JP3320098B2 - Single-lens reflex camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention has a function of predicting the position of a subject and controlling the lens position. When the photographing lens is at a predetermined position, the subject moves to a focus position of the photographing lens, thereby performing a release operation. one that automatically starts
The present invention relates to an improvement of a reflex camera.

[0002]

2. Description of the Related Art In a conventional camera equipped with an automatic focusing device, a photographic lens is fixed so as to focus on a certain subject distance, focus detection is repeatedly performed, and the subject moves to a focusing position. There is a so-called "catch-in-focus" camera control system that detects the fact and automatically performs a release operation. In order to cope with this case even when the moving speed of the subject is high, a method of predicting the moving speed of the image plane of the subject and performing a release operation in consideration of the time lag until the release of the camera is also disclosed in Japanese Patent Application Laid-Open No. HEI 1 (1999) -197686.
No. 300212.

FIG . 7 is a view for explaining "catch-in focus" proposed in the above-mentioned Japanese Patent Application Laid-Open No. 1-302212.

In FIG . 7 , the vertical axis represents the image plane position of the subject,
The horizontal axis represents time t.

The solid line curve in FIG . 7 represents the image plane position x = x ₀ (t) of the subject at each time, and the dotted straight line in the figure represents the lens image plane position (l = constant) at each time (1 (The image plane position at the set lens position).

In order to predict the point in time at which the subject is in focus, the image plane position of the subject is repeatedly detected several times, and the image plane position of the subject is defined by a quadratic function. That is, the past 3
Point image plane positions A (t ₃ , x ₀ (t ₃ )), B (t ₄ , x ₀ (t 3
₄ )), C (t ₅ , x ₀ (t ₅ )) are detected, and a quadratic function x = at ² + bt + c (11) is obtained. The predicted focusing time t ₆ is obtained as the intersection of the following equations (12) and (13).

[0007] x = 1 ............ (12) x = at 6 2 + bt 6 + c ............ (13) t 6 = {- b ± √ (b 2 -4a (c-1))} / 2a However, there is a relationship of t ₆ > t ₅ . The predicted focus position is the position of D (t ₆ , x (t ₆ )).

If a time lag (release time lag) from the start of the release operation to the start of actual exposure is assumed to be t ₁ , a time F (t ₆
The release operation may be started at −t ₁ , 1).

[0009]

However, since the amount of defocus that can be actually detected is limited, if the lens is fixed, the defocus amount may be too large to detect the defocus. Even if the subject moves and the amount of defocus can be detected, the subject passes the in-focus position before the defocus data enough to make a prediction is obtained, and a focused photograph cannot be taken.

Further, when the lens position is fixed, it is necessary to perform framing on the viewfinder with the moving object being blurred, and it is difficult for the photographer to follow the object to be photographed.

An object of the present invention is to make it impossible to detect a focus when automatically starting a release operation by moving a subject to a focus position of a photographing lens when the photographing lens is at a predetermined position. To prevent
An object of the present invention is to provide a single-lens reflex camera that can always perform framing in a focused state.

[0012]

In order to achieve the above object, the present invention according to claim 1, according to the present invention, after a predetermined time based on data obtained by the defocus amount detection and lens driving operation performed a plurality of times in the past A predictive auto-focusing method having a first calculating means for obtaining the image plane position of the subject by a predetermined function, and driving the photographing lens to a position corresponding to the image plane position obtained by the first calculating means In a single-lens reflex camera, lens position storage means for storing a photographing position of a photographing lens set in advance by a photographer, and when the photographing lens is set to the stored photographing position and the photographing is performed, the subject is focused. A second calculating means for calculating a release start time for making the state coincide with the first calculating means by using an arithmetic expression of the first calculating means; Position of the first imaging lens in accordance with the image plane position determined by the calculating means time in consideration of the release time lag in time for detecting the two after the time of addition exceeds the stored photographing position When it is determined that the shooting position is reached, the shooting lens is driven to the stored shooting position independently of the drive control in the predictive autofocus, and at the time of the release start calculated by the second calculation means. Single-lens release to start release operation
It is an off camera. According to another aspect of the present invention, an image plane position of a subject after a predetermined time based on data obtained by detecting a defocus amount and performing a lens driving operation performed a plurality of times in the past. the has a first arithmetic means for calculating with a predetermined function, SLR mosquito predictive autofocusing driving position to the photographing lens in accordance with the obtained image plane position at said first computing means <br A lens position storing means for storing a photographing position of a photographing lens set in advance by a photographer, and focusing on the subject when photographing with the photographing lens set to the stored photographing position. And a second calculating means for calculating a release start time for setting the shutter in a state using the calculating formula of the first calculating means. When the elapsed time of the time required for output to <br/> two times is determined to be the time when only the release start time, independently said storage and drive control of the imaging lens in the prediction autofocus The single-lens reflex camera is driven to the set photographing position and starts the release operation at the time of the release start calculated by the second calculating means.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

( First Embodiment) FIG. 1 is a diagram for explaining the operation of an automatic focusing apparatus according to a first embodiment of the present invention.

In FIG . 1 , similarly to FIG. 7 , the vertical axis represents the image plane position x of the subject, and the horizontal axis represents time t. The solid curve in the drawing represents the image plane position x = x ₀ (t) of the subject at each time, and the dotted straight line in the drawing represents the set lens position 1. Further, the dotted curve in the figure represents a quadratic function approximation formula x = at ² + bt + c of the image plane position of the subject obtained from the past image plane position of the object, and the broken line in the figure represents the lens position x =
LM (t).

First, the past three image plane positions A (t ₃ , x ₀₎
(t ₃ )), B (t ₄ , x ₀ (t ₄ )), C (t ₅ , x ₀ (t ₅ ))
And find the quadratic function equation passing through those points. If the intersection of this quadratic function equation and the set lens position 1 is obtained, the point in time at which the subject is in focus can be predicted.

[0017] The origin of the quadratic function as the lens stop position at time t _5, the period from time t ₃ to t ₄ TM1,
The time from the time t ₄ to t ₅ and TM2. Further, the defocus amount of the subject at the lens position at time t ₃ is expressed by DF
1, the defocus amount of the object at the lens position at time t ₄ DF2, the defocus amount of the object at the lens position at time t ₅ DF, the lens drive amount that is driven based on the measurement result of the time t ₃ Assuming DL1 (the difference between the lens position at time t ₃ and the lens position at time t ₄ ) and the lens drive amount driven based on the distance measurement result at time t ₄ as DL2, points A, B, and C are , A: (-TM2-TM1 , DF1-DL2-DL1) B: (-TM2 , DF2-DL2) C: (0 , DF) By substituting these into the above-described equation (11) to obtain the coefficients of the quadratic function, a = [TM2 (DF1-DF2-DL1) + TM1 (DF-DF2-DL2)] Zb = [(TM1 + TM2) ^2. (DF-DF2-DL2) + TM2 2 · (DF1-DF-DL1-DL2)] becomes / Z c = DF. However, Z = TM1 · TM2 (TM1 + TM2)
It is.

In this way, a quadratic function formula (prediction formula) for predicting the image plane position of the subject is obtained.

Next, the image plane position is predicted using this equation.

[0020] First, the lens driving by the distance measurement at time t _5, after the lens drive, obtains the image plane position in the case of starting the release operation. Then, the time TM from when the lens driving is completed to when the release becomes possible is determined by the past distance measurement interval TM1,
Predict from TM2. That is, if the longer one of TM1 and TM2 is used this time, TM = max (TM1, TM2)
(Not necessarily the larger one, for example,
The average of TM1 and TM2 may be used). Further from the start of the release operation, the time until the shutter is traveling, if the so-called release time lag and t _1, the time TL to predict the image plane position, the TL = TM + t1. this,
By substituting into equation (11), the predicted image plane position DTL
Can be requested.

Next, the image plane position DTL 'when the distance measurement is performed again next time and then the release is performed is determined.

By comparing these values with the set lens position 1, if the relationship of DTL <1 <DTL 'is established, the lens is driven to the set lens position 1 and release is permitted. . If the above relationship is not established, the lens is driven as usual.

Next, an example of a specific configuration of the electric control block of a camera having an automatic focusing device of the first embodiment will be described with reference to FIG.

In FIG . 2 , reference numeral 1 denotes a microcomputer, which controls the operation of the following components of the camera.

Reference numeral 2 denotes a lens control circuit which controls a distance ring and an aperture of a photographic lens (not shown). The lens control circuit 2 performs serial communication via the data bus DBUS while receiving the LCOM signal from the microcomputer 1, controls a motor (not shown) based on the communication content, and controls the distance ring and the aperture. Further, the microcomputer 1 communicates lens focal length information, distance information, best focus correction information, and other various correction information.

Reference numeral 3 denotes a liquid crystal display circuit, which is a circuit for displaying camera shooting information such as a shutter speed and an aperture control value. While receiving the DPCOM signal from the microcomputer 1, the liquid crystal display circuit 3 performs serial communication via the data bus DBUS, and performs liquid crystal display based on the communication content.

Reference numeral 4 denotes a switch sense circuit, which is always supplied with power together with the liquid crystal display circuit 3, and in a normal camera, a switch SW1 linked to a first stroke for starting a shooting preparation of a release button of the camera, and other switches. A switch for determining an exposure mode (not shown) and a switch for determining a mode of automatic focus adjustment (AF) of the camera can be read at all times. In particular, in this example, it is configured to read whether the AF mode setting switch is a catch-in focus mode or another AF mode. When the switch is switched, the switch sense circuit 4 performs serial communication via the data bus DBUS to communicate each switch information to the microcomputer 1.

Reference numeral 5 denotes a strobe light emission control circuit which controls light emission and dimming of the strobe light, a circuit portion for storing electric charge for light emission, a xenon tube as a light emitting portion, a trigger circuit portion, and a stop of light emission. The circuit includes an existing circuit such as a circuit section for performing light measurement, a film surface reflected light metering circuit section, and an integrating circuit, and starts flash emission (flash light) by turning on an X contact that is turned on when the front curtain of the shutter unit runs.

Reference numeral 6 denotes a focus detection unit, which comprises an optical system mechanism including a line sensor device SNS shown in FIG . Line sensor device SNS is 2 to 4 in total
Sensor rows SNS-1a, SNS-1b, SNS-2
a, SNS-2b, and charge accumulation is controlled by a control signal from the sensor drive circuit SDR. When the sensor drive circuit SDR receives a sensor accumulation start signal from the microcomputer 1, the sensor drive circuit SDR starts sensor accumulation and causes accumulation to be performed until the accumulation level of the sensor becomes constant. When the accumulation level becomes constant, the accumulation of the sensors is terminated, and the completion of the accumulation of the sensors is serially communicated to the microcomputer 1 via the data bus DBUS. From the microcomputer 1 to the CCD drive circuit S
When the sensor signal reading communication is performed to the DR, the sensor drive circuit SDR outputs a sensor drive signal to the line sensor device SNS, reads the signal stored in the line sensor device SNS, and transmits the signal to the microcomputer 1; In the microcomputer 1, A / D conversion is performed in synchronization with the sensor drive signal, and from the A / D converted image signal of the subject, it is detected from the existing phase difference which position the subject is focused by the photographing lens. It is detected by calculation according to the method.

Reference numeral 7 denotes a photometry circuit which divides the screen into a plurality of areas, and performs TTL photometry of the brightness of the subject in each area and sends the TTL photometry to the microcomputer 1.

A shutter control circuit 8 controls a shutter unit (not shown) according to a control signal of the microcomputer 1.

Reference numeral 9 denotes a feeding circuit which controls a film feeding motor in accordance with a control signal of the microcomputer 1 to wind and rewind the film.

FIG . 3 is a diagram showing a schematic configuration of an optical system used for focus detection in this embodiment.

In FIG . 3 , MSK is a field mask having a cross-shaped opening MSK-1 at the center. F
LDL is a field lens. DP has four openings DP-1a and DP-1 in the center, one pair at the top, bottom, left and right.
b, DP-1c, and DP-1d are apertures respectively provided, and the field lens FLDL has a function of forming an image of these pairs of apertures near the exit pupil of an objective lens (not shown). AFL has 2 pairs of 4 lenses AFL-1
a, AFL-1b, lens AFL-2a, AFL-2b
, And are disposed behind and corresponding to the respective apertures of the diaphragm DP. SNS is a total of four sensor rows SNS-1a, SNS-1b, SNS
2a and the SNS-2b shown in FIG. 2, and are arranged so as to receive the image corresponding to the respective secondary imaging lenses AFL.

In the focus detection optical system shown in FIG. 3, when the focus of the photographing lens is located in front of the film surface, the subject images formed on the pair of left and right sensors (or on the pair of upper and lower sensors) are separated from each other. When the subject comes closer and the focal point is at the rear, the subject images are separated from each other.
Since the relative displacement of the subject image has a specific functional relationship with the defocus amount of the photographing lens, if each sensor array pair performs an appropriate operation on the sensor output, the defocus of the photographing lens is deviated. Amount, a so-called defocus amount, can be detected.

By adopting the above-described configuration, an object whose light amount distribution changes only in one direction, up and down or left and right, near the center of the range photographed or observed by an objective lens (not shown) can be obtained. Can also measure distance.

The control operation of the automatic focus adjustment performed in the camera of the present embodiment having the above-described focus detection device and the like will be specifically described below.

When power is supplied to the circuit shown in FIG .
The microcomputer 1 starts the operation from the steps of FIG. 4 (101).

First, in step (102), the switch S which is turned on by pressing the release button in the first stage
The state of W1 is detected, and if it is OFF, step (10)
The process proceeds to 3) to initialize variables in the program and flags of the CPU, and returns to step (102). If the switch SW1 is turned on during the repetition of this routine, the process proceeds to step (104), and the camera starts a shooting preparation operation.

In step (104), an "AF control" subroutine is executed. Here, accumulation of sensors, calculation of focus detection, and automatic focus adjustment operation of lens driving are performed. When the "AF control" subroutine ends, the process proceeds to step (105), and it is determined whether or not a release operation is performed in step (105). In the catch-in focus mode, the release / non-permission judgment is performed in the "AF control" subroutine. In other modes, the switch S which is turned on by pressing the second step of the release button is set.
The determination is made based on the state of W2. If the result of this determination is that the release operation is not to be performed, control proceeds to step (106), where photometry, state detection and display of various switches are performed, and control returns to step (102).

When the release operation is performed in step (105), the flow shifts to step (107), where steps (108) and (108) are performed.
The release operation following (109), (110), (111), and (112) is executed. Specifically, step (1)
In step 07), driving of the mirror driving motor is started, the mirror is raised, and when the mirror is completed, the motor is stopped. In step (108), aperture drive communication is performed on the lens, and aperture control is performed. In step (109),
The first curtain and the second curtain of the shutter are run to perform shutter control. In step (110), communication is performed with the lens to open the aperture. In step (111), the mirror driving motor is driven to lower the mirror. When the mirror goes down, stop the motor and clear the release permission state. In step (112), the film winding motor is driven to wind the film. When the winding of one frame of film is completed, the winding motor is stopped.

When the photometry and display operations in step (106) or the reloose operation in steps (107) to (112) are completed, the process returns to step (102) again as described above, and returns to step (104) until the switch SW1 is turned off. ) Repeat the following operations.

FIG . 5 is a flowchart showing the operation of the "AF control" subroutine executed in step (105).

When the "AF control" subroutine is called, the program proceeds to step (201) through step (201).
2) Subsequent AF control is started.

In step (202), the AF mode is set to the catch-in focus mode (the taking lens is set at a predetermined position).
It is determined whether the mode is an AF mode in which the release operation is automatically started by moving the subject to the in-focus position of the photographing lens at a certain time) or another mode. Then, the AF control according to the mode is performed, and the process proceeds to step (204) to return this subroutine.

On the other hand, if the AF mode is the catch-in focus mode, the process proceeds to step (205). In step (205), a "focus detection" subroutine for detecting the focus of a plurality of subject areas and detecting the defocus amount of each area is executed. Then, when the defocus amounts in the plurality of subject areas are obtained, the process proceeds to step (206), and the "sensor selection" subroutine is executed. In the "sensor selection" subroutine, a subject area for finally performing focus adjustment is selected from a plurality of focus-detectable subject areas (sensors).

Next, the process proceeds to step (209), where an equation (predictive equation) representing the time change of the image plane position is obtained using the past distance measurement time interval, distance measurement defocus and lens drive amount. Next, a predicted image plane position DTL at a time (t ₅ + TL) when a release is performed after driving the lens this time,
The time (t) when the release is performed after the next ranging
₅ + TL ′) is calculated (see FIG. 1 ).

Next, proceeding to step (210), the predicted image plane position calculated in the step (209) is compared with a preset lens position 1, and the lens position 1 is compared with the predicted image plane positions DTL and DTL '. Step (21)
Branch to 3). If it is not between the predicted image plane positions DTL and DTL ', the process proceeds to step (211).

In step (213), the amount of lens drive before the release operation is determined. In order to drive the lens to a preset position at the time of release, the difference between the current lens position and the set lens position is obtained, the lens is driven by that amount, release is permitted, and the "AF control" subroutine is executed. After the end, the release operation is started.

Next, the routine proceeds to step (214), where the release timing is calculated . That is, step (209)
In substituting the set lens position calculated prediction equation to determine the time t ₆ to come to lens position 1 set of the object by solving the equation. Since in order to expose the film at time t ₆ it is necessary to start a fast release operation by a predetermined release time lag t _1, the time to start the actual shutter release operation is - (t ₆ t _1).

In the next step (215), step (2)
Wait until the release timing calculated in 14). After waiting, the process proceeds to step (204), and this subroutine is returned.

In the step (210),
The set lens positions are the predicted image plane positions DTL and DTL '.
If it is determined that the time is not within the range, the process proceeds to step (211). In this case, since the release operation is not performed after driving the lens, only the time (TM) until the next focus detection is predicted. For the time until the next focus detection, the longer one of the past two focus detection intervals TM1 and TM2 is used, or the average thereof is used. Then, the process proceeds to step (212).

In step (212), step (21)
The image plane moving amount calculated in 1) is converted into a lens driving amount, and lens driving is performed in the next step (213), and this subroutine is returned in step (204).

( Second Embodiment) In the first embodiment described above, first, a prediction formula is obtained, and then the image plane position at the time when the release operation becomes possible after driving the lens is predicted. Is compared with the set lens position, and the lens drive amount and the release permission are determined. In the second embodiment, first, a prediction formula is obtained, and then a time at which a release operation is to be started in order to take a picture at a set lens position is calculated backward to determine release permission.

Description will be made with reference to FIG. 1 as in the first embodiment.

First, the past three image plane positions A (t ₃ , x ₀
(t ₃ )), B (t ₄ , x ₀ (t ₄ )), C (t ₅ , x ₀ (t ₅ ))
And find the quadratic function expression x = at ² + bt + c passing through those points. Points A, B, and C are the same as in the first embodiment. A: (-TM2-TM1 , DF1-DL2-DL1) B: (-TM2 , DF2-DL2) C: (0 , DF) When the coefficient of the quadratic function is obtained by substituting into the equation (11), a = [TM2 (DF1-DF2-DL1) + TM1 (DF-DF2-DL2)] / Z b = [(TM1 + TM2) ² · (DF the ^{-DF2-DL2) + TM2 2 ·} (DF1-DF-DL1-DL2)] / Z c = DF. However, Z = TM1 · TM2 (TM1 + TM2)
It is.

In this way, a quadratic function formula (prediction formula) for predicting the image plane position of the subject is obtained.

In order to predict the time t ₆ at which the subject moves to the set lens position, the intersection of this equation and x = 1 may be obtained. By substituting x = 1 and solving for t, t ₆ = {− b ± {(b ² -4a (c−1))} / 2a, where t ₆ > 0.

In order to take a picture in focus at time t ₆ , it is necessary to start the release operation at a time earlier by the release time lag (t ₁ ), that is, at time F (t ₆ −t ₁ , 1).

When the timing for starting the release operation is obtained, it is next determined whether or not the focus detection operation is possible again after driving the lens this time.

First, the lens is driven by measuring the distance at time t ₅ , and the time at which the lens driving ends is determined by the distance measurement interval TM in the past.
1, Predict from TM2. If the time TM required for one focus detection operation is predicted to be longer of TM1 and TM2, TM = max (TM1, TM2). Time t
_{The time} at which the focus detection operation is started at ₅ and the focus detection operation is completed is (t ₅ + TM), and when the focus detection operation is performed again (t ₅ + 2TM). The release start time is (t
₆₋ t ₁ ), the relationship of t ₅ + TM <t ₆ −t ₁ <t ₅ + 2TM holds, so that the lens position 1 where the lens is set
And release permission. If the above relationship is not established, the lens is driven as usual.

[0062] Figure 6 is a flowchart in the second embodiment of a portion corresponding to FIG. 5 of the first embodiment, a flow chart of the "AF control" subroutine executed in step (105) of FIG. The same operation parts as those in FIG. 5 are denoted by the same step numbers.

When the "AF control" subroutine is called, the AF control starting from step (202) is started via step (201).

In step (202), it is determined whether the AF mode is the catch-in focus mode or another mode. If the mode is another mode, the process proceeds to step (203), where AF control is performed according to the mode. (2
Go to 04) and return this subroutine.

On the other hand, if the AF mode is the catch-in focus mode, the process proceeds to step (205), where the "focus detection" subroutine is executed, and then step (2)
Proceeding to 06), the "sensor selection" subroutine is executed.

Next, the process proceeds to step (209 '), and an equation (predictive equation) representing the time change of the image plane position is obtained by using the past distance measurement time interval , distance measurement defocus, and lens drive amount.

Then, the process proceeds to a step (214), where a release timing is calculated. That is, step (20)
By substituting the set lens position into the prediction formula calculated in 9 ′) and solving the formula, a time t ₆ at which the subject comes to the set lens position 1 is obtained. Since in order to expose the film at time t ₆ it is necessary to start a fast release operation by a predetermined release time lag t _1, the time to start the actual shutter release operation is - (t ₆ t _1).

[0068] then proceeds to step (210 '), compared with the step release start time and the current focus detection end time calculated in (214) (t ₅ + TM) and the next focus detection end time (t ₅ + 2TM) Then, it is determined whether or not to permit the release operation. As a result, “t ₅ + TM <t
_{If 6−} t ₁ <t ₅ + 2TM ”is satisfied, the flow branches to step (213). Also, (t ₆ −t ₁ ) is (t ₅
If it is not between (+ TM) and (t ₅ + 2TM), the process proceeds to step (211 ′).

At step (213), the lens drive amount before the release operation is obtained. In order to drive the lens to a preset position at the time of release, the difference between the current lens position and the set lens position is obtained, the lens is driven by that amount, release is permitted, and the "AF control" subroutine is executed. After the end, the release operation is started.

Next, the flow advances to step (214) to calculate the release timing . That is, step (20)
Substituting the lens position set in the prediction formula calculated in 9 ') and solving the formula, the lens position 1 where the subject is set is obtained.
At time t ₆ . Since in order to expose the film at time t ₆ it is necessary to start a fast release operation by a predetermined release time lag t _1, the time to start the actual shutter release operation is (t ₆ -t _1).

In the next step (215), step (2)
Wait until the release timing calculated in 14). After waiting, the process proceeds to step (204), and this subroutine is returned.

In step ( 210 ' ), (t ₆ -t
_If ( ₁ ) is not between (t ₅ + TM) and (t ₅ + 2TM), the process proceeds to step (211 ′) as described above. In this case, since the release operation is not performed after driving the lens, only the time (TM) until the next focus detection is predicted. For the time until the next focus detection, the longer one of the past two focus detection intervals TM1 and TM2 is used, or the average thereof is used. Next, the process proceeds to step (212).

In step (212), step (21)
1 ′) is converted into a lens drive amount,
In step (213), the lens is driven, and in step (2)
At 04), this subroutine is returned.

According to the first and second embodiments, the time when the lens comes to the memorized position is predicted in consideration of the release time lag while the lens follows the object, and the lens driving is performed. Also, since the release operation is performed, the defocus of the set lens position and the subject is large, so that the defocus detection becomes impossible,
Further, it is possible to provide an automatic focusing camera capable of performing framing while always being in focus.

More specifically, in the conventional catch-in focus, since the lens position is fixed, if the subject moves away from a predetermined focus position (placement pin position), it is difficult to blur and form a framing. Is stored, the lens is driven to follow the subject, the timing at which the lens comes to the stored position is predicted, and the release is started. Thus, it is possible to perform framing while always being in focus.

[0076]

As described above, according to the present invention ,
When the taking lens is in a predetermined position,
When the subject moves to the focal position, the release
When starting automatically, focus detection may not be possible.
And keep the frame in focus at all times.
Ming can be performed .

[Brief description of the drawings]

FIG. 1 is an image plane position of a subject in a first embodiment of the present invention .
FIG. 3 is a diagram for explaining an arrangement, a lens position, and the like.

FIG. 2 is an automatic focusing apparatus according to the first embodiment of the present invention .
FIG. 2 is a block diagram illustrating a configuration of a main part of a camera provided with a device.

FIG. 3 is a focus detection optical system according to the first embodiment of the present invention .
FIG.

FIG. 4 is a main flowchart of the camera in FIG . 2;

FIG. 5 is a flowchart showing an “AF control” subroutine of FIG . 4;
It is a chart.

FIG. 6 shows an “AF control” service according to the second embodiment of the present invention .
9 is a flowchart showing a routine.

FIG. 7 shows a conventional self-timer according to the first and second embodiments of the present invention .
The image plane position, lens position, etc.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microcomputer 2 Lens control circuit 6 Focus detection unit

Continuation of the front page (56) References JP-A-2-181108 (JP, A) JP-A-3-235586 (JP, A) JP-A-62-215215 (JP, A) JP-A-5-5830 (JP) JP-A-3-56948 (JP, A) JP-A-5-196860 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B ^7/ 28-7/40

Claims (2)

(57) [Claims] A first calculating means for obtaining, by a predetermined function, an image plane position of a subject after a predetermined time based on data obtained by detecting a defocus amount and a lens driving operation performed a plurality of times in the past. In a predictive auto-focus single-lens reflex camera that drives the photographing lens to a position corresponding to the image plane position obtained by the first calculating means, the photographing position of the photographing lens preset by the photographer is stored. Lens position storage means, and setting the photographing lens at the stored photographing position and photographing the subject at the time of photographing with the photographing lens in focus when the photographing lens is in focus. a second computing means for computing using provided, by adding the time for performing defocus detected twice time considering the release time lag for prediction autofocus When it is determined that the position of the photographing lens corresponding to the image plane position obtained by the first arithmetic unit after a short time is beyond the stored photographing position, the photographing lens is moved in the predictive autofocus. A single-lens camera that drives to the stored photographing position independently of drive control, and starts a release operation at a release start time calculated by the second calculating means.
Reflex camera. And a first calculating means for obtaining, by a predetermined function, an image plane position of a subject after a predetermined time based on data obtained by a defocus amount detection and a lens driving operation performed a plurality of times in the past. In a predictive auto-focus single-lens reflex camera that drives the photographing lens to a position corresponding to the image plane position obtained by the first calculating means, the photographing position of the photographing lens preset by the photographer is stored. Lens position storage means, and setting the photographing lens at the stored photographing position and photographing the subject at the time of photographing with the photographing lens in focus when the photographing lens is in focus. second and a computing means is provided, defocus detecting the elapsed time of the time required to perform twice the release for the prediction autofocus from the present time to operation using When it is determined that the time comes after the start time, the photographing lens is driven to the stored photographing position independently of the drive control in the predictive autofocus, and the photographing lens is computed by the second computing means. one, characterized in that to start the release operation by the release start time
Eye reflex camera.