JPH06339067A - Exposure controller of video camera and method therefor - Google Patents

Abstract

PURPOSE:To perform an exact exposure control by using a turret diaphragm. CONSTITUTION:A preliminary photographing is performed and an object image is formed through the diaphragm aperture 23 of a turret diaphragm 22. Based on the brightness signal components of a video signal outputted from a CCD 4, a photometry is performed for the object brightness. In an EEPROM 20, correction data when the diaphragm value to be used in the preliminary photographing and the diaphragm value to be used in a real photographing are different is stored. From the photometry value of the preliminary photographing, shutter speed and the diaphragm value are determined. When the diaphragm values of the preliminary photographing and the real photographing are different, corresponded correction data is read from the EEPROM 20 and is corrected. Thus, a proper exposure control is performed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exposure control apparatus and method for a video camera represented by an electronic still camera.

[0002]

BACKGROUND ART An electronic still camera is provided with a diaphragm for exposure control. Examples of this diaphragm include a turret diaphragm having a plurality of diaphragm openings corresponding to the diaphragm value and an iris diaphragm having continuously variable openings.

In the case of a turret diaphragm, an area error may occur in the formed diaphragm opening, and the area of the diaphragm opening may differ for each turret plate. Therefore, even if the same aperture value is set and the shutter speed is the same, the exposure amount may be different.

[0004]

DISCLOSURE OF THE INVENTION The present invention, as represented by a turret diaphragm, has a plurality of predetermined apertures of different sizes, and controls the exposure using a diaphragm whose apertures are switchable. The purpose is to perform appropriate exposure control in the camera.

The present invention uses a diaphragm having a plurality of predetermined types of diaphragm apertures of different sizes, and these diaphragm apertures are switchable, and the light incident through the imaging lens and the diaphragm aperture of the diaphragm is used. In a video camera equipped with a solid-state electronic image pickup device for converting an image into a video signal and outputting the image signal, the luminance signal component of the video signal outputted from the solid-state electronic image pickup device is integrated over a photometric region set in the photographing region. Incident light amount measuring means for obtaining an integrated value, and previously storing a photometric value / integral value characteristic representing a relationship between a photometric value and an integral value corresponding to the one or more representative apertures of the plurality of apertures of the aperture. In the characteristic storage means and the pre-shooting, the video signal output from the solid-state electronic image sensor based on the optical image incident through any of the representative apertures is recorded. A photometric means for converting the integrated value obtained from the incident light amount measuring means into a preliminary photometric value by referring to the photometric value / integral value characteristics of the representative aperture stored in the characteristic storage means, and obtained by the photometric means. Exposure determining means for determining a pair of an aperture opening and a shutter speed to be used in the main photographing, based on the obtained preliminary photometric value,
A correction value storage unit that stores in advance a correction value that corrects a photometric value error between the representative aperture used in the preliminary shooting and another aperture opening, and the aperture opening determined by the exposure determination unit are used in the preliminary shooting. If the shutter speed determined by the exposure determining means is used as it is, the corresponding correction value stored in the correction value storage means is used when the shutter speed is different from the one used in the preliminary shooting. It is characterized by comprising shutter speed correction means for adjusting the shutter speed determined by the exposure determination means.

Further, according to the present invention, an aperture having a plurality of different types of aperture openings of predetermined sizes, and these aperture apertures being switchable is used, and the light enters through the imaging lens and the aperture aperture of the aperture. In a video camera equipped with a solid-state electronic image pickup device for converting an optical image into a video signal and outputting the video signal, a photometric value and an integral value corresponding to the photometric value for one or a plurality of representative apertures of the apertures A photometric value / integral value characteristic indicating the relationship and a correction value for correcting a photometric value error between the representative aperture used in the preliminary shooting and another diaphragm aperture are stored in advance, and one of the representative apertures is used in the preliminary shooting. The luminance signal component of the video signal output from the solid-state electronic image sensor based on the light image incident through the light is integrated over the photometric area set in the shooting area. The minute value is obtained, and the obtained integrated value is converted into a preliminary photometric value with reference to the previously stored photometric value / integral value characteristic for the representative aperture, and based on the obtained preliminary photometric value, The pair of aperture opening and shutter speed to be used in the main shooting was determined, and when the determined aperture opening was the one used in the preliminary shooting, the determined shutter speed was directly adopted and used in the preliminary shooting. When it is different from the above, the shutter speed determined by using the corresponding correction value stored in advance is adjusted.

In the above, the photometric value / integral value characteristic may be stored for all aperture openings formed in the aperture. The correction value stored in advance may be one that corrects a measurement value error between the representative aperture and another diaphragm aperture, or one that corrects a measurement value error between the representative apertures.

According to the present invention, at the time of photographing, the preliminary photographing is first performed, and the preliminary photometric value is obtained by referring to the prestored photometric value / integral value characteristic. A pair of a diaphragm aperture and a shutter aperture in the main photographing is determined from the preliminary photometric value. When the determined aperture opening is the one used in the preliminary shooting, the determined shutter speed is adopted as it is, and when it is different from that used in the preliminary shooting, it is determined using the stored correction value. The shutter speed is adjusted.

The photometric / integral value characteristics are stored in advance for one or a plurality of representative apertures according to each video camera. Therefore, the pair of aperture opening and shutter speed determined from the preliminary photometry value obtained in preliminary photometry is
The error of the diaphragm aperture is taken into consideration. Therefore, at the time of actual photographing, when a subject is photographed using the aperture opening used for preliminary photometry, an error is taken into consideration in the aperture opening, so accurate exposure is performed. However, when the aperture opening determined for the main shooting and the aperture opening used for the preliminary shooting are different, the effect of lens aberrations varies depending on the size of the aperture opening, so accurate exposure cannot be performed. There is.

According to the present invention, the correction for correcting the measurement value error (aperture area error, caused by lens aberration) between the representative aperture used in the preliminary photographing and the other diaphragm apertures (including the representative aperture) The value is stored in advance, and when the diaphragm opening used in the preliminary shooting is different from the diaphragm opening used in the main shooting, the shutter speed is corrected by the corresponding correction value. Therefore, almost accurate exposure is always performed.

By photographing the reference light source and the like in the adjustment process of the video camera, the photometric value / integral value characteristic is created. In the present invention, since the photometric value / integral value characteristic is created for the representative aperture, it is possible to reduce the labor for creating the photometric value / integral value characteristic for all aperture openings. Further, the memory capacity for storing the photometric / integral value characteristics can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to 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.

A clock signal generation circuit (hereinafter referred to as CG) 1 includes a clock signal CLK, a horizontal transfer pulse H for driving the horizontal transfer path of the CCD 4, a substrate extraction pulse SUB for sweeping unnecessary charges, and an A field vertical transfer. A pulse VA and a B field vertical transfer pulse VB are generated. Further, CG1 generates a field index signal FI and an X timing signal XTM for strobe emission.

The clock signal CLK is given to a synchronizing signal generating circuit (hereinafter referred to as SSG) 2, and the SSG2 generates a horizontal synchronizing signal HD and a vertical synchronizing signal VD based on this clock signal CLK and gives it to CG1.

The horizontal transfer pulse H is given to the CCD (solid-state electronic image pickup device) 4, and the substrate extraction pulse SUB and the A field vertical transfer pulse VA are passed through the V driver 5.
The B field vertical transfer pulse VB is applied to the CCD 4 via the V driver 6.

The field index signal FI, the X timing signal XTM and the horizontal synchronizing signal HD are the CPU
Given to 3. A shutter enable signal TS indicating that the exposure condition has been set from the CPU 3 to the CG 1.
An electronic shutter control signal TS1 for starting exposure in EN and CCD 4 is applied.

The digital still camera is provided with a turret diaphragm 22 having a plurality of diaphragm openings 23 having different aperture areas. As will be described later, the subject brightness is obtained and the motor 21 is controlled according to the subject brightness. The rotation of the turret diaphragm 22 is controlled by the motor 21, and the diaphragm aperture 23 having a diaphragm value determined by the subject brightness and the shutter speed is selected.

As will be described later, the digital still camera shown in FIG.
Luminance signal components are integrated from a video signal obtained by forming an image on the CCD 4 through a predetermined area within the photographing area, and the photometric value is calculated based on the integrated value / photometric value characteristic shown in FIG. The aperture value and the shutter speed are calculated based on the calculated photometric value, and the actual shooting is performed. The integrated value / photometric value characteristic is created for the representative diaphragm apertures of the diaphragm values F3.5 and F14 and is stored in the EEPROM 20. A method of creating the integrated value / photometric value characteristic will be described later.

Since the integrated value / photometric value characteristic is created in consideration of the lens aberration and the aperture error, when the aperture value used in the preliminary shooting and the aperture value used in the main shooting are the same, Although almost accurate exposure is performed, when the aperture value used in the preliminary shooting and the aperture value used in the main shooting are different, the effect of lens aberrations will differ depending on the size of the aperture opening, so accurate Exposure may not be performed. For this reason, in this digital still camera, when the aperture value of the preliminary shooting is different from the aperture value of the main shooting, the shutter speed of the aperture value and the shutter speed determined by the photometric value of the preliminary shooting is corrected. This correction data is also EEPRO
It is stored in M20.

In addition to the correction data, the EEPROM 20 stores data for determining the amount of extension of the image pickup lens 24, strobe light emission amount data, color balance adjustment data, and the like.

The subject image is formed on the CCD 4 by the imaging lens 24 through the diaphragm aperture 23 of the turret diaphragm 22.

In the CCD 4, the substrate extraction pulses SUB, A
By the field vertical transfer pulse VA, the B field vertical transfer pulse VB, and the horizontal transfer pulse H, interlaced shooting is performed, and video signals of the A field and the B field (color sequential signals of GRGB) are alternately generated every one field period. Are sequentially read. The driving of the CCD 4 (imaging and reading of a video signal) is performed at least at the time of photographing and in the photometric processing prior thereto.

The video signals of the A field and the B field output from the CCD 4 are given to a color separation circuit 8 through a correlated double sampling circuit (CDS) 7, and 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) 9 and then gradation correction is performed by a gamma correction circuit 10 to perform clamping and resetting. Input to the sampling circuit 11.

The clamp and resampling circuit 11 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 blanking circuit 12. The gain control and blanking circuit 12 amplifies the color sequential signal to an appropriate level for recording and adds the blanking signal to it. The output signal of the circuit 12 is subsequently converted into digital image data by the A / D converter 13.

As will be described later in detail, prior to photographing, photometric processing and exposure control (control of iris and shutter speed) based on the photometric value are performed. This photometric processing is GCA9.
Based on the output signal of Shooting is performed after such photometric processing and exposure control. Then, the video signal obtained from the CCD 4 by photographing is the above-mentioned circuit 10, 1
It becomes digital image data through 1, 12 and 13 and is processed by Y / C separation, data compression, etc. by an image data processing circuit (not shown) and then recorded on a recording medium such as a memory card. Become.

The digital still camera is capable of macro shooting, tele shooting and wide shooting, and includes a macro shooting setting switch 28 for setting macro shooting, a tele shooting setting switch 29A, and a wide shooting setting switch 29B. ing. The digital still camera can also be equipped with a wide converter and a macro adapter. Further, the digital still camera is also capable of stroboscopic photography, and a stroboscopic light emitting device 27 is included for this purpose.

The digital still camera includes a photometric sensor 25 and a distance measuring sensor 26, respectively. Aperture value is determined by the photometric sensor 25 so that almost proper exposure is performed, and then detailed preliminary photometry is performed. The distance to the object is measured by the distance measuring sensor and focusing control is performed.

A Y _L combining circuit 14, a gate circuit 15, an integrating circuit 16 and an amplifying circuit 17 are provided for photometric processing. An example of a specific electrical configuration of these circuits is shown in FIG. The CPU 3 outputs a window signal WIND that controls the gate circuit 15 and a reset signal HLRST that resets the integration circuit 16. These signals WIND
The timing of HLRST will be described later. Further, in this embodiment, the CPU 3 has an A / D converter 18 built-in.

The color signals R, G and B output from the gain control circuit 9 are added by the Y _L synthesizing circuit 14,
A relatively low frequency luminance signal Y _L (hereinafter simply referred to as luminance signal Y _L
Is generated). The luminance signal Y _L passes through the gate circuit 15 while the window signal WIND is being applied in the required horizontal scanning period. The integrating circuit 16 is reset when the reset signal HLRST is given,
After that, the luminance signal Y _L input from the gate circuit 15 is integrated. The integrated signal of the integrating circuit 16 is amplified by the amplifying circuit 17, and immediately before the integrating circuit 16 is reset, the A /
Converted to digital integral data by D converter 18,
It is taken in by the CPU 3. The reference voltage divisions V1 and V2 of the integrating circuit 16 and the amplifying circuit 17 give an appropriate offset thereto.

In this embodiment, average photometry (hereinafter referred to as AV photometry) for measuring the average brightness of almost the entire field of view, and average brightness of the upper part of about 1/3 of the field of view are measured. Average upper metering (hereinafter referred to as AV upper metering), average lower metering (hereinafter referred to as AV lower metering) that measures the average brightness of the lower part of the field of view, and brightness of the main subject in the field of view The spot photometry (hereinafter, referred to as SP photometry) for measuring is performed.

The SP photometry is effective when the brightness of the main subject in the field of view and the brightness of the background are different and it is necessary to set an appropriate exposure condition according to the brightness. Further, in the case of outdoor photography, the sky is often captured in the upper area within the field of view. Therefore A
When V photometry is performed and the exposure condition is determined accordingly and the image is taken, the lower region in the visual field may become dark. In such a case, AV lower photometry is effective.

When the macro position is set by the macro setting button 23 or when the macro adapter is attached to the camera and the main subject is photographed with a dark central part, if automatic exposure is performed, the spot metering value and the average value are obtained. Depending on the brightness difference from the photometric value, exposure control based on spot photometry or daytime synchro photography may be performed and a broken image may be captured.

Further, when the main subject is bright and the background is dark, the brightness level of the entire photographic area becomes low. Therefore, when the exposure control is performed by the AV photometry value based on the entire photographic area, the main subject image obtained by the photography is overexposed. Or the background becomes dark. Further, if the exposure control is performed by the SP photometric value of the area in the center of the shooting area, the background becomes dark. In any case, the proper image cannot be taken. Therefore, in this digital electronic still camera, as will be described later, it is possible to obtain an A based on the AV lower area of the lower 2/3 of the shooting area including the SP area.
The exposure is controlled using the V lower photometric value. The influence of the brightness value of the main subject and the influence of the background can be reduced, and relatively appropriate exposure control can be performed.

Since it is considered that the A field image and the B field image which form one frame represent the field images at substantially the same time, in this embodiment, the video signal of the A field is AV upper photometry, AV lower photometry and AV lower photometry. For AV photometry, the B field video signal is used for SP photometry, respectively. The AV upper photometry is performed in almost the first half of the A field, and the AV lower photometry is performed in the latter half of the A field. AV metering value is A
It is obtained from the sum of the integrated value for V upper photometry and the integrated value for AV lower photometry.

Further, in this embodiment, the integration by the integration circuit 16 and the A / D conversion operation and addition processing by the A / D converter 18 are alternately performed every horizontal scanning period.

FIG. 3 shows an AV upper photometry area, an AV lower photometry area, an AV photometry area, and an SP photometry area, which are set in the photographing area 25 of the CCD 4.

The AV upper photometry area is almost 1 / th of the photographing area.
Set over the top of 3. In this embodiment, the AV upper photometry area is 40 in the horizontal direction after 16.15 μs has elapsed from the fall of the horizontal synchronizing signal HD (at the start of the horizontal scanning period).
It is set in the period of μs and is set in the vertical direction from the 35th horizontal scan line to the 100th horizontal scan line.

The AV lower photometry area is approximately 2 / of the photographing area.
3 over the lower region. In this embodiment, A
The V lower photometry area is set for a period of 40 μs after 16.15 μs has elapsed from the falling edge of the horizontal synchronizing signal HD (at the start of the horizontal scanning period) in the horizontal direction, and the vertical direction is from the 101st horizontal scanning line. It is set up to the 246th horizontal scan line.

The AV metering area is a combination of the AV upper metering area and the AV lower metering area.
It is set over almost all 25 areas. In this embodiment, A
In the V photometry area, after the lapse of 16.15 μs from the falling edge of the horizontal synchronizing signal HD (at the start of the horizontal scanning period) in the horizontal direction,
The period is μs, and the vertical direction is from the 35th horizontal scanning line to the 246th horizontal scanning line.

The SP photometric area is set as a small area at an arbitrary position within the photographing area 25. In this embodiment, the SP metering area is set at the center of the photographing area 25, and the horizontal direction is 14 μs after 29.15 μs has elapsed from the fall of the horizontal synchronizing signal HD.
In the vertical direction from the 101st horizontal scan line to the
It is set up to the 208th horizontal scan line.

Both the AV upper photometry and the AV lower photometry are performed in the A field period, and only the setting lines of the horizontal scanning lines in the vertical direction are different. Because of this
In both of the V upper photometry and the AV lower photometry, FIG.
As shown in FIG. 5, a window signal WIND having a pulse width of 40 μs is applied to the gate circuit 15 16.15 μs after the trailing edge of the 35th horizontal synchronizing signal HD. While the window signal WIND is given, the gate circuit 15 allows the input luminance signal Y _L to pass through, and the luminance signal Y _L is input to the integrating circuit 16.

The integrating circuit 16 has already been reset in the preceding field and integrates the luminance signal Y _L which has passed through the gate circuit 15 and is input. Window signal WIND
Becomes L level and the input of the luminance signal Y _{L to} the integrating circuit 16 is stopped, the integrated output of the integrating circuit 16 is held as it is and the integrated output of the integrating circuit 16 is A / D converted in the CPU 3. It is converted into digital data by the device 18. In this embodiment, the time required for A / D conversion is
15 μs. After that, the integrating circuit 16 is reset by the horizontal line reset signal HLRST given from the CPU 30 to prepare for the next integrating operation.

A memory attached to the CPU 30 (for example, RA
M) has an AV upper integrated data storage area for storing data obtained by AV upper photometry and an AV lower integrated data storage area for storing data obtained by AV lower photometry.

The AV upper integrated data storage area is cleared in synchronization with the 34th horizontal synchronizing signal HD. A / D
The integrated value converted into digital data by the converter 18 is added to the previous data (which is cleared in the first case and is zero) and stored in this AV upper integrated data storage area.

The A / D conversion by the A / D converter 18, the reset of the integrating circuit 16 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 16 on one horizontal scanning line in the AV upper photometry area, and A / D conversion and integration of the integrated signal obtained by this integration The resetting of the circuit 16 and the addition of the integrated data to the memory are alternately repeated every horizontal scanning period. Then, this repetition is performed until the 100th horizontal scanning period.

Thus, the AV photometric value is obtained from the data stored in the AV upper integrated data storage area and the data stored in the AV lower integrated data storage area.

In SP photometry in the B field period, as shown in FIG. 5, a window signal WIND having a pulse width of 14 μs is given to the gate circuit 15 29.15 μs after the falling edge of the 87th horizontal synchronizing signal HD. During this period, the integrating circuit 16 integrates the input luminance signal Y _L.
The window signal WIND is the 193rd signal every other horizontal scanning period.
It is performed until the second horizontal scanning period. A / D conversion of the integration signal output from the integration circuit 16 into integration data, integration circuit
The 16 resets and the addition of the integration data in the memory are performed in the next horizontal scanning period after the integration operation, as in the case of the AV photometry described above.

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 if a D converter is used, it can be sufficiently dealt with. Then, even if the integration is performed every other horizontal scanning line, even SP photometry can be performed on 54 horizontal scanning lines so that a sufficient amount of integration data can be obtained to obtain a photometric value. .

In the above description, AV upper part, AV lower part and AV metering are performed in the A field period, and SP metering is performed in the B field period. Conversely, SP metering is performed in the A field period and AV upper part in the B field period. , AV lower part and AV metering may be performed, or needless to say, only AV metering (AV upper part, AV lower part metering) or SP metering may be carried out in both fields or one field. .

FIG. 6 shows the overall operation of the photometric processing performed by the CPU 3. This photometric processing is performed using the video signal obtained by preliminary shooting.

The CPU 3 initializes the exposure condition when starting the photometric processing, and controls at least one of the turret diaphragm 22 and the electronic shutter so that the initial exposure condition is realized. As the initial exposure condition, the most statistically possible exposure condition, for example, the exposure amount E
v10.52 (aperture F3.5, shutter speed 1/120 sec) is preferable. If it is determined by photometry that this exposure condition is not appropriate, the exposure condition is changed and the photometric process is performed again.

In both AV photometry and SP photometry,
When the horizontal scanning period within the photometric region is reached (step 31), the window signal WIND is output as described above, and the integrating circuit 16 is caused to perform the integrating operation during the first photometric period (step 32). After the first photometric period has elapsed, the A / D converter 18 is driven to perform A / D conversion of the integrated signal of the integrating circuit 16 to obtain integrated data.

The obtained integral data is added to the value in the integral data area of the memory (step 33), and if it is still within the photometric area (step 34), the process returns to step 32.

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 34), the photometric value (subject brightness) is obtained based on the added value (integrated value) of the integrated data obtained up to that point (step 35).

The relationship between the added value and the photometric value is predetermined for each exposure condition. FIG. 7 shows an example of the added value / photometric value standard characteristic. For example, the exposure condition is EV10.5
If the obtained addition value is M ₀ when it is 2, the photometric value is calculated as A ₀ from the graph of EV 10.52. Such addition value / photometric value conversion is performed using a table or according to an arithmetic expression.

The CPU 3 determines the exposure conditions such as the aperture, the shutter speed, and the presence / absence of stroboscopic light emission based on the result of this calculation (photometric value).

The added value / photometric value characteristic shown in FIG. 7 is obtained by actually photographing the reference light source. The added value / photometric value characteristic is composed of four graphs L1 to L4 in this digital still camera.

The reference light source was changed from 5.52 EV to 9.52 EV with an aperture value of F3.5 and a shutter speed of 1/15 sec.
A graph L1 is obtained from the relationship between the added value and the brightness value obtained at that time. Similarly, with the aperture value F3.5 and the shutter speed 1/120 sec, the reference light source is 8.52 EV to 12.52 EV.
Then, the graph L2 is obtained, and the reference light source is 11.52 EV to 15.5 with an aperture value of F14 and a shutter speed of 1/60 seconds.
2 Change to EV and take a picture to obtain graph L3. Aperture value F
14, with a shutter speed of 1/240 second and a reference light source of 13.52 E
The graph is changed from V to 17.52 EV and photographed to obtain a graph L4.
The added value / photometric value characteristic thus obtained is EEPR
Stored in OM20.

In this way, the added value / photometric value characteristic is F3.5.
And F14 are used as the aperture value of the representative aperture. Therefore, when the aperture value used in preliminary photometry is the same as the aperture value used in actual shooting, the aperture value and shutter speed determined from the photometric value calculated based on the added value / photometric value characteristic. However, if the aperture value used in the preliminary photometry and the aperture value used in the actual shooting are different, the aperture value and shutter speed determined from the calculated photometric value will be determined. The exposure amount determined by the above includes an error. For example, if the added value obtained in the preliminary photometry is M with reference to FIG. 7, the photometric value is 10.52 EV from the graph L2. It is assumed that the aperture value F5.6 and the shutter speed 1/45 seconds are determined from the photometric value 10.52 EV. When the same subject having a brightness value of 10.52 EV at the determined aperture value F5.6 and a shutter speed of 1/45 seconds is photographed, the added value may be M _{0 and the} photometric value may be A ₀ .

Therefore, in this digital still camera, when the aperture value used in the preliminary photometry is different from the aperture value used in the main photographing, the correction is performed. For example, in the above example, 12.52 EV
-A ₀ EV is the amount to be corrected.

A table showing this correction amount is shown in FIG.

Representative aperture F3 used in preliminary photography.
When 5 or F14 and the aperture opening used in the actual shooting have the same aperture value, the correction is not performed, and when they are different, the correction is performed. This correction is performed by adjusting the shutter speed.

For example, in the preliminary shooting, an aperture opening having an aperture value of F3.5 is used, and in the main shooting, F5.6,
When an aperture aperture having an aperture value of F8, F11 or F14 is used, the brightness is corrected by an amount of ΔD ₁₂ , ΔD ₁₃ , ΔD ₁₄ or ΔD ₁₅ , and the aperture aperture having an aperture value of F14 is obtained in the preliminary shooting. Is used, and F3.5 is used in the actual shooting.
, F5.6, F8 or F11, when a diaphragm aperture having a diaphragm value of ΔD ₂₁ , ΔD ₂₂ , ΔD ₂₃ or ΔD is used.
A brightness correction of ₂₄ amounts is performed.

These correction amounts are obtained by using a reference light source having the same brightness,
It can be obtained by changing the aperture value and actually photographing at a shutter speed such that the same exposure amount is obtained. These correction amounts are generally about 0.1 EV to 0.4 EV,
The specific correction amount is different for each camera.

The shutter speed is corrected so that these correction amounts are corrected, and the actual photographing is performed. The correction of the shutter speed is performed as follows in the following AE shooting mode.

When the brightness value is EV, the aperture value is F, and the shutter speed is T (T ₀ , T ₁ ), the following equation holds.

[0070]

## EQU1 ## 2 ^EV = F / T ₀ ... Equation 1

Therefore, if the corrected brightness amount is ΔD, the aperture value F does not change, and therefore the following equation holds.

[0072]

2 ^{(EV + ΔD)} = F / T ₁ Equation 2

T ₁ obtained from the equation 2 is the corrected shutter speed, and the shutter speed is adjusted so as to be the corrected shutter speed, and the actual photographing is performed. The shutter speed is similarly corrected in other shooting modes.

9 to 12 show program diagrams for determining the shutter speed and the aperture value from the photometric values obtained in the preliminary photometry.

FIG. 9 is a program diagram of the AE shooting mode. (A) is used when tele shooting, wide shooting or a wide converter is attached, (B) is used when macro shooting, C) is used when the macro adapter is installed.

FIG. 10 is a program diagram for daytime sync mode photography, in which (A) is used for wide photography and (B) is used for tele photography.

11 and 12 are program diagrams of the low-intensity flash photography mode. FIG. 11 (A) shows wide photography,
Figure 11 (B) is macro photography, Figure 12 (A) is tele photography, and Figure 12 (B).
Is used when the macro converter is installed.

The program diagram to be used is determined depending on the type of photographing.

In the program diagram shown in FIG. 9, the shutter speed and the aperture value are determined from the photometric values obtained by the preliminary photographing. In the program diagrams shown in FIGS. 10, 11, and 12, the shutter speed is determined from the distance to the subject and the photometric value obtained by preliminary shooting, and the aperture value is determined by the distance to the subject.

FIG. 13 is a flow chart showing a procedure for determining a photometric value used for exposure control of the digital electronic still camera.

By pressing the shutter release button in the first step, the Y _L synthesizing circuit 14, the gate circuit 15, the integrating circuit
16, photometry processing is performed using the amplifier circuit 17, etc., and the AV photometry value, the AV upper photometry value, the AV lower photometry value, and the SP photometry value are obtained and stored in respective areas of the memory attached to the CPU 30. Further, the distance to the subject is calculated based on the distance measurement data provided from the distance measurement sensor 22.

Further, whether or not a wide converter or a macro adapter is mounted on the digital electronic still camera based on the macro setting button, tele, wide setting button 29A, 29B, etc., whether macro setting, tele, wide setting is made. Is determined.

When the wide converter is mounted (YES in step 41), the shooting angle of view is larger than the strobe irradiation angle, and the strobe light is emitted only to a part of the photographing area, so that the strobe light is emitted. No (steps 43-49).

When the wide converter is not attached to the camera 10 (NO in step 41), the state of the strobe mode is checked. If the strobe mode is off, the strobe will not fire, and the AV lower metering value or A
Exposure control is performed based on the V photometry value (step
43-49). When the strobe mode is set to the forced light emission mode, the forced light emission mode is set (step 42), and the light emission amount is determined according to the distance to the subject, and the exposure control is performed based on the light emission amount. In the forced flash mode, the aperture value is set manually, and the shutter speed is set to 1/30 second for tele shooting and 1/60 second for wide shooting. If the strobe mode is set to auto, it is determined whether the macro setting, the tele setting, the wide setting, or the mounting of the macro adapter (step 43).

When the wide shooting is set by the wide setting button 29B, it is determined whether the AV photometric value is 8.6 EV or less (step 44). When the AV photometric value is 8.6 EV or less (YES in step 44), the exposure is controlled based on the AV photometric value (step 220) because it is not affected by the backlight and does not need to be considered. The mode is set (step 61) and the flash fires.
At this time, the aperture value and the shutter speed are determined based on FIG. 11 or 12. When the AV metering value is 8.6 EV or more, there is a possibility of backlighting, and when the exposure control based on the AV metering value is performed, the main subject may become dark, so either the AV metering value or the SP metering value is set. Based on this, it is decided whether or not to perform the exposure control. For this determination, the SP photometric value is subtracted from the AV photometric value to calculate the photometric value difference ΔEV (ΔEV = AV-SP) (step 48).

If the difference ΔEV in photometric value is 1 or more, it is determined whether the distance to the main subject is less than 3 m (step 49). If the difference ΔEV in the photometric value is 1 or more, it is determined that the main subject is backlit, and if the distance to the main subject is 3 m or less, even if the exposure control is performed by the AV photometric value, the backlight is appropriate. Since shooting is not performed, daytime synchronized shooting is performed (steps 50 and 51). At this time, the aperture value and the shutter speed are determined based on FIG. As a result, the brightness of the main subject and the background is reduced, and relatively appropriate shooting is performed even with backlight. If the distance to the subject is 3 m or more, the strobe light does not reach, so the exposure control is performed based on the AV photometry value or the AV lower photometry value, and the strobe light is not emitted (step 53).
~ 59).

Even when tele shooting is set by the tele setting switch 29A, the magnitude of the AV photometric value is judged and the AV
When the photometric value is 9.6 EV or less, the low-luminance emission mode is set (YES in step 45, steps 60 and 61). AV photometric value
If it is larger than 9.6 EV, the exposure control is set according to the difference ΔEV in the photometric value.

When the difference ΔEV in the photometric value is 0.5 ≦ ΔEV ≦ 1, the brightness of the main subject has a great influence on the entire photographing area, and therefore the exposure control is performed based on the SP photometric value (step 52). ).

When the difference ΔEV in photometric value is less than 0.5, the main subject may be brighter than the background, and therefore the AV photometric value is subtracted from the SP photometric value to calculate the difference (step 53). If the difference is 0.5 EV or more, the AV photometric value and the AV lower photometric value are compared, and if the AV photometric value is larger than the AV lower photometric value, the exposure control is performed based on the AV lower photometric value (step 55). ). Since the AV lower area includes the SP area, the AV lower photometric value is affected by the SP photometric value but is less affected by the background, so that relatively appropriate exposure control is performed. The AE program mode is entered (step 58). At this time, the aperture value and the shutter speed are determined based on FIG.

The difference obtained by subtracting the AV photometric value from the SP photometric value is
If 0.5 EV or less or the AV photometric value is larger than the AV lower photometric value, the exposure control is performed based on the AV photometric value (step 59).

When the macro position is set by the macro setting button 28, it is judged whether the AV photometric value is 12.0 EV or more (step 46). AV photometric value is 12.0
When it is equal to or less than EV, exposure control is performed based on the AV photometry value (step 60), and strobe light is emitted (step 61). If the AV photometric value is larger than 12.0 EV, the flash is not emitted and the exposure is controlled based on the AV photometric value (step 59).

When the macro adapter is attached to the camera, the magnitude of the AV photometric value is determined (step 47). When the AV photometric value is 13.0 EV or less, the exposure is controlled based on the AV photometric value and the stroboscopic flash photography is performed. Done (step 6
0, 61). AV If the metering value is greater than 13.0EV, AV
The exposure is controlled based on the photometric value, and the picture is taken without flash firing (steps 58 and 59).

AV is set when the macro position is set or when the macro adapter is attached to the camera.
Exposure control is performed based on the photometric value. Therefore, even if a main subject whose center is dark is photographed, daytime synchronization photography and correction based on the SP photometric value are not performed, and a relatively proper photographed image can be obtained.

FIG. 14 is a flow chart showing a processing procedure until a subject is photographed by using the digital still camera shown in FIG.

This flowchart is applied during daytime synchronization mode photography (step 51 in FIG. 13) or AE program mode photography (step 58 in FIG. 13). In the low-luminance light emission mode or the forced light emission mode, the strobe light is dominant in determining the exposure amount, and therefore the shutter speed correction is not performed.

The distance measuring sensor 26 measures the distance to the subject (step 70), and preliminary photometry is performed as described above (step 71). A photometric value is calculated from the added value obtained by the preliminary photometry based on the added value / photometric value standard characteristic (step 72).

From the calculated photometric value, the aperture value and shutter speed are calculated based on one of the program diagrams shown in FIGS. 9 to 12 (step 73). It is determined whether the calculated aperture value is different from the aperture value of the aperture used in the preliminary photometry (step 71) (step 74).

When the aperture value calculated in step 73 is the same as the aperture value of the aperture used in the preliminary photometry (NO in step 74), the exposure amount is appropriate corresponding to the brightness of the subject, and thus it is calculated. The actual shooting of the subject is performed by the aperture of the aperture value and the shutter speed (step 7).
7, 78).

When the aperture value calculated in step 73 is different from the aperture value of the aperture used in the preliminary photometry (YES in step 74), the aperture value used in the preliminary photometry is changed as shown in FIG. The correction data stored in the EEPROM 20 is searched according to the aperture value and the calculated aperture value (step 75). The shutter speed is corrected so that the retrieved correction data amount is obtained, and the main photographing of the subject is performed (steps 76 to 78).

Although the turret diaphragm is used as the diaphragm in the above-mentioned embodiments, the diaphragm is not limited to the turret diaphragm, and it has a plurality of predetermined apertures of different sizes, and these apertures are switchable. The present invention can be applied to any aperture.

[Brief description of drawings]

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

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

FIG. 3 shows a photometric area set within a shooting area.

FIG. 4 is a time chart when performing average photometry.

FIG. 5 is a time chart when spot photometry is performed.

FIG. 6 is a flowchart showing a procedure for obtaining an added value by a CPU.

FIG. 7 is a graph showing integrated value / photometric value conversion.

FIG. 8 shows a table in the case of performing correction at the time of actual shooting.

9A to 9C show program diagrams in the AE photographing mode.

10A and 10B show program diagrams of daytime synchronization mode photography.

11A and 11B show program diagrams of a low-luminance light emission mode.

12A and 12B show program diagrams of a low-luminance light emission mode.

FIG. 13 is a flowchart showing a procedure for determining a photometric value used for exposure control.

FIG. 14 is a flowchart showing a processing procedure of a CPU until a subject is photographed.

[Explanation of symbols]

3 CPU 4 CCD 14 Y _L synthesis circuit 15 gate circuit 16 integration circuit 17 amplification circuit 20 EEPROM 22 turret diaphragm 23 diaphragm opening

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

Claims (2)

[Claims] 1. A diaphragm having a plurality of predetermined different kinds of diaphragm apertures, and these diaphragm apertures are switchable, and an optical image incident through the imaging lens and the diaphragm aperture of the diaphragm is used. In a video camera equipped with a solid-state electronic image sensor for converting to a video signal for output, the luminance signal component of the video signal output from the solid-state electronic image sensor is integrated and integrated over a photometric area set within the shooting area. Incident light amount measuring means for obtaining a value, characteristics for pre-storing a photometric value / integral value characteristic representing a relationship between a photometric value and an integral value corresponding to one or a plurality of representative apertures of the plurality of apertures of the aperture In the storage means and in the preliminary photographing, the incident light of the video signal output from the solid-state electronic image sensor based on the optical image incident through any one of the representative apertures. The integrated value obtained from the quantity measuring means is
Photometric means for converting into a preliminary photometric value by referring to the photometric value / integral value characteristics of the representative aperture stored in the characteristic storage means, and in the main photographing based on the preliminary photometric value obtained by the photometric means. Exposure determining means for determining a pair of diaphragm aperture and shutter speed to be used, correction value storage means for storing in advance a compensation value for compensating a photometric value error between the representative aperture used in preliminary photography and another diaphragm aperture. , And when the aperture opening determined by the exposure determining means is used in the preliminary shooting, the shutter speed determined by the exposure determining means is used as it is, and is different from that used in the preliminary shooting. Sometimes, the shutter speed determined by the exposure determining means is calculated using the corresponding correction value stored in the correction value storage means. Shutter speed correction means for adjusting the speed, exposure control apparatus for a video camera with a. 2. An optical image incident through the imaging lens and the diaphragm aperture of the diaphragm is used by using a diaphragm having a plurality of predetermined types of diaphragm apertures of different sizes, and these diaphragm apertures are switchable. In a video camera equipped with a solid-state electronic image pickup device for converting into a video signal and outputting the video signal, the relationship between a photometric value and an integral value corresponding to one or a plurality of representative apertures of the apertures is expressed. The photometric value / integral value characteristic and the correction value for correcting the photometric value error between the representative aperture used in the preliminary shooting and the other apertures are stored in advance, and are passed through one of the representative apertures in the preliminary shooting. Based on the incident light image, the luminance signal component of the video signal output from the solid-state electronic image sensor is integrated over the photometric area set in the shooting area to obtain the integrated value. The integrated value thus obtained should be converted into a preliminary photometric value by referring to the previously stored photometric value / integral value characteristic for the representative aperture, and based on the obtained preliminary photometric value, it should be used in actual photography. A pair of the aperture opening and the shutter speed is determined, and when the determined aperture opening is used in the preliminary shooting, the shutter speed determined is adopted as it is, and it is different from that used in the preliminary shooting. An exposure control method for a video camera, which adjusts a shutter speed determined by using the corresponding correction value stored in advance.