JP2840562B2 - Camera having focus detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a point detection device. [0002] 2. Description of the Related Art Conventionally, one type of focus detection device for a camera is known.
As a rule, the exit pupil of the taking lens is divided
Observe the relative positional displacement of multiple images formed by the passed light beam.
Detects the focus state of the taking lens by measuring
Methods are known. [0003] Specifically, an optical system for focus detection is used.
And divide the exit pupil of the taking lens into two
Each light beam passing through the two regions is a storage-type photoelectric conversion element array.
(E.g., a CCD sensor array). Soshi
After the A / D conversion of the sensor output signal,
Or extract and process a portion of the signal.
Thus, the relative position displacement between the two images can be known. [0004] Focus detection processing is performed in a viewfinder.
Focus detection with a relatively narrow range of signals corresponding to the ranging frame
In the process, and for example, undetectable low contrast etc.
In the case of, the signal of a wider range than that is detected again
There is a way to make it work. [0005] SUMMARY OF THE INVENTION However, relatively
Focus detection is performed with a narrow range of signals to achieve low contrast.
Even if it is judged, the shooting lens used at that time is
The maximum defocus amount caused by noise is relatively narrow
From the focus detection capability when performing focus detection with a signal in the range
Is small, even if the above range is enlarged,
Inability to properly detect focus for the target
It will be. Therefore, in the above case, the focus detection is performed by expanding the range.
When the shooting process is executed,
There is a risk that the focus detection operation will be performed. [0007] SUMMARY OF THE INVENTION The present invention has been made in view of the above.
The maximum distortion caused by the attached photographing lens.
The amount of scum is within the focus detection capability in the relatively narrow range described above.
Sometimes, the focus detection operation in the narrow range makes it impossible to detect the focus.
Even if the judgment is made, execution of the focus detection operation with the range expanded is prohibited.
Stop the above-mentioned inconveniences
It is. [0008] DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of focus detection in the present invention will be described.
This will be described with reference to FIG. Focusing lens to be detected
A field lens FLD is arranged with the same optical axis as the LNS.
Is placed. Two symmetrical positions with respect to the rear optical axis
Secondary imaging lenses FCLA and FCLB are arranged. Further
, Sensor arrays SAA and SAB are arranged behind the sensor array. 2
An aperture DI is provided near the next imaging lenses FCLA and FCLB.
A and DIB are provided. Field lens FLD is taken
The exit pupil of the shadow lens LNS is connected to two secondary imaging lenses FCL.
A, An image is almost formed on the pupil plane of FCLB. As a result,
Ray bundles incident on the image lenses FCLA and FCLB, respectively
Are the secondary imaging lenses on the exit pupil plane of the taking lens LNS.
ＦＣ ＦＣ ＦＣ ＦＣ FCLA, FCLB
It is emitted from a region of equal area without the above. Fi
The aerial image formed near the field lens FLD is secondary formed.
Sensor rows SAA, S by image lenses FCLA, FCLB
When re-imaged on the plane AB, the aerial image position in the optical axis direction is
Based on the displacement, the two images on the sensor arrays SAA and SAB are
Will be changed. Therefore, two images on the sensor array
Detecting the amount of displacement (deviation) of the relative position of
The focus state of the LNS can be known. FIG. 2 shows the sensor array formed on the sensor arrays SAA and SAB.
An example of the photoelectric conversion output of the obtained two images is shown. Output SAA to A
(I) The output of the SAB is B (i). Note that in this example
Assuming that the number of pixels of the sensor is 40 pixels (i = 0,..., 39)
I have. From the image signals A (i) and A (i), the image shift amount P
Japanese Patent Application Laid-Open No. 58-142 discloses a signal processing method for detecting R.
306, JP-A-59-107313,
Japanese Patent Application Laid-Open No. Sho 60-1015313 or Japanese Patent Laid-Open No.
No. 160824 is proposed by the present applicant.
You. According to the methods disclosed in the above publications, etc.
Adjust the focus of the taking lens based on the image shift
FIG. 3 shows that the relationship between the two images in the so-called in-focus state has been shown.
At this time, the two images exhibit a shift amount of Δ.
This is caused by the adjustment of the secondary imaging optical system shown in FIG.
This is the displacement amount of the optical image on the two sensor arrays in the in-focus state.
In the present invention, as described below, this △ is adjusted in the processing apparatus in the adjusting process.
Stored in the non-volatile memory of the
The amount obtained by subtracting △ from the amount PR is within a predetermined value.
I try to consider it as in focus. The photoelectric conversion signal trains shown in FIGS.
GC (Auto Gain Control) is a sensor
When valid in the center area of the row SAA (hereinafter referred to as “central area A
GC ”). That is, “AG” shown in FIG.
The brightness of the optical image formed on the pixels in the "C range"
Control the accumulation operation of the sensor to saturate the photoelectric conversion signal in that range.
It is controlled so as not to be performed. The signals in FIGS. 2 and 3 are
Since the maximum value of the signal is within the AGC range at the center, proper output
Although it is a force, as shown in FIG.
When the maximum value of the signal output is outside, the output within the AGC range
Is appropriate, but signals outside the range will be electrically saturated,
When the signal processing of the image shift amount detection is performed using this image signal,
An incorrect image shift amount was detected due to the effect of the saturated part.
I will. Therefore, in such a case, the range of AGC is
By extending to the entire row (hereinafter referred to as “entire AGC”)
Therefore, an appropriate photoelectric conversion signal as shown in FIG. 5 can be obtained.
Wear. A line sensor capable of switching the AGC range.
FIG. 6 shows an example of the device SNS. The sensor arrays SAA and SAB are of a known CCD type.
In-sensor, which corresponds to the sensor row in FIG.
You. φ₁ , Φ_Two Is the clock for using the CCD drive, SH is specified
Time high potential (hereinafter abbreviated as “H”, low potential is abbreviated as “L”)
The charge accumulated in the photoelectric conversion element is changed to C
The signal to be transferred to the CD unit (charge transfer unit), CLR,
A clear signal that clears the photoelectric conversion element in the “H” state.
You. SSCNT is the signal φ₁, Φ_Two , SH, CLR
Control within the SNS that controls the photoelectric conversion element and CCD
Control circuit. Formed on sensor arrays SAA and SAB
The photoelectric conversion output of the light image is output via a conversion image width OAMP to φ
₁ , Φ_Two Time-sequentially output as signal OS in synchronization with
You. ST₁ , ST_Two , ST_Three Is photometry for AGC
Element, consisting of a photodiode, a conversion amplifier
It is output as a signal AGC via AAMP. Sen
The light image formed on the row SAA is ST₁ , ST_Two , ST
_Three Also formed on the SAA, so that the same light image as on the SAA
It will be used for C control. MOS1 and MOS2
MO for switching output of photometric elements ST1 and ST3
S transistor, which is activated when signal CAGC is "H".
The signal SAGC passes through the photometric elements ST1, ST2, ST3.
It is the sum of each output. Signal CAGC is "L"
, The MOS1 and MOS2 become non-conductive, and the signal SAG
C is only the output of the central photometric element ST2. Above
When the signal CAGC is "H", the entire area AGC
In the case of "L", it is the central part AGC. The specific method of AGC control is described below.
This will be described in detail using a flowchart described later. FIG. 7 shows an automatic focusing apparatus according to the present invention.
FIG. 2 is a circuit diagram showing an embodiment of a camera according to the present invention. In the figure, PRS is a camera control device.
For example, a CPU (central processing unit), ROM, RA
M, EEPROM (Electrically Erasable Programmable RO
M) One-chip micro computer with A / D conversion function
And the camera sequence stored in ROM
Automatic exposure control function, automatic focus detection according to the program
Function, camera operation such as film winding / rewinding
Is going. EEPROM is a type of nonvolatile memory.
Various adjustment data, including the data of ① described above,
It is written in. The computer PRS receives the communication signals SO, S
Communicates with peripheral circuits and lenses using I and SCLK
Then, the operation of each circuit and lens is controlled. SO is output from the computer PRS
The data signal and SI are data input to the computer PRS.
Data signal and SCLK are synchronization signals of the signals SO and SI.
You. LCM is a lens communication buffer circuit,
When the camera is operating, the lens power supply VL is applied to the lens.
The signal CLCM from the computer PRS is
In the case of a bell, it serves as a buffer for communication between the camera and the lens.
You. Computer PRS changes CLCM to "H"
And transmits predetermined data from SO in synchronization with SCLK.
Then, the buffer circuit LCM sets the camera / lens indirect point.
Through each of the buffer signals LCK, SCLK, SO,
DCL is output to the lens. At the same time from the lens
The buffer signal of the signal DLC is output to SI,
PRS receives the SI signal in synchronization with SCLK and
Enter the data. SDR is a licensor device SN for focus detection
S drive circuit, select when signal CSDR is “H”
Then, the computer PRS is operated by SO, SI and SCLK.
Controlled from. Note that the signal CK is a CCD driving clock φ.
₁ , Φ_Two And a clock for generating the signal INT.
END is a signal notifying the PRS that the storage operation has been completed.
No. The output signal OS of the licensor device SNS is
Lock φ₁ , Φ_Two Image described in Fig. 6 in time series synchronized with
Signal and amplified by the amplifier circuit in the drive circuit SDR
Later, it is output to the computer PRS as an AOS signal.
You. The computer PRS converts the AOS signal to an analog input terminal.
A / D conversion in synchronization with the signal CK
After the A / D conversion by the function, it is sequentially stored in the specified address of the RAM.
I do. The output signal SAG is also output to the device SNS.
C is an AGC control sensor in the device SNS (ST in FIG. 6).
₁ ~ ST_Three ), Which is input to the circuit SDR,
Used for storage control of the device SNS. One of the circuits SDR
The operation of the series will be described later. The SPC receives light through the taking lens
This is a photometric sensor for exposure control, and its output SSPC is
Input to the analog input terminal of the computer PRS,
After the D conversion, it is used for moving exposure control (AE). DDR is a switch sense and display circuit.
Is selected when the signal CDDDR is "H", and
Control from computer PRS using O, SI, SCLK
Is controlled. That is, sent from the computer PRS
Switch camera display based on data, not shown
Release button (switch SW₁ , SW_Two Linked to)
At first, a button linked to various operation members such as the mode setting button
The on / off state of the switch group SWS is determined by the computer PRS.
Contact MDR1 and MDR2 are for film feeding,
Driving motor MTR1 and MTR2
Road, motor with signals M1F, M1R, M2F, M2R
Execute normal rotation and reverse rotation. MG1 and MG2 are the first and second shutter curtains, respectively.
Curtain running start magnet, increase signal SMG1, SMG2
Power is supplied to the width transistors TR1 and TR2,
Shutter control is performed. The switch sensing and display circuit DD
R, motor drive circuit MDR1, MDR2 shutter system
The description is omitted because it is not directly related to the present invention.
Abbreviate. AUT is an auxiliary light projecting unit.
Attached to the camera body with the members shown
The transistor ATR is turned on in response to SAL, and the auxiliary light
The source LED and ALED are energized to emit light. ALN
S is a lens for properly irradiating the ALED light to the subject.
It is. The control circuit in the lens is synchronized with the synchronization signal LCK.
The signal DCL input to the road LPRS is
The data of the instruction to the FLNS
The operation of the lens is predetermined. The circuit LPRS is operated according to a predetermined procedure.
Of the focus adjustment and aperture control, and the output D
Various parameters of lens from LC (open F number,
(Focal length, defocus amount vs. extension coefficient)
Do the force. In the embodiment, an array of single lenses which are fully extended is shown.
Is displayed when a focus adjustment command is sent from the camera.
In this case, focus on the drive amount and direction
The point adjustment motor LMTR is activated by the signals LMF and LMR.
To adjust the focus by moving the optical system in the optical axis direction.
U. The amount of movement of the optical system is determined by the pulse signal of the encoder circuit ENC.
Monitored by No. SENC and when the specified movement is completed
Then, the signals LMF and LMR are set to “L”, and the motor LMT
Control R. When an aperture control command is sent from the camera
In accordance with the number of aperture stages sent at the same time,
Use a well-known stepping motor DMTR
Move. In addition, the stepping motor has open control.
Possible, requires an encoder to monitor operation.
No need. FIG. 9 shows the operation of the camera having the above configuration.
The description will be made according to the flow of When a power switch (not shown) is operated, the
Power supply to the microcomputer PRS is started, and PRS
Starts execution of the sequence program stored in the ROM.
Start. FIG. 9 shows the overall flow of the above program.
FIG. The above operation starts the execution of the program.
Then, in step (002), the release button
Switch SW that turns on in one stroke₁ Status detection
Switch SW₁ Is off when step
For control set in RAM in PRS at (003)
Are all cleared. Note that this switch SW₁
Detection of the signal CDDDR from the computer PRS to H
Circuit DDR and switch SW₁ Command to detect
By transmitting all SO signals to DDR, the switch S
W₁ Is detected by DDR and the result is
To the PRS. The above steps (0
02) and (003) are switches SW₁ Turns on,
Alternatively, repeat until the power switch is turned off.
And SW₁ Is turned on, the step (00)
Go to 4). Step (004) is a step of "AE control".
Means broutine. This "AE control" subroutine
The photon calculation processing, exposure control, and
A series of camera operations such as charge and film winding
Control is performed. The "AE control" subroutine is described in the present invention.
Is not directly related to this, so a detailed description is omitted.
The outline of the function of the subroutine is as follows. SW₁ While this is on, this "AE control"
Routine, the camera mode settings and metering
And exposure control calculation and display are performed. Lilly not shown
Switch SW with the second stroke of the button_Two Is on
Then, the interrupt processing of the micro-commutator PRS
Release operation is started by the
Aperture or shutter based on the amount of exposure calculated
Control after shutter release, and after the
Film and film feeding operation
One frame is shot. In step (004), the "AE system
When the “control” ends, the “AF control” in step (005)
The subroutine is executed. FIG. 10 is a flowchart of the "AF control" subroutine.
The chart is shown. First, in step (102), the flag PRMV
Detect the state of. PRMV is a lens
This is a flag related to control.₁ Oh
During the operation, all flags are cleared in step (003).
SW₁ First step from ON (00
5) When the "AF control" subroutine is called
In step (106), the flag PRMV is also 0.
Move to. In step (106), the flag AUXJF
Detect the state of. AUXJF has a function related to auxiliary light control.
Lag, and the flag AUXJF is also φ as described above.
Then go to step (108). Step (108) is a step of "image signal input".
Is a subroutine that executes this subroutine
Is a predetermined address on the RAM of the microcomputer PRS.
A / D conversion signal of image signal from sensor device SNS
Is stored. The "image signal input" subroutine is shown in FIG.
A flowchart is shown in FIG. 11, and details will be described later.
It is described in. In step (111), the flag AUXMO
The state of D is detected. Auxiliary light mode of flag AUXMOD
This is a flag indicating that this is a password. Auxiliary light system
I will tell you later. As described above, the flag AUXMOD is also 0.
If so, the process proceeds to step (112). Step (1
In 12), the state of the flag LLFLG is detected. LLF
LG is the "image signal input" subroutine of step (108).
If the subject brightness is low,
Set to 1. Here, the subject brightness is sufficient
(LLFLG is 0) and the description proceeds. Flag LLF
Since LG is 0, the process proceeds to step (113) where the subject
Since the body brightness is sufficient, the auxiliary light mode flag
Clear AUXMOD. Next, in step (114), "focus detection"
Execute the "out" subroutine. The flowchart of this subroutine is shown in FIG.
As shown in Fig. 3, in this subroutine, RAM
Detecting the focus of the shooting lens from stored image signal data
If the subject is in focus, the focusing flag JF is set to 1 and the subject is
If focus detection was not possible due to low contrast
If the focus detection is not possible, the flag AFNG is set to 1 and the
In either case, the lens drive is prohibited.
Set lens drive prohibition flag LMVDI to 1 and retard
On. Also, if the contrast is high and out of focus,
Find the defocus amount. At this time, the flag LMV
DI is kept at 0. In the next step (115), focusing or
"Display" subroutine to display focus detection failure
Execute. This communicates predetermined data to the display circuit DDR
And display it on the display device DSP.
Since the operation is not directly related to the present invention, no further explanation will be given.
Is omitted. In the next step (116), the flag L
Detect the state of the MVDI. As mentioned earlier, the lens
If drive is not required, LMVDI is set to 1.
Therefore, in step (116), the flag LMVDI
If "1", the "AF control" subroutine is executed in step (117).
Return the routine. Step if LMVDI is 0
Proceeding to (118), the lens driving subroutine "Lens
Drive ”. We will discuss this subroutine later.
You. The "lens drive" subroutine (118)
When the process is completed, the lens drive execution process is performed in step (119).
After setting the lag PRMV to 1, step (12)
In step 0), the "AF control" subroutine is returned. Return "AF control" subroutine.
And return to step (002), switch SW₁ Is on
As long as the AE control and AF control subroutines are returned
You. Now, in the main flow of FIG.
(2nd time) Call "AF control" in step (005)
In step (102), the flag PRMV is set.
Is detected. In focus in the previous "AF control" routine
If the focus cannot be detected, the flag PRMV is set to 1.
Since the processing has not been performed, the above-mentioned steps after step (106) are performed.
Run the row again. When the lens was last driven
In this case, PRMV is set to 1 in step (119).
Then, the process proceeds to step (103). In step (103), communication with the lens is performed.
To detect the current driving status of the lens, and
Predetermined driving specified in step (118) is completed.
Is notified, the flag PRM is set in step (105).
V is set to 0, and the flow after step (106) is executed.
Go on. This determination is made by the encoder ENC.
During operation, the monitor signal SENC is sent.
The signal SENC from the computer PRS
It is performed in. Also, make sure that the lens is still
Is sent to step (104),
The "AF control" subroutine is returned. Therefore, in the “AE control” subroutine,
New focus detection only when the lens is not driving
Operation and lens control. That is, in the normal mode, the switch SW₁ But
AE and AF control subroutine are returned as long as
In the AF control subroutine, the default
Focus if scum amount is detected and low contrast is determined
If no focus is detected and the focus is determined, the focus is displayed.
If the amount of defocus is found out of focus,
The lens is driven by the amount of occus, and the lens shifts to the focused state.
The Rukoto. Next, the operation related to the auxiliary light will be described.
You. In the AF control subroutine, the subject
If the luminance is low, the step "108"
Flag LLFLG is set to 1 in the
The LLFLG state detection in step (112).
The process moves to step (121). In step (121), an auxiliary light unit (not shown)
The unit AUT detects the state of the knit AUT
If is not attached, the process proceeds to step (113),
The same operation as the normal operation described so far is performed. unit
If is attached, the process proceeds to step (122),
The optical mode flag AUXMOD is set to one set. Next, in step (123), the flag AUXU
Detect the state of SE. AUXUSE is actually an auxiliary light
When light is emitted, (the flag AUXMOD is set to 1)
"Image signal input" of step (108)
Set to 1 when a subroutine is executed
This is a flag. Auxiliary light for the first time in the situation just described
Mode, the auxiliary light
No light is being emitted and the AF control
”Is returned. That is, in this case, step (1)
08) The image signal data input in
Discard the image signal in the auxiliary light projection state in the next "AF control".
A signal is input and used for focus detection. Now, for the first time in step (122), the AU
With XMOD set to 1, AF control is reset.
After turning, restart the AF control as described above.
When the routine is called, the step "108"
In the `` Signal input '' subroutine, an image signal is
The auxiliary light mode flag AU in step (111).
When the XMOD state is detected, the process proceeds to step (121).
If the auxiliary light unit AUT is not removed during this time
Move to step (122). If removed
(113) and the auxiliary light mode flag AUX
MOD is set to 0, the auxiliary light mode is released, and the normal AF
Return to you. After steps (121) and (122),
In step (123), the auxiliary light use flag AUXUSE
Perform state detection. Already assisted in step (108)
Execute the “image signal input” subroutine in the light
AUXUSE is set to 1 so step
Go to (114) and execute “Focus detection” subroutine
I do. Subsequent operations are the same as in the normal AF control. As described above, in the case of low brightness,
Only when the light unit is attached, it becomes the auxiliary light mode,
Focusing operation and execution based on the detected image signal under the auxiliary light emission
However, if focus is achieved in the fill light projection state,
Auxiliary light in the “focus detection” subroutine of step (114)
The focusing flag AUXJF is set to 1, and in this case, "A
In the flow of “F control”, in step (106), A
UXJF status is detected and proceed to step (107)
After that, the "AF control" subroutine is returned. Immediately
When focusing is performed in the auxiliary light projection state, the switch SW₁
The focus adjustment operation and lens drive are not performed again until
I will not know. FIG. 11 is a flowchart of the "image signal input" subroutine.
Shows a raw chart. In step (202), the flag AGCFLG
Detect the state of. AGCFLG is the AGC on the sensor row.
This is a flag for controlling the range.₁ Is off
Has been cleared. SW₁ Set and clear while on
This is performed in the “focus detection” subroutine. flag
If AGCFLG is 0, go to step (203).
Connect the output CAGC terminal of the microcomputer PRS
Set to “L”, and if 1, go to step (204) and C
Set the AGC terminal to "H". That is, the flag AGCFLG
If the value is 0, the sensor is in the center AGC, and if the value is 1,
Becomes the whole area AGC. Therefore, the first "AF control" subroutine
Then, it becomes the central part AGC. In the next step (205), the flag AUXM
OD status is detected, and if it is 1 (assist light mode),
In step (206), the microcomputer PR
Set the S output SAL terminal to "H" to emit auxiliary light.
In step (207), the auxiliary light use flag AUXUS
Set E to 1. When AUXMOD is 0 (normal light
Mode), go from step (205) to (208)
However, no auxiliary light is emitted. In step (208), the sensor device SNS is
The accumulation of the light image is started. Specifically, a microcomputer
Data PRS sets CSDR to H, sensor drive circuit SD
R sends an “accumulation start command” as an SO signal to R
The road SDR receives this command, and the light of the sensor device SNS is received.
When the clear signal CLR of the electric
Start accumulation. In step (209), the data is set on the RAM.
Initializes the stored accumulation time counter INTCNT to 0
I do. In step (210), the 1-millisecond timer
Reset and start the clock from the reset state. In addition, this
Microcomputer PRS is a 1 millisecond timer
It has a timer function. In the step (211), the input IN of the PRS
Detects the state of the TEND terminal and determines whether or not the accumulation has been completed.
Find out. The sensor drive circuit SDR outputs a signal
Set INTEND to “L” and set AGC signal S from SNS.
AGC is monitored, and when SAGC reaches a predetermined level,
The signal INTEND is set to “H”, and at the same time, the charge transfer signal S
H is set to “H” for a predetermined time, and the charge of the photoelectric conversion element portion is changed to C.
It has a structure to transfer to the CD part. In step (211), the computer PRS
Detects the INTEND terminal and the signal INTEND is
If "H", it means that the accumulation is completed, and the step (21)
Go to 6), if "L", the accumulation has not been completed yet
Then, the process proceeds to step (212). Accumulate
If not, 1mm reset earlier in step (212)
Check if the second timer has counted 1 millisecond. 1 mm
If the second has not elapsed, the process proceeds to step (211),
Wait for the end of the product or elapse of 1 millisecond. 1 mm before the end of the accumulation
After a lapse of seconds, the process proceeds to step (213). Steps
At (213), one accumulation time counter INTCNT is counted.
And proceeds to step (214). Steps
At (214), the counter INTCNT and the predetermined constant MAX
Compares INT, but MAXINT is in milliseconds
Is the longest accumulation time represented by
If less than INT, return to step (210) and store again
Wait for completion. INTCNT matches MAXINT
Then, the process proceeds to step (215), and the accumulation is forcibly terminated.
Let Completion of forced storage from microcomputer PRS
An SO signal is sent to the sensor drive circuit SDR in the same manner as described above.
This is executed by sending a "storage end command".
SDR sends “storage end command” from PRS
And set the charge transfer signal SH to "H" for a predetermined time to perform photoelectric conversion.
The charge of the section is transferred to the CCD section. Step (216)
The accumulation of the sensor is completed by the flow up to this point. At step (216), the output SA of the PRS is
Set the L terminal to “L”, and in step (206), the SAL terminal
Is "H", the auxiliary light remains emitting
Therefore, light emission is stopped by setting it to “L”. That is, auxiliary light
Will emit light only during accumulation of the sensor. In step (217), an accumulation time counter
Compare INTCNT with a predetermined constant AUXTINT.
Constant AUXINT is low luminosity expressed in accordance with accumulation time
Is the accumulation time, and INTCNT is larger than AUXINT.
When the threshold is high, the process proceeds to step (219) and the low luminance
Set lag LLFLG to 1 and step when smaller
The process moves to (218) to clear LLFLG. That is,
If the storage time is longer than the predetermined time, it is determined that the brightness is low.
I refuse. In step (220), the sensor device SNS
A which is obtained by amplifying the image signal OS of FIG.
A / D conversion of OS and RAM format of the digital signal
Make payment. More specifically, the circuit SDR is
Computer drive in synchronization with the clock CK from the computer PRS.
Operation clock φ₁ , Φ_Two To generate the internal control of the device SNS
To the control circuit SSCNT, SNS is φ₁ , Φ_Two By
The CCD unit is driven, and the charge in the CCD is converted to an image signal.
It is output in time series from the output OS. This signal is SDR
After being amplified by the internal amplifier, PRS
Input to analog input terminal. Computer PRS
A / D conversion in synchronization with clock CK output by itself
And the digital image signals after the A / D conversion are sequentially stored in the RAM.
At a predetermined address. When the input of the image signal is completed in this way,
In step (221), the "image signal input" subroutine is executed.
To return. As described above, in the image signal input subroutine, the image
The signal accumulation time is controlled, and the accumulation time exceeds a predetermined time.
Is too long, the flag LLFLG is set to 1 and
Transition to auxiliary light mode in AF control subroutine
Allowed and assisted when in assist light mode
Image accumulation under light projection is performed. Also, the flag AGCFL
Central AGC or whole AGC depending on the setting state of G
Is performed. FIG. 12 is a flowchart of the "lens drive" subroutine.
Shows a raw chart. When this subroutine is called,
Communicates with the lens at the
Input "S" and "PTH". "S" is a shooting lens
Unique “defocus amount” vs. “adjustment of focusing lens”
Coefficient, for example,
Lens, the entire taking lens is a focusing lens
To S = 1, but in the case of a zoom lens,
S changes depending on the position. "PTH" is linked to the movement of the focusing lens
Of the focusing lens per one pulse of the encoder ENC
It is the amount of extraction. The encoder moves the lens unit.
Consists of a pulse plate that outputs one pulse according to the amount
Have been. Therefore, the current defocus amount DEF and the
Information S. PTH allows the amount of focus adjustment lens to be drawn out
Amount converted to the number of encoder pulses, so-called lens drive
The quantity FP is given by: FD = DEF × S / PTH (1) In step (303), equation (1) is used as it is.
To be executed, and a lens corresponding to the detected defocus amount DEF described later is executed.
The number of pulses FP from the encoder that represents the
It is. In step (304), step (30)
The FP obtained in 3) is sent to the lens, and the focus adjustment
Lens (in the case of a single lens of the whole
Command), and in the next step (305)
The "lens drive" subroutine is returned. The above data "S" and "PTH" are
It is input to the memory in LPRS and the computer
Change the CLCM to H in PRS,
The SO signal as a command is supplied to the circuit LP via the circuit LCM.
To tell the RS, the data in the memory
"S" and "PTH" are DLC and SI signals
The data is input to the data PRS and the data is read. Similarly, the FP is also used as a signal SO as a circuit.
Is transmitted to the LPRS, and the circuit LPRS responds to the input FP.
Either the signal LMF or LMR is H and the motor is
Rotate in the direction corresponding to the FP to shift the lens to the focusing direction
You. At this time, the encoder SENC is used to determine the amount of lens movement.
Is transmitted in accordance with the number of pulses, and the number of pulses is transmitted to the circuit LP.
Count by the counter inside the RS, and match with the input FP
Signal LMF, LMR is set to L and the motor is stopped
In this way, the lens is driven by the FP. Therefore, the lens driving subroutine is called.
Then, the lens is driven by the detected defocus amount as described above,
Move to focus position. FIG. 13 is a flowchart of the "focus detection" subroutine.
The chart is shown. This subroutine is an AF control subroutine.
When called in the step (114) being executed, the step
In step (402), communication with the lens is
"LF" and "MAXDEF" from the lens
Enter "LF" is the focal length data of the taking lens
Yes, in the case of a zoom lens, of course,
The LF changes depending on the program position. "MAXDEF" is the best
This is data called a large defocus amount,
When the lens is in focus at infinity,
When there is a subject at a short distance and the subject is measured
Is the defocus amount. MAXDEF is therefore
The maximum amount of defocus that can occur when a lens is attached
Can be considered a value. These data are also stored in the memory in the circuit LPRS.
Has been entered. The concept of this maximum defocus amount
Regarding this, the applicant has filed Japanese Patent Application No. 60-272563.
It is presented in the gazette. In general, telephoto lenses and zoom lenses
MAXDEF is a big thing. In step (403), the flag AGCFL is
G is detected, and AGCFLG is 1, that is,
Move to step (420) to detect the defocus amount
The subroutine "WPRED" is executed. If AGCFLG is 0, that is, if AGC is in the center,
If so, the process proceeds to step (404). Switch SW1 is off
In the first “AF control”, AGCFLG becomes 0
Therefore, step (404) and subsequent steps will be described first.
I do. In step (404), the focal length LF and the constant
CHLF is compared. CHLF has a certain focal length
If the focal length of the taking lens is CHLF or more,
To the step (406), where the defocus amount detection
Execute the routine "MPRED", and if it is less, step
Go to (405) and execute the subroutine "NPRED"
Execute. "MPRED" and "NPRED"
Is also a defocus amount detection subroutine.
The number of pixels to be calculated when detecting the defocus amount from
Maximum and different defocus that can be detected by it
The amount is different. FIG. 8 shows “WPRED”, “MPRED”,
The correspondence of "NPRED" is shown. In the finder
Sensor array SAA for every ranging frame FFRM
(SAB) is arranged as shown in the figure. Further, the range of the central AGC described above is a distance measuring frame.
It is set almost equal to the frame FFRM. "WPR
ED, MPRED and NPRED subroutines
Of each image (the image signal in that area)
WRGN, MR
GN and NRGN are as shown in FIG. That is, "WPRED" covers the whole area of the sensor.
And “MPRED” is the range of the central AGC inside
Are equal and "NPRED" is further inside. This
When executing “WPRED” from these correspondences,
During the accumulation process of the sensor, the whole area AGC is set to “MPRED”, “NP
It is necessary to select the central part AGC when executing "RED"
It turns out that there is. Returning to FIG. 13, description of the flowchart will be continued.
I do. Step (40) according to the focal length of the lens
5) "NPRED" or step (406) "M
After the “PRED” is executed, the process proceeds to step (407).
To detect the state of the flag LCFLG. LCFLG is
Defocus amount detection subroutine "NPRED" "MP
Low contrast flag set in “RED”
If the contrast of the image signal in the calculation area is lower than a predetermined value
Set to 1 In step (407), the flag LCF
If LG is 0, it is determined that there is sufficient contrast.
(408), and the focus detection impossible flag AFNG
Is cleared to 0. Then in step (409)
Absolute value of detected defocus amount DEF and predetermined constant J
Compare with FFLD. JFFLD can be considered in-focus
It represents the upper limit of the focus amount, and is a so-called focus width. S
In step (409), the absolute value of the defocus amount is J
If FFLD or less, proceed to step (410) to focus
Both the flag JF and the lens drive inhibition flag LMVDI are set to 1
And the absolute value of the defocus amount is calculated from JFFLD
If it is larger, the process proceeds to step (411) and the flag JF,
Clear both the LMVDI and "Focus" in step (414).
Return to the "point detection" subroutine. When in focus
In step (412), the auxiliary light mode
The state of the flag AUXMOD is detected. AUXMOD
Is 0, that is, if it is not the auxiliary light mode, step (414)
Returns the "focus detection" subroutine. AUXM
If OD is 1, ie, the auxiliary light mode, step (413)
Go to and set the auxiliary light chorus flag AUXJF to 1
Then, the subroutine is returned. The operation of the following focus detection subroutine is summarized.
The result is as follows. When the focal length is smaller than a predetermined value, NPR
Defocus is detected by ED and it is larger than the specified value.
In the case of, the defocus is detected by MPRED.
The NPRED and MPRED routines use the flag AGCF.
The image signal input subroutine is performed when LG is 0.
As described above, the signal CAGC is L and the central part A
GC has been chosen. Therefore, at this time,
Range that matches the defocus amount detection picture element range.
AGC is performed with the output of the enclosed picture element. The above-described defocus amount detection result is determined to be in focus.
Then, the flag JFLMVDI is set to 1.
Then, after returning to the AF control subroutine, the focusing table described above is obtained.
An indication is made. In addition, focus determination is made in the auxiliary light mode.
And the flag AUXJF is set to 1 and the subsequent image signal input
Force focus detection and lens driving are prohibited. In addition,
If not, the flag LMVDI is set to 0.
Therefore, after the focus detection subroutine is completed,
Is executed and the above NPRED or MPRED subroutine is executed.
Lens drive of the defocus amount determined by the
Is done. The above NPRED or MPRED
And the flag LC
Focus detection sub-blue when FLG is set to 1
In the step (407) during the implementation of the
It is detected that the strike flag LCFLG is 1 and the step
Proceeding to (415), the auxiliary light mode flag AUXMO
The state of D is detected. At this time, AUXMOD is 1, that is,
If the mode is the optical mode, the process proceeds to step (419) and the AUFMO
If D is 0 and the mode is not the auxiliary light mode, go to step (416).
Transition. In step (416), the maximum differential
The focus amount MAXDEF is compared with the variable MD. Variable M
D is a defocus amount detection subroutine "MPRED",
This is a value set in “NPRED”.
The maximum value of the defocus amount that can be detected in the
I mean. Therefore, in step (416), MA
Comparing XDEF and MD means that
The amount of defocus that can occur with the taking lens
Whether it is higher than the detection capability of the
Is to judge. That is, MAXDEF ≦
For MD, "MPRED" or
Is sufficient for defocus detection capability of "NPRED"
Think. Therefore, in step (416), MA
If XDEF ≦ MD, proceed to step (419) and
Since the point detection is impossible, the focus flag JF is cleared to 0.
A. Set the focus detection impossible flag AFNG to 1 and
After setting the stop drive inhibition flag LMVDI to 1,
Return to "Focus detection" subroutine in step (425)
I do. That is, in such a case, sufficient default
Focus amount cannot be detected and the contrast is low.
Signal from the proper ranging range for the subject
Because it is the last, the flag AFNG and LMVDI
Set 1 and return to AF control subroutine to disable focus detection
AF control without display and lens drive
Execute subroutine. On the other hand, in step (416), MAXDE
If it is determined that F> MD, the subroutine "NPRE
"D" indicates the usage level of "MPRED" in a relatively narrow range.
This is when the defocus detection ability for the lens is insufficient. Yo
In this case, for example, like a lens or a telephoto lens
If the distance measurement range is appropriate for the lens used
If the focus is set, the contrast will not be low.
there is a possibility. Therefore, in this case, step (417)
The AGC range selection flag AGCFLG is set to 1.
The AF control subroutine at step (418).
Returns the chin itself. That is, in the above case
Does not judge that the focus or focus cannot be detected.
Subroutine "NPRE" in "AF control" subroutine
D ”and“ MPRED ”instead of“ WPRE ”
D) to detect the defocus amount.
is there. Now, the AGC range selection flag AGCFLG
"AF control" subroutine with "1" set
Is called again before the "Focus detection" subroutine.
In the "image signal input" subroutine executed on
As described above, the image signal accumulated in the entire AGC state is
Is entered. Then, the “focus detection” subroutine
The flag AGCFLG in step (403).
Is detected, and the process proceeds to step (420).
Then, the defocus detection subroutine "WPRED" is executed.
Is performed. "WPRED" means "NPRED" or "M
Computes a wider area of the image signal compared to "PRED"
The maximum value of the defocus amount detected by the
Is also getting bigger. Execution of subroutine "WPRED" is completed.
Then, in step (421), the flag AGCFLG is set.
clear. This is again possible in the next “AF control”.
To run "NPRED" or "MPRED"
That's because. Next, in step (422), low contrast is obtained.
The state of the flag LCFLG is detected. LCFLG is
Flag born in "WPRED" of the top (420)
If LCFLG is 1, the subject is low contrast
Then, the process proceeds to step (419) and the focus cannot be detected.
After determining that there is, the focus detection is performed in step (425).
The "out" subroutine is returned. Step (422)
If the flag LCFLG is 0 at step (42),
Absolute defocus amount DEF detected after moving to 3)
Compare the value with the constant SDFLD. SDFLD is near focus
Represents the upper limit of the defocus amount that can be regarded as. If | DEF |> SDFLD, step
Proceeding to (424), the focus flag JF and the focus
All the lag AFNG and the lens drive prohibition flag LMVDI
Clear, and in step (426), "focus detection" subroutine
Return the routine. In step (423) |
If DEF |> SDFLD is not satisfied, that is, the in-focus vicinity range
If not, in step (422), LCFLG is 1
In the same manner as in the case where
Suppose that it is impossible to go out. This is a subroutine "WPR
"ED" is "Tefoca" with "NPRED" and "MPRED"
Is executed when the detection result is low contrast
WPRED defocus detection result
The fact that the result is within the in-focus range means that the distance measurement
Detected the defocus amount of the subject outside the frame FFRM
it is conceivable that. Therefore, the focus determination and the
When the lens is driven, the camera focuses on the subject outside the frame.
As described above to avoid it
In the subroutine "WPRED", the result is in the near focus range
If it is within the range, it is forcibly determined that the focus cannot be detected.
You. "Focus detection" subroutine for FIG.
In general, the operation of the subroutine "NPRE
D ”or“ MPRED ”(depending on the focal length of the lens)
One of the two is selected)
Detection, and if the result is low contrast,
The camera is not in the assist mode and a telephoto lens is attached.
Subroutine only for the next "NF control"
Recalculate with "WPRED". Also, "NPRED"
When “MPRED” is executed, the state of the central AGC
The sensor accumulation is performed in the state, and “WPRED” is executed.
The sensor is stored in the state of the whole area AGC.
You. When the auxiliary light is used, the above low contrast is obtained.
Is detected immediately without executing "WPRED"
"MPRED" or "NPRE"
D "is performed. That is, in the focus detection subroutine,
First, depending on the focal length, NPRED or MPRED
Is selected, and the AGC at this time is
Selects the central AGC and selects the AGC area
Perform a match and defocus the image signal found in that area.
If the contrast is not low in the
The lens drive and the in-focus display according to the focus amount are performed.
When it is determined that the contrast is low,
Defocus detection capability in the area
Larger than the large defocus amount, that is, sufficient defocus
It has a detection capability, and
The amount of defocus detected properly
Focus detection disabled display only when the amount of focus is indicated
Is performed. Further, the defocus detection ability is the highest in the lens.
Smaller than the large defocus amount, ie, NPRED, MPRE
From the defocus detection capability of the D routine,
The large defocus amount is large, and the maximum
Defocus detection capability (depending on calculation
If the defocus amount detection is performed in the
When the contrast is not determined, the flag AGC is used.
FLG is set to 1 and the calculation target area is large and WPR
ED subroutine is executed, and at this time AGC is set all over
AGC is not performed, and a match is made with the calculation target area. This WP
RED subroutine determines low contrast
When a focus is detected, a focus detection impossible display is performed. Also, low contra
WPRED routine if no strike is determined
When the defocus detected at is large, the defocus
Lens drive based on the amount of focus
When the subject is within the vicinity of focus, the subject is outside the focusing frame
May be determined to be in focus.
Focusing on body (subject captured in distance measurement frame)
The focus detection is not possible and display
You. Therefore, the AGC area matches the calculation target area.
The person who can always perform the appropriate AGC operation can be used.
In the calculation target area that matches the maximum defocus amount
The defocus amount can be detected correctly and the calculation target area is
When switching from the inside of the ranging frame to the area that covers the outside
Prevents objects outside the focusing frame from being in focus.
Can be stopped. Further, the calculation target area according to the subject situation is automatically
Dynamically selected focus detection operation as appropriate as possible
Is done. The calculation target areas are NRGN and MRNG.
Select according to the focal length of the lens.
Focuses on NRGN when he chooses MRGN
Image processing is performed on the calculation target area suitable for the distance and it is appropriate
Focus detection is performed. FIG. 14 shows a subroutine for detecting a defocus amount.
“NPRED”, “MPRE”, “WPRED”
Shows a raw chart. The functions of the three subroutines are
From the obtained image signal, the amount of deviation of two is detected, and then
In addition, the defocus amount is determined.
The method has been previously described by the present applicant in Japanese Patent Application No. 61-160824.
No. 6,009,045. Therefore, detailed description is omitted.
However, the basic operation is performed as follows. [0124] [Outside 1] A (I) and B (I) are signals of two images, respectively.
It is. f {} is max {a, b}, min {a,
b｝ function, the former extracts the larger value of a and b
The latter means extracting a smaller value. X (K) calculates a specific range of the image signal
The range is "NPRED", "MP
The difference between RED and WPRED
It is as expected. The range is the variables HB and NPX in the previous equation.
Is defined by This will be described with reference to FIG.
In the "out" subroutine, the defocus amount detection
When the routine “MPRED” is called, step (5)
02) on the RAM of the microcomputer PRS
The constant NHB is stored in the variable area HB set in
The constant NNPX is stored and “MPRED” is called.
For example, in step (513), the variables HB and NPX are
The constants MHB and MNPX are called "WPRED"
Then, in step (515), the constants WHB and W
NPX is stored. This will be described in more detail with reference to FIG.
In the figure, NPGN, MRGN, and WRGN are sub-blue, respectively.
Chin “NPRED”, “MPRED”, “WPRED”
Represents the calculation target area on the sensor array. Example
And the number of pixels in the sensor row is 40 pixels
Assign numbers such as [0], [1] ... [39]
Then, the calculation target area NRGN of “NPRED” becomes ｛[1
2] to [27]}. Therefore, the constants NHB = 12 and NNPX = 16
Is set. Similarly, the calculation target area M of “MPRED”
Since RGN is {[10] to [29]}, MHB = 1
0, MNPX = 20, calculation target area W of “WPRED”
Since RGN is {[0]-[39]}, WHB =
0, WNPX = 40. Now, steps (502), (503),
In (504), in addition to the variables HB and NPX, the variable M
D is set. The variable MD is explained in FIG.
As described above, each defocus amount detection subroutine
Represents the maximum detected defocus amount. This change
The role of several MDs is described below. The operation shown in equation (2) is evaluated as X (K).
By calculating the quantity in the range KB ≦ K ≦ KE, 2
The shift amount of the image is detected. According to the equation (2),
Evaluation with K as a variable as the absolute value of K increases
The number M of calculation pixels for obtaining the amount X (K) decreases (M
= NPX- | K | -1). It goes without saying that an increase in | K |
Becomes too small, then the S / N ratio of X (K) becomes low.
Down. Therefore, the calculation accuracy that depends on the number M of calculation pixels is ensured.
In order to maintain the upper limit of | K |
It is necessary to determine. If NPX increases, | K |
Can be increased, which results in a large displacement between the two images.
Can be dealt with, and therefore the amount of defocus
This means that the detection capability can be increased. Steps (502), (513), (51)
The constants NMD, MMD and WMD in 5) are the subroutines.
Default of | K | allowed by NPX in Chin
This is converted to the amount of scum. How small the number of operation pixels M can be
Whether or not the S / N of the entire focus detection system
Although it is difficult to unambiguously determine the accuracy of the present invention,
Since the number of pixels of the sensor array in the example is 40 pixels,
Let the lower limit of M be 10 pixels. Then each sub
The upper limit of | K | in the routine is M = NPX- | K |-
1 is determined as follows. In "NPRED"
The upper limit of | K | is 16-10-1 = 5, "MPRED"
20-10-1 = 9, smells "WPRED"
40-10-1 = 29. Image shift of these values
When the amount is converted to a defocus amount, multiplying by a constant C gives
Find maximum detected defocus amount in subroutine
Can do things. The constant C is obtained from the configuration of the secondary optical system for focus detection.
When the determined value is, for example, C = 2, the subroutine "N
The maximum detected defocus amount NMD of “PRED” is 5 × 2 =
10, the same amount MMD of “MPRED” is 9 × 2 = 18,
The same amount WMD of “WPRED” is 29 × 2 = 54. Returning to the description of the flowchart of FIG.
In step (503), the variable MD and the variable MAX
DEF is compared, but the above value is stored in the variable MD.
Is stored in the variable MAXDEF.
The maximum possible defocus amount of the shadow lens "focus detection"
Already stored in the first step of the subroutine. If the result is MD> MAXDEF,
Step (504) if MD ≦ MAXDEF
Move to (505). In the step (504), the variable MD
Restore the value of MAXDEF and go to step (505).
Transition. In step (505), the variable MD is described first.
The variable MSFT is obtained by dividing by the constant C. This variable M
SFT represents the upper limit of | K |. In the step (503), the variable MD and
The reason for comparing the variable MAXDEF is that the maximum
Defocus amount detection sub-level at that time
In the condition where the defocus amount is smaller than the maximum
It is not necessary to calculate the variable MSFT from the variable MD.
It is sufficient to use the other value. Therefore MD> MAXD
In the case of EF, in step (504), the variable MAXD
The value of EF is stored again in the variable MD. Next, in step (506), equation (2) is used.
The lower limit KB and upper limit KE of K are set according to the following equations. KB = −MSFT + △ (3) KE = MSFT + △ In equation (3), a constant △ is added to KB and KE.
As described above, △ is 2
It is the amount of image shift, and is K from the maximum defocus amount of the lens.
This is an offset when setting B and KE. Next, in step (507), the expression
Japanese Patent Application No. 61-160824 based on (2)
By the method shown, the image shift amount PR and the contrast
The amount ZD is obtained. In step (508), the step
From the image shift amount PR obtained in step (507).
Is calculating the amount of money. DEF = (PR− △) · C (4) That is, the image shift amount の at the time of focusing is subtracted from the image shift amount PR.
Later, the image shift amount is multiplied by the coefficient C of the defocus amount.
Thus, the defocus amount DEF is obtained. In step (509), step (50)
The contrast amount ZD obtained in 7) and the constant LCLVL are
Compare. LCLVL is a command that enables correct focus detection.
This is the lower limit of the trust amount, and when ZD≥LCLVL
It is determined that the contrast is sufficient for the step (510).
Clears the low contrast flag LCFLG to 0,
When D <LCLVL, the contrast is insufficient.
Then, in step (511), the low contrast flag LC
Set to 1 in FLG. By default,
The detection of the focus amount is completed, and in step (512)
Defocus amount detection subroutine "NPRED", "M
PRED "and" WPRED "are returned. As described above, each of NPRED, MPRED, WP
Since the RED routine is configured,
Defocus amount based on the amount of image shift in the corresponding calculation area
Detection is performed, and the defocus amount is
Each of the above-described processes is performed. In addition, in the above calculation processing, the deviation amount △ is considered.
Offset, the correct image shift amount is always detected.
Be informed. In the embodiment, the image signal sensor array
A special AGC sensor was installed near the camera.
The C sensor does not need to be dedicated, and the image signal is
For a sensor device configured to output as an AGC signal
Even so, it is clear that the present invention is effective. [0147] As described above, according to the present invention, the narrow range
If the focus cannot be detected based on the photoelectric conversion element output,
The maximum amount of defocus generated by the taking lens at that time is
The photoelectric conversion element range is set only when the
Since focus detection was performed by enlarging,
Prevents inconvenience such as focus detection for the subject
What you get.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing the principle of focus detection according to the present invention. FIG. 2 is an explanatory diagram showing an example of an output state of the sensor of FIG. FIG. 3 is an explanatory diagram showing a sensor output state in a focused state. FIG. 4 is an explanatory diagram illustrating an example of an output state of a sensor. FIG. 5 is an explanatory diagram illustrating an example of an output state of a sensor. FIG. 6 is a circuit diagram showing a configuration of a sensor device used in the present invention. FIG. 7 is a circuit diagram showing an embodiment of a camera having a focus detection device according to the present invention. FIG. 8 is an explanatory diagram showing a positional relationship between a finder ranging frame and a sensor. FIG. 9 is a diagram showing a main flowchart for explaining the operation of the embodiment of the present invention. FIG. 10 is a flowchart illustrating an autofocus operation. FIG. 11 is a flowchart illustrating an image signal processing operation. FIG. 12 is a diagram illustrating a flowchart for explaining a lens driving operation. FIG. 13 is a flowchart illustrating a focus detection determination operation. FIG. 14 is a diagram illustrating a flowchart for explaining an arithmetic processing operation. [Description of Signs] SAA Sensor Example SAB Sensor Example PRS Computer

Claims (1)

(57) [Claims] 1. Multiple photoelectric conversions that receive the light beam that has passed through the imaging optics
Light-receiving circuit comprising exchange element and photoelectric conversion element of the light-receiving circuit
Focus based on the photoelectric conversion element output from a predetermined range
In a camera having a focus detection device that performs detection calculation,
The photoelectric conversion element from the first range among the photoelectric conversion elements of the light receiving circuit.
First mode for performing focus detection calculation based on conversion element output
And a photoelectric conversion element from a second range wider than the first range
Has a second mode for performing focus detection calculation based on output
Arithmetic processing means;Focus detection operation in the first mode
First determining means for determining whether or not focus detection is impossible in the calculation
According to the first range in the first mode.
Caused by the focus detection capability and the imaging optics
The defocus amount is determined based on the defocus amount.
No. to determine whether the detection capability is exceeded2Judgment means
And the saidIn the focus detection calculation in the first mode,
The first determination means determines that the focus cannot be detected, andPrevious
Note2The amount of defocus is determined by the judging means to be the focus detection capability.
The second mode is selected when it is determined that
However, even if the first determination unit determines that the focus cannot be detected,
The defocus amount is determined by the second determination means to be a focus detection capability.
When it is not determined that the force is exceeded, the second mode is used.
Prohibit selection ofHaving focus means.
A camera having a point detection device.