JPH08248510A - Automatic focusing device for composite camera - Google Patents

Abstract

PURPOSE: To perform focusing by an appropriate control system in accordance with the actions of a camera and the movement of a subject. CONSTITUTION: In this composite camera 50 having a still camera part 51, a video camera part 52 and a photographie lens 53 common to them; a control means 56 performs servo control based on the repeated detection of a focus detection means 54 when a movement detection means 57 detects at the time of taking a still picture that the subject is moving, and performs one-shot control for performing focus lock by stopping the driving of a lens in the case of attaining a focusing state once when the means 57 detects that the subject does not move. Thus, the control state of AF is automatically optimized in accordance with the acting state of the camera and the movement of the subject.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focus adjusting device for a compound camera in which a still camera and a video camera are integrated by using a common taking lens.

[0002]

2. Description of the Related Art Conventionally, a still camera for taking a still picture (still picture) using a silver salt film and a video camera for taking a moving picture (video picture) using a magnetic tape have been used together with a common taking lens. There has been proposed a composite camera in which a video camera unit is attached by replacing a viewfinder section of a single-lens reflex still camera or a combined camera housed in one housing.

Japanese Patent Laid-Open No. 63-247738 discloses, as such a compound camera, a still camera section and a video camera section that share means for focus adjustment and exposure control. Also, in order to share the shooting lens, the light flux from one shooting lens is split by a half mirror, and one is guided to the silver salt film and the other is guided to the image sensor of the video camera section, and still images are shot. Japanese Unexamined Utility Model Publication No. 59-180566 discloses that the same angle of view is used for shooting and moving images.

Further, Japanese Patent Application Laid-Open No. 62-263728 filed by the applicant of the present application discloses a plurality of past focus detections in order to perform good focus adjustment on a moving subject during still image shooting. A predictive control technique is disclosed in which a tracking delay amount of a lens caused by movement of a subject is predicted and calculated based on the result, and the lens is corrected and driven based on the calculated value.

In the above-mentioned predictive control, AF is the time required from the start of focus detection to the end of lens driving during still image shooting.
Time lag and trigger switch (release switch)
Predictive calculation to eliminate the tracking delay (focus shift amount) that occurs when the subject moves during both the release time lag and the release time lag, which is the time from when the film is turned on to when the film is exposed To adjust the focus. By performing such predictive control, it is possible to take a photograph with a good focus when taking a still image.

[0006]

In the above-described compound camera, since the subject is often moving when shooting a moving image, servo AF in which focus adjustment for the subject is repeated is generally performed. On the other hand, since the subject is often stopped during still image shooting, one-shot AF is generally performed in which the focus is adjusted and the focus is locked (focus lock) once the subject is in focus. It is being appreciated. Therefore, it is difficult for a compound camera that shares the same image pickup lens to achieve both moving image shooting and still image shooting with different focus adjustment methods.

Further, when a still image of a moving subject is photographed, predictive control is performed to eliminate a focus shift amount (following delay) caused by the movement of the subject during the release time lag. The predictive control was unsuitable for video shooting where continuous shooting was performed because the control state was likely to become unstable.

The present invention has been made to solve the above problems, and provides an automatic focus adjusting device for a compound camera, which appropriately changes the control method of focus adjustment according to the operating condition of the camera and the condition of the subject. With the goal.

[0009]

SUMMARY OF THE INVENTION In the present invention, a still camera unit for taking a still image, a video camera unit for taking a moving image, and a focus lens commonly used for the still camera unit and the video camera unit are provided. In an automatic focus adjusting device for a composite camera having a taking lens including a focus lens, a focus detecting unit that repeatedly detects a focus state of the focus lens to obtain a defocus amount, a lens driving unit that drives the focus lens, and the focus. Based on the defocus amount obtained by the detection unit, a lens drive amount that obtains a focused state is obtained, and a control unit that controls the lens drive unit according to the lens drive amount and whether or not the subject is moving. And a motion detection unit that detects whether the subject is the subject by the motion detection unit when the still image is captured. When detected that have performs focus adjustment based on the repeated detection of the focus detection means,
When it is detected that the subject is not moving, one-shot control is performed to stop the lens drive once the focus state is achieved.

[0010]

[Function] One-shot AF that performs servo AF control that repeatedly repeats focus adjustment during movie shooting and movie shooting standby, and locks focus during still image shooting
The control is performed and it is determined whether or not the subject is moving. If the subject is moving, the one-shot AF control is changed to the servo AF control. In addition, non-predictive control is performed in order to perform stable control during moving image shooting, and predictive control with high focus adjustment accuracy is performed in servo AF control during still image shooting.

With the above operation, when a moving image is taken, stable servo AF control is performed, so that a stable moving image can be taken. When a still image of a stationary subject is taken, the one-shot AF control is performed. Since the focus is locked, you can freely change the framing after focusing, and when you shoot a still image of a moving subject, use the servo AF control that performs predictive control with high tracking performance. Since it is performed, it is possible to take a photograph without a tracking delay. In this way, since it is possible to detect the operating state of the camera and the state of the subject and perform focus adjustment control suitable for the shooting condition,
Even photographers who are unfamiliar with shooting can easily take good shots, and the need for troublesome focus adjustment or shooting mode settings or changes is eliminated, allowing the photographer to always focus on shooting. .

Further, when a still image is taken during moving image shooting, the lens is corrected and driven during the release time lag to compensate for the difference between the non-predictive control and the predictive control, so that stable moving image shooting and high tracking performance (accuracy) can be obtained. It can be compatible with the still image shooting. Then, by stopping the focusing lens drive motor during the exposure of the film, it is possible to prevent the photographing blur during the still photography.

[0013]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram conceptually showing the present invention. In FIG.
Reference numeral 50 denotes the entire compound camera. Reference numeral 51 is a still camera unit for shooting a still image, 52 is a video camera unit for shooting a moving image, 53 is a shooting lens common to the still camera unit 51 and the video camera unit 52, and 54 is the focus of the shooting lens 53 repeatedly detected. Focus detection means for respectively obtaining the defocus amount, 55 is a lens drive means for driving the focus lens in the photographing lens 53 in the optical axis direction, and 56 is a lens drive means 55 based on the defocus amount obtained by the focus detection means 54. Reference numeral 57 is a control means for controlling the movement of the subject, and 57 is a movement detecting means for detecting the movement of the subject during still image shooting.

Next, the operation of the above configuration will be described. When taking a still image, the still camera unit 51 takes a subject image from the taking lens 53 and exposes it on a silver salt film. When shooting a moving image, the video camera unit 52 converts a subject image from the shooting lens 53 into a video signal by the solid-state image sensor and records the video signal on a magnetic tape.

The control means 56 performs servo control based on repeated detection of the focus detection means 54 when the motion detecting means 57 detects that the subject is moving during still image shooting, and the subject moves. If it is detected that the lens is not in focus, the one-shot control for stopping the lens drive is performed once the focus state is achieved.

The control means 56 drives the lens so as to eliminate the defocus amount obtained by the focus detection means 54 in the servo control at the time of moving image shooting, and is generated by the movement of the object during a predetermined time lag at the time of still image shooting. The lens is driven so as to cancel the defocus amount to be performed and the calculated defocus amount. The above-mentioned predetermined time at the time of shooting a still image is the sum of the release time lag and the AF time lag.

Next, a detailed description will be given according to each embodiment. FIG. 7 is a left side sectional view showing the structure of the compound camera according to the present invention. In FIG.
Is a lens unit for capturing images on silver salt film,
Reference numeral 3 is a lens barrel for holding the lens element and constituting the lens unit 2, 4 is a diaphragm for photographing a still image, and 5 is a silver salt film. In this embodiment, the lens unit 2 is a zoom lens, and is driven by information from a variable power lens element group that can move on the optical axis in conjunction with an automatic or manual zoom operation, and information from an automatic focusing device described later. It has a focusing lens element group.

A shutter device 6 is arranged immediately in front of the silver salt film 5, and is a shutter curtain 6a supported by a supporting portion 6b.
The silver salt film 5 is exposed by opening and closing. Reference numeral 7 denotes a semi-transparent thin film mirror for distributing a light flux forming a subject image emitted from the lens unit 2 to a silver salt film 5 side and a solid-state image sensor 13 side described later, and 7a denotes an optical axis emitted from the lens unit. , 7b are optical axes that pass through the semitransparent thin film mirror 7 and reach the silver salt film 5, 7c, 7b.
Reference symbol d denotes an optical axis that reaches the solid-state image sensor 13 after being reflected by the semi-transmissive film mirror 7. Reference numerals 8a and 8b are field lenses for aligning the exit pupil of the lens unit 2 with the entrance pupil of the reduction lens unit 10, 9 is a reflecting mirror for deflecting the photographing optical axis 7c, and 10 is an optical axis 7d.
It is a reduction lens unit provided above and includes a video aperture unit 11 for shooting a moving image inside. Reference numeral 12 is an optical low-pass filter, and 13 is a solid-state image sensor such as a CCD.
An aerial image 40 is formed at a position equivalent to the silver salt film 5, and is re-formed on the solid-state image pickup device 13 via the reduction lens unit 10.

Reference numeral 14 denotes a sub-mirror disposed behind the semi-transmissive thin film mirror 7 and capable of retracting at the time of photographing a still image, and guides a part of photographing light to a focus detecting device 15. The focus detection device 15 in the present embodiment uses a conventionally known phase difference detection method, detects the positions (phases) of two images generated by the light flux that has passed through two different regions of the photographing lens, and detects that position. The defocus amount and the direction on the film surface are calculated from the phase difference.

Reference numeral 16 is a light shielding plate for protecting the shutter curtain 6a from the light flux transmitted through the semitransparent thin film mirror 7 and for preventing light leakage, which is retracted during film exposure.
Reference numeral 17 denotes a back lid unit that holds the silver salt film 5 when it is loaded, and is opened and closed when the film is taken out and loaded. An electronic viewfinder unit 18 outputs an image to a small liquid crystal 79 to monitor the image signal from the solid-state image pickup device 13, and the reflection mirror 2
Observe through 0 and the eyepiece 21. The electronic viewfinder unit 18 is rotatable about a rotary shaft 22 as a spindle.

In the present embodiment, the aperture 4 for still image shooting is always kept open during moving image shooting, and is stopped down to a predetermined aperture value when the release switch for still image shooting described later is pressed. Therefore, at the time of shooting a moving image, the exposure control is performed only by the video aperture unit 11 in the reduction lens unit 10, and the solid-state image sensor 1 is used as necessary.
By changing the accumulation time of No. 3 and the gain of the signal processing system, a video signal of an appropriate level is obtained.

Next, reference numeral 23 denotes a secondary battery which is detachably attached to the lower part of the compound camera, and which is a power source for supplying electric power to each part. In front of this lens unit 3, an openable / closable barrier 25 incorporating a strobe is provided, and also serves as an interface with a microphone 26 for recording voice during moving image shooting and an external device such as a television or a stereo device. External terminals 27 and the like are provided.

FIG. 8 is a top view of the compound camera, where 28 is a cartridge chamber of the silver salt film 5 and 29 is the silver salt film 5.
It is a spool for winding up. In this embodiment, a prewind method is adopted in which the film is loaded up to the spool up to the last frame in advance and the exposed frame is sequentially rewound into the patrone during shooting.

Reference numerals 30 and 31 are a zoom driving motor and a focus driving motor of the taking lens. Reference numeral 32 is a zoom button arranged at a position that can be operated by the photographer's right hand, 33 is a main mode selection switch that also serves as a power switch, 34 is a trigger button for video recording, and 35 is a silver salt film 5. It is a release button for shooting still images. On the side opposite to each of the above operating members, it is possible to select and use in common with both moving image shooting and still image shooting such as program exposure mode, portrait mode with many open apertures, sports mode with shutter speed priority, backlight compensation mode, etc. A photographing mode selection dial 36 is provided.

In the present embodiment, the side light calculates the brightness of the subject from the output signal level of the solid-state image pickup device 13 and the aperture value of the video aperture unit 11. The solid-state imaging device 13 is electrically divided into areas, and backlight detection is performed from the luminance signal of each divided area.

Next, 37 is a video tape cassette housing portion arranged on the right side of the lens unit 2. In this embodiment, a video tape having a tape width of 8 mm is used as a recording medium. The cassette housing portion 37 has a recording / reproducing mechanism including a magnetic head cylinder, a capstan, a pinch roller, etc., and a control panel 38 for performing operations such as recording / reproducing of a video tape on its upper surface.
An eject button 39 for ejecting the videotape and loading the videotape is arranged.

FIG. 9 is a block diagram showing the configuration of the electric circuit of the present embodiment. The camera microcomputer 41 for controlling AF, zoom, release operations and the like, and the release operation and mode setting of the camera body are accepted and controlled. Mode microcomputer 4
2. The video signal processing board 4 with the mechanical microcomputer 43 that controls the recording / playback of the video tape and the servo mechanism as the core.
4, an audio signal processing board 45, a flash board 46, a power board 47, and various operation switches and sensors are provided.

FIG. 2 is a flow chart for explaining the operation of the entire compound camera according to the first embodiment of the present invention. When the main mode selection switch 33 of FIG. 8 is operated to turn on the power of the camera and power is supplied to the electric circuit of FIG. 9, various microcomputers 41 and 4 for controlling the camera are provided.
Reference numerals 2 and 43 control the camera in the following manner according to the program stored in the ROM. When the power of the camera is turned on, the process proceeds to step S2 via step S1. In step S2, the state of the video standby switch (not shown) is detected, and if the standby operation for video recording is performed, the process proceeds to step S3, and if not, the process proceeds to step S10.

In step S3, the licensor of the focus detection device 15 is controlled to convert a pair of subject images formed by the light fluxes transmitted through different regions of the lens unit 2 into electric signals, and the camera microcomputer 41 performs A / A conversion. After D conversion, it is stored in the memory. In the next step S4, the shift amount (phase difference) of the relative position of the image signal captured in step S3 is calculated, and the defocus amount of the lens unit 2 is calculated from this phase difference. The method of calculating the phase difference and the defocus amount is a known technique, and detailed description thereof will be omitted.

In step S5, the focus lens is driven by the motor 31 to eliminate the defocus amount calculated in step S4, and focus adjustment is performed. By performing such control, when the movement of the subject is relatively small, a state in which the subject is substantially in focus can be obtained. In the next step S6, the state of the trigger button 34 for starting and stopping the video recording is detected. If the trigger switch 34 is in the on state, the process proceeds to step S7, and if not, the process returns to step S2.

In step S7, it is determined whether or not the video recording operation is being performed. If the video recording operation is being performed, the process proceeds to step S8. If the video recording action is not performed, the process proceeds to step S9. Start recording operation. Thus, each time the trigger switch 34 is pressed, the recording operation is repeatedly started and stopped, and the control state of the operation is displayed on the display section of the electronic viewfinder 18. When step S8 or S9 is executed, the process returns to step S2.

In step S10, the release button 35
The switch S that is turned on by the first stroke of
If the state of W1 is detected and SW1 is in the ON state,
Go to step S12, otherwise step S1
After proceeding to 1 and initializing various variables and flags used at the time of still image shooting, the process returns to step S2.

Next, steps S12 to S37 are a flow chart when a still image is photographed using a silver salt film. In step S12, the subject brightness is calculated from the output signal of the solid-state image sensor 13 and the aperture value of the video aperture unit 11, and the shutter for performing appropriate exposure from the subject brightness and the sensitivity of the loaded silver salt film 5. Seconds and aperture value are calculated and stored in a predetermined area of RAM.
The switch SW2 that is turned on by pressing the second stroke of the release button described later is turned on, and when the film exposure operation is performed, the shutter and the aperture are controlled based on the values stored in this memory.

In step S13, similarly to step S3, the line sensor of the focus detection device 15 is controlled to capture the image signal, and in the following step S14, the image signal of the lens unit 2 is obtained from the image signal obtained in step S13. Calculate the defocus amount. In step S15, the state of the subject is determined by the flag AFM that determines whether or not the subject is moving. When AFM = 1, the subject is moving, and thus the process proceeds to step S25.
If not, the process proceeds to step S16. Step S
At 16, it is determined whether or not the focus is locked by the flag AFJ. If AFJ = 1, the focus is once set, and the focus is locked, so if the process does not proceed to step S23, go to step S17. Transition.

In step S17, it is determined whether or not the focus state is in focus depending on whether or not the defocus amount obtained in the focus detection operation this time is smaller than a predetermined value. In step S18, the flag AFJ is set to 1 to lock the focus. When it is determined that the object is out of focus, the process proceeds to step S19 and the counter COU that counts the number of times the focus adjustment operation is executed.
Count up NT. In the next step S20, the defocusing lens is driven to adjust the focus so as to eliminate the defocus amount detected in step S14.
Then, in step S21, it is determined whether or not the value of the counter COUNT is 3, and if COUNT = 3, the process proceeds to step S22, the flag AFM indicating that the subject is moving is set to 1, and then the process proceeds to step S2. Return.

In step S23, moving body detection is performed to determine whether or not the subject is moving. If it is determined to be a moving body, the process proceeds to step S24. If not, the process returns to step S2. Here, the method of detecting a moving body in step S23 will be described later, and thus detailed description thereof will be omitted here.

In step S24, the graph AFM indicating that the object is moving is set to 1, and in the next step S25, a "prediction calculation" subroutine for calculating the lens drive amount in consideration of the movement of the object is executed. Since the contents of this subroutine will be described later, detailed description thereof is omitted here. In the next step S26, the focusing lens is driven based on the lens drive amount calculated in step S25, focus adjustment is performed, and the process returns to step S2.

As described above, according to the present embodiment, when a still image is taken, once the focus state is achieved, the focus is locked, and thereafter it is determined whether or not the subject is moving, and it is determined that the subject is a moving body. Then, the focus lock is released and the focus adjustment operation is restarted. In the lens control in this case, the predictive control is performed in consideration of the amount of movement of the subject between the release time lag and the AF time lag. By performing such control, in still image photography in which a still subject is often photographed, the focus is locked when the subject is in focus, and the focus adjustment is not needlessly repeated. Further, when the subject is a moving body, focus adjustment for predictive control is performed. As a result, it is possible to take a photograph without a tracking delay. In addition, by repeating focus adjustment for driving the lens so as to eliminate the detected defocus amount at the time of shooting a moving image, stable lens control can be performed although a slight delay in tracking occurs. This is because smooth and stable control is more important than accuracy when shooting a moving image.

Next, the release button 35 is further pressed while the steps S12 to S26, which are focus adjustment operations for still image shooting, are being executed, and the release switch SW2 is pressed.
When is turned on, the interrupt function immediately shifts to step S27 to start the release operation. In step S28, it is determined whether or not the lens drive is being executed,
If the lens is being driven, the lens driving is stopped in step S29 and the process proceeds to step S30. If the lens is not being driven, the process immediately proceeds to step S30. In step S30, the sub mirror 14 and the light blocking member 16 of the camera
Is retracted out of the shooting optical path. This is executed by controlling a motor (not shown). In the next step S31, the aperture 4 is driven by a stepping motor (not shown) to the aperture control value stored in the memory by the photometric subroutine of the previous step S12.

Submirror 14 in steps S30 and S31
It is determined in step S32 whether the evacuation and the aperture control have been completed.
The retreat of the sub mirror 14 and the light shielding member 16 can be confirmed by a detection switch (not shown) provided in the sub mirror drive system, and the diaphragm control is confirmed by whether or not the driving of the stepping motor is completed. If any of them is not completed, the process waits at this step and the state detection is continued. If both control ends are confirmed, the process proceeds to step S33. In step S33, the shutter is controlled by the shutter control value already stored in the photometric subroutine of step S12, and the film is exposed.

When the control of the shutter is completed, the stepping motor is driven so as to open the diaphragm in the next step S34, and subsequently the sub mirror 14 is operated in step S35.
And the return operation of the light shielding member 16 is performed. The return operation of the sub mirror 14 and the light shielding member 16 is drive-controlled by a motor (not shown). In the next step S36, step S
Similar to 32, the control waits for the control of the return of the sub mirror 14 and the opening of the diaphragm to be completed, and when the control of both is completed, the process proceeds to step S37. In step S37, one frame of film is wound by properly controlling the motor. The above is the sequence of the compound camera capable of shooting moving images and still images.

FIG. 3 is a flowchart of the moving body detection subroutine of step S23 of FIG. When this subroutine is called, it goes through step S101 to step S1.
In 02, it is determined whether distance measurement (focus detection) is possible.
This is a focus detection calculation from a plurality of check items such as whether there is a correlation between a pair of image signals input in the image signal input subroutine, whether there is sufficient contrast, and whether the signal level is sufficient. It is determined whether or not the image signal is suitable for. If it is determined that distance measurement is possible (an image signal suitable for focus detection), the process proceeds to step S103, and if not, the process proceeds to step S111.

At step S103, whether the moving direction of the object changed between the two times before and the previous focus detection detected from the change amount of the defocus amount is the same as the moving direction of the object changed between the previous focus detection and the current focus detection. If the same direction is determined, the process proceeds to step S104, otherwise the process proceeds to step S111. In step S104,
It is determined whether or not the defocus amount changed between the previous focus detection and the current focus detection is 0.5 mm or less, and the change amount is 0.5 mm.
If the following is true, the process proceeds to step S105. If not, the process proceeds to step S111. Thus, from step S102
In S104, whether focus detection is possible or not, reversal of the moving direction,
If it is determined that focus detection is not performed on the same subject due to a rapid change or the like, the process proceeds to step S111, the counter MCONT for performing moving body determination is reset,
If not, MCONT is incremented by 1 in step S105.

Next, in step S106, it is determined whether or not the rear focus is 0.2 mm or more. If it is determined that the rear focus is 0.2 mm or more (the main subject is in front of the focus position), MCONT is set in step S107. The count is incremented by 1, and the process proceeds to step S108. If not, the process immediately proceeds to step S108. In step S108, if the change in the defocus amount between the previous focus detection and the current focus detection is in the rear focus direction (the subject is approaching), the process proceeds to step S109. If not, the process proceeds to step S112.

In step S109, it is determined whether or not the amount of change in the defocus amount between the previous focus detection and the current focus detection is 0.08 mm or more, and if it is 0.08 mm or more, step S11.
When 0, MCONT is incremented by 1 and step S
If not, go to step S112 immediately.
Move to. In step S112, the counter MCON
It is determined whether or not the value of T is 6 or more. If it is 6 or more, it is determined to be a moving body in step S113, and if not, it is determined to be a non-moving body in step S114. The above is the description of the moving object detection subroutine.

FIG. 4 is a flow chart of the "prediction calculation" subroutine of step S25 of FIG. In this subroutine, the lens drive amount is calculated by correcting the tracking delay for the AF time lag + release time lag in order to eliminate the tracking delay during still image shooting. When this subroutine is called, it goes through step S201 to step S20.
In 2, the defocus data is updated. DF here
The defocus amount DF2 at the time of focus detection two times before is stored in 1 and the defocus amount at the previous focus detection is stored in DF3, and the defocus amount obtained by the focus detection operation this time is stored in DF3.

In step S203, the lens drive amount data converted into the defocus amount is updated, and the lens drive data of the previous two times is stored in DL1, and the previous lens drive data is stored in DL2. In step S204, the time lag TL used for the prediction calculation is calculated. here,
AF time lag TM which is the time required for the previous focus adjustment
It is executed by obtaining the sum of 2 and the release time lag TR. In step S205, the coefficient A of the quadratic term of the prediction formula using the quadratic function is calculated, and in step S206, the coefficient B of the primary term is calculated. Since the present applicant has already disclosed this calculation method, detailed description thereof will be omitted.
In a succeeding step S207, the lens driving amount DL is calculated by a predictive calculation using a quadratic function, and the present subroutine is returned in step S208.

FIG. 5 is a flow chart for explaining the operation of the second embodiment of the present invention, and since the configuration of the camera is the same as that of the first embodiment, its explanation is omitted here. The second embodiment is the operation of the camera when a still image is shot during movie shooting. During the movie shooting, servo control is performed to drive the lens so as to eliminate the detected defocus amount. If a still image is shot during servo control, a predictive calculation is performed to calculate the correction drive amount to eliminate the tracking delay during the release time lag, and the lens is corrected and driven based on this calculation result before exposure of the film. I'm trying to do.

When the power of the camera is turned on, step S30
After 1, the process proceeds to step S302. In step S302, the state of a video standby switch (not shown) is detected, and when the standby operation for video recording is performed, the process proceeds to step S303, and otherwise stays in this step. In step S303, the brightness of the subject is calculated from the output signal of the solid-state image sensor 13 and the aperture value of the video aperture unit, and the shutter speed and aperture for proper exposure are calculated from the subject brightness and the sensitivity of the loaded film. The value is calculated and stored in a predetermined area of RAM. Then, the switch SW2 that is turned on by pressing the second stroke of the release button is turned on, and when performing the exposure operation of the film, the shutter and the aperture are controlled based on these values.

In the next step S304, the focus detection device 1
The line sensor 5 is controlled to convert a pair of subject images formed by the light fluxes transmitted through different regions of the lens unit 2 into an electric signal, and the electric signal is A / D converted by the camera microcomputer 41. Store in memory.
In the next step S305, the relative positional deviation amount (phase difference) of the two images from the image signal captured in step S304.
Is calculated, and the defocus amount of the lens unit 2 is calculated from this phase difference. The method of calculating the phase difference and the defocus amount is a known technique, and detailed description thereof will be omitted.

In step S306, in order to cancel the defocus amount calculated in step S305, the focus adjustment motor is driven by the focus adjustment motor to adjust the focus. Here, the resolution of the moving image of the video camera unit is lower than the resolution of the still image by the silver halide film. Therefore, even if some AF tracking delay occurs during moving image shooting, it does not cause a problem.

In the next step S307, the state of the trigger button 34 for starting and stopping video recording is detected, and if the trigger button 34 is in the on state, step S3.
08, otherwise, the process returns to step S302. In step S308, it is determined whether or not the video recording operation is being performed. If the video recording operation is being performed, the process proceeds to step S309 to stop the recording operation.
If the recording operation is not performed, step S3
Proceed to 10 to start the recording operation. In this way, each time the trigger button 34 is pressed, recording is started and stopped repeatedly, and the control state of the operation is controlled by the electronic viewfinder 18.
Is displayed on the display. When step S309 or S310 is executed, the process returns to step S302.

When the release button 34 is further pressed and the release switch SW2 is turned on while the video shooting control is being performed in steps S302 to S310, the process immediately proceeds to step S311 by the interrupt function. Release operation starts.

In step S312, the defocus amount (correction drive amount) due to the tracking delay that occurs during the AF time lag and the release time lag due to the movement of the subject is calculated from the past focus adjustment data by predictive calculation. Then, in the next step S313, lens driving for eliminating the tracking delay calculated in step S312 is started.

In the next step S314, the sub mirror 14 and the light shielding member 16 of the camera are retracted out of the optical path of the photographing light flux. This is executed by controlling a motor (not shown). In the next step S315, in the previous step S3
The aperture is driven by a stepping motor (not shown) up to the aperture control value stored in the photometry subroutine 03. Whether or not the sub-mirror withdrawal and diaphragm control in steps S314 and S315 have been completed is detected in step S316. The withdrawal of the sub-mirror 14 and the light shielding member 16 is a detection switch (not shown) provided in the sub-mirror drive system. The aperture control is confirmed by whether or not the driving of the stepping motor is completed. If any of them is not completed, the process waits in step S316 and the state is continuously detected. If both control ends are confirmed, the process proceeds to step S317.

In step S317, it is detected whether or not the lens driving performed in step S313 is completed. If the lens driving is still in progress, this step S317 is performed.
When the lens driving is completed, the process proceeds to step S318. In step S318, the shutter already stored in the photometric subroutine of step S303 is controlled by the control value to expose the film. When shutter control is completed,
In the next step S319, the stepping motor is driven so as to open the diaphragm, and subsequently, the returning operation of the sub mirror 14 and the light shielding member 16 is performed in step S320. The returning operation of the sub mirror 14 and the light shielding member 16 is drive-controlled by a motor (not shown).

In the next step S321, step S31
As in the case of 6, the control waits for the control of the return of the sub-mirror 14 and the opening of the diaphragm to be completed, and when the control of both is completed, the process proceeds to step S322. In step S322, one frame of film is wound by properly controlling the motor.

The above is the sequence of the camera when the still image is taken during the moving image shooting, and the lens driving for correcting the tracking delay is performed during the release time lag only when the still image shooting which requires a high focus accuracy is performed. Servo control (lens drive to eliminate the detected defocus amount) is performed during stable motion picture recording, where high focus accuracy is not required but rather smooth focus adjustment is required. I am trying. The focus lens is not driven during film exposure for still image shooting.

FIG. 6 is a flowchart of the prediction calculation subroutine of step S312, which is slightly different from the prediction calculation subroutine of the first embodiment. When this subroutine is called, step S401 is followed by step S402.
The time lag TL of tracking delay is calculated at. This is executed by obtaining the sum of the time (AF time lag) TM2 required for the previous focus adjustment and the release time lag TR.

In step S403, the coefficient A of the quadratic term of the prediction formula using the quadratic function is calculated, and in step S404, the coefficient B of the primary term is calculated. The present applicant has already disclosed this arithmetic expression, and detailed description thereof will be omitted here. Here, DF1 is a defocus amount at the time of focus detection two times before, DF2 is a defocus amount at the time of previous focus detection, and DF3 is a defocus amount detected this time, and DL
1 is the lens drive amount DL2 before the last time, and 2 is the previous lens drive amount. In step S405, the lens drive amount DL for performing the follow-up correction is calculated by the prediction calculation using the quadratic function, and in step S406, the present subroutine is returned.

[0061]

As described above, according to the present invention,
In a compound camera that has a moving image shooting function and a still image shooting function and shares the focus adjustment device of the image pickup lens, (1) a moving subject is often taken during moving image shooting, which is suitable for such shooting scenes. By performing servo control (AF control that constantly repeats focus adjustment) and performing lens drive corresponding to the detected defocus amount, smooth and stable lens drive control required during movie shooting is performed. be able to. At this time, a tracking delay occurs due to the AF time lag, but the depth of field of the video camera is relatively deep, and this is not a problem in a general shooting scene.

(2) Since a still object is often photographed when a still image is photographed, the one-shot control is performed so that the focus is locked once the subject is in focus, so that the framing can be freely changed. Besides, when the subject is moving, it is possible to perform AF control suitable for the moving subject by detecting this and switching to servo control.
Since the depth of field at the time of capturing a still image is shallow, it is possible to perform high-focus-accuracy photography by performing predictive control that corrects the tracking delay caused by the AF time lag and the relays time lag.

(3) When performing still image shooting during movie shooting, by performing correction drive for the tracking delay during the release time lag of still image shooting, stable lens drive control during movie shooting and still image shooting It is possible to achieve both high precision focus photography. Then, by not driving the focusing lens during the exposure of the still image shooting, it is possible to prevent the focus shift and the shooting blur during the still image shooting.

As described above, since the AF control state can be automatically optimized according to the operating state of the camera and the subject,
The photographer does not need to perform troublesome operation and mode setting, and can concentrate on shooting and can prevent shooting failure due to operation or setting error.

[Brief description of drawings]

FIG. 1 is a block diagram conceptually showing the present invention.

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

FIG. 3 is a flowchart of a moving body detection subroutine of FIG.

4 is a flowchart of a prediction calculation subroutine of FIG.

FIG. 5 is a flowchart showing the overall operation of the compound camera according to the second embodiment of the present invention.

6 is a flowchart of a prediction calculation subroutine of FIG.

FIG. 7 is a side sectional view showing an embodiment of a compound camera.

FIG. 8 is a top view showing an embodiment of a compound camera.

FIG. 9 is a block diagram showing an electric circuit of the compound camera.

[Explanation of symbols]

 50 compound camera 51 still camera unit 52 video camera unit 53 shooting lens 54 focus detection unit 55 lens drive unit 56 control unit 57 motion detection unit

Claims (3)

[Claims] 1. A composite camera having a still camera section for taking a still image, a video camera section for taking a moving image, and a taking lens including a focus lens which is commonly used by the still camera section and the video camera section. In the automatic focus adjustment device, the focus state of the focus lens is repeatedly detected to obtain a defocus amount, a lens drive unit that drives the focus lens, and a defocus amount obtained by the focus detection unit. Calculate the lens drive amount to obtain the in-focus state based on
A control means for controlling the lens drive means according to the lens drive amount and a motion detection means for detecting whether or not a subject is moving are provided, and the control means uses the motion detection means at the time of shooting the still image. When it is detected that the subject is moving, focus adjustment based on repeated detection of the focus detecting means is performed, and when it is detected that the subject is not moving, the lens drive is stopped once the focus state is achieved. An automatic focus adjustment device for a compound camera, characterized by performing one-shot control. 2. The control means drives the lens so as to eliminate the defocus amount obtained by the focus detection means in the focus adjustment at the time of shooting the moving image, and during a predetermined time lag at the time of shooting the still image. 2. The automatic focus adjusting device for a compound camera according to claim 1, wherein the lens is driven so as to eliminate the defocus amount generated by the movement of the subject and the calculated defocus amount. 3. The predetermined time lag is a sum of an AF time lag, which is a time required for focus detection and focus adjustment, and a release time lag, which is a time required for a release operation during still image shooting. 2. An automatic focusing device for a compound camera as described in 2.