JPH0320709A - Camera system - Google Patents

Abstract

PURPOSE:To eliminate an unpleasant feeling given to a photographer at the time of detecting a focal point and to detect a focal point highly speedily and accurately by processing an image signal formed by means of a photoelectric conversion means, detecting the focal point, and monitoring a video. CONSTITUTION:The image of a photographic zoom lens 101 is converted into an electric signal, and it is supplied to a signal processing circuit 103 and an A/D converting circuit 104. The circuit 103 inputs a focal point detecting signal, which is divided into spatial frequencies, to a main CPU 107 which sends a lens driving signal to a circuit 109 based on the focal point detecting signal, an image analysis signal from a CPU 105 dedicated to signal processing, and a lens information signal from the lens control circuit 109. At the same time, an image signal which is transmitted to a video signal output circuit 110, is sent out to the CPU 105. The circuit 109 monitors the information on the lens 101, and also varies a lens position, diaphragm, and zoom value. Thus, the focal point can be highly speedily and accurately detected without giving the photographer an unpleasant feeling at the time of focusing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a camera system, specifically, a focus detection method by calculating a video signal from a subject image formed on a photoelectric conversion means such as an image sensor. The present invention relates to a camera system capable of monitoring the video signal.

[Prior Art] As is well known, in-focus point detection methods for cameras, etc., which perform focus detection by processing a video signal obtained from a subject image formed on a photoelectric conversion means, such as an image sensor, include: Broadly speaking, there are passive methods that detect focus based on brightness distribution information of the subject, and active methods that project a beam of infrared light or ultrasonic waves onto the subject and detect focus based on the reflected signal. There is. Examples of methods that belong to the above passive method include a phase difference detection method that detects the defocus direction and approximate amount of defocus from data on multiple optical paths, and a method that moves the photographing lens in the direction that increases the value indicating the degree of focus. There is a known contrast detection method that is configured to detect a peak position and then stop there.

This contrast detection method is a method that focuses on the frequency components of an image, and is classified as detecting a focused point by moving a part of the imaging optical system or a sensor system.
"Automatic focus adjustment of television cameras using mountain-climbing servo system" published by Mr. Ishida et al. in Vol. "Autofocus system" etc. are provided.

The "automatic focus adjustment of TV cameras using a mountain-climbing servo system" announced in the above NHK technical report detects the definition of the screen based on the high frequency content of the video signal, and performs hill-climbing control to maximize the definition. This paper describes the principles and circuit design conditions of a device that automatically adjusts the optical focus of a television camera. Based on measurements of the response of an experimental circuit to a two-dimensional object and simulation experiments using an analog computer, we found that the shape of the hill-climbing curve, which changes depending on the lens aperture and focal length, determines the accuracy of focusing using the hill-climbing servo system. Accuracy is improved by increasing the gain of the control system and decreasing the time constant of the delay element, and the time constants of the detection and hold circuits in the control system are set to 0. It is disclosed that if one second is selected, a focusing accuracy of 5% can be obtained for a fourfold change in each of the height and slope of the hill-climbing curve. Furthermore, if we use adaptive control to detect the shape of the hill-climbing curve and control the gain of the control system,
It is also disclosed that it is possible to expand the control range and improve accuracy.

In addition, in the ``autofocus system for television cameras'' announced at the above-mentioned Television Society, the amount of out-of-focus is constantly changed at a constant cycle by mechanically making small fluctuations on the sensor side, and in response, the video signal increases. The frequency component undergoes amplitude modulation, but the phase of this vibration modulation component changes by 180 degrees depending on whether the direction of defocus is toward the front bin or the rear bin.
When in focus, the amplitude is zero. Therefore, focusing accuracy is improved by controlling the focal position of the lens using this amplitude modulation component.

The phase difference detection method provides a monitor function and performs integral control so that the output within the focus area is optimized.

[Problems to be Solved by the Invention] By the way, when detecting a focused point using this contrast detection method, since the direction in which the photographic lens is to be driven is unknown at first, it is necessary to first move a part of the imaging optical system, especially the photographic lens. By moving the lens, changes in frequency power are detected, and the focusing direction is detected based on this. However, if the photographic lens is initially operated in the direction opposite to the in-focus point, the AF
For the photographer looking through the camera's viewfinder, the subject image within the viewfinder field of view should originally move in the direction that it is in focus, but once it moves in the direction that the subject image is out of focus. After that, the camera moves on to the focusing operation, which causes discomfort to the photographer.

Therefore, in the above-mentioned "autofocus system for television cameras" proposed by Mr. Toyoda et al., the focusing direction is detected by mechanically vibrating the image sensor. That is, in FIG. 11, which shows the characteristics of the Takagi frequency component with respect to the focus matching position in the contrast detection method, the image pickup element is slightly varied in a sinusoidal manner as a1 or a2 by, for example, a motor. The fine fluctuation a1 is the fine fluctuation of the image sensor when the photographing lens is at a position d2 which is closer than the focus position d, and the Takagi frequency component at this time is as shown in b1 due to the focus change due to the fine fluctuation a1. undergoes vibrational modulation. Also, the photographing lens is at the focus position d.
If l is located at a position d3 on the far side, the amplitude is modulated as shown in b2 due to the focus change due to the slight fluctuation a2.

As is clear from the figure, the phase of the amplitude modulation b t = b 2 is reversed depending on whether the focus position d1 is near or far from the focus position d1. Therefore, the amplitude modulated signal shown at b1 is synchronously detected with the reference frequency signal, and this synchronously detected signal moves the motor in the direction of arrow C1, and b
2 in the direction of the arrow c2, it becomes possible to detect the focusing direction, thereby stabilizing the point where the Takagi frequency component is maximum, that is, the focused point.

However, when the subject brightness is low contrast, even if the slight fluctuations ai and a2 shown in FIG. Even if b2 is detected using the reference frequency signal, the driving direction of the photographing lens, that is, the focusing direction cannot be determined. Therefore, the camera photographer who is looking into the viewfinder field frame of the AF camera will feel uncomfortable.

In addition, even in the phase difference detection method using an area sensor, it is necessary to optimize the data within the focus area in the focus area of the area sensor, and when the brightness within the focus area differs greatly from the entire screen,
Since the integration time of the focus area is controlled to be optimal, the image quality of the screen outside the focus area may be degraded, giving an unpleasant feeling.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a camera that has a monitor means such as an electronic viewfinder so as to show the camera operator an unpleasant display when detecting a focus point in a camera that detects the focus point. There is no need to provide a camera system.

[Means and Effects for Solving the Problems] The camera system of the present invention includes an image sensor that converts subject light guided by an imaging optical system into an electrical signal, and converts the electrical signal of the imaging device into an electric signal. A camera system comprising a focus detection means for detecting a focus direction and a focus point of the system, the camera system comprising: a signal accumulation means for accumulating the electric signal; and a signal accumulation means for accumulating the electric signal; an electric signal selection means for selecting either the electric signal from the element or the electric signal accumulated in the signal accumulation means; and a monitor means for visualizing the selected electric signal;
The present invention is characterized in that it includes a control means for controlling the electric signal selection means to select the accumulated electric signal during the focus detection period.

[Example] Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 is a conceptual block diagram showing the camera system of the present invention from a functional perspective. In the figure, a signal from an imaging optical system 11 is converted into an electrical signal by an imaging element 12, and this electrical signal is sequentially taken into a signal storage element 14. The electrical signal photoelectrically converted by the image sensor 12 is also supplied to a signal processing system 16, where the signal is processed and the power corresponding to the frequency is detected. At the same time, the drive control system 13
By detecting the amount of change in power while driving the
The focus direction is detected. During the period in which the focusing direction is being detected, only the output of the signal storage element 14 immediately before driving the drive control system 13 is read out by the readout system 15, and this read signal is output to the monitor means 17. As a result, it is possible to prevent the photographer of the camera from seeing fluctuations in the image while the drive control system 13 is being driven, so that it is possible to detect the focusing direction without causing discomfort to the photographer.

FIG. 2 is a concrete block system diagram of a camera system showing one embodiment of the present invention. A block system diagram showing a more detailed configuration of the signal processing circuit 103 in FIG. 2 is shown in FIG. 3(A). A diagram plotting the shear power is shown in Figure 4 (A).
In (B), the detailed configurations of the DCPU 105 and the image memory 106 in FIG. 2 are shown in FIG. 5, respectively.

The structure of this embodiment will be explained below with reference to FIGS. 2 to 5.

In FIG. 2, a subject image that has passed through a photographing zoom lens 101 is converted into an electrical signal by an imaging circuit 102 and supplied to a signal processing circuit 103 and an A/D conversion circuit 104.

The signal processing circuit 103 supplies the focus detection signal divided into each spatial frequency to the main CPU (hereinafter abbreviated as MCPU) 107 . The above A/D conversion circuit 104
Then, the analog signal is converted to a digital signal, and a dedicated signal processing CPU (hereinafter abbreviated as DCPtJ) 105
supply to.

The DCPU 105 manages bidirectional transfer of image signals to the image memory 106, image analysis, bidirectional communication with the MCPU 107, transfer of image signals to the video signal output circuit 110, and the like. Also, MCPU107
is the focus detection signal from the signal processing circuit 103, DCP
Image analysis signal from U105. A lens drive signal is sent to the lens control circuit 109 based on the lens position signal, lens aperture signal, zoom value signal, etc. from the lens control circuit 109. At the same time, MCPU107
05, a signal determining the content of image data to be transferred to the video signal output circuit 110 is sent.

The lens control circuit 109 controls the lens position of the photographing zoom lens 101. It has a function of monitoring the aperture position and zoom value, and drives the motor 108 using a lens drive signal supplied from the MCPU 107. This motor 108 can change the lens position, aperture value, and zoom value of the photographing zoom lens 101.

FIG. 3(A) is a block system diagram showing the detailed configuration of the signal processing circuit 103 shown in FIG. 2. A plurality of circuits shown in FIG. 3(A) are combined for each spatial frequency band. The signal processing circuit] 03 shown in FIG. 2 is configured. In this FIG. 3(A), the gate circuit 121
and the synchronous separation circuit 126, the imaging circuit 102 shown in FIG.
When the electrical signal photoelectrically converted is supplied, the synchronization separation circuit 126 and the gate control circuit 127 transmit a position signal for applying a gate to the analog image signal to the gate circuit 121.
Output to. The position where the gate is applied to this analog image signal can be selected arbitrarily, but as shown in Fig. 3 (B),
Generally, a position signal is generated by specifying a region 129 consisting of a plurality of pixels located at the center of the analog image 128. The analog image signal gated by the gate circuit 121 based on the signal from the gate control circuit 127 is filtered by a bandpass filter (hereinafter abbreviated as B-P-F) 122 to extract only a specific frequency component, and then sent to the detection circuit 122. After being detected by and integrated by the integrating circuit 124,
The A/D conversion circuit 125 performs A/D conversion to obtain a digital value, which is output to the MCPU 107 shown in FIG.

Figure 4 (A). (B) is B-P-F, which has a normal band in the low frequency region, and B-P-F, which has a normal band in the high frequency region.
FIG. 3 is a diagram showing the relationship between lens position and power for each of P-F. As is clear from the figure, when using a BPF that bandpasses low frequency components, the fourth
As shown in Figure 4 (A), the power changes with respect to changes in the lens position are broad, whereas when using B-P/F, which bandpasses high frequency components, the lens position changes as shown in Figure 4 (B). It can be seen that the power change with respect to the change in becomes sharp. B-P◆F122, which band-passes such low frequency components and high frequency components (see Figure 3)
The signal that has passed through is detected and integrated, and then A/D converted by the A/D conversion circuit 125, and then sent to the MCPU 10 shown in FIG.
7.

FIG. 5 is a block system diagram showing a more detailed configuration of the DCPU 105 and image memory 106 shown in FIG. 2 above. In the figure, the first image signal RAMI 3 1 that saves the image signal converts the digital signal from the A/D conversion circuit 104 (see FIG. 2) that is manually input into the input terminal.
The data is saved based on the control signal of the MCPU 107. The image signal stored in this first image signal RAM 131 is
A second image signal RAM 13 that saves image signals via a control unit 130 configured with an analog switch, etc., for example.
2 and is saved. This second image signal RA
M132 disturbs the control signal supplied from the MCPU 107 (see Fig. 2) and performs high-speed processing such as vertical and horizontal Fourier transform 133, data binarization 134, center of gravity detection 135, image comparison 136, and the results. MCPU10
Send to 7.

First image signal RAM 131 for saving the above image signal
The image signal read out from the image memory 1 shown in FIG.
It is also supplied to 06. This image memory 106 includes a first memory 106a that stores image signals saved prior to the start of the focus detection operation, and a first memory 106a that stores image signals during the focus detection operation, and as a result, the most recent image signal is stored. and a second memory 106b. Further, the control unit 130 supplies the image signal outputted from either the first image signal RAM 131 or the image memory 106 to the second image signal RAM 132 based on the control signal from the MCPUl07, or supplies the image signal to the second image signal RAM 132. It operates as a changeover switch for selecting whether or not to supply to the output circuit (see FIG. 2) 110.

Next, the operation of this embodiment configured as described above will be explained below based on the flowchart shown in FIG. This FIG. 6 shows M consisting of steps 81 to S16 in the center of the figure
The flow of the CPU 107 is shown in step S21 on the left side of the diagram.
The flow of the DCPυ 105 consisting of steps S25 to S25 is shown on the right side of the figure.
3 is a flowchart from AF start to focus determination showing the flowcharts shown in FIG. 3 in parallel.

When the camera operation starts, the process advances to step S21, where the DCPU 105 performs normal image signal processing. That is, normally the A/D conversion circuit 104 shown in FIG.
The image signal converted into a digital value is taken into the first image signal RAMI 31 shown in FIG. By doing so, it is displayed continuously on the monitor.

When a release button (not shown) is pressed, the process proceeds to step S1 where "the AF operation signal is turned on."

Then, the process advances to step S22, and the DCPU 105 reads the first image signal RAM at the moment this AF operation signal is turned on.
Video signal output circuit 1 for the image signal taken into I31
10 and stores it in the first memory 106a of the image memory 106.

Then, the image signal stored in this first memory 106a is outputted to the video signal output circuit 110 to be output to the monitor means 17.
Display the image above. An image signal supplied after the image signal when the AF operation signal is on, which is stored in the first memory 106a, is written into the second memory 106b. The image signal stored in this second memory 106b is rewritten each time so that the latest image signal is always stored.

That is, a new image signal is input to the second memory 106b of the image memory 106, and the new image signal is already input to the second memory 106b of the image memory 106.
Although the image signal recorded in 6b is erased and written, it is not output to the video signal output circuit 110. As described above, the image signal output to the output circuit 110 is stored in the first memory 106 prior to the start of this focus detection operation.
This is the image signal saved in a. This first memory 1
06a is a so-called signal storage means in the present invention, and the flow of step S22 constitutes an electric signal selection means.

The above is the DCPU 10 when the AF operation signal is turned on.
5, the operation of the signal processing circuit 103 in step S31 and the operation of the MCPU in step S2 are as follows.
The operation of 107 will be explained.

Proceeding to step S31, the signal processing circuit 1 shown in FIG.
03 B-P-F 122 performs "power detection" of a specific frequency whose passband is defined. 'At the same time,
Proceeding to step S2, the MCPU 107 commands "AF motor drive", thereby driving the photographing lens by a minute amount. Then, in step S3, the first focusing "direction detection" is performed after the photographic lens is moved by a minute amount.

If the focusing direction is detected by the operation in step S3 above, the process proceeds to step S6, and the AF operation signal is turned off. If the focusing direction cannot be detected, the process proceeds to step S4, where the MCPU 107 directs the AF operation signal to the DCPU 105. The data processing signal is transmitted. When the DCPU 105 receives this data processing signal, the image memory 10 shown in FIG.
The image signals stored in the first memory 106a and the second memory 106b of 6 are transferred to the second image signal RAM.
132, and the RAMi 32 performs data processing such as Fourier expansion. Based on this processing data, the process proceeds to step S5, where the MCPU 107 performs a second focusing "direction detection", and if "direction detection" is achieved, the step S5 is performed.
The process proceeds to step S6 to turn off the AF operation signal, and if the in-focus direction is not determined even after this second focusing ``direction detection'', the process proceeds to the next step S7.

The reason why the focusing direction is not determined even after the second focusing direction detection described above is often because the subject image has no fundus, so A is determined by the aperture information, lens information, distance information, etc.
The above step S until the predetermined drive amount Mx of the F motor is reached.
Returning to step 2, "AF motor drive" is performed. Then, the first and second focusing "direction detection" is repeated, but when the AF motor drive reaches its predetermined drive 11Mx without "direction detection", step S16
The process jumps to "stops the AF motor at a predetermined position" and ends.

First focusing "direction detection" in step S3 above.
When "direction detection" is performed during the second focusing "direction detection" in step S5, and as a result, "AF operation signal is turned off" in step S6, the process proceeds to step S24. In this step S24, the DCPU 105 stores the first memory 106a and the second memory 106 shown in FIG.
After erasing the image signals saved in each of the first image signal RAM 131, the image signals saved in the first image signal RAM 131 are outputted to the video signal output circuit 110 for display on the monitor, and normal operation is resumed.

That is, from "outputting the contents of the first memory to the video signal output circuit" in step S22 above to step S24
"Cleaning the image signal of the first and second memory" in "
The flow up to outputting the image signal saved in the first image signal RAM to the video signal output circuit constitutes the control means.The electric signal selection means in step S22 and the flow from step S22 to This step S2
The gist of the present invention is to prevent the photographer of the camera from seeing uncomfortable lens driving during focusing direction detection at the initial stage of the focusing operation by means of the control means formed through the steps up to step 4.

In parallel with the operation of the DCPUI○5 in step S24, the MCPυ107 performs the "AF" operation in step S8.
In step S32, the signal processing circuit 103 performs "power detection" at a specific spatial frequency accompanying the movement of the photographing lens by the "AF motor drive".Then, as shown in FIG. 4(A). As shown in B), the peak of the power accompanying the movement of the lens position, that is, the in-focus point is found at 1 in-focus 1'', which indicates the first in-focus state in step S9. In this step S9 “
When focus 1'' cannot be obtained, that is, when the photographic lens is moved in one direction and the power continues to increase, the focus has not yet been reached, so step S24, S8, and S
Returning to step 32, these steps are repeated until "focus 1" is detected.

“Focus 1# in step S9 has poor focusing accuracy, but
At the same time as this is detected, the AF motor is stopped and the process proceeds to step S10, where "the focusing operation signal is turned on 2."
The DCPU 105 transfers the image signal at focus 1 from the first image signal RAM 131 to the first memory 106a in step S25, and outputs the contents of this first memory 06a to the video signal output circuit 110. and display it on the monitor.

Further, when proceeding to step Sll, ~fcPUI. 07 drives the zoom motor 108 (see FIG. 2) to take a picture of the center part 129 corresponding to the area 273 of the finder field frame 128 shown in FIG. 3(B).
Reference! ! α) Enlarge the angle of view 372 times so that the entire image is captured. Normally, the main subject is almost included in two-thirds of the screen, so by further miniaturizing this part and performing power detection, focus detection with improved accuracy is attempted.

Steps 512 and 533 are the flow of "driving the AF motor" and "detecting the power" as described in step S8S32 above. Proceed to step 813 and
It is checked whether "in-focus 2", which indicates the in-focus state of the camera, has been reached. Focusing 2 in step S13 has a higher focusing accuracy than "focusing 1" in step S9, in accordance with the enlargement of the angle of view by driving the zoom motor in step Sll. Until "focus 2" is established in step S13, the steps S12 and 933 are performed.
Repeat these steps, and when the image is in focus, proceed to step S14.

In step S14, the zoom mode is driven again to return the photographing angle of view to the state before step S11, and then the process proceeds to step S15, where the focusing operation signal is turned off. Then, in step S26, the DCPU 105 returns the image signal output to the video signal output circuit 110 to the signal saved in the first image signal RAM 131 (see FIG. 5), and then ends the process.

As described above, in this embodiment, a smooth and highly accurate focus detection method is provided to the camera operator by digitally processing the signal and storing it in memory. This can also be achieved by storing it in memory. Furthermore, it goes without saying that a zoom lens drive for improving focusing accuracy may be inserted just before the imaging circuit.

7 to 10 show other embodiments of the present invention. The concept of the camera system of this embodiment is also
As shown in the figure, signals from the photographing optical system 11 are converted into electrical signals by the image sensor 12, and these electrical signals are sequentially taken into the signal storage element l4. Further, the electrical signal photoelectrically converted by the image sensor 12 is also supplied to a signal processing system 16 . Then, the processing system 16 detects the integral monitor value and performs AF calculation processing, and sends the movement amount data to the drive control system 13.

In addition, in order to obtain data for the AF calculation described above, an integral time is set based on the integral monitor value, and the set integral time and AF
During the period until the calculation data is taken into the signal processing system 16, only the output of the signal storage element 14 immediately before starting the integration for AF calculation data is read out by the readout system 15, and this read signal is output to the monitor means 17. .

This allows the photographer to see a well-balanced image based on average photometry.

FIG. 7 shows the specific details of the camera system of this embodiment. It shows a block system diagram.

The subject light beam that has passed through the photographic lens 201 is split by a half mirror (not shown), one part goes to an optical finder (not shown), the other part is split into a pupil by the AF lens 202, and the other part goes to a photoelectric conversion element in the imaging circuit 203. The divided images are photographed so that they do not overlap.

The A/D conversion circuit 20 converts one electric signal of this photographed image into
4, and is output to an image memory 208 and a video signal output circuit 209 via a main CPU (MCPU) 205.

The MCPU 205 includes an imaging circuit 203, an image memory 2
08. Controls the video signal output circuit 209, detects the amount of image shift between the two paired images of the imaging circuit 203, detects the in-focus point by compensation calculation, and controls the lens control circuit 20.
Send the driving amount data to 6.

FIG. 8 shows the relationship between the two images of the focus area, and FIG. 9 shows the shift amount interpolation calculation Σ1a1■-b1■1,j.

Returning to FIG. 7 again, the lens control circuit 206 obtains lens information such as the aperture and lens position of the photographing lens 201, and outputs it to the MCPU 205. Also, MCPU2
According to the lens drive amount from 05, a signal is output to the motor 207 to drive the photographing lens 20'l to the in-focus position.

Next, the operation of this embodiment configured as described above will be briefly described based on the flowchart shown in FIG. 10. The operation starts with the first release of the release operation button (not shown) (step S101). Then step S
Proceed to step 102, step Sl02, step S103
, step S104, the image signal (only one image) is stored in the image memory 208, and the signal is repeatedly output to the video signal output circuit 209 until the AF data is completed.

Moreover, when starting, in step S110, the image signal (
The focus area signals are read out in sets of two from all), and then subjected to A-D conversion processing in step S111. Then, in step S112, an integration time tm with better conditions is set, and the process proceeds to step S113 to start integration.

Next, in step S114, t-tm is checked and the integration ends (step S115). after that,
As shown in steps S116 and S117, the A
-D conversion processing is performed, the AF data processing ends, and the process proceeds to step S105, where new image data (only one image) is always stored in the image memory 208 and the video signal output circuit 20
Send output to 9.

On the other hand, as shown in steps S118 and S119, using the A-D converted AF data, correlation calculation and correction calculation are performed to detect the amount of deviation, and the in-focus point is detected, and step S
At 120, the motor is driven to move the photographing lens 201, and at the in-focus point, the motor is stopped (step S121) L, and the process ends (step S122).

As described above, in this embodiment, the monitor output is read out, but the same effect can be obtained by performing integral control in real time.

[Effects of the Invention] As described above, according to the present invention, in the contrast detection method, the signal storage element and the means for reading out arbitrary signals are used to: 1) detect the focusing direction at the initial stage of the focusing point detection operation; This makes it possible to detect the focusing direction without the camera operator noticing any lens deviation that may occur in the camera.

2) The configuration is simple, that is, it can be realized using only signal storage elements.

Furthermore, in the phase difference detection method, even when information about only the focus area is required, the in-focus point can be detected quickly and accurately without causing discomfort to the photographer.

A number of remarkable effects such as these are exhibited.

[Brief explanation of drawings]

FIG. 1 is a conceptual block diagram showing the camera system of the present invention from a functional perspective. FIG. 2 is a concrete block diagram of the camera system showing an embodiment of the present invention. ) is a block system diagram showing the detailed configuration of the signal processing circuit in FIG. 2 above, and FIG. 3(B) is a block diagram showing the detailed configuration of the signal processing circuit in FIG. Front view, Figure 4 (A). (B)
are characteristic diagrams plotting the power against the lens position at a specific frequency determined by B-P・F in Fig. 3 above. Fig. 4 (A) shows the power at low frequency, Fig. 4 (B)
5 is a block diagram showing the detailed configuration of the DCPU and image memory in FIG. 2, and FIG. 6 is a diagram showing the high frequency state.
FIG. 7 is a specific block system diagram of a camera system showing another embodiment of the present invention; FIG. 8 is a focus area in the embodiment shown in FIG. 7; FIG. 9 is a diagram showing the interpolation from the 3-fold calculation value in the embodiment shown in FIG. 7, and FIG. 10 is a diagram showing the example of FIG. 7 above. Flowchart 1 for explaining the operation of FIG. 11 is a diagram illustrating means for detecting a matching direction in focus detection using a conventional contrast method. 11... Imaging optical system (focus detection means) 1
2... Image sensor (fish point detection means) 13.
...... Drive control system (focus detection means) 14...
......Signal storage element (signal storage means) 15...
...... Readout system (selection means and control means) 16 ...... Signal processing system (focus detection means) 1
7...Monitoring means

Claims (1)

[Claims] (1) It has an image sensor that converts the subject light guided by the imaging optical system into an electrical signal, and includes a focus detection means that detects the focusing direction and focus point of the imaging optical system from the electrical signal of the imaging device. A camera system comprising: a signal accumulation means for accumulating the electric signal; and a signal accumulation means for accumulating the electric signal, and an electric signal accumulated in the signal accumulation means from the image sensor prior to the start of the focus detection operation. electrical signal selection means for selecting one of the electrical signals; monitoring means for visualizing the selected electrical signal; A camera system comprising: a control means for controlling the selection of the .