming lens group L1 is detected as an absolute position by the zoom position detecting means 21 and transmitted to the lens information generating means 7.

Next, the tracking drive will be described with reference to FIG.

The vertical axis represents the movement of the lens and the movement of the subject, and the horizontal axis represents the passage of time. A straight line 81 represents the movement of the subject moving at a constant speed. The trajectory 83 represents the movement of the lens, and starts from the position 83a.

In normal driving, a defocus amount is detected at a lens stop position, and a drive corresponding to the detected defocus amount is performed. That is, the first drive performs the drive corresponding to the defocus amount 87, and the second drive performs the drive corresponding to the defocus amount 89. Thereafter, since this operation is repeated, the lens is driven along the locus indicated by the solid line 83b and the broken line 83c. In this state, since the subject continues to move in each drive, the lens cannot reach the focal point.

Next, when the moving subject is determined and the tracking mode is entered, it is determined that the subject is moving since the focusing point is not reached by a plurality of driving operations within the range of the first solid line 83b. Thereafter, the lens is driven along the locus 85 indicated by the solid line. In other words, the lens is driven by a drive amount 93 that is corrected in a direction in which the drive amount is increased in anticipation of the movement of the subject during driving with respect to the conventionally driven amount 91.

FIG. 3 shows the case of intermittent drive in which the lens drive is stopped to perform defocus detection. However, in the case of performing defocus detection while performing lens drive,
By performing speed control that matches the trajectory of the movement of the subject, higher focusing accuracy can be obtained.

Next, referring to FIG. 2, a zoom lens having a focal point shift will be described.

The vertical axis indicates the change in the focal length.
Or the detected position of the zoom position detecting means 21. The horizontal axis represents the change in distance, which corresponds to the rotation angle of the distance operation ring 17 or the detection position of the focus position detection means 15. The scale 51 indicates the shooting distance at the wide end.
Trajectories 53 to 69 are obtained by connecting distance operation ring rotation angles at respective focal lengths corresponding to the same photographing distance, and represent focal point movement. The range A is a region where the focal point does not move due to zooming. For example, the focal positions at the shooting distances of 20 m and 10 m do not change due to zooming. The range B is an area where the focal point moves. For example, at a distance ring position where the focus is set to 3 m at the wide end, the focus is set to 5 m at the tele end, but the subject at 3 m is not focused. In other words, if zooming is performed after focusing on a 3 m object at the wide end, the image forming plane moves from the film plane.
This state is similar to the state in which the subject is moving as shown in FIG.

Therefore, if zooming is performed while viewing a stationary subject, the control means 5 erroneously recognizes that the subject is moving, and performs tracking mode driving with overcorrection as indicated by a locus 85 in FIG. . If zooming is stopped in this state, the lens drive will overrun because the subject is stationary, and the focal point will be too far in focus. as a result,
It is difficult to focus or the focusing time is increased by the time required to return to the focal point, and the usability is deteriorated.

In order to avoid this problem, the present invention performs the processing shown in the flowcharts of FIGS. These processes are processes in the control unit 5 in the camera body 2.

FIG. 4 shows a first embodiment. Step 111
The AF operation is started at step 117, and at step 117, it is checked whether the focus movement flag obtained from the lens is 1 or 0. The focus movement flag is determined by the lens information generating means 7 shown in FIG. 1 using the position information from the focus position detecting means 15 to determine whether the focusing lens group is located in the area B shown in FIG. You. The lens information generating means 7 transmits a value 1 indicating that there is a focus shift to the control means 5 in the camera body 2 when the lens is located in the area B, and there is no focus shift when the lens information is located in the area A. Is transmitted to the control means 5.

If the result of step 117 is 1, since the focal point has moved due to zooming, step 1 is executed.
At 21, the lens is driven in the normal mode. If the result of step 117 is 0, there is no focus movement due to zooming, so it is checked in step 123 whether the subject is a moving subject. If it is determined that the subject is a moving subject, the lens is driven in the tracking drive mode in step 127. If it is determined that the subject is not a moving subject, the lens is driven in the normal mode in step 121. Thereafter, the same processing is repeated every time the defocus is detected.

FIG. 5 shows a second embodiment. In the second embodiment, it is determined in step 215 whether or not zooming is being performed. To determine whether zooming is in progress, the lens information generating means 7 transmits the set focal length information based on the information of the zoom position detecting means 21 to the camera body side control means 5, and the control means 5 changes from the previous focal length information. Perform whether or not there was. Steps corresponding to those in the first embodiment shown in FIG.

In step 215, it is determined whether or not zooming is in progress. If zooming is not in progress, a moving subject is determined in step 223. That is, if zooming is not performed, the imaging plane does not move even in a region where the focal point moves. If zooming is being performed, the focus movement flag is checked in step 217. The following is the same as in the second embodiment.

FIG. 6 shows a third embodiment. In the third embodiment, a tracking flag is added. The tracking flag is set to a value of 1 in the tracking mode, and is set to a value of 0 in the normal mode. Steps corresponding to those in the second embodiment shown in FIG.

In step 313, the tracking flag is checked. If the tracking flag is 1, the moving object is determined in step 323 because the tracking mode has already been entered. In other words, once the moving subject has been determined and the tracking mode has been entered, it is highly likely that the subject will continue to move even if the lens is located in the area where the focus is moved by zooming. The moving subject may be determined without performing the middle determination or the focus movement flag determination. If the tracking flag is 0, a determination is made during zooming in step 315, and a focus movement flag determination is performed in step 317. Steps 315 and 31
7, 321, 323, and 327 are the same as those in the second embodiment. However, if the lens is driven in the normal mode, the tracking flag is set to 0 in step 319, and if the lens is driven in the tracking drive mode, 1 is set to the tracking flag in step 325. As a result, the tracking flag can be determined in step 313 in the next process.

In the embodiment, the determination during zooming is made as follows.
It was performed inside the camera body by detecting the change in the focal length information sent from the interchangeable lens.However, it is determined that zooming is being performed within the interchangeable lens, and information indicating that zooming is being performed is transmitted from the interchangeable lens to the camera body. You may tell.

In the embodiment, the focus movement information is shown as the information transmitted from the lens to the camera body in the interchangeable lens system. However, even in the case of a lens-integrated camera, the use of an optical system which causes the focus movement by zooming is used. Alternatively, a similar signal may be used in the camera body.

[0029]

As described above, according to the automatic focusing apparatus and the interchangeable zoom lens of the present invention, the signal indicating that the focal point shift occurs in the area where the focal point shift due to zooming is generated, thereby achieving the zooming operation. With this, it is possible to avoid entering the tracking mode by mistake. By detecting the zooming by the zooming detecting means for detecting that the set focal length of the photographing lens has changed, it is possible to enter the tracking mode even in an area where the focal point moves, without zooming. Further, in a region where the focus movement does not occur, a moving subject determination is appropriately performed on a subject that actually moves in the optical axis direction, and a tracking mode can be entered.

[Brief description of the drawings]

FIG. 1 is a block connection diagram illustrating an example of a camera having an automatic focusing device.

FIG. 2 is a characteristic diagram illustrating an example of an automatic focusing device.

FIG. 3 is a characteristic diagram illustrating an example of an automatic focusing apparatus.

FIG. 4 is a flowchart showing a first embodiment of the automatic focusing apparatus and the interchangeable zoom lens according to the present invention.

FIG. 5 is a flowchart showing a second embodiment of the automatic focusing apparatus and the interchangeable zoom lens according to the present invention.

FIG. 6 is a flowchart showing a third embodiment of the automatic focusing apparatus and the interchangeable zoom lens according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photographing lens 2 camera body main body 3 focus detecting means 5 camera body side control means 7 lens information generating means 9 lens driving means 15 focus position detecting means

Claims (11)

[Claims] A first drive mode for detecting a movement of a subject in an optical axis direction and correcting the drive of the lens in accordance with the movement of the subject; and a second drive mode for not correcting the drive of the lens. In the automatic focusing apparatus, in a region where the focus movement by the zooming operation of the photographing lens occurs, an output unit (117, which outputs a focus movement signal indicating that the focus movement by the zooming operation occurs)
217, 317) and a prohibiting means (123, 223, 323) for prohibiting driving in the first driving mode in response to the focal point movement signal. 2. A zooming detecting means (215) for detecting that the set focal length of the photographing lens has changed, wherein said inhibiting means (223, 323) includes a zooming detecting means (215). 2. The automatic focusing apparatus according to claim 1, wherein driving in the first drive mode is inhibited when an operation is detected and a focus movement signal is output by the output unit. 3. The apparatus according to claim 2, wherein said prohibiting means ignores said focus movement signal during driving in said first drive mode, and employs said focus movement signal when not in said first drive mode. The automatic focusing device according to claim 1. 4. A first drive mode for detecting a movement of a subject in the optical axis direction and correcting the drive of the lens according to the movement of the subject, and a second drive mode for not correcting the drive of the lens. An interchangeable lens that can be attached to an autofocus camera, comprising: output means (7) for outputting to the autofocus camera a focus shift signal indicating that a focus shift occurs due to a zooming operation of the taking lens; An interchangeable zoom lens, wherein the drive in the first drive mode is restricted according to the following. 5. A first driving mode in which a movement of a subject in the optical axis direction is detected to correct the driving of the lens in accordance with the movement of the subject, and a second driving mode in which the driving of the lens is not corrected. In an interchangeable lens that can be mounted on an autofocus camera, an output unit (fourth focus output signal) that outputs to the autofocus camera a focus shift signal indicating that a focus shift occurs due to the zooming operation in an area where the focus shift occurs due to the zooming operation of the taking lens. 7) The interchangeable zoom lens, wherein the drive in the first drive mode is restricted according to the focal point movement signal. 6. A defocus amount detecting means (3) for detecting a defocus amount of a photographing lens with respect to a subject; a driving amount calculating means (5) for calculating a driving amount of the photographing lens based on the defocus amount; A first mode in which the movement of the subject in the optical axis direction of the photographing lens is detected and the drive is corrected in accordance with the movement; and a second mode in which the correction is not performed
And a control device (5) having a mode, wherein the photographing lens has a variable focal length, and includes a first area in which the focal position of the photographing lens changes within a variable range of the photographing distance. Detecting means (5) for detecting that the shooting distance is set in the first area; and detecting the first distance when the detecting means detects that the shooting distance is set in the first area. An automatic focusing device comprising: a prohibition unit (5) for prohibiting correction by a mode. 7. The prohibition unit performs correction in the first mode while the focal length is changing and when the detection unit detects that the focal length is set in the first area. The automatic focusing device according to claim 6, wherein the automatic focusing device is prohibited. 8. The prohibition of correction by said prohibition means (5)
The control is performed in the second mode.
3. The automatic focusing device according to claim 1. 9. The step (117) wherein the prohibiting means (5) determines whether or not the focus movement signal has been output.
When the focus movement signal is being output, the first
7. The automatic focusing apparatus according to claim 6, wherein driving in a driving mode is prohibited (123). 10. A step (215) wherein said prohibiting means (5) determines whether or not the taking lens is in a zooming operation.
(217) determining whether or not the focus movement signal is output. When the photographing lens is performing a zooming operation and the focus movement signal is output, the first drive mode 7. The automatic focusing apparatus according to claim 6, wherein the driving by the control unit is prohibited (223). 11. A step of judging whether or not the prohibiting means (5) is in a tracking mode for performing drive control so as to continuously obtain an in-focus state for a subject moving in the optical axis direction. (313), a step (315) of determining whether or not the photographing lens is performing a zooming operation, and a step (3) of determining whether or not the focal point movement signal is output.
17) when the camera is not in the tracking mode, when the photographing lens is in the zooming operation, and when the focus movement signal is output, the driving in the first driving mode is prohibited (323). The automatic focusing device according to claim 6, wherein: