JPH05297433A - Control method for camera - Google Patents

Abstract

PURPOSE:To freely set depth of field and to obtain a proper exposure with the control of shutter speed by providing a depth of field priority automatic exposure control mode as a photographing mode capable of being selected by a photographer. CONSTITUTION:When the depth of field priority AE mode is selected by a photographing mode selecting means 16, the depth of field desired by the photographer is set by a depth of field setting means 15. The depth of field priority diaphragm value calculating part 54 of an Arithmetic processing circuit 5, calculates a diaphragm value so as to obtain the set depth of field but not to obtain blurring, while referring to allowable circle diameter of confusion data, based on set data from the depth of field setting means 15 and measurement data from each of a diaphragm value detecting means 9, a focal distance detecting means 10, and a field distance detecting means 11. The depth of field priority diaphragm value calculating part 54 controls a diaphragm 2 so as to obtain the calculated diaphragm value, and sets an aperture, and moreover, the diaphragm and shutter control value calculating part 52 of the arithmetic processing circuit 5, controls an exposure at the shutter speed so as to obtain the proper exposure at the set diaphragm value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a video camera, an electronic still camera, a single-lens reflex camera or the like, and more particularly to a camera control method for easily setting the depth of field. Regarding

[0002]

2. Description of the Related Art A video camera converts an optical signal into an electric signal by an image pickup device and then performs signal processing by a signal processing circuit to output a video signal conforming to a color television system (for example, NTSC system). Is. In this video camera, it is necessary to adjust the exposure to an appropriate level so that an optical signal with an appropriate amount of light is input to the image sensor. As is well known, in still cameras, the exposure has been adjusted with the aperture value and the shutter speed for a long time, but in the old type video camera, the exposure adjustment was performed only with the aperture value. However, even in video cameras in recent years, for example, "TV Technology", Electronic Technology Publishing Co., Ltd .; January 1989, 8
Means for varying shutter speed have been developed as described on pages 8-91.

Here, as is well known, the aperture value is an element that determines the exposure and also an element that determines the depth of field. For example, a shooting method such as so-called portrait shooting, in which the depth of field is made shallow by making the aperture shallow, the background is blurred and only the person is focused and the person is highlighted, is often used in single-lens reflex cameras. , Conventionally, it was a technology peculiar to still cameras. However, even with a video camera, the means to change the shutter speed as described above has been realized, so the exposure can be adjusted with the aperture value and shutter speed. Therefore, as with single-lens reflex cameras, aperture priority automatic exposure control (aperture priority) It has become possible to perform shooting in the AE) mode, that is, to prioritize the aperture value (aperture aperture) manually selected by the operator and perform light amount control at the shutter speed to obtain proper exposure. A video camera in which the aperture priority AE mode or the like can be selected is described, for example, in "Television Technology", Electronic Technology Publishing Co., Ltd .; March 1990, pp. 25-28.

[0004]

By the way, in the conventional camera, the change (setting) of the depth of field is performed by directly designating the aperture value, and in determining the actual depth of field, It is necessary to confirm it from the image of the viewfinder that is actually being taken, or to confirm it with the aperture value → depth of field conversion table, and for operators who are intent to confirm the depth of field instantly Had the problem of being difficult. In addition, even if the depth of field is set once, if the distance to the subject changes or the focal length of the lens changes, the depth of field must be set again and the operation is complicated. It was

The present invention has been made in view of the above points,
The purpose is that the depth of field can be easily set by directly specifying the depth of field itself, and even if the distance to the subject is changed or the focal length of the lens is changed, An object of the present invention is to provide a camera control method that can maintain the depth of field at a set value and that has good operability.

[0006]

In order to achieve the above-mentioned object, the present invention has a diaphragm aperture value detecting means, a lens focal length detecting means, a subject distance detecting means, and data obtained from these detecting means. And a calculation processing circuit for performing a predetermined calculation processing according to the calculation processing, and the exposure control can be performed by controlling the aperture value of the diaphragm and / or the shutter speed based on the output of the calculation processing circuit. A depth-of-field priority automatic exposure control mode is provided as a shooting mode that can be selected by, and when this depth-of-field priority automatic exposure control mode is selected, setting data obtained from the depth-of-field setting means and each Based on the data obtained from the detection means, the arithmetic processing circuit calculates the aperture value that gives the set depth of field, and sets the aperture value to this calculated aperture value. State, is exposed so as to adjust the shutter speed.

[0007]

The aperture value to be actually set is calculated by the arithmetic processing circuit from the measurement information obtained from each of the above-mentioned detecting means and the depth of field data set by the operator, and the aperture value (aperture opening) is calculated.
Is set to the calculated value, and at the same time, the shutter speed is controlled to adjust the exposure. As a result, the depth of field can be freely set by the variable setting control of the aperture value, and the proper exposure can be obtained by controlling the shutter speed.

Details of the relationship between the aperture value and the depth of field will be described below with reference to FIG. In the figure, 101
Is a lens, 102 is an aperture, 103 is a subject,
a ₀ and a ₁ represent the distance from the subject 103 to the lens 101, and b ₀ and b ₁ represent the distance from the lens 101 to the image formation point. The relationship between a ₀ and b ₀ and a ₁ and b ₁ is
It can be expressed by the following equation using the focal length f of the lens 101. 1 / a ₀ + 1 / b ₀ = 1 / f Formula ... 1 / a ₁ + 1 / b ₁ = 1 / f Formula ... Now, let us consider a case where an image sensor is arranged at a distance b ₀ from the lens 101. Considering this, when the subject 103 is at the distance a ₀ , the image sensor is an image forming point, so that the subject is accurately focused.
On the other hand, when the subject moves by Δa and reaches the position of the distance a ₁ , the image forming point is located at the distance b ₀ to b ₁ from the lens 101.
The focus is out of focus because it is moved by p (hereinafter referred to as an image forming point error). At this time, light does not converge on the image pickup device and a circle of a certain diameter is drawn, and the diameter δ of this circle is called the confusion circle diameter. The diameter of the circle of confusion δ serves as an index representing the degree of out-of-focus, and the diameter of the circle of confusion δ is expressed by the following equation by the image forming point error p and the aperture value F of the diaphragm 102. δ = p / F ... Equation As is clear from this equation, if the diaphragm 102 is narrowed (F
The larger the value, the smaller the diameter of the circle of confusion δ. If the aperture is opened (the smaller the F value), the diameter of the circle of confusion δ can be increased. This is Δa from the distance a _{0 at} which the focus is accurately achieved.
This means changing the degree of blurring of a distant subject 103. That is, the depth of field can be controlled by adjusting the aperture value (opening) of the aperture 102.

The image forming point error p is represented by (b ₁ -b ₀ ). Using the equation, p = f ² (1 / a ₁ -1 / a ₀ ) / {1-f ( 1 / a ₁ + 1 / a ₀ ) + f ² / a ₁ a ₀ } ... Here, the distances a ₀ and a ₁ to the subject 103 are
Considering that it is much larger than the focal length f of the lens 101, the denominator can be regarded as almost 1, and the above equation can be expressed by the following equation. p = f ² (1 / a ₁ −1 / a ₀ ) = Δaf ² / (a ₀ −Δa) a ₀ ………… By using the above formula, F = Δaf ² / (a ₀ −Δa) a ₀ δ ... The expression is obtained.

Since it is possible to determine that the focus is in focus when the diameter of the circle of confusion δ is less than or equal to δ ₀ (the diameter of the circle of confusion), the depth of field Δa, the distance a ₀ to the object, the focus It can be seen that the desired aperture value F can be obtained from the distance f and the permissible circle of confusion diameter δ ₀ . In the above description, the subject 1
The case where 03 is located on the short distance side with respect to the lens 102 has been described, but the same applies to the case where it is located on the far distance side.

[0011]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram of a main part of a video camera according to a first embodiment of the present invention, in which 1 is a lens and 2 is a lens.
Is a diaphragm, 3 is an image pickup means, 4 is a signal processing circuit, 5 is an arithmetic processing circuit, 6 is a drive circuit of the image pickup means 3, 7 is a motor for adjusting the diaphragm 2, 8 is a motor driver, 9 is an aperture value detection means,
10 is a focal length detecting means, 11 is a subject distance detecting means,
12 to 14 are A / D converters, 15 is a depth of field setting means, and 16 is a shooting mode selection means. The calculation processing circuit 5 includes an exposure state determination unit 51, an aperture / shutter control value calculation unit (AE control unit) 52, an allowable confusion circle diameter level data storage unit 53, a depth of field priority aperture value calculation unit 54, and the like. The driving circuit 6 includes a CCD driver 6
1. A shutter control unit 62 is provided.

In the above structure, the optical signal passing through the lens 1 is converted into an electric signal by the image pickup means 3 after the light amount is adjusted by the diaphragm 2, and the electric signal is inputted to the signal processing circuit 4. The signal processing circuit 4 generates a video signal conforming to the color television system, outputs the video signal, and outputs a brightness level signal indicating the current brightness signal level to the arithmetic processing circuit 5. Then, in the automatic exposure control (AE) mode, the arithmetic processing circuit 5 controls the aperture value F of the aperture 2 via the motor 7 so that an optical signal having an appropriate light amount is input to the image pickup means 3. Alternatively, the drive circuit 6
The exposure is adjusted by controlling the shutter speed of the image pickup means 3 via.

FIG. 2 is a diagram showing a schematic structure of the image pickup means 3, which is a CCD having a well-known vertical overflow drain (VOD) structure having a variable speed electronic shutter function.
The structure of (Charge Coupled Device) is schematically shown. In the figure, 21 is a vertical transfer CC
D is connected to a large number of vertically-arranged photodiodes (photosensitive elements) 22 arranged vertically, and one end of this vertical transfer CCD 21 is connected to a horizontal transfer CCD 23. Now, when an optical image is formed on the image area of the image pickup means 3 through the lens 1 and the diaphragm 2, a photocharge corresponding to the light intensity is generated in each photodiode 22. By applying a predetermined voltage ΔV to V ₀ , unnecessary charges accumulated in the photodiode 22 are swept out to the n-type substrate, the charges are accumulated by maintaining the substrate voltage V ₀ only for a necessary period, and the accumulated photoelectric charges are
Vertical transfer CCD every 1 field period (1/60 seconds)
An output signal (not shown) is output from the output unit 21 via the horizontal transfer CCD 23 to form a video signal. Ie 1
The charge accumulation time during the field period (1/60 seconds)
By changing to a part of one field period (for example,
In other words, by setting 1/250 seconds, 1/8000 seconds, etc.), in other words, unnecessary charges are swept from the beginning of one field period to a predetermined time point in the middle of one field period, and after that predetermined time point By outputting the electric charges accumulated by the end to the signal processing circuit 4, the shutter speed is, for example, 1/60 second to 1/1.
Variable control can be performed within a range of 5750 seconds (1H period).

FIG. 3 is a block diagram showing a schematic configuration of the signal processing circuit 4. In the figure, 31 is a noise removal circuit, 32 is an AGC (automatic gain control) circuit, and 33 is A /
D converter, 34 is a luminance signal generation circuit, 35 is an edge enhancement circuit, 36 is a luminance level extraction circuit, 37 is an image synthesis processing unit, 38 is a primary color signal generation circuit, 39 is a color difference calculation circuit, 4
0 is an encoder. Signals output from the image pickup means 3 (known yellow, cyan, magenta and green complementary color signals)
Noise components are removed by the noise removal circuit 31,
After the gain control processing is performed by the C circuit 32, the signal is converted into a digital signal by the A / D converter 33 in this embodiment, and is output to the luminance signal generation circuit 34 and the primary color signal generation circuit 38. The luminance signal generating circuit 34 generates a luminance component signal from the input signal, and the contour emphasizing circuit 35 performs known contour emphasizing processing, and then outputs it to the encoder 40. The output of the brightness signal generation circuit 34 is also sent to the brightness level extraction circuit 36, which extracts the current brightness signal level and generates a brightness level signal based on the current brightness signal level, as described above. To the arithmetic processing circuit 5. Furthermore, the output of the luminance signal generating circuit 34 is also sent to the image synthesizing processing unit 37, and the image synthesizing processing unit 37 synthesizes the character image data output from the arithmetic processing circuit 5 as necessary, It is output to a known electronic viewfinder of a video camera. On the other hand, in the primary color signal generation circuit 38, R (red),
G (blue) and B (green) primary color signals are generated and output to the color difference calculation circuit 39. The color difference calculation circuit 39 performs known color difference calculation processing and outputs the output to the encoder 40. The encoder 40 generates a video signal conforming to the NTSC system based on the outputs of the contour emphasizing circuit 35 and the color difference calculating circuit 39, and outputs the video signal to the video recorder unit or the television receiver. In the case of the color electronic viewfinder, the primary color signal from the primary color signal generation circuit 38 and the character image data output from the arithmetic processing circuit 4 are combined.

The exposure state determination unit 51 of the arithmetic processing circuit 5
Takes in the above-mentioned luminance level signal from the signal processing circuit 4 and the current exposure state is at an appropriate level (within an allowable range).
If the exposure is not proper, a command is sent to a character image data generation unit (not shown) to generate alarm message information, and this is sent to the image synthesis processing unit 37. The electronic viewfinder displays an alarm message. The aperture / shutter control value calculation unit 52 of the calculation processing circuit 5
When the shooting mode selected by the operator is the automatic exposure control (AE) mode, the exposure state determination unit 51 that takes in the above-mentioned brightness level signal from the signal processing circuit 4 to obtain an appropriate exposure level is output from the exposure state determination unit 51. While referring to the output and the measurement information from each of the detection means 9 to 11 described above,
Control value data for variably controlling at least one of the aperture value F and the shutter speed is calculated. The aperture / shutter control value calculation unit 52 sends an output according to the calculation result to the motor driver 8 to control the aperture value (F value) of the aperture 2 via the motor 7, or the calculation result. Output to the shutter control unit 62 in the drive circuit 6, and the shutter control unit 62 controls the shutter speed of the image pickup means 3 via the CCD driver 61 by using the method described in FIG. To be controlled.

The permissible circle of confusion diameter data storage unit 53 of the arithmetic processing circuit 5 stores in advance the permissible circle of confusion diameter δ _{0, which} is the circle of confusion that cannot be detected by the video camera of this embodiment, as data. ing. The depth-of-field priority aperture value calculation unit 54 of the calculation processing circuit 5 is obtained from the depth-of-field setting means 15 when a depth-of-field priority automatic exposure control (AE) mode described later is selected. Based on the data set by the operator and the data obtained from each of the detection means 9 to 11, the aperture value at which the set depth of field is obtained is calculated with reference to the permissible circle of confusion diameter δ ₀ . An output according to the calculation result is sent to the motor driver 8 and the aperture value (F value) of the aperture 2 is set to the calculated aperture value via the motor 7. The arithmetic processing circuit 5
The shutter control unit 62 in the drive circuit 6 is actually composed of a microcomputer (microcomputer) that executes processing based on various programs created in advance and various measured values, and the functional blocks described above are processed by the microcomputer. To be realized.

The aperture value detecting means 9 detects the aperture value F, and is composed of, for example, a hall element or the like for detecting the opening of the aperture 2. The focal length detecting means 10 detects the focal length f of the lens 1, and is composed of, for example, a potentiometer for detecting the rotation amount of the zoom ring. The subject distance detecting means 11 detects the distance a ₀ to the subject, and is composed of, for example, a potentiometer for detecting the rotation amount of the range ring. The measurement information obtained by the three detecting means 9 to 11 is obtained by the A / D converter 12 described above.
.. to 14 are converted into digital data and inputted to the arithmetic processing circuit 5 as data of aperture value F, focal length f, and subject distance a ₀ , respectively.

In this embodiment, five shooting modes as shown in FIG. 4 are prepared as the shooting modes selectable by the operator. That is, the manual mode in which the operator manually sets the aperture value and the shutter speed, the shutter priority AE mode in which the operator manually sets the shutter speed and prioritizes the shutter speed and adjusts the exposure by the aperture control, and the operator sets the aperture value. Is a manual setting, aperture priority AE mode that adjusts the aperture and adjusts the exposure at the shutter speed, a program AE mode that adjusts the exposure by aperture value control and shutter speed control, and a depth of field that is set manually by the operator. The depth-of-field priority AE mode in which the aperture value is calculated accordingly, the aperture is set to the calculated aperture value, and the exposure is adjusted at the shutter speed is selectable. The selection of the photographing mode is performed by the photographing mode selection means 16 described above.
The photographing mode selection means 16 is composed of, for example, the rotary switch shown in FIG. The manual mode, shutter priority AE mode, aperture priority A described above
The E mode and the program AE mode are publicly known, and are also described in the above-mentioned "TV Technology", Electronic Technology Publishing Co., Ltd .; March 1990, pp. 25-28, so the description thereof is omitted here. The depth of field priority AE mode will be described below. Further, in FIG. 1, although the means for the operator to manually set the aperture value and the shutter speed is omitted, a known appropriate means can be used for this.

When the depth-of-field priority AE mode is selected by the photographing mode selection means 16, the arithmetic processing circuit 5 takes the mode and the depth-of-field setting means 15 is selected.
The input of the desired depth of field setting data Δa is waited for. The method of setting the depth of field by the depth of field setting means 15 is arbitrary, but in the present embodiment, as shown in FIG. 6, for example, setting A (depth of field approximately ± 1) is used.
m), setting B (depth of field approximately ± 3 m), and setting C (depth of field approximately ± 10 m), three types of depth of field can be set. Further, in order to consciously set the front focus and the rear focus, it is possible to perform the gradual setting (fine adjustment) to the front focus side and the gradual setting (fine adjustment) to the rear focus side. This can be selected by, for example, a depth of field setting means 15 composed of a plurality of push switches and a front-pin / rear-pin adjustment push switch 18 as shown in FIG. When the depth of field Δa desired by the operator is set by the depth of field setting means 15, the depth of field priority aperture value calculation unit 54 of the calculation processing circuit 5
Based on the setting data from the depth of field setting means 15 and the measurement data from the detecting means 9 to 11, the set depth of field is obtained while referring to the permissible circle of confusion diameter δ _0. And the aperture value without blurring is calculated. The depth-of-field priority aperture value calculation unit 54 controls the aperture 2 to set the aperture as described above so that the calculated aperture value is obtained, and the aperture / shutter control value calculation unit of the arithmetic processing circuit 5. 52 executes a process of adjusting the exposure at the shutter speed so that the proper exposure can be performed at the set aperture value.

FIG. 8 shows an example of an image on the electronic viewfinder at the time of depth-of-field priority AE mode shooting.
In this embodiment, as shown in the figure, a message 61 indicating that the depth-of-field priority AE mode is selected and a message indicating the currently selected depth of field are displayed on the electronic viewfinder 60. 62 and are displayed.

FIG. 9 shows another example of the image of the electronic viewfinder at the time of depth-of-field priority AE mode shooting. The figure shows the exposure state determination unit 51 of the arithmetic processing circuit 5.
Is unsuitable for the current exposure state (fixed to the set aperture value,
The display state is shown in which it is determined that proper exposure cannot be obtained by adjusting the exposure only with the shutter speed, and an alarm message 62 prompting the resetting of the depth of field is displayed together with the blinking portion 62a. Shows.

Next, the processing method for the depth-of-field priority AE mode shooting will be described with reference to the flowchart of FIG.
In step ST1 of FIG. 10, the operator receives an instruction to set the depth of field to Δa, and the process proceeds to the next step ST2, in which the distance a ₀ to the subject and the focal length f are captured. In the next step ST3, the aperture value F ₀ to be set is calculated based on these information according to the following formula (the depth-of-field priority aperture value calculation unit 54 calculates Δa, a ₀ , f, δ _0).
Based on the calculation). ^{_{F 0 = Δaf 2 / (a}} 0 -Δa) a 0 δ 0 ......... formula In the next step ST4, the current aperture value F of the diaphragm 2 output by taking the arithmetic processing circuit 5 of the aperture detecting means 9
While controlling the motor 7 so as to obtain the calculated aperture value F ₀ , the arithmetic processing circuit 5 (aperture / shutter control value arithmetic unit 52) changes the shutter speed so as to maintain the exposure at an appropriate level. A control signal is output to the drive circuit 6. In the next step ST5, it is asked whether or not the proper exposure is obtained (whether or not the determination result of the exposure state determination unit 51 is OK), and if the proper exposure is obtained (the aperture value to be set) If the F _0, is properly exposed with a shutter speed corresponding to the aperture value F ₀ can be realized)
, This flow ends. However, if it is determined in step ST5 that the exposure is not proper (aperture value F ₀
If it is not possible), go to step ST6, display an alarm message as shown in FIG. 8, set the shutter speed and aperture value to appropriate levels so as to maintain proper exposure in step ST7, and then go to step ST1. It is made to wait for the return depth of field to be reset. In this embodiment, in step ST7, the depth of field designated by the operator (aperture value F ₀ based on the designated depth of field) is ignored, and proper exposure is obtained for the time being. However, shooting in the depth-of-field priority AE mode is special, and the operator sets the set depth-of-field Δa and the distance a ₀ to the subject.
In a system on the premise that the proper exposure may not be obtained depending on the focal length f, the processing in step ST7 can be omitted.

As described above, according to the present embodiment, the depth of field can be easily set in the video camera, and the desired depth of field can be maintained even if the distance to the subject or the focal length changes. , The usability is greatly improved.

In the above embodiment, the camera in which the exposure is adjusted by the aperture and the shutter speed has been described.
Aperture and gain control (for example, the AGC circuit 3 in FIG. 3)
The present invention can also be applied to a camera that performs gain control of 2). In addition, in the above description, an example in which a certain distance is focused before and after the in-focus point has been described, but the target subject may be positioned anywhere within the range of the focused distance. Obviously, intentionally setting the front pin and the rear pin can be easily realized in this embodiment.

Next, a second embodiment of the present invention will be described with reference to FIGS. 11 and 12. FIG. 11 is a block diagram of a main part of a video camera according to a second embodiment of the present invention. In FIG. 11, parts that are the same as those in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted to avoid duplication. In FIG. 11, 17 is an aperture setting means for the operator to set an aperture value,
According to an instruction from the aperture setting means 17, the arithmetic processing circuit 5 sets the opening of the aperture 2 by the motor 7 according to the set aperture value. Also,
Reference numeral 55 is a depth-of-field calculation unit provided in the calculation processing circuit 5.

In this embodiment, the depth of field priority AE is used.
No mode is provided, and the aperture adjustment of the aperture 2 to obtain a desired depth of field is performed by the operator manually selecting the aperture priority AE mode and using the aperture setting means 17. The arithmetic processing circuit 5 calculates the current depth of field based on the aperture value and the current shooting conditions, and displays it on the electronic viewfinder. That is, the depth-of-field calculation unit 55 of the calculation processing circuit 5 has an aperture value F (manually set aperture value) obtained from the aperture value detection means 9, a focal length f obtained from the focal length detection means 10, The depth of field Δa is calculated based on the distance a ₀ to the object obtained from the object distance detection means 11 and the allowable confusion circle diameter δ ₀ preset in the allowable confusion circle diameter data storage unit 53. The calculated data is converted into character image data, sent to the signal processing circuit 4, and displayed on the electronic viewfinder. In the aperture-priority AE mode, the arithmetic processing circuit 5 controls the shutter speed of the image pickup means 1 via the drive circuit 6 so that the light signal of the proper light amount is converted into an electric signal in the image pickup means 1. Adjust the exposure.

Next, the depth of field calculation method of this embodiment will be described with reference to the flowchart of FIG. In step ST21 of FIG. 12, the operator sets the aperture value F of the aperture stop 2, and in the next step ST22, the set aperture value F, the distance a ₀ to the subject, and the focal length f are fetched.
It proceeds to step ST23. In step ST23, the arithmetic processing circuit 5 calculates the depth of field Δa according to the following equation based on these pieces of information. This equation is a modification of the above equation. Δa = a ₀ ² δ ₀ F / (f ² + a ₀ δ ₀ F) ... Formula At the next step ST24, this depth of field Δa information is output to the signal processing circuit 4 and superimposed on the video signal. At the same time as displaying on the electronic viewfinder, the arithmetic processing circuit 5
Outputs a control signal to the drive circuit 6 so as to change the shutter speed so that the exposure maintains an appropriate level. In the next step ST25, it is asked whether or not the proper exposure has been obtained, and if the proper exposure has been obtained, this flow ends. However, if it is determined in step ST25 that the exposure is not proper (if the aperture value is unreasonable), step ST25
After proceeding to step 26 and displaying an alarm, step ST2
It returns to 1 and waits for the resetting of the depth of field.

As described above, according to the present embodiment, the operator can know the depth of field currently obtained as a number by only operating the diaphragm 2 and the usability is improved. It should be noted that, even in the present embodiment, the camera in which the exposure is adjusted by the aperture and the shutter speed is described, but the present invention is also applicable to the camera in which the exposure is performed by the aperture and the gain control.

Although a video camera has been taken as an example in the above-mentioned embodiment, the present invention uses the aperture value F and the focal length f.
It is obvious to those skilled in the art that the present invention can also be applied to a still camera that can obtain the distance a ₀ to the subject.

[0030]

As described above, according to the present invention, the depth of field can be directly set and the numerical value of the depth of field can be visually recognized instantly, and the depth of field is emphasized. Shooting can be done easily and surely, and the operability is greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a video camera according to a first embodiment of the present invention.

FIG. 2 is an explanatory view schematically showing the image pickup means of FIG.

FIG. 3 is a block diagram showing an example of the arithmetic processing circuit of FIG.

FIG. 4 is an explanatory view showing a table of selectable shooting modes in the first embodiment of the present invention.

5 is an explanatory diagram showing an example of a photographing mode selection unit in FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing a table of selectable depth of field and the like in the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of the depth of field setting means and the like in FIG.

FIG. 8 is an explanatory diagram showing an example of message information displayed on the electronic viewfinder in the first embodiment of the present invention.

FIG. 9 is an explanatory diagram showing another example of message information displayed by the electronic viewfinder in the first embodiment of the present invention.

FIG. 10 is a flowchart showing a processing method during depth-of-field priority AE mode shooting according to the first embodiment of the present invention.

FIG. 11 is a block diagram showing a main configuration of a video camera according to a second embodiment of the present invention.

FIG. 12 is a flowchart showing a depth of field calculation processing method and the like in the second embodiment of the present invention.

FIG. 13 is an explanatory diagram for helping understanding of a relationship between an aperture value and a depth of field.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 lens 2 aperture 3 image pickup means 4 signal processing circuit 5 arithmetic processing circuit 6 drive circuit 7 motor 8 motor driver 9 aperture value detection means 10 focal length detection means 11 subject distance detection means 12, 13, 14 A / D converter 15 covered Depth of field setting means 16 Shooting mode selection means 17 Aperture setting means 51 Exposure state determination section 52 Aperture / shutter control value calculation section 53 Allowable confusion circle diameter data storage section 54 Depth of field priority aperture value calculation section 55 Depth of field Arithmetic section

Claims (6)

[Claims] 1. An aperture value detection means for a diaphragm, a focal length detection means for a lens, a subject distance detection means, and an arithmetic processing circuit for performing a predetermined arithmetic processing based on data obtained from the respective detection means. In a camera in which the exposure can be adjusted by controlling the aperture value and / or the shutter speed based on the output of this arithmetic processing circuit, a depth of field priority automatic exposure control mode is provided as a shooting mode selectable by the operator. When the depth of field priority automatic exposure control mode is selected, the arithmetic processing circuit is set based on the setting data obtained from the depth of field setting means and the data obtained from each of the detecting means. The aperture value is calculated so that the depth of field can be obtained, and the exposure is adjusted by the shutter speed while the aperture value is set to the calculated aperture value. Control method for a camera, characterized in that there was Unishi. 2. When the aperture value that gives the depth of field set by the operator does not provide an appropriate level of exposure, the arithmetic processing circuit causes the display unit to display a warning to that effect. A camera control method characterized by the above. 3. An aperture value detecting means for an aperture, a focal length detecting means for a lens, an object distance detecting means, and an arithmetic processing circuit for performing a predetermined arithmetic processing based on data obtained from each of the detecting means. In a camera whose exposure can be adjusted by controlling the aperture value and / or shutter speed of the aperture based on the output of this arithmetic processing circuit, when the operator manually sets the aperture value of the aperture, A method of controlling a camera, wherein the arithmetic processing circuit calculates a current depth of field based on data obtained from the means, and displays the calculated depth of field on a display means. 4. When the aperture value manually set by the operator does not provide an appropriate level of exposure, the arithmetic processing circuit causes the display means to display a warning to that effect. How to control the camera. 5. An aperture value detection means for an aperture, a focal length detection means for a lens, a subject distance detection means, and an arithmetic processing circuit for performing a predetermined arithmetic processing based on data obtained from each of the detection means, In a camera in which the exposure can be adjusted by controlling the aperture value and / or the gain of the aperture based on the output of this arithmetic processing circuit, a depth-of-field priority automatic exposure control mode is provided as a shooting mode selectable by the operator. When the depth-of-field priority automatic exposure control mode is selected, the arithmetic processing circuit is configured to set the object to be set based on the setting data obtained from the depth-of-field setting means and the data obtained from each of the detecting means. An aperture value that gives a depth of field is calculated, and the exposure is adjusted by gain control in a state where the aperture value is set to the calculated aperture value. Method of controlling the camera. 6. An aperture value detection means for a diaphragm, a focal length detection means for a lens, a subject distance detection means, and an arithmetic processing circuit for performing a predetermined arithmetic processing based on data obtained from each of the detection means. In a camera in which the exposure can be adjusted by controlling the aperture value and / or the gain of the aperture based on the output of this arithmetic processing circuit, when the operator manually sets the aperture value of the aperture, it is obtained from each of the detecting means. A method of controlling a camera, wherein the arithmetic processing circuit calculates a current depth of field based on the received data and causes the display unit to display the calculated depth of field.