JPH07303205A - Image pickup device and its image pickup method - Google Patents

Abstract

PURPOSE:To permit only an image pickup element to adjust a focus and exposure so as to reduce release time lag by permitting a first release switch to start focus adjustment and exposure adjustment by means of the image pickup element and to permit a second release switch to start exposure. CONSTITUTION:A focus evaluation value showing the focused degree of an optical image is detected by using the image pickup element 4 and the focus is adjusted based on the focus evaluation value. Appropriate exposure quantity is calculated by using the image pickup element 4, and exposure is adjusted in accordance with the appropriate exposure quantity. System control CPU 10 is started by the operation of the first release switch in an operation part 12 so as to start a photographing operation, and the focus and exposure are adjusted. The second release switch instructs the start of exposure by the second release switch after the adjustment of the focus and exposure. Thus, the processings of automatic exposure(AE), automatic focusing(AF) and automatic white balance(AWB) are conducted without using a photoelectric conversion element except for the image pickup element 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus using an image pickup element for converting an optical image into an electric signal and an image pickup method thereof.

[0002]

2. Description of the Related Art Conventionally, a digital electronic camera has been known as an image pickup apparatus of this type. FIG. 18 is a block diagram showing the configuration of a conventional digital electronic camera. In the figure,
Reference numeral 100a is a digital electronic camera, and 101a is a recording medium such as a memory card.

The digital electronic camera 100a includes an image pickup lens 1a whose focal length and angle of view can be adjusted, an aperture shutter 2a having an aperture function and a shutter function, and a mechanical system drive circuit 3a for driving the image pickup lens 1a and the aperture shutter 2a. An image pickup device 4a for converting the reflected light from the subject into an electric signal is provided.

Further, a timing signal generation circuit (TG) 5a for generating a timing signal necessary for operating the image pickup device 4a, and an image pickup for amplifying a signal from the timing signal generation circuit 5a to a level at which the image pickup device 4a can be driven. A pre-processing circuit 7a including an element driving circuit 6a, a correlated double sampling circuit (CDS circuit) and an automatic gain control circuit (AGC circuit) for removing output noise of the image sensor 4a, A /
The D converter 8a includes a memory for temporarily storing the A / D-converted digital signal, and an imaging signal processing circuit 9a for processing the digital signal stored in the memory.

Further, the system control CPU 10a, an operation display section 1 showing a display for assisting operation and a state of the camera.
1a, an operation unit 12a having a switch capable of performing two-step operation of a first stroke switch SW1 and a second stroke switch SW2 for an external photographer to operate the camera to start photographing, a digital electronic camera 100a, and a recording medium 1.
A recording medium I / F 13a for connecting to 01a is provided.

Further, the timing signal generating circuit 5a includes
A distance measuring sensor 14a for measuring the distance between the image pickup apparatus and the subject for adjusting the focus of the image pickup lens 1a and a photometric sensor 15a for measuring the brightness of the subject are connected.

The operation of the conventional image pickup apparatus will be described.
FIG. 19 is a flowchart showing a conventional image pickup processing routine. The first, which is a photographer's command to start photographing from the operation unit 12,
When the stroke switch SW1 is pressed, the distance measuring sensor 14a starts operating and its output is the system control CPU.
10a is input (step S301). The system control CPU 10a calculates the amount of movement of the focus adjustment lens based on the output of the distance measuring sensor 14a (step S302), and moves the focus adjustment lens of the imaging lens 1 through the mechanical system drive circuit 3a to bring it into focus. When the movement of the focus adjusting lens is completed, the focus adjusting lens is not moved thereafter in the automatic focus lock (AF LOCK) state (step S3).
03). After that, the output of the photometric sensor 15a is input to the system control CPU 10a until it is detected that the second stroke switch SW2 is pressed (step S304). When it is detected that the second stroke switch SW2 is pressed (step S305), the photometric sensor 15
The brightness of the subject is detected from the output of a, and the aperture value and shutter speed corresponding to the detected value are calculated (step S306). The aperture and the electronic shutter timing of the timing signal generator are set according to the calculated exposure conditions, the image sensor 4 is exposed, and the output of the image sensor 4a is read (step S307). A preprocessing circuit 7a performs signal processing such as correlated double sampling (CDS) processing and gain control on the read output of the image sensor 4a. At this time, the gain of the gain control circuit is determined by the sensitivity of the image pickup device, and thus is set when the image pickup apparatus is manufactured. The output of the front-end circuit 7a is the A / D converter 8
It is converted into a digital signal by a and input to the imaging signal processing circuit 9a. The image pickup signal processing circuit 9a and the system control CPU 10a reconfirm the exposure condition from the image pickup output (step S308), and detect the error from the proper exposure to change the shutter speed setting. The image pickup device 4a is exposed again according to the changed exposure condition and the output is read (step S309). The output of the image pickup device 4a is converted into a digital signal, and after being converted into a specific format by the image pickup signal processing circuit 9a, the recording medium I / F
A captured image signal is recorded on the recording medium 101 via 13a.

[0008]

However, in the conventional digital electronic camera, various sensors other than the image pickup device 4a such as the distance measuring sensor 14a and the photometric sensor 15a are used, so that the device is downsized and the cost is reduced. Was difficult.

Further, the technique of providing only the image sensor without using various sensors, and the image sensor substituting the functions of the various sensors has been implemented in equipment such as a video camera recorder. However, unlike the video camera recorder, in the shooting release. It was considered that the electronic camera, which requires the release time lag from the time when the shutter is pressed until the image is recorded, to be as short as possible, cannot exhibit its performance sufficiently.

Therefore, an object of the present invention is to provide an image pickup apparatus capable of performing focus adjustment and exposure adjustment in a short time only by an image pickup element without using a distance measuring sensor or a photometric sensor, and reducing a release time lag. To do.

[0011]

In order to achieve the above object, an image pickup device according to claim 1 of the present invention comprises an image pickup device for converting an optical image into an electric signal, and the optical image pickup device using the image pickup device. Focus evaluation value detecting means for detecting a focus evaluation value indicating a focus degree, and focus adjusting means for performing focus adjustment for focusing the optical image on the image sensor based on the detected focus evaluation value. An exposure amount detecting means for detecting an appropriate exposure amount using the image pickup device, an exposure adjusting means for performing an exposure adjustment according to the detected appropriate exposure amount, and a first instruction for instructing to start the focus adjustment and the exposure adjustment. Release switch, main exposure image pickup means for performing main exposure after the focus adjustment and exposure adjustment, and a second release switch for instructing the start of the main exposure.

According to a second aspect of the present invention, there is provided an image pickup apparatus according to the first aspect, further comprising a diaphragm for limiting an incident exposure amount of the image pickup device, and the focus evaluation value detecting means is instructed by the first release switch. After the aperture is opened, the first focus evaluation value is detected, and the focus adjustment unit performs the focus adjustment according to the detected first focus evaluation value, and then the aperture diameter of the aperture is subjected to the main exposure. The second focus evaluation value is detected in the same manner as the above, and the third focus evaluation value is detected by setting the aperture state substantially the same as the main exposure according to the instruction of the second release switch. Compares the second focus evaluation value with the third focus evaluation value, and performs main exposure when the difference is less than or equal to a predetermined value.

According to a third aspect of the present invention, there is provided the image pickup apparatus according to the second aspect, wherein the exposure amount detecting means detects the proper exposure amount when detecting the second focus evaluation value and the third focus evaluation value. To detect.

According to a fourth aspect of the present invention, there is provided an image pickup device according to the first aspect, further comprising an automatic focus lock switch for setting an automatic focus mode and a diaphragm for limiting an incident exposure amount of the image pickup device. When the lock switch is not in the auto focus mode, the focus evaluation value detection means performs the focus adjustment by opening the diaphragm according to the instruction of the first release switch, and then performs the main exposure of the aperture diameter of the diaphragm. The second focus evaluation value is set to be the same as the aperture diameter, and the third focus evaluation value is detected according to the same aperture state as the main exposure according to the instruction of the second release switch. When the difference between the second focus evaluation value and the third focus evaluation value is smaller than a predetermined value, the main exposure is performed, and when the automatic focus lock switch is in the automatic focus mode, Performing as the exposure according to an instruction of the second release switch without detection of the second focus evaluating value and the third focus evaluation value.

According to a fifth aspect of the present invention, in the image pickup apparatus according to the first aspect, there is provided a timer for measuring the time from the completion of the detection of the focus evaluation value or the focus adjustment to the pressing of the second release switch. The main exposure is performed when the measured time is within a predetermined time, and the focus evaluation value is detected or the exposure is corrected again when the predetermined time has elapsed.

According to a sixth aspect of the present invention, in the image pickup apparatus according to the second aspect, the second release switch instructs after the detection of the first focus evaluation value or the second focus evaluation value is completed. A timer for measuring the time until the measurement is performed is provided, and when the measured time is within a predetermined time, the main exposure is performed without performing the subsequent focus adjustment.

According to a seventh aspect of the present invention, in the image pickup apparatus according to the first aspect, when the focus evaluation value is detected, the image pickup system that drives the image pickup device is turned off, and the second image pickup apparatus is used.
When the release switch is pressed, the power is turned on again.

An image pickup apparatus according to claim 8 is provided with a timer for measuring a time from when the focus evaluation value is detected in the image pickup apparatus according to claim 7 until the second release switch is pressed. When the time measured by is shorter than the predetermined value, the main exposure is performed without turning off the power supply of the image pickup system.

According to a ninth aspect of the present invention, there is provided an image pickup apparatus according to the first aspect, further comprising a fourth focus evaluation value deriving means for deriving a fourth focus evaluation value from the output of the image pickup element at the time of main exposure. Release switch detection means for detecting that the first release switch or the second release switch is pressed after completion of the main exposure, and the release switch detection means for detecting the first release switch or the second release switch. Fifth focus evaluation value is derived when it is detected that the release switch is pressed.
Focus evaluation value deriving means, and when the difference between the fourth focus evaluation value and the fifth focus evaluation value is within a predetermined value and the second release switch has already been pressed, the Exposure is performed, and when the second release switch is not pressed, it waits until the second release switch is pressed, and when the difference exceeds a predetermined value, the aperture is opened again and the first release switch is opened. Adjust the focus when is pressed.

An image pickup apparatus according to a tenth aspect comprises the fourth focus evaluation value deriving means for deriving a fourth focus evaluation value from the output of the image pickup element at the time of main exposure in the image pickup apparatus according to the first aspect, Release switch detection means for detecting that the first release switch or the second release switch is pressed after completion of the main exposure, and from the completion of the main exposure until the second release switch is pressed. And a timer for measuring the time, and when the time measured by the timer is shorter than a predetermined time, the next main exposure is photographed as it is, and when it is longer than the predetermined time, a fifth focus evaluation value is detected, The difference between the focus evaluation value of 4 and the fifth focus evaluation value is derived, and when the difference is within a predetermined value, the timer is reset again and the operation is performed by pressing the second release switch. To repeat, the difference is perform focus adjustment when the first release switch is depressed to release the stop again when exceeding a predetermined value.

According to the eleventh aspect of the present invention, an image pickup device converts an optical image into an electric signal, detects a focus evaluation value indicating a focus degree of the optical image, and based on the detected focus evaluation value. A first release switch that performs focus adjustment for focusing the optical image on the image sensor, detects an appropriate exposure amount using the image sensor, and performs exposure adjustment according to the detected appropriate exposure amount. To instruct the start of the focus adjustment and the exposure adjustment. After the exposure adjustment and the focus adjustment, the main shutter is instructed by the second release switch.

[0022]

In the image pickup apparatus according to the first aspect of the present invention, the optical image is converted into an electric signal by the image pickup element, and the focus evaluation value detecting means uses the image pickup element to evaluate the focus of the optical image. Value is detected, focus adjustment is performed by the focus adjustment means to focus the optical image on the image sensor based on the detected focus evaluation value, and proper exposure is performed by the exposure amount detection means using the image sensor. Amount is detected, exposure adjustment means performs exposure adjustment in accordance with the detected proper exposure amount, and a first release switch instructs the focus adjustment and the start of the exposure adjustment. After the exposure adjustment, the main exposure is performed, and the start of the main exposure is instructed by the second release switch.

In the image pickup apparatus according to claim 2, the focus evaluation value detection means opens the diaphragm for limiting the incident exposure amount of the image pickup device in response to an instruction from the first release switch to open the first focus evaluation value. And the focus adjustment means performs the focus adjustment according to the detected first focus evaluation value, and then the second focus evaluation value is detected by setting the aperture diameter of the diaphragm to be substantially the same as the main exposure. Then, in response to an instruction from the second release switch, a diaphragm state substantially the same as that of the main exposure is set to detect a third focus evaluation value, and the main exposure image pickup means detects the third focus evaluation value and the third focus evaluation value. Focus evaluation values are compared, and when the difference is less than or equal to a predetermined value, main exposure is performed.

In the image pickup apparatus according to the third aspect, the exposure amount detecting means detects the proper exposure amount when detecting the second focus evaluation value and the third focus evaluation value.

In the image pickup apparatus according to the fourth aspect, when the automatic focus lock switch is not in the automatic focus mode, the focus evaluation value detection means limits the incident exposure amount of the image pickup device according to an instruction from the first release switch. After performing the focus adjustment with the diaphragm in the open state, the aperture diameter of the diaphragm is made the same as the aperture diameter for the main exposure, the second focus evaluation value is detected, and the main exposure is performed by the instruction of the second release switch. A third focus evaluation value is detected in accordance with the same diaphragm state as the above, and the main-exposure image pickup means sets the second focus evaluation value and the third focus evaluation value.
Of the second focus evaluation value and the third focus evaluation value when the automatic focus lock switch is in the automatic focus mode. The main exposure is directly performed according to the instruction of the second release switch without performing the detection.

In the image pickup apparatus according to the fifth aspect, the time from the completion of the detection of the focus evaluation value or the focus adjustment to the pressing of the second release switch is measured by a timer, and the measured time is measured. When the predetermined time has elapsed, the main exposure is performed, and when the predetermined time has elapsed, the focus evaluation value is detected or the exposure is corrected again.

In the image pickup apparatus according to the sixth aspect, the time from when the detection of the first focus evaluation value or the second focus evaluation value is completed by the timer until the second release switch is instructed. When the measured time is within a predetermined time, the main exposure is performed without performing the subsequent focus adjustment.

In the image pickup device according to the seventh aspect, when the focus evaluation value is detected, the power source of the image pickup system for driving the image pickup element is turned off, and when the second release switch is pressed, the power source is turned on again. Throw in.

In the image pickup apparatus according to the present invention, a timer is provided for measuring the time from the detection of the focus evaluation value to the pressing of the second release switch, and the time measured by the timer has a predetermined value. Shorter than that, main exposure is performed without turning off the power supply of the imaging system.

In the image pickup apparatus according to the ninth aspect, the fourth focus evaluation value deriving means derives the fourth focus evaluation value from the output of the image pickup element at the time of main exposure, and the release switch detecting means performs the main exposure. After completion, it is detected that the first release switch or the second release switch is pressed, and the release switch detection means presses the first release switch or the second release switch. The fifth focus evaluation value deriving means derives a fifth focus evaluation value when a is detected, and the difference between the fourth focus evaluation value and the fifth focus evaluation value is within a predetermined value, and When the second release switch has already been pressed, the main exposure is immediately performed, and when the second release switch is not pressed, the second release switch is pressed. Wait, when the difference exceeds a predetermined value, it performs the focus adjustment when the first release switch is pressed the stop again as open.

In the image pickup apparatus according to the tenth aspect, the fourth focus evaluation value deriving means derives the fourth focus evaluation value from the output of the image pickup element at the time of the main exposure, and the release switch detecting means performs the main exposure. After the completion, it is detected that the first release switch or the second release switch is pressed, and the timer measures the time from the completion of the main exposure to the press of the second release switch. When the time measured by the timer is shorter than the predetermined time, the next main exposure is photographed as it is, and when it is longer than the predetermined time, the fifth focus evaluation value is detected, and the fourth focus evaluation value and the fifth focus evaluation value are detected. Of the focus evaluation value of D, and when the difference is within a predetermined value, the timer is reset again and the above operation is repeated until the second release switch is pressed, and the difference is set to the predetermined value. The first release switch to release the stop again when crossing performs focus adjustment when pressed.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the image pickup apparatus and the image pickup method of the present invention will be described with reference to the drawings. The image pickup apparatus of this embodiment is applied to a digital camera.

[First Embodiment] FIG. 1 is a block diagram showing the arrangement of a digital camera according to the first embodiment. In the figure,
Reference numeral 100 is a digital electronic camera, and 101 is a recording medium such as a memory card.

The digital electronic camera 100 includes an image pickup lens 1 whose focal length and angle of view can be adjusted, a shutter 2 which also serves as an aperture and a shutter function, a mechanical system drive circuit 3 for the image pickup lens 1 and a shutter 2 which serves as an aperture, and a subject. The image pickup device 4 for converting the reflected light from the light into an electric signal is provided.

Further, a timing signal generating circuit (TG) 5 for generating a timing signal necessary for operating the image pickup device 4, and an image pickup for amplifying a signal from the timing signal generation circuit 5 to a level at which the image pickup device 4 can be driven. A device driving circuit 6, a preprocessing circuit 7 having a correlated double sampling (CDS) circuit for removing output noise of the image pickup device 4 and an automatic gain control (AGC) circuit, an A / D converter 8, and an A / D The imaging signal processing circuit 9 has a memory for temporarily storing the converted digital signal and processes the digital signal stored in the memory.

Further, the system control CPU 10 and the operation display unit 1 showing the display for assisting the operation and the state of the camera.
1. An operation unit 12 having a first stroke switch SW1 and a second stroke switch SW2 that can be operated in two steps by a switch for an external photographer to start photographing of the camera, a digital electronic camera 100, and a recording medium 101. A recording medium I / F 13 for connecting to and is provided.

The operation of the digital camera having the above configuration will be described. FIG. 2 is a flowchart showing the image pickup processing routine. The system control CPU 10 is activated by the operation of the first stroke switch SW1 of the operation unit 12 to start the photographing operation. First, the system control CPU 10
Starts rough adjustment of exposure (step S2).

FIG. 3 is a flowchart showing the exposure coarse adjustment subroutine. In the rough exposure adjustment subroutine, the system control CPU 10 sets initial values (R0 = 0, R1 = 2, R2 = 1) for designating the position of the focus adjustment lens (step S201). FIG. 13 is an explanatory diagram showing the lens position of the focus adjustment lens. Here, lens positions 0, 1, 2, 3
... is the position of the focus adjustment lens, 0 is the longest focus side, 1
0 is the shortest focus side.

Subsequently, the control of the optical system is started, and the focus adjustment lens is moved to the position of R0 (0 as an initial value, that is, the longest focus side) (step S202). The diaphragm is closed to bring it into a light shielding state (step S203), and in order to obtain a reference value for photometry, the output of the image pickup device in the light shielding state is read out (step S204). At the time of this reading, in order to increase the reading speed, the vertical and horizontal transfer units are driven at a higher speed than at the time of normal video signal extraction. For example, in the case of using an interline CCD having an effective pixel count of about 440,000 that drives vertical transfer at about 15 KHz and horizontal transfer at about 14 MHz during normal reading,
By driving the vertical transfer signal at 1 MHz and the horizontal transfer at 28 MHz, it becomes possible to read all the pixels of the image sensor within 1 ms. In this way, the reference black level value is derived based on the read signal (step S20).
5).

As a concrete method of this high-speed transfer, several modes can be considered in the relationship between vertical transfer and horizontal transfer. FIG. 11 is an explanatory diagram showing vertical transfer and horizontal transfer. In the figure, the frequency of the vertical transfer pulse is 1 MHz.
Then, all the vertical lines are read out and the charges for all the pixels are accumulated in the horizontal transfer register. After the transfer of all the charges, the charges in the horizontal register are transferred by the horizontal transfer pulse and output through the output amplifier.

At this time, the signal charges of the respective pixels are mixed in the horizontal transfer register. However, the purpose of this rough adjustment is to set the exposure amount of the image pickup device to a level at which the focus can be adjusted. Does not pose a problem since it is necessary to perform integration processing on all pixel signals. In this way, the signal output after horizontal transfer is processed by the preprocessing circuit 7, A /
It is input to the image pickup signal processing circuit 9 via the D converter 8.
The output signal input to the image pickup signal processing circuit 9 is the black level detection value for realizing the rough exposure adjustment by integrating the output signal for the horizontal transfer period.
Input to 0.

Further, in the case of the figure, the vertical transfer is divided into 5 times, and the signals accumulated in the horizontal register after each vertical transfer are horizontally transferred and output. In this case, the amount of charge accumulated in the horizontal register is ⅕ of that in the case of, so that the risk of overflow of the horizontal register is reduced.

Further, in the case of the figure, the vertical transfer of 1 MHz is continuously performed for all the vertical pixels, and at the same time, the horizontal transfer is performed at 28 MHz. However, in order to read all the last pixels, the horizontal transfer pulse is longer by one horizontal transfer. By the way, in the case of this driving method, not only the pixels are mixed in the vertical direction but also the pixels are mixed in the horizontal direction, but as in the case described above, there is no problem due to the purpose of this operation.

As described above, the image pickup signal read out in step S204 is integrated over all pixels in the image pickup signal processing circuit 9 via the preprocessing circuit 7 and the A / D converter 8. At this time, the gain of the preprocessing circuit 7 is set at the time of manufacturing depending on the sensitivity of the image sensor 4. After the black level is derived in step S205 according to the calculation in the CPU by the integrated signal, the optical system is controlled to minimize the aperture of the aperture / shutter 2 in the settable range (step S205).
206). In this minimum aperture state, exposure is performed at the highest electronic shutter speed within a settable range, and the image sensor is driven in the same manner as the black level detection (step S20).
7). The read image output is read by the preprocessing circuit 7 and A.
The image pickup signal processing circuit 9 through the / D converter 8 integrates all pixels.

The gain of the preprocessing circuit 7 at this time is also set at the time of manufacture depending on the sensitivity of the image pickup device 4. Further, by subtracting the exposure output data integrated by the system control CPU 10 and the integrated black level data, the brightness of external light is detected, and the exposure amount for focus adjustment is determined. Since exposure is performed with the aperture open during focus adjustment, the shutter speed at the open aperture is derived (step S208). Further, the optical system is controlled to set the open aperture (step S209), the electronic shutter of the image sensor 4 is set to the derived shutter speed (step S210), the present subroutine is ended, and the process returns to the main routine.

Next, in step S3, focus adjustment, exposure fine adjustment, and light source flicker detection are performed. 4 to 7 are flowcharts showing the focus adjustment / exposure fine adjustment / light source flicker detection subroutine. First, it is confirmed whether or not the movement of the focus adjustment lens instructed by the rough exposure adjustment is completed (step S211), and if not completed, the process waits until it is completed. When it is completed, the electronic shutter is exposed for the set exposure time, and the output of the image sensor 4 is read (step S212).

FIG. 12 is an explanatory diagram showing a range of pixels to be read out. At the time of reading the output from the image pickup element 4, as shown in FIG. 12A, the normal reading is performed on the pixel in the central portion (a), and the high-speed reading is performed on the other upper and lower portions (a). That is, as shown in FIG. 10, the vertical transfer pulse and the horizontal transfer pulse are read in the high-speed transfer state and the normal transfer state. The read signal is used in the preprocessing circuit 7
And the A / D converter 8 is input to the image pickup signal processing circuit 9, and in the image pickup signal processing circuit 9, a distance measurement signal F0 which is an evaluation signal for determining the focus degree of the optical system and an exposure correction signal The photometric signal L0, which is a brightness level detection signal, is derived (step S213). At this time, for example, when the range-finding range designation frame displayed in the viewfinder is designated within the range shown by the shaded area in FIG. 12A, it is normally read from the portion (A) of the image sensor 4. The center portion (hatched portion in FIG. 12) of the extracted signal is extracted by a line memory (not shown) in the image pickup signal processing circuit 9 and focus adjustment is performed only with the extracted signal, thereby forming a range-finding range designation frame. It is possible to match the range of the actual extracted signal.

Next, the system control CPU 10 derives the exposure amount and shutter speed for the next exposure from the photometric signal L0 (step S213). It is checked whether or not the distance measurement signal F0 is larger than the predetermined value a (step S2
14) If it is smaller than the predetermined value a, the distance measuring area read from the image sensor 4 is changed (step S215). As for this change, as shown in FIG. 12B, the area (a) for normal reading is set above the image sensor 4, and the other area (a) is read at high speed. It can be carried out by changing the drive of. Even in this driving method, when the edge signal is not detected from the distance measuring area, the normal reading area is set below the image sensor 4 to detect the distance measuring signal.

It should be noted that the order is changed and normal reading is first performed from the lower part of the image sensor 4, and if no edge signal is detected in the signal from the lower part of the image sensor 4, the signal from the upper part of the image sensor 4 is read. You can

In step S214 of FIG. 4, when the distance measurement signal F0 is larger than the predetermined value a, it is determined that focus adjustment is possible, and the focus adjustment lens is moved to R1 (step S216). Since R1 is set to R1 = 2 when initially set, the focus adjusting lens is moved to the position 2 in FIG. When the movement of the focus adjustment lens is completed, the electronic shutter is set to the shutter speed derived from the photometric signal L0, and the signal of the image pickup distance measuring area is read out similarly to step S212 (step S217). The distance measuring signal F1 and the photometric signal L1 are derived from the read signal, the next exposure amount is determined, and the light source flicker detection signal is derived by subtracting the photometric signal L1 from the photometric signal L0 (step S218). This light source flicker signal detects a light source having flicker such as a fluorescent lamp and corrects its color reproduction in the process of image pickup signal processing, or detects that the light source illuminating the subject has been changed in the process of focus adjustment. Can be used for.

Subsequently, the magnitudes of the distance measurement signal F1 and the distance measurement signal F0 are compared (step S219), and if the distance measurement signal F1 is larger, it is determined that the optimum focus point exists on the short focus side and after step S225. Process shifts to. Also,
If the distance measurement signal F1 is small, it means that the optimum focus point is at the lens position 0 or 1, so that the step S
At 220, the focus adjustment lens is moved to R2 = 1. When the movement of the focus adjustment lens is completed, the electronic shutter is set again and the image pickup distance measuring area is read (step S221).

Subsequently, similarly to step S218, the distance measurement signal F2, the light measurement signal L2 and the light source flicker detection signal (L1-L2) are derived (step S222), and the magnitudes of the distance measurement signal F2 and the distance measurement signal F0 are compared. Compare (step S
223). If F2> F0, it is considered that the focus adjustment is completed, and this subroutine is ended and the process returns to the main routine. On the other hand, F
If 2 ≦ F0, the focus adjustment lens is moved to R0 = 0 (step S224), and then this routine is ended and returns to the main routine.

If F1> F0 in step S219, it is confirmed whether R0 is 10 (step S225). Since R = 0 in this case, the process proceeds to step S226.
In step S226, R0 = R0 + 2 = 2, R1 = R1
+ 2 = 4, R2 = R2 + 2 = 3, R3 = R2 = 1, F0
= F1, L0 = L2, and the focus adjustment lens is moved to R1 with the constant setting (step S228). When the movement is completed, the signal of the imaging distance measuring area exposed at the set shutter speed is read (step S229).

The following steps S230 to S23
4 operates in the same manner as steps S219 to S223 in FIG. If F2 ≦ F0 in step S234, it means that the optimum focus point is finally on the long focus side of R0, and the focus adjustment lens is moved to R3 = 1. After the completion of the moving operation, the imaging output is read out and each signal is derived as in steps S232 and S233. If F3> F0 in step S238,
The focus adjustment lens is left as it is, and if F3 ≦ F0, the focus adjustment lens is moved to R0, the focus adjustment is completed, the present subroutine is ended, and the process returns to the main routine. Also,
If F1> F0 in step S230, the optimum in-focus point is considered to be on the short focus side, and the process returns to step S225 again to perform the same processing operation. After repeating this operation 5 times, when R0 = 10, the process proceeds from step S225 to step S240.

In step S240, R0 = R0 + 2, R1
= R0 + 1, R2 = R0 + 2, R3 = R0-1, F0 =
F1 and L0 = L2 are set, and the focus adjustment lens is moved to R1, that is, the lens position 11 (see FIG. 13) (step S241). After the movement is completed, the second time of the electronic shutter is set so that the proper exposure amount is obtained, and the signal of the image pickup distance measuring area is read (step S242). The distance measuring signal F1 and the photometric signal L1 are derived to derive the light source flicker detection signal and the exposure amount (step S243). In step S244, the distance measurement signals F0 and F1 are compared. The distance measurement signal F0 has a higher focusing rate, and if F0 <F1, the process proceeds to step S250. If F0> F1 is not satisfied, the focus adjustment lens is moved to R2, that is, the lens position 13 (step S2).
45). After the movement is completed, the electronic shutter is reset and the signal in the distance measuring area is read (step S246). The distance measurement signal F2, the photometry signal L2, the light source flicker detection signal, and the exposure amount are derived. In step S248, the distance measurement signal F2 and the distance measurement signal F1 are compared, and if F2> F1 is not satisfied, the focus adjustment lens is moved to R1 (step S249) and this subroutine is ended. If F2> F1, it is left as it is. This subroutine is finished and the process returns to the main routine.

If F0> F1 in step S244, the focus adjustment lens is first moved to R3 (step S2).
50), signal readout and each detection signal are derived (step S251). The distance measurement signal F3 is compared with the distance measurement signal F0. If F3> F0 is not satisfied, the focus adjustment lens is moved to R0. If F3> F0 is satisfied, this subroutine is terminated and the process returns to the main routine.

Returning to FIG. 2, the shutter speed and aperture are determined based on the photometric signal derived from the image pickup output for the previous exposure. The aperture and shutter speed are set according to the determined exposure setting, and the image pickup signals of the distance measuring area or all pixels are read out. Further, the focus adjustment detection signal (Fx) and the exposure correction signal are derived based on the read image pickup signal (step S4).

Subsequently, it is detected whether or not the second stroke switch SW2, which is an image pickup command, is pressed (step S5), and if not pressed, the distance measurement signal F1 at the most focused lens position, Fx is compared (step S
6). If the difference between the two signals is within a predetermined value, it means that the lens is in focus, and the exposure position correction lens and light source flicker detection are performed (step S7) before returning to step S5.

In step S6, the distance measuring signal F1 and the distance measuring signal F
If the difference from x is greater than or equal to a predetermined value, it is determined that the lens is out of focus, and focus adjustment is performed again. In this case, R0-2 is set as the lens position for the readjustment start in order to start near the lens position at the time of the previous focus adjustment (step S
8) Return to step S3. Step S3, Step S4
Then, the same processing operation as described above such as focus adjustment and fine exposure adjustment is performed again, and the operation is repeated until it is detected in step S5 that the second stroke switch SW2 is pressed.
In this case, when the focusing lens position is largely deviated to the tele side, the calculation of R0-2 is repeated.

On the other hand, if it is detected in step S5 that the second stroke switch SW2 is pressed, the process proceeds to step S9, and the automatic focus lock (AF LOC) is performed.
Make sure that K) is applied. When the automatic focus lock is applied, the process directly proceeds to step S11,
If the automatic focus lock is not activated, focus confirmation is performed in step S10 (step S10). FIG. 8 is a flowchart showing the processing procedure of step 10 in FIG. The focus confirmation in step 10 is performed by the same processing operation as in step S4 described above except for the already set diaphragm. That is, the electronic shutter is used for exposure for a predetermined time, and the output of the image sensor 4 is read (step S263). The distance measuring signal Fy and the photometric signal Ly are derived from the read signal (step S264). If the difference between the distance measurement signal Fy and the photometry signal Ly is smaller than the predetermined value b, it is determined that the focus state has not changed, and the process proceeds to step S11 (step S26).
5). If the difference is greater than or equal to the predetermined value b, the process returns to step S3 to readjust.

In step S11, final exposure adjustment is performed. FIG. 9 is a flowchart showing the final exposure adjustment subroutine in step 11 of FIG. The image pickup signal exposed under the exposure condition determined by the previous photometric signal is read (step S256), and the final photometric signal Ls0 and the flicker detection signal are derived from the signal (step S257).

In this case, all pixels are read out instead of the specific region of the image sensor 4, the detection pixel range for photometry is widened, and not the specific region of the image sensor 4 but all pixels are read out and the detection for photometry is performed. It is also possible to widen the pixel range and detect the levels of the central area and the peripheral area of the image sensor 4 and compare the values to perform the evaluation photometry to improve the accuracy of the AE adjustment. Similarly, in the operation before the final exposure adjustment, the image sensor 4 is also operated within a range in which the time reduction is not a problem.
It is also possible to expand the read-out range of or to perform evaluative metering. As described above, after the final exposure adjustment is performed, the main exposure shooting is performed (step S12).

In the main-exposure shooting, after exposure with the set value derived in the final exposure adjustment, the output of the image pickup device 4 is read, the read signal is processed, and recorded in the recording medium 101. However, if the flicker detection signal detected at each adjustment stage exceeds a predetermined value, it can be determined that the light source at the shooting location is a fluorescent lamp, and in that case, the image pickup signal according to the magnitude of the flicker signal. By reducing the gain of the green signal system of the processing unit, better colors can be reproduced.

Further, the focus adjustment lens is moved to infinity. By doing so, the image pickup lens is moving to infinity when the image pickup operation is started next time, so that the moving time can be saved.

In the above-described embodiment, the exposure coarse adjustment is performed by reading out the image pickup signal once, but the image sensor 4 has a wide photometric interlocking range, and the image pickup element 4 reaches the signal level at which the focus can be adjusted in one read. If the output of 2 is not reached, the image pickup output for coarse exposure adjustment may be read several times to set the appropriate exposure amount.

As described above, according to the image pickup apparatus of the first embodiment, automatic exposure (AE), automatic focus (AF), automatic white balance (AWB) are used without using photoelectric conversion elements other than the image pickup element 4. The processing operation of is performed. Moreover, adjustment can be completed in a short time by combining the driving of the image sensor 4 with various reading methods different from the normal reading rate during the imaging preparation period.

Further, the aperture is minimized during the coarse adjustment of image pickup,
Moreover, since the exposure amount is minimized by setting the shutter time to the shortest, the accumulated charge amount of each pixel becomes small relative to the dynamic range of the image sensor 4, and the image sensor 4 does not saturate and corresponds to a wide photometric interlocking range. It becomes possible to do. On the other hand, the reduction of the exposure amount increases the ratio of the noise amount in the image pickup output, but the pixel mixture during the transfer in the image sensor and the integration processing in the process for the output of the image sensor 4 are averaged, The degree of influence is reduced, and at the stage of rough adjustment, it can be set to a level that does not actually cause harm.

In the above embodiment, both the aperture and the shutter speed were controlled, but depending on the width of the photometric interlocking range, either one may be controlled, or the maximum shutter speed and the minimum aperture may not be used, respectively. The setting may be lower or larger than the above.

Further, by reading the image pickup signal at a rate different from the normal reading rate, the flicker component of the light source such as a fluorescent lamp can be detected at 100 Hz or 120 Hz. As a result, it is possible to determine whether the light source at the shooting location is a flicker light source or not based on the level of the flicker component, so color correction that matches the light source and information on the shooting location are used as image information and audio as attribute information. It is possible to record at the same time.

Further, the exposure amount cannot be sufficiently limited by setting the aperture and the shutter speed in the photometric interlocking range,
And when the signal reaches the saturation state in the image sensor vertical transfer unit, the readout method of the image sensor is set to the pixel in the vertical direction.
By performing so-called frame reading by skipping one pixel and reading, the sensitivity of the image sensor can be lowered, and saturation in the vertical transfer unit can be prevented, so exposure adjustment can be effectively dealt with.

[Second Embodiment] An image pickup apparatus according to the second embodiment will be described below. In the first embodiment, the automatic focus lock in step S9 of FIG. 2, the focus confirmation in step S10, and the final exposure adjustment in step S11 are performed after the second stroke switch SW2 is input. The image pickup apparatus may not perform this operation to improve the shooting response. This operation is usually performed because the probability that the distance to the subject and the brightness change will increase if the time from the processing operation of step S4 to the second stroke switch SW2 is long.

FIG. 14 is a flow chart showing the image pickup processing routine of the second embodiment. In the figure, the same components as those of the first embodiment are designated by the same reference numerals, and the same applies to the following embodiments.

The timer measures the time from the end of step S4 until the second stroke switch SW2 is pressed (steps S30 and S31). If the time is within the predetermined time, steps S9, S10 and S11.
Is omitted, and if the predetermined time is exceeded, steps S9 and S1
0 and S11 may be performed (step S3
2). This can improve the shooting response.

[Third Embodiment] In the first and second embodiments, the power supply of the image pickup system is kept from being started by the first stroke switch SW1 until the image pickup is completed. The power of the imaging system may be temporarily turned off after the adjustment in step S4 of FIG. 2 of the example is completed. FIG. 15 is a flow chart showing the image pickup processing routine of the third embodiment. In the figure, the power supply of the image pickup system is once turned off after the adjustment in step S4 is completed (step S40). After the second stroke switch SW2 is pressed, the power source is turned on again (step S41), and the processes from step S9 are performed as in the first embodiment. By doing so, it is possible to prevent wasteful consumption of electric power when the first stroke switch SW1 is being pressed and is in a standby state, and it is possible to delay battery consumption.

FIG. 16 is a flow chart showing a modification of the image pickup processing routine of the third embodiment. Step S
In step 5, it is detected whether or not the second stroke switch SW2 is pressed. If the second stroke switch SW2 is pressed, the process proceeds to step S9, and the process after step S9 is performed while the power is on. If the second stroke switch SW2 is not pressed, the process proceeds to step S40,
Immediately, the power of the image pickup system is turned off (step S40). After the power is interrupted, the process waits until it is confirmed that the second stroke switch SW2 has been pressed (step S42). As soon as the input of the second stroke switch SW2 is confirmed, the power supply to the imaging system is restarted (step S41) and the process proceeds to step 9.

In this way, the first stroke switch S
In the case of quick-shooting photography in which W1 and the second stroke switch SW2 are pressed almost at the same time, that is, when the second stroke switch SW2 has already been pressed at the end of step S4, the power supply is interrupted. Since the shooting operation can be continued, the shooting time can be shortened. On the other hand, if there is a time after the first stroke switch SW1 is pressed until the second stroke switch SW2 is pressed, power supply can be temporarily stopped to save power.

As described above, when the power is turned on and off during the photographing operation, the time constant of the clamp circuit is reduced so that the rise time of the circuit can be shortened,
Set the clamp pulse active time immediately after power is supplied to be long.

With this setting, it is possible to shorten the time from the restart of the power supply to the start of the image pickup signal reading operation, which is effective in shortening the shooting time.

[Fourth Embodiment] Next, an image pickup apparatus according to a fourth embodiment will be described. FIG. 17 is a flowchart showing a modification of the image pickup processing routine of the fourth embodiment. In the present embodiment, after the first imaging is completed and the focus adjustment lens is moved to the infinite position in step S3, it is detected whether or not the first stroke switch SW1 is still pressed (step S50), If it has not been pressed, the power is turned off (step S51), and this routine ends. If the first stroke switch SW1 is pressed in step 50, the process proceeds to step S52. In step S52, the photographing operation is performed with the same aperture as the previous photographing, and the focus is confirmed by the level of the distance measurement signal. If the difference from the previous evaluation value is within a predetermined value, it is determined to be in focus, and the second
Wait for the stroke switch SW2 to be pressed. If the in-focus state cannot be confirmed in step S52, the process proceeds to step S3, and focus adjustment is performed again.

By starting the image pickup lens 1 when starting the readjustment of the focus from the vicinity of the position of the focus adjustment lens in the previous photographing, it is possible to increase the probability of completing the focus adjustment in a shorter time. Also, if the time from the end of the first shooting to the next shooting (second stroke switch SW2) is long and the time during which the first stroke switch SW1 is pressed exceeds the predetermined time, check the focus. Instead, focus adjustment may be restarted immediately. In this case, there is a high probability that the distance to the subject has changed, so that it is not necessary to spend unnecessary time checking the focus.

[0081]

According to the image pickup apparatus of the first aspect of the present invention, the image pickup device converts an optical image into an electric signal, and the focus evaluation value detecting means uses the image pickup device to focus the optical image. Is detected by the focus adjustment means, focus adjustment is performed for focusing the optical image on the image sensor based on the detected focus evaluation value, and the image sensor is exposed by the exposure amount detection means. To detect the proper exposure dose using
After the exposure adjustment means performs the exposure adjustment according to the detected proper exposure amount, the first release switch instructs the start of the focus adjustment and the exposure adjustment, and the main exposure image pickup means performs the focus adjustment and the exposure adjustment. Since the main exposure is performed and the start of the main exposure is instructed by the second release switch, the focus adjustment and the exposure adjustment can be performed in a short time only with the image sensor without using the distance measuring sensor or the photometric sensor. The time lag can be reduced. As a result, downsizing and cost reduction can be achieved.

According to the second aspect of the image pickup apparatus, the focus evaluation value detecting means opens the diaphragm for limiting the incident exposure amount of the image pickup element in accordance with an instruction from the first release switch to open the first state. After the focus evaluation value is detected and the focus adjustment is performed by the focus adjusting means in accordance with the detected first focus evaluation value, the aperture diameter of the diaphragm is set to be substantially the same as the main exposure, and the second focus evaluation is performed. The value is detected and the second
In response to an instruction of the release switch, the third focus evaluation value is detected by setting the diaphragm state substantially the same as the main exposure state, and the main exposure image pickup means compares the second focus evaluation value with the third focus evaluation value. However, since the main exposure is performed when the difference is equal to or less than the predetermined value, it is possible to accurately perform focus adjustment and exposure adjustment of the diaphragm in a short time.

According to the third aspect of the image pickup apparatus, since the proper exposure amount is detected when the second focus evaluation value and the third focus evaluation value are detected, it can be performed in a shorter time. .

According to the image pickup device of the fourth aspect, when the automatic focus lock switch is not in the automatic focus mode, the focus evaluation value detection means sets the incident exposure amount of the image pickup device according to the instruction of the first release switch. After performing the focus adjustment with the diaphragm to be limited opened, the aperture diameter of the diaphragm is made the same as the aperture diameter for the main exposure, the second focus evaluation value is detected, and the second release switch is instructed. The third focus evaluation value is detected according to the same diaphragm state as the main exposure, and the main exposure image pickup means compares the second focus evaluation value and the third focus evaluation value, and the difference is less than or equal to a predetermined value. When the main exposure is performed and the automatic focus lock switch is in the automatic focus mode, the second release switch is instructed without detecting the second focus evaluation value and the third focus evaluation value. Since it performs the exposure, focus adjustment in a short time only by the image pickup device by also omitting the imaging operation in accordance with each situation in the auto-focus mode, it is possible to perform exposure adjustment.

According to the image pickup device of the fifth aspect, the time from the completion of the detection of the focus evaluation value or the focus adjustment to the pressing of the second release switch is measured by the timer, and the measurement is performed. The main exposure is performed when the time is within a predetermined time, and the focus evaluation value is detected or the exposure is corrected again when the predetermined time has elapsed. Therefore, the operation is performed only when a long waiting time is detected by the timer. It is possible to shorten the release time lag at the time of shooting, reduce the power consumption, and extend the life of the battery by adding the.

According to the sixth aspect of the image pickup apparatus, from the time when the detection of the first focus evaluation value or the second focus evaluation value is completed by the timer until the second release switch is instructed. The time is measured, and when the measured time is within the predetermined time, the main exposure is performed without performing the subsequent focus adjustment. Adjustment and exposure adjustment can be performed.

According to the image pickup device of the seventh aspect, when the focus evaluation value is detected, the power supply of the image pickup system for driving the image pickup device is turned off, and when the second release switch is pressed again. Since the power is turned on, the power consumption can be reduced and the battery life can be extended.

According to the eighth aspect of the present invention, there is provided a timer for measuring the time from the detection of the focus evaluation value to the pressing of the second release switch, and the time measured by the timer is measured. When the value is shorter than the predetermined value, the main exposure is performed without turning off the power supply of the image pickup system, so that it is possible to improve the responsiveness while saving power.

According to the ninth aspect of the image pickup apparatus, the fourth focus evaluation value deriving means derives the fourth focus evaluation value from the output of the image pickup element at the time of main exposure, and the release switch detecting means makes the main focus. After the exposure is completed, it is detected that the first release switch or the second release switch is pressed, and the release switch detection means presses the first release switch or the second release switch. Fifth when it is detected that
The fifth focus evaluation value deriving means derives the fifth focus evaluation value, the difference between the fourth focus evaluation value and the fifth focus evaluation value is within a predetermined value, and the second release switch has already been pressed. If the second release switch is not pressed, the main exposure is immediately performed, and if the second release switch is not pressed, the exposure is waited, and when the difference exceeds a predetermined value, the aperture is opened again. As described above, the focus adjustment is performed when the first release switch is pressed, so that it is possible to perform imaging in response to a change in conditions.

According to the image pickup device of the tenth aspect, the fourth aspect is provided.
The focus evaluation value deriving means derives a fourth focus evaluation value from the output of the image pickup device at the time of main exposure, and the release switch detection means causes the first release switch or the second release after the main exposure is completed. When the switch is pressed, the timer measures the time from the completion of main exposure until the second release switch is pressed. If the time measured by the timer is shorter than the predetermined time, Of the main exposure, and when the time is longer than the predetermined time, the fifth focus evaluation value is detected, and the difference between the fourth focus evaluation value and the fifth focus evaluation value is derived. When it is within the predetermined value, the timer is reset again and the above operation is repeated until the second release switch is pressed. When the difference exceeds the predetermined value, the aperture is opened again and the first release is performed. Since perform focus adjustment when a switch is pressed, it is possible to cope with the changing conditions while saving power.

According to the imaging method of the eleventh aspect, the first
The start is instructed by the release switch, the optical image is converted into an electric signal by the image pickup device, the focus evaluation value indicating the degree of focus adjustment is detected, and the image pickup device is provided with the focus evaluation value based on the detected focus evaluation value. A second release switch performs focus adjustment for focusing an optical image, detects an appropriate exposure amount of the image sensor by using an output of the image sensor, and performs exposure adjustment according to the detected appropriate exposure amount. Thus, since the main exposure is performed after the exposure adjustment and the focus adjustment, it is possible to perform the focus adjustment and the exposure adjustment in a short time only with the image pickup device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital camera of a first embodiment.

FIG. 2 is a flowchart showing an imaging processing routine.

FIG. 3 is a flowchart showing an exposure coarse adjustment subroutine.

FIG. 4 is a flowchart showing a focus adjustment / fine exposure adjustment / light source flicker detection subroutine.

FIG. 5 is a flowchart showing a focus adjustment / exposure fine adjustment / light source flicker detection subroutine subsequent to FIG. 4;

FIG. 6 is a flowchart showing a focus adjustment / exposure fine adjustment / light source flicker detection subroutine subsequent to FIG. 5;

FIG. 7 is a flowchart showing a focus adjustment / exposure fine adjustment / light source flicker detection subroutine following FIG. 6;

FIG. 8 is a flowchart showing a processing procedure of step 10 in FIG.

FIG. 9 is a flowchart showing a final exposure adjustment subroutine in step 11 of FIG.

FIG. 10 is an explanatory diagram showing vertical transfer pulses and horizontal transfer pulses.

FIG. 11 is an explanatory diagram showing vertical transfer and horizontal transfer.

FIG. 12 is an explanatory diagram showing a range of pixels to be read.

FIG. 13 is an explanatory diagram illustrating a lens position of a focus adjustment lens.

FIG. 14 is a flowchart showing an image pickup processing routine of a second embodiment.

FIG. 15 is a flowchart showing an image pickup processing routine of the third embodiment.

FIG. 16 is a flowchart showing a modified example of the image pickup processing routine of the third embodiment.

FIG. 17 is a flowchart showing a modified example of the imaging processing routine of the fourth embodiment.

FIG. 18 is a block diagram showing a configuration of a conventional digital electronic camera.

FIG. 19 is a flowchart showing a conventional imaging processing routine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Imaging lens 2 ... Shutter also used as a shutter 4 ... Imaging element 9 ... Imaging signal processing circuit 10 ... System control CPU 12 ... Operation part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 5/238 Z

Claims (11)

[Claims] 1. An image pickup device for converting an optical image into an electric signal, a focus evaluation value detecting means for detecting a focus evaluation value indicating a focus degree of the optical image by using the image pickup device, and the detected focus. Focus adjustment means for performing focus adjustment for focusing the optical image on the image pickup element based on an evaluation value, exposure amount detection means for detecting an appropriate exposure amount using the image pickup element, and the detected appropriateness Exposure adjustment means for performing exposure adjustment according to an exposure amount; and a first instruction for instructing start of the focus adjustment and the exposure adjustment.
And a second release switch for instructing the start of the main exposure, the main exposure image pickup unit performing the main exposure after the focus adjustment and the exposure adjustment. 2. An aperture stop for limiting an incident exposure amount of the image pickup device is provided, and the focus evaluation value detection means opens the aperture according to an instruction of the first release switch to change the first focus evaluation value. After detecting and performing the focus adjustment by the focus adjusting means according to the detected first focus evaluation value, the second focus evaluation value is detected by setting the aperture diameter of the diaphragm to be substantially the same as the main exposure. In response to an instruction from the second release switch, a third focus evaluation value is detected by setting a diaphragm state substantially the same as that of the main exposure, and the main exposure image pickup unit is configured to detect the second focus evaluation value and the third focus evaluation value. The image pickup apparatus according to claim 1, wherein the focus evaluation values are compared with each other, and main exposure is performed when the difference is less than or equal to a predetermined value. 3. The image pickup apparatus according to claim 2, wherein the exposure amount detecting means detects the appropriate exposure amount when detecting the second focus evaluation value and the third focus evaluation value. . 4. An automatic focus lock switch for setting an automatic focus mode, and an aperture for limiting an incident exposure amount of the image pickup device, and when the automatic focus lock switch is not in the automatic focus mode, the focus evaluation value detection means. Adjusts the focus by opening the diaphragm according to the instruction of the first release switch, and then detects the second focus evaluation value by setting the aperture diameter of the diaphragm to be the same as the aperture diameter for main exposure. , A third focus evaluation value is detected in accordance with the same aperture state as the main exposure according to an instruction of the second release switch, and the main exposure image pickup means compares the second focus evaluation value and the third focus evaluation value. Then, when the difference is less than or equal to a predetermined value, main exposure is performed, and when the automatic focus lock switch is in the automatic focus mode, the second focus evaluation value and the third focus evaluation value are detected. 2. The image pickup apparatus according to claim 1, wherein the main exposure is performed as it is according to an instruction from the second release switch. 5. A timer for measuring the time from the detection of the focus evaluation value or the focus adjustment to the pressing of the second release switch is provided, and the measured time is within a predetermined time. The main exposure is performed, and when the predetermined time has elapsed, the focus evaluation value is detected again or the exposure is corrected again.
The imaging device described. 6. A timer for measuring the time from when the detection of the first focus evaluation value or the second focus evaluation value is completed to when the second release switch is instructed, comprising: 3. The image pickup apparatus according to claim 2, wherein the main exposure is performed without performing subsequent focus adjustment when the remaining time is within a predetermined time. 7. The power source of an image pickup system for driving the image pickup element is turned off when the focus evaluation value is detected, and is turned on again when the second release switch is pressed. The image pickup apparatus according to claim 1. 8. A timer for measuring the time from the detection of the focus evaluation value to the pressing of the second release switch is provided, and when the time measured by the timer is shorter than a predetermined value, the imaging is performed. 8. The image pickup apparatus according to claim 7, wherein the main exposure is performed without turning off the power supply of the system. 9. The fourth from the output of the image sensor during the main exposure.
Release focus detection value deriving means for deriving a focus evaluation value of, and a release switch detection means for detecting that the first release switch or the second release switch is pressed after completion of the main exposure. And fifth focus evaluation value deriving means for deriving a fifth focus evaluation value when the release switch detection means detects that the first release switch or the second release switch is pressed. When the difference between the fourth focus evaluation value and the fifth focus evaluation value is within a predetermined value and the second release switch has already been pressed, the main exposure is immediately performed, and When the second release switch is not pressed, the control waits until the second release switch is pressed, and when the difference exceeds a predetermined value, the aperture is opened again and the first release is performed. 2. The image pickup apparatus according to claim 1, wherein the focus adjustment is performed when the release switch is pressed. 10. A fourth focus evaluation value deriving means for deriving a fourth focus evaluation value from an output of an image pickup device at the time of main exposure, comprising the first release switch or the first focus switch after completion of the main exposure. Release switch detecting means for detecting that the second release switch is pressed, a timer for measuring the time from the completion of the main exposure until the second release switch is pressed, and the time measured by the timer. When it is shorter than the predetermined time, the next main exposure is photographed as it is, and when it is longer than the predetermined time, the fifth focus evaluation value is detected, and the fourth focus evaluation value and the fifth focus evaluation value are compared. The difference is derived, and when the difference is within the predetermined value, the timer is reset again and the above operation is repeated until the second release switch is pressed. When the difference exceeds the predetermined value, the aperture is opened again. Then first
2. The image pickup apparatus according to claim 1, wherein the focus adjustment is performed when the release switch is pressed. 11. An optical image is converted into an electric signal by an image pickup device, a focus evaluation value indicating a focus degree of the optical image is detected, and the optical image is detected by the image pickup device based on the detected focus evaluation value. A focus adjustment for focusing an image is performed, an appropriate exposure amount is detected by using the image sensor, an exposure adjustment is performed according to the detected appropriate exposure amount, and the focus adjustment and the exposure are performed by a first release switch. An imaging method of instructing the start of adjustment, and being instructed by a second release switch to perform main exposure after the exposure adjustment and focus adjustment.