JPH06205279A - Still video camera and its exposure monitor method - Google Patents

Abstract

PURPOSE:To allow the photographer to immediately discriminate whether or not an exposure is proper at image pickup of the still video camera just after image pickup. CONSTITUTION:A photometry value is detected by allowing an integration circuit 14 to integrate a luminance signal component extracted from a video signal outputted from a CCD 4 in the preliminary image pickup at a YL synthesis circuit 12 over a photometry region placed in an image pickup region and an exposure condition is set. The exposure is detected by integrating the luminance signal component of the video signal outputted from the CCD 4 in the image pickup operation over the same region as the photometry region. The actual exposure and the photometry value (set exposure) are compared to discriminate whether the exposure is proper, deficient or excessive and the result of discrimination is displayed on a display device 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a still video camera including an image pickup optical system including a solid-state electronic image pickup device that converts an incident light image into a video signal and outputs the image signal, and an exposure monitoring method during the photographing.

[0002]

2. Description of the Related Art In a still video camera, subject brightness is measured prior to shooting, and the exposure amount is set based on this photometric value. The diaphragm, the shutter speed, and the strobe light emission amount are controlled in some cases so that the incident light amount of the set exposure amount is incident on the solid-state electronic image sensor. Photographing is performed under the controlled exposure amount as described above, and the video signal for one frame output from the solid-state electronic image pickup device is stored in the magnetic recording medium or the semiconductor memory through a predetermined process.

On the other hand, in the movie video camera, the constant exposure amount is detected based on the video signal continuously output from the solid-state electronic image pickup device every 1/60 second or 1/30 second. A properly exposed movie image is obtained by feedback control in which shooting is performed while changing the exposure condition based on the exposure amount.

However, in the still video camera, as described above, shooting is performed for each frame, and feedback control of the exposure amount cannot be performed as in the movie video camera. Therefore, during photometry and shooting. If the subject brightness is different from time to time, for example, when the light is on during photometry but the sun is over when shooting, it is not always possible to obtain a properly exposed still image. Not exclusively.

Conventionally, the determination as to whether or not the photographed still image was properly exposed had to be made by reproducing the photographed still image on an external monitor display device. Such work is complicated and it is difficult to shoot outdoors.

[0006]

DISCLOSURE OF THE INVENTION It is an object of the present invention to make it possible to determine whether or not the exposure amount of a still video camera at the time of shooting was appropriate, immediately after the shooting without performing a reproduction operation of the taken image. To do.

According to the present invention, in a still video camera provided with an image pickup optical system including a solid-state electronic image pickup device for converting an incident light image into a video signal and outputting the image signal, the subject brightness is measured and based on the light measurement value. Exposure amount setting means for setting an exposure amount for photographing, an exposure amount control means for causing the incident light amount of the exposure amount set by the exposure amount setting means to enter the solid-state electronic image pickup device, the exposure amount Luminance signal extraction means for extracting a luminance signal component from the video signal output from the solid-state electronic image pickup device by photographing with the exposure amount realized by the control means, and a luminance signal component extracted by the luminance signal extraction means To obtain an integrated value by integrating over a predetermined photometric region, and to measure the actual exposure amount based on this integrated value Comparing means for comparing the set exposure amount set by the step with the actual measured exposure amount measured by the exposure amount measuring means, and display means for displaying the comparison result by the comparing means. .

The present invention also provides an exposure monitoring method for the above still video camera.

According to the present invention, the brightness of the object is measured prior to photographing, and the exposure amount for photographing is set based on this photometric value. The diaphragm, shutter speed, and strobe light emission amount are controlled as necessary so that the incident light amount of the set exposure amount is incident on the solid-state electronic image sensor. Photographing is performed under such exposure control.

On the other hand, the video signal output from the solid-state electronic image pickup device by photographing is stored in the magnetic recording medium or the semiconductor memory device (memory card) after being subjected to the predetermined processing as described above. On the other hand, a luminance signal component is extracted from the video signal output from the solid-state electronic image pickup device, and based on an integrated value obtained by integrating the luminance signal over a predetermined photometric region, the exposure amount during measurement (measurement exposure) Quantity) is measured.

The measured exposure amount is compared with a set exposure amount set for the photographing, and as a result of the comparison, for example, whether the exposure is proper exposure, underexposure, overexposure, or a still video camera. Is displayed on the display device provided in the.

The photographer can immediately know whether or not the photographed image has been properly exposed by looking at the above display immediately after photographing. If the image taken is not properly exposed, the image can be retaken immediately.

Further, the invention is particularly effective in stroboscopic photography in which it is difficult to control the light emission amount.

Since the display of the comparison result can be performed by a simple and inexpensive display device, even if it is provided in the still video camera, the camera does not become large or expensive.

The present invention is effective when applied to a still video camera in which preliminary photographing is performed prior to photographing and subject brightness is measured based on a video signal output from the solid-state electronic image pickup device. This still video
In the camera, the exposure amount setting means obtains an integral value by integrating the luminance signal component extracted by the luminance signal extracting means over the same area as the photometric area in preliminary photographing prior to photographing, and obtains this integral value. The exposure amount is set based on this.

In such a still video camera, part or all of the brightness signal extracting means and the exposure amount setting means can be shared with part or all of the exposure amount setting means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention suitable for a digital still camera will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a digital circuit of an embodiment of the present invention.
It is a block diagram which shows the electric constitution of a still camera.

The overall operation of the digital still camera is controlled by the CPU 1.

The image pickup optical system comprises an image pickup lens system 2, an iris 3 and a CCD 4 for forming a subject image.

The CPU 1 sends the iris 3 the aperture control signal I
R is output to perform aperture control, and an electronic shutter control signal ST is output to the CCD 4 to perform shutter control. By this diaphragm control and shutter control, photometric processing and exposure control during photographing are achieved. A strobe device is also used as necessary in the shooting mode.
Further, the CPU 1 is an image pickup lens driving device (not shown).
A focus control signal is output to control focus of the imaging lens 2.

Interlaced shooting is performed by the CCD 4, and video signals (GRGB) of the A field and the B field are recorded.
Color sequential signals) are alternately generated every one field period and sequentially read out. The driving of the CCD 4 (imaging and reading of video signals) is performed at least at the time of photographing and at the photometric processing (preliminary photographing) prior to that.

Video signals of the A field and the B field output from the CCD 4 are given to a color separation circuit 6 through a correlated double sampling circuit (CDS) 5, and the three primary colors representing a subject image, G (green), R ( Red) and B
It is separated into (blue) color signals.

The color signals G, R, and B are subjected to color balance adjustment by a gain control circuit (hereinafter referred to as GCA) 7 and then gradation correction is performed by a gamma correction circuit 8 for clamping and resetting. Input to the sampling circuit 9.

The clamp and resembling circuit 9 is
The three color signals R, G, B are clamped and re-converted into GRGB color sequential signals by resampling. This color-sequential signal is input to the gain control and banging circuit 10. The gain control and blanking circuit 10 amplifies the color sequential signal to an appropriate level for recording and adds the blanking signal to it. The output signal of the gain control and blanking circuit 10 is subsequently converted into digital image data by the A / D converter 11.

As will be described later in detail, prior to photographing, photometric processing and exposure control based on the photometric value (control of iris and shutter speed, and preparation for stroboscopic light emission as necessary) are performed. This photometric processing is performed based on the output signal of the gamma correction circuit 8. Shooting is performed after such photometric processing and exposure control. Then, the CCD 4
The video signal obtained from the above becomes digital image data through the circuits 9, 10 and 11 described above, and is subjected to processing such as Y / C separation and data compression by an image data processing circuit (not shown), and then a memory card or the like. Will be recorded on the recording medium.

A Y _L combining circuit 12, a gate circuit 13, an integrating circuit 14 and an amplifying circuit 15 are provided for photometric processing. An example of a specific electrical configuration of these circuits is shown in FIG. The CPU 1 outputs a window signal WIND that controls the gate circuit 13 and a reset signal HLRST that resets the integration circuit 14. These signals WIND
The timing of HLRST will be described later. These circuits for photometric processing are also used for detecting the exposure amount, which will be described later.

The color signals R, G and B output from the gamma correction circuit 8 are added by the Y _L synthesizing circuit 12 and the luminance signal Y _L having a relatively low frequency (hereinafter simply referred to as the luminance signal Y _L ).
Is generated. The luminance signal _Y L passes through the gate circuit 13 during the period in which the window signal WIND is given in the required horizontal scanning period. The integrating circuit 14 is reset when the reset signal HLRST is given, and then integrates the luminance signal Y _L input from the gate circuit 13. The integrated signal of the integrating circuit 14 is amplified by the amplifying circuit 15, and is converted into digital integrated data by the A / D converter 16 immediately before the integrating circuit 14 is reset, and is taken into the CPU 1. Reference voltage divisions V1 and V2 of the integration circuit 14 and the amplification circuit 15
Gives an appropriate offset to this.

The strobe device comprises an electronic volume circuit (hereinafter referred to as EVR) 17, a light emission control circuit 18, a strobe drive circuit 19, a light emitting section 20, and a gate circuit 21.

A strobe light emission timing signal XT given from a synchronizing signal generation circuit (not shown) is provided only while the strobe light emission enable signal XonEN is given from the CPU 1.
After passing through M, the light emission control circuit 18 and the strobe drive circuit 19 are given a strobe light emission command signal Xon.

EVR17 is a kind of D / A converter,
A voltage signal representing the amount of light emitted from the CPU 1 is output and applied to the light emission control circuit 18. An example of a specific electrical configuration of the light emission control circuit 18 is shown in FIG. In FIG. 3, the output voltage of the EVR17 is a capacitor via a resistor.
Given to 181. A switch 182 connected in parallel with the capacitor 181 is for clearing (discharging) the electric charge of the capacitor 181 before starting the flash light emission. switch
182 is normally turned on, and is turned off when the strobe light emission command signal Xon of the CPU 1 is given. When the switch 182 is turned off, the voltage output from the EVR 17 starts charging the capacitor 181. The output voltage of the capacitor 181 is given to the positive input terminal of the differential amplifier circuit 183. The negative input terminal of the differential amplifier circuit 183 is connected to the reference power supply 184, and is supplied with a predetermined reference voltage.

When the electric charge is accumulated in the capacitor 181, and the output voltage becomes equal to the reference voltage, the stop signal STOP is output from the differential amplifier circuit 183 and is given to the strobe drive circuit 19. In this way EVR17
Strobe emission time is controlled by the output voltage of.

An example of a specific electrical configuration of the strobe power supply circuit 19 is shown in FIG. The strobe drive circuit 19 includes a power supply 191, a booster circuit 192, a main capacitor 193, and a trigger circuit.
194 and stop circuit 195.

The voltage of the power supply 191 is boosted by the boosting circuit 192 and the main capacitor 193 is charged. Main capacitor
The charging voltage of 193 is detected by being applied to the A / D port of the CPU 1 through an appropriate voltage reducing circuit or voltage detecting circuit (not shown). This allows the CPU 1 to know that charging of the main capacitor 193 has been completed.

The strobe light emission is started by applying the strobe light emission command signal Xon to the trigger circuit 194.
The trigger circuit 194 triggers the discharge in the discharge tube 201 when the strobe light emission command signal Xon is given. The electric charge stored in the main capacitor 193 is discharged through the discharge tube 201 of the light emitting unit 20, and strobe light emission starts.

This strobe light emission is a stop signal S output from the differential amplifier circuit 183 of the light emission control circuit 18 described above.
It is stopped by applying TOP to the stop circuit 195. The stop circuit 195 includes a switching element, and when the switching element is turned off in response to the stop signal STOP, the current flowing in the discharge tube 201 is cut off.

Referring again to FIG. 1, the digital still
The camera has a distance measuring circuit 22. The distance measuring circuit 22 includes a distance measuring sensor, starts measuring the distance to the object (distance measuring) in response to the distance measuring start signal AF1 given from the CPU 1, and outputs the data read signal AF2 given from the CPU 1.
In response to, the obtained distance measurement data is given to the CPU 1.
The distance measurement data is used for driving the lens 2 to perform focusing processing and for determining the strobe light emission amount.

A display device 23 for displaying the exposure amount determination result is connected to the CPU 1. The display device 23 includes an orchest lamp 231 indicating that the exposure amount at the time of shooting was appropriate in the determination of the exposure amount described later, an over lamp 232 for indicating that the exposure amount was excessive, and Under lamp 233 to indicate underexposure
Is provided.

The shutter release button (not shown) has a two-step stroke. When the button is pressed in the first step, the signal S1 is generated. In response to this, as will be described later, shooting including pre-shooting is performed. The preparatory operation is started, and when the shutter release button is pressed in the second step, the signal S2 is generated and the main photographing is performed. These signals S1 and S2 are sent to the CPU1.
Given to.

Before describing the overall operation of the video camera, the photometric processing performed in the preliminary shooting and the exposure amount detection processing after the main shooting will be described.

First, the photometric processing will be described.

In this embodiment, average photometry (hereinafter referred to as AV photometry) for measuring the average brightness in the visual field is performed. A field image and B that make up one frame
Since it is considered that the field image represents a field image at almost the same time point, photometry is performed in the A field in this embodiment, but photometry may be performed in the B field.

Further, in this embodiment, the integration by the integration circuit 14 and the A / D conversion operation and the addition processing by the A / D converter 16 are alternately performed every horizontal scanning period.

FIG. 5 shows an AV photometric area set in the photographing area 30 of the CCD.

The AV metering area is basically set over almost the entire shooting area. In this embodiment, the AV photometric area is set in the horizontal direction for a period of 40 μs (first photometric period) after 16 μs has elapsed from the fall of the horizontal synchronizing signal HD (at the start of the horizontal scanning period), and the vertical direction. Is set from the 35th horizontal scanning line to the 246th horizontal scanning line (second photometric period).

As shown in FIG. 6, in AV photometry in the A field period, a window signal WIND having a pulse width of 40 μs is applied to the gate circuit 13 16 μs after the trailing edge of the 35th horizontal synchronizing signal HD. While the window signal WIND is given, the gate circuit 13
It passes the luminance signal Y _L for inputting the luminance signal Y _L
Is input to the integrating circuit 14.

The integrating circuit 14 has already been reset in the preceding field and integrates the luminance signal Y _L which has passed through the gate circuit 13 and is input. Window signal WIND
Becomes L level and the input of the luminance signal Y _{L to} the integrating circuit 14 is stopped, the integrated output of the integrating circuit 14 is held as it is, and the integrated output of the integrating circuit 14 is amplified by the amplifying circuit 15 and then A It is converted into digital data by the / D converter 16. The time required for A / D conversion is 15 μs in this embodiment. After this, the integrating circuit 14 is operated by the CPU 1
The signal is reset by the horizontal line reset signal HLRST given from the above to prepare for the next integration operation.

A memory attached to the CPU 1 (for example, RA
The AV integrated data storage area M) is cleared in synchronization with the 34th horizontal synchronizing signal HD. The integrated value converted into digital data by the A / D converter 16 is this A
It is added to the previous data (which is zero in the first case and is zero) and stored in the V integrated data storage area.

The A / D conversion by the A / D converter 16, the reset of the integrating circuit 14 and the addition processing of the integrated data are performed as follows.
It is performed in the 36th horizontal scanning period.

As described above, the integration of the luminance signal Y _L by the integrating circuit 14 on one horizontal scanning line in the AV photometric area and the integration signal A obtained by this integration are performed.
The / D conversion, the reset of the integrating circuit 14 and the addition of the integrated data to the memory are alternately repeated every horizontal scanning period. Then, this repetition is performed until the 246th horizontal scanning period, that is, over the entire AV photometry area.

In this way, the luminance signal Y _L is integrated every other horizontal scanning period, and A / D conversion and other processing are performed in the next horizontal scanning period after the integration. Even using a D converter is sufficient. Even if the integration is performed every other horizontal scanning line, a sufficient amount of integration data can be obtained to obtain the photometric value.

FIG. 7 shows the overall operation of the photometric processing performed by the CPU 1.

The CPU 1 initializes the exposure condition when starting the photometric processing, and controls at least one of the iris 3 and the electronic shutter so that the initial exposure condition is realized. The initial exposure condition is statistically most likely, for example, the exposure amount Ev = 10.
(Aperture F4, shutter speed 1/60 second, or aperture F2.
8, shutter speed 1/125 second) is preferable.

In the horizontal scanning period within the AV photometric area (step 51), as described above, the window signal WIN
D is output to cause the integrating circuit 14 to perform the integrating operation during the first photometric period (step 52). After the lapse of the first photometric period, the A / D converter 16 is driven to perform A / D conversion of the integrated signal of the integrating circuit 14 to obtain integrated data.

Next, it is judged whether the obtained integrated data is within a predetermined range (step 53). This is to determine whether the obtained integrated data can be used as a photometric value for one horizontal line. In the case where the horizontal scanning line which is the object of photometry has a very high brightness portion in that part and the brightness signal Y _L is saturated, the integrated data is not suitable for use as a photometric value. This predetermined range is CC
In consideration of the dynamic range of D4, the gain of the GCA 7 and the amplifier circuit 15, etc., it is set to such an extent that integrated data based on the saturated luminance signal Y _L can be eliminated. As the predetermined range, not only the upper limit value but also the lower limit value may be set. It is not appropriate to use the integrated data as the photometric value even when the portion of the horizontal scanning line which is the object of photometry is extremely dark and the luminance signal Y _L is almost due to the noise component. Therefore, the lower limit value of the predetermined range will be set to the level at which the integrated data in which the noise component is dominant is excluded.

If the obtained integrated data is a value within a predetermined range, the integrated data is added to the value in the integrated data area of the memory (step 54), and if it is still within the photometric area (step 54). 55) Return to step 52. If the integrated data is out of the predetermined range, the line number counter is incremented by 1 (step 57), and the addition processing of the integrated data is not performed. That is, the integrated data is not used as a photometric value. The line number counter counts the number of horizontal lines whose integrated data is outside a predetermined range. If the value of the line number counter is within the predetermined value (step 58), the process returns to step 52 through step 55.

The above-described operation is repeated over the entire photometry area while repeating two horizontal scanning periods as one cycle. Then, when it goes out of the range of the photometric area (step 55), the photometric value is calculated using the added value of the integrated data obtained up to that point (step 56). This photometric value calculation includes a calculation of dividing the added value of the integrated data by the number of lines added as the integrated data to obtain the average value of the integrated values per horizontal scanning line. The number of lines added as the integrated data is obtained by subtracting the value of the line number counter from half of the horizontal scanning lines in the photometric area. A table or an arithmetic expression indicating the correspondence between the integrated value and the photometric value (exposure amount) is preset, and the photometric value is calculated using the integrated value according to this table or the arithmetic expression.

Based on the photometric values thus obtained, the CPU 1 determines the exposure conditions such as the aperture, the shutter speed, the presence / absence of strobe light emission, and the strobe light emission amount in the presence of the strobe light emission, as will be described later.

Further, when the value of the line number counter for counting the number of horizontal lines whose integrated data is outside the predetermined range exceeds the predetermined number (step 58), the CPU 1 changes the exposure condition (step 59). After clearing the integral data area of the memory, the photometric processing from step 51 is repeated at the start of the next frame or field.

When the exposure condition is changed, the exposure amount is made smaller than the initially set exposure amount when much of the integrated data exceeds the predetermined range, and is increased in the opposite case. 1 step exposure amount (eg ± 2 Ev)
You should change each. When the initial exposure amount is not so different from the actual brightness of the field of view, an appropriate exposure amount may be obtained by repeating the photometric processing shown in FIG. 7 once or twice (one frame to two frame periods). .

Although AV metering is performed in the above embodiment, spot metering (hereinafter referred to as SP metering) for measuring the brightness of the main subject in the field of view may be performed. This SP
The photometric area is set as a small area at an arbitrary position of the photographing area 30A. This SP photometric area is set at the center of the photographing area 30. For example, as shown in FIG. 5, the horizontal direction is the 87th vertical direction during the 15 μs period 28.5 μs after the fall of the horizontal synchronizing signal HD. 194th from horizontal scan line
It is set up to the second horizontal scan line. SP
The photometric procedure for the photometric area is the same as in the case of AV photometry.

Next, the process of detecting the actual exposure amount after the main photographing will be described.

The detection of the actual exposure amount is obtained based on the integrated value obtained by integrating the luminance signal Y _L generated by the Y _L synthesizing circuit 12 by the integrating circuit 14 as in the case of the photometry.
The integration of the luminance signal component Y _L for detecting the exposure amount is performed over the same region (the exposure amount detection region) as the AV photometric region of FIG. 5, and the integration circuit 14 integrates the luminance signal Y _L at that time. A / D conversion of the integrated signal obtained by integration,
The timing of resetting the integrating circuit 14 and adding the integrated data to the memory is the same as in the case of photometry shown in FIG.

FIG. 8 shows the overall operation of the exposure amount detection performed by the CPU 1.

When the horizontal scanning period (see FIG. 5) in the exposure amount detection area (second photometry period) is reached (step 61), the window signal WIND is output to output the first photometry as in the case of the photometry process. The integrating circuit 14 is caused to perform an integrating operation during the same period as the period (step 62). After the same period as the first photometric period has elapsed, the A / D converter 16 is driven to drive the integration circuit.
A / D conversion of 14 integrated signals is performed to obtain integrated data.

Next, the integrated data is added to the value in the integrated data area of the memory (step 63), and if it is still within the exposure amount detection area (step 64), the process returns to step 62.

The above operation is repeated over the entire exposure amount detection region while repeating two horizontal scanning periods as one cycle.
When it goes out of the exposure amount detection area (step 6
4) Then, the exposure value is calculated using the added value of the integrated data obtained up to that point (step 65). This actual exposure amount calculation is also performed according to a preset table or a calculation formula showing the relationship between the integrated addition value (or the average value of the integrated values) and the exposure amount.

Next, the overall operation of the still video camera including the detection of the exposure amount after the main shooting will be described with reference to the flow charts of FIGS. 9 to 12 showing the operation of the CPU 1 and FIG.
It will be explained based on the time chart of.

When the operator sets the slow shutter mode, the flash light emission prohibition mode is set. If the flash discharge prohibit mode is not set (step 71) and the flash charging is not completed yet (step 72), sufficient flash is allowed (step 73). In the flash firing prohibition mode and when the flash charging is completed, the flash charging is prohibited.

It is judged whether or not the signal S1 is generated by pressing the shutter release button in the first step (step 75). When the signal S1 is generated, the distance measurement start signal AF1 is transmitted in response to the signal S1. It is given to 22 and the distance measurement is started (step 76).

Further, the output of the window signal WIND and the horizontal line reset signal HLRST is started, and the above-described photometric processing is started (step 77).

When the distance measurement is completed (step 78), the distance measurement data is read (step 80). During this time, the pressing of the shutter release button is stopped, and when the signal S1 is turned off, the initial state is restored (step 79).

When the photometric value Ev is obtained by the photometric processing,
It is determined whether this photometric value Ev is 9 or more (step 81). If Ev ≧ 9, the subject is bright and the automatic exposure shooting mode is set. When Ev <9, it is determined that the subject is dark and the brightness is low. In this case, it is judged whether or not the strobe prohibit mode is set (step 83).

In the strobe prohibited mode, a camera shake warning is given by a method such as turning on a warning lamp in the finder (step 86), and a slow shutter photographing mode is set (step 87). If the strobe prohibit mode is not set, it is next determined whether or not the strobe charge is completed (step 83).

When the charging of the strobe is not completed yet, the release is locked (step 88) and the operator cannot press the shutter release button any more. When the strobe is fully charged, the strobe shooting mode is set (step 85).

After setting the photographing mode based on the photometric value obtained by the preliminary photographing as described above, if the shutter release button is further pressed and the signal S2 is generated (step 90), the sequence of the main photographing is performed. . If the pressing of the shutter release button is stopped and the signal S1 is stopped (step 89), the state returns to the initial state.

In the main photographing sequence, focus adjustment is first performed on the basis of the distance measurement data previously obtained (step 91). Further, it is judged whether or not the strobe photographing mode is set (step 92).

When the flash photography mode is not set, Tv + Av = Ev (T
v: Effective exposure time of shutter, Av: Aperture value of lens,
The aperture value and the shutter speed are calculated based on the equation (Ev: photometric value) (step 93). The diaphragm 3 is controlled so as to have the calculated diaphragm value (step 94). Strobe charging is prohibited to avoid mixing noise (step 95),
Exposure, that is, photographing is performed under the calculated shutter speed (step 96).

In the flash photography mode, the photometric value Ev
The guide number GN is determined based on F = GN /
The aperture value is determined based on the formula of L (F: aperture value, GN: guide number, L: subject distance) (step 98),
The aperture control signal IR controls the aperture value of the iris 3 to be the determined aperture value (step 99). C
The flash light emission enable signal XonEN is output from the PU1 to the gate circuit 21 to enable the flash light emission (step 100). X given to the gate circuit 21
Timing signal XTM is strobe light emission enable signal X
By passing through the gate circuit 21 by onEN and being given to the strobe device as a strobe light emission command signal Xon, strobe light emission is performed. The output voltage of the EVR17 that defines the strobe light emission time is determined by the guide number GN. During this time, the CCD 4 is exposed (step
101).

In any of the photographing modes, strobe charging is prohibited after the exposure is completed (steps 97 and 102), C
Reading from the CD4 is performed for two field periods, and the exposure amount ev is detected by the method described in the flow chart of FIG. 8 using the video signal read during this period (steps 103 and 10).
Four ). Further, various processes are performed on the read video signal, and the video signal is finally converted into digital image data and recorded.

When the photographing is performed in the automatic exposure photographing mode, the difference ΔEv = ev-Ev between the detected exposure amount ev and the photometric value Ev obtained by the photometry is calculated,
Also, if the shooting was done in strobe shooting mode,
A difference ΔEv = ev−Ev ₀ between the detected exposure amount ev and the exposure amount Ev ₀ (corresponding to the guide number GN and the photometric value ev) set in this strobe photographing mode is calculated. Whether this difference ΔEV is -1 Ev or less, or +1 Ev or more,
It is judged whether or not it is within the range of -1Ev to + 1Ev (step 105).

When ΔEv ≦ -1Ev, the under lamp 233 of the display device 23 for displaying the exposure amount is turned on to display that the exposure is insufficient (step 106). -1 Ev <
When ΔEv <1Ev, orche lamp of display device 23
231 is turned on to display that the exposure amount is appropriate (step 107). When ΔEv ≧ 1Ev, display device
The over lamp 232 of 23 is turned on to indicate that overexposure has occurred (step 108).

The photographer can know whether or not the exposure amount at the time of photographing is appropriate by observing the lighting of the lamp of the display device 23 as described above.

After this, if the recording process of the video signal is completed (step 109), the diaphragm 3 is returned to the original state (step 110), and if the signal S1 is stopped (step 111).
The exposure amount determination display on the display device 23 disappears.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention.
It is a block diagram of an electric composition of a still video camera.

2 is a block diagram showing a more specific electrical configuration of a circuit portion required for photometry in the digital still video camera of FIG.

FIG. 3 is a block diagram showing a specific electrical configuration of a light emission control circuit.

FIG. 4 is a block diagram showing a specific electrical configuration of a strobe power supply circuit.

FIG. 5 shows a photometric area set within a shooting area.

FIG. 6 is a time chart when performing average photometry.

FIG. 7 is a flow chart showing a procedure of photometric processing by a CPU.

FIG. 8 is a flow chart showing a procedure of an exposure amount detection process after photographing by a CPU.

FIG. 9 is a flow chart showing the overall operation of a still video camera by a CPU.

FIG. 10 is a continuation of the flow chart of the flow chart of FIG.

11 is a flowchart following the flowchart of FIG. 10, mainly showing a shooting sequence.

FIG. 12 is a continuation of the flow chart of the flow chart of FIG.

FIG. 13 is a time chart showing the timing of the overall operation of the still video camera.

[Explanation of symbols]

1 CPU 4 CCD 12 Y _L Composite circuit 13 Gate circuit 14 Integrator circuit 15 Amplifier circuit 16 A / D converter 23 Display device 231 Orchestra lamp 232 Over lamp 233 Under lamp 30 Photometric area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigekazu Fukada 3-11-46 Izumisui, Asaka-shi, Saitama Prefecture Fuji Shashin Film Co., Ltd.

Claims (6)

[Claims] 1. A still video camera equipped with an image pickup optical system including a solid-state electronic image pickup device for converting an incident light image into a video signal and outputting the image signal. The stillness of the object is measured, and photographing is performed based on the measured light value. Exposure amount setting means for setting an exposure amount for controlling the exposure amount so that the incident light amount of the exposure amount set by the exposure amount setting means is incident on the solid-state electronic image pickup device, the exposure amount control means A luminance signal extracting unit that extracts a luminance signal component from a video signal output from the solid-state electronic image pickup device by performing photographing with an exposure amount realized by: a luminance signal component extracted by the luminance signal extracting unit; Is obtained by integrating over the photometric region of, and the exposure amount measuring means for measuring the actual exposure amount based on this integration value, and the exposure amount setting means. And setting an exposure amount set Te,
A still video camera comprising: a comparison means for comparing the actual exposure dose measured by the exposure dose measuring means; and a display means for displaying a comparison result by the comparison means. 2. The exposure amount setting means obtains an integral value by integrating the brightness signal component extracted by the brightness signal extracting means over the same area as the photometric area in preliminary shooting prior to shooting, and the integrated value is obtained. The still amount according to claim 1, wherein the exposure amount is set based on the value.
Video camera. 3. The comparing means calculates a difference between the set exposure amount and the measured exposure amount and determines whether or not the difference is within a predetermined range, and the display means compares the comparison amount. When the difference is determined to be within the predetermined range by the means, the proper exposure is displayed, and when it is determined that the measured exposure amount is smaller and the difference is outside the predetermined range, the exposure is insufficient. Display,
The still video camera according to claim 1, wherein an overexposure is displayed when it is determined that the measured exposure amount is larger and the difference is outside the predetermined range. 4. A still video camera equipped with an image pickup optical system including a solid-state electronic image pickup device which converts an incident light image into a video signal and outputs the image signal, by measuring the subject brightness and photographing based on the photometric value. The exposure amount is set to control the exposure amount so that the incident light amount of the set exposure amount is incident on the solid-state electronic image sensor, and the photographing is performed with the exposure amount realized by the exposure amount control. The luminance signal component is extracted from the video signal output from the solid-state electronic image sensor, and the integrated value is obtained by integrating the extracted luminance signal component over a predetermined photometric area. Based on this integral value, the actual exposure amount is calculated. An exposure monitoring method for a still video camera that measures and compares the set exposure amount that has been set with the measured actual exposure amount and displays the comparison result. 5. Preliminary photographing prior to photographing, by extracting a luminance signal component from a video signal output from the solid-state electronic image pickup device, and integrating the extracted luminance signal component over the same region as the photometric region. 5. An integrated value is obtained, and an exposure amount is set based on this integrated value.
An exposure monitoring method for a still video camera described in 1. 6. A difference between the set exposure amount and the measured exposure amount is calculated, and it is determined whether or not the difference is within a predetermined range. When the difference is determined to be within the predetermined range, it is appropriate. Exposure is displayed, and when it is determined that the measured exposure amount is smaller and the difference is outside the predetermined range, an underexposure display is displayed, and the measured exposure amount is larger and the difference is larger than the predetermined range. The exposure monitoring method for a still video camera according to claim 4, wherein an overexposure display is performed when it is determined that the exposure is out of the range.