JPH10319471A - Imaging device, imaging method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To take a photograph at a proper controlled light level, in accordance with the reflectance of an object, the occupancy ratio of a photometry area, etc., by applying prescribed weight coefficients different in each of plural photometry blocks and comparing the result of the first photometry with a reference value, so as to change each weight coefficient with the result of the comparison and calculate the brightness of the second light emission. SOLUTION: A stroboscopic light emitting part 15 attains the first light emission and the second light emission for irradiating an object. Plural photometry areas are divided into the plural photometry blocks smaller in number than the plural photometry areas. The prescribed weighting coefficients different in each of the plural photometry blocks are applied and the result of photometry in the first light emission in the plural photometry blocks is compared with the reference value. A total control arithmetic part 9 changes the respective weight coefficients of the plural photometry blocks into coefficients different from the prescribed weight coefficients, with the result of the comparison, to calculate the brightness of the second light emission. Then, the brightness of the second light emission is controlled with the result of the calculation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus for converting an optical image into an electric signal by an image pickup means using a solid-state image pickup device, and more particularly to an image pickup apparatus for performing preliminary light emission for exposure control, an image pickup method, and a storage medium. It is.

[0002]

2. Description of the Related Art Conventionally, an image pickup apparatus having a solid-state image pickup device performs preliminary light emission in advance to measure an exposure condition of a subject before actual exposure for actual photographing. There is known a method of obtaining main light emission conditions and performing main light emission. In this conventional method, there is only one photometry area and the size is about the angle of view, and the light measurement level (main light emission level) is determined by averaging the photometry results in this area. Also, even if there are multiple photometric areas,
This is a system in which one area having the maximum average value is selected from a plurality of areas, and dimming is performed using the photometric result.

[0003]

However, in the case where there is one large photometric area having a shooting angle of view, the average result is largely influenced by the reflectance and brightness of the subject and the proportion of the subject in the photometric area. Sometimes the shooting results did not reach the proper regulation level. Further, even when one area having the maximum average value is selected from a plurality of areas and light control is performed using the photometric result, if there is an object having a reflectance higher than that of the main subject, the reflection may be reduced. There were scenes that were not good enough, such as the shooting result being under, because light was emitted according to the high rate.

The present invention has been made under such circumstances, and an image pickup apparatus, an image pickup method, and a storage medium capable of taking an image at an appropriate dimming level in accordance with the reflectance of an object, the ratio of the object to the photometric area, and the like. The purpose is to provide.

[0005]

In order to achieve the above-mentioned object, according to the present invention, an image-capturing apparatus is provided as follows (1) to (6), and an image-capturing method is provided as follows (7). The configuration is as shown in the following (8).

(1) Imaging means for capturing an optical image of a subject from a solid-state image sensor, light emitting means for performing first and second light emission for irradiating the subject, and a signal transmitted from the imaging means. In the image pickup apparatus having a photometric unit that processes and obtains photometric information from a plurality of photometric areas, the plurality of photometric areas are divided into a plurality of photometric blocks smaller than the number of photometric areas, and a predetermined predetermined different for each of the plurality of photometric blocks. A weighting coefficient is given, a photometric result of the first light emission in the plurality of photometric blocks is compared with a reference value, and a weighting coefficient of each of the plurality of photometric blocks is determined by the comparison result as the predetermined weighting coefficient. An image pickup apparatus having control means for changing the coefficient to a different coefficient, calculating the brightness of the second light emission, and controlling the brightness of the second light emission based on the calculation result. .

(2) The predetermined weighting coefficient given to each of a plurality of photometric blocks is made different for each area.
An imaging device according to any one of the preceding claims.

(3) Imaging means for capturing an optical image of a subject from a solid-state imaging device, light emitting means for performing first and second light emission for irradiating the subject, and processing of a signal sent from the imaging means In an imaging apparatus having photometric means for obtaining photometric information from a plurality of photometric areas, a position of a subject is assumed by comparing photometric values of the plurality of photometric areas by the first light emission with a predetermined value, and the assumed position is assumed. The photometry area is divided into a plurality of photometry blocks smaller than the number of photometry areas around a position, and a different predetermined weighting coefficient is given to each of the plurality of photometry blocks, and the first light emission in the plurality of photometry blocks is performed. Comparing the photometric result of the plurality of photometric blocks with a reference value, changing the weighting coefficient of each of the plurality of photometric blocks to a coefficient different from the predetermined weighting coefficient, Ri said second calculates the brightness of the light emission, the imaging apparatus having a control means for controlling the brightness of the second light-emitting the result of the operation.

(4) The predetermined weighting coefficient given to each of the plurality of photometric blocks is made different for each area (3).
An imaging device according to any one of the preceding claims.

(5) When calculating the brightness of the second light emission, the control means removes the influence of the external light by using the photometric value of only the external light from the photometric means. The imaging device according to any one of 4).

(6) Distance measuring means for obtaining a distance to a subject is provided, and the control means determines the brightness of the second light emission calculated based on the photometric result of the first light emission by the distance measuring means. If the brightness exceeds a predetermined multiple of the brightness of the light emission obtained from the result,
The imaging device according to any one of (1) to (4), wherein the brightness of the second light emission is limited to within the predetermined magnification.

(7) An image pickup method in an image pickup apparatus for converting an optical image into an electric signal by an image pickup means using a solid-state image pickup device, wherein a first step of performing preliminary light emission and the image pickup means in the first step An imaging method comprising: a second step of examining the presence or absence of a subject in each photometry block based on a photometry result; and a third step of performing main light emission based on the examination result in the second step.

(8) A storage medium storing a program for realizing the imaging method according to (7).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to a still video camera embodiment. The present invention is not limited to an imaging device dedicated to still images, but can be implemented by an appropriate imaging device such as an imaging device for both moving images and still images. The present invention is not limited to the imaging apparatus, and can be implemented in the form of an imaging method and in the form of a storage medium such as a memory card storing a program for implementing the imaging method.

[0015]

【Example】

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a "still video camera" which is Embodiment 1.

In FIG. 1, reference numeral 1 denotes a barrier that serves both as protection of the lens and as a main switch, 2 as a lens for forming an optical image of a subject on the solid-state image pickup device 4, and 3 as an aperture for varying the amount of light passing through the lens 2. Reference numeral 4 denotes a solid-state imaging device for capturing a subject formed by the lens 2 as an image signal, 5 denotes an imaging signal processing circuit that performs various corrections, clamping, and the like on an image signal output from the solid-state imaging device 4; An A / D converter for performing analog-to-digital conversion of an image signal output from the imaging signal processing circuit 5;
A signal processing unit that performs various corrections on the output image data and compresses the data; a solid-state imaging device 4, an imaging signal processing circuit 5, an A / D converter 6, a signal processing unit 7, and various timing signals , A general control / arithmetic unit 9 for controlling various operations and the entire still video camera, a memory unit 10 for temporarily storing image data, and 11 for recording or reading on a recording medium. 12 is a detachable recording medium such as a semiconductor memory for recording or reading image data, 13 is an interface for communicating with an external computer or the like, and 14 is a first stroke and a second stroke. A release switch having a stroke, 15 is a strobe light emitting section, and 16 is when there is little external light or when there is little contrast in the subject. An auxiliary light emitting unit to the light.

The operation of the still video camera at the time of shooting in the above configuration will be described with reference to the flowchart of FIG.

When the barrier 1 is opened, the main power is turned on, then the power of the control system is turned on, the lens position of the AF lens is driven to the reset position, and the AF switch is turned on in response to the first stroke of the release switch 14. First
Wait until the switch is turned on. When the first switch is turned on (S201), the lens position of the AF lens is again driven to a predetermined position, and the imaging signal processing circuit 5 and the A
The power of the imaging system circuit such as the / D converter 6 is turned on.

The overall control / arithmetic unit 9 opens the diaphragm 3 (S202). The signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4 is converted by the A / D converter 6, and then the signal is processed. Input to the unit 7. Exposure calculation is performed by the overall control / calculation unit 9 based on the data (S203).

The brightness is determined based on the result of the photometry (S204), and the overall control / arithmetic unit 9 is operated according to the result.
Controls the aperture (S206). In addition, when it is determined that the light is dark, when the backlight is determined, or when the external operation member for strobe forced light emission is pressed, a flag is set, and the strobe light emitting unit 1 is controlled by the overall control / calculation unit 9.
When the light emitting device 5 emits light, the capacitor for storing energy is sufficiently charged (S205). In other cases, the charging is not performed without setting the flag.

Next, based on the signal output from the image pickup signal processing circuit 5 through the solid-state image pickup device 4, high-frequency components are extracted and the distance to the subject is calculated by the overall control / calculation section 9 (S209). At this time, when it is determined that the contrast difference between the subjects is small or dark (S207), the auxiliary light emitting unit 16 emits auxiliary light (S208). afterwards,
The lens is driven to determine whether or not focus is achieved (S210). If it is determined that focus is not achieved, the lens is driven again to perform distance measurement.

After focusing, if the flag is set in S205, it is determined that the flash mode is set (S211).
If not, the process waits until the second switch that is turned on in response to the second stroke of the release switch 14 is turned on (S212). When the second switch is turned on, main exposure is performed (S213), and photographing is performed. finish.

If it is determined in S211 that the flash mode is set, the process waits until the second switch of the release switch 14 which is turned on in response to the second stroke is turned on (S214). S when the second switch is turned on
The aperture is controlled based on the distance information obtained in step S209 (S21).
5) The first photometry is performed (S216), and the photometry result is stored.

In the photometry, as shown in FIG. 3B, photometry is performed for each of the photometry blocks of the blocks A, B and C. In the photometry block, the shooting angle of view is divided into 64 areas of 8 * 8 (FIG. 3A), of which block A uses 2 * 2, block B uses 4 * 4, and block C uses 6 * 6. . The centers of the photometric blocks A, B, and C are the same and coincide with the center of the angle of view, and the block positions are fixed. The area ratio of the photometric block B is about three times and that of the photometric block C is about five times based on the photometric block A. The electronic shutter speed at the time of this photometry 1 is set to the same shutter speed as S218 described later.

The aperture control in S215 is performed in S217.
When the first light emission always emits light with a constant light amount, control is performed such that reflected light that changes depending on the distance to the subject and the reflectance enters the solid-state imaging device 4 with an appropriate light amount. The aperture value at that time can be expressed by equation (1).

Av = 2 * Log ₂ (D / L) + Y (1) Av: aperture value L: distance information D, Y: predetermined value D and Y shown in the equation (1) are predetermined values. It is not necessary to change the light emission amount of one light emission if it is constant, but the aperture control amounts D and Y may be switched depending on the mode so that the reflected light from the subject enters the solid-state imaging device 4 with a more appropriate light amount. . For example, a macro mode for shooting at a close distance, a document mode for shooting paper with high reflectance, a day / day mode forcibly emitting light in a backlight, a black and white mode for expressing with contrast, and the like may be provided and switched. Needless to say, the modes may be combined to set a more detailed mode for switching.

Thereafter, the first light emission is performed (S217).
At the same time when the light emission ends, the electronic shutter is closed (S21).
8). At this time, the first light emission is performed in a maximum of 4 to 5 steps at the time of full light emission because the charging energy for the second light emission is not reduced as much as possible and the light emission amount necessary and sufficient for photometry can be sufficient. The amount of light emission that falls is good. In this case, the voltage drop of the charging capacitor due to the first light emission is about 7 to 10% of the full charge, and the remaining charge voltage after the first light emission has a substantially constant value. Also, the electronic shutter speed is such that the first light emission time is about 20 [μsec].
Therefore, the shutter speed is set to about 1/10000 to 1/15000 seconds, which is about one horizontal period. By releasing the electronic shutter, the amount of exposure due to external light during the time when the strobe is not emitting is not accumulated compared to the case where exposure is continued for one field, so that the photometric accuracy of the strobe light in the photometry 2 is improved.

In the photometry 1 and photometry 2 (S219), the signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4 is converted by the A / D converter 6 and the data input to the signal processing unit 7 is obtained. Control over the amount of reflected light from the subject
Calculation is performed by the calculation unit 9 to obtain a photometric value. Then, a difference (ΔEv) from the appropriate level is obtained from the photometric value by the following method.

First, the difference from the reference value for each block is obtained by the equation (2) (ΔA, ΔB, ΔC) (Equation (2) describes only the block A. The blocks B and C are similarly obtained).

ΔA = Log ₂ (Pre_A−Prepre_A) / (Ref−Prepre_A) (2) Prepre_A: photometric value of photometric 1 Pre_A: photometric value of photometric 2 Ref: reference value At this time, the solid in photometric 2 The output from the image sensor 4 is a mixture of strobe light and external light. In order to obtain the light amount of only the pure strobe light with respect to the appropriate value, the result of photometry 1 which is a photometry value of only external light is subtracted from the result of photometry 2 in which the strobe light and the external light are mixed. As for photometry 2, as described in S218, the effect of external light is reduced by cutting the electronic shutter speed quickly, and the result of photometry 1 which is a photometry value of only external light exposed at the same shutter speed is subtracted. Thus, it is possible to know the exact amount of only the strobe light by the first light emission.

Further, the required level of the strobe light changes according to the brightness of the external light, but this is handled by subtracting the photometric value of photometry 1, that is, the external light component, from the reference value. Can be determined accurately.

Next, ΔA, ΔB,
From ΔC, a difference ΔEv from the appropriate level is obtained by equation (3).

ΔEv = (a * ΔA + b * ΔB + c * ΔC) / (a + b + c) + d (3) where the coefficients a, b, c, and d in the equation (3) are compared with predetermined values as described later. Classify according to the result.

The coefficients are a = 3, b = 1, c = 4, d = 0
Is the default value.

For comparison, ΔA, ΔB, and ΔC are compared with a predetermined value X. If the values are larger than the predetermined value, the coefficients (a, b, c) are used as default values as they are.

If it is smaller than a predetermined value, the coefficients (a, b,
c) is set to “0”. However, if all are smaller than the predetermined value, all the coefficients are left as they are.

In this method, the presence or absence of a subject in each photometry block is checked based on the amount of reflected light, and when the amount of reflected light is smaller than a predetermined value, it is determined that there is no subject, and information on the block is not used. However, if all are smaller than the predetermined value, all information is used.

As a result of the comparison, the cases are divided into the following cases.

When all of Case 1 are smaller than a predetermined value ａ a = 3, b = 1, c = 4, d = 0 Case 2 ΔC is larger than a predetermined value ∴ a = b = 0, c = 4, d = 1. 74 Case 3 When ΔA alone is smaller than a predetermined value ∴ a = 0, b = 1, c = 4, d = 1.32 Case 4 Other than Case 1 to Case 3 ∴ a, b, c are d = 0 as in the comparison result. Each correction term is added to the calculation result, and a guide number (GNo.) Required for final main light emission is obtained from equation (4).

[0040]

(Equation 1)

The correction term 1 is a term that changes according to the brightness of external light as shown in FIG. In addition, various scenes can be handled by changing the pattern that changes as shown in FIG.

The correction term 2 is a term that can be set flexibly, such as when it is desired to finely adjust ± the number of steps relative to the appropriateness.
For example, when the photographer wants to emit strobe light brighter by +0.2 steps, it is possible to cope by setting β = 0.2 by setting the operation member to +0.2 steps.

Here, the guide number necessary for the second light emission obtained in S219 is calculated by using the distance measurement information obtained in S209 and S2.
The guide number obtained from the aperture value set in 15 is compared (S220), and the guide number obtained in S219 is compared with S20.
If the guide number obtained in steps S209 and S215 is larger than the guide number obtained in steps S209 and S215 by two or more steps, the guide number of the second light emission is used (S221). In the case of two or less stages, it is left as it is.

For example, the guide number obtained in S219 is "8", and the distance measurement result obtained in S209 is "1.5".
[M] ”, when the aperture set in S215 is“ f = 2.5 ”, the guide number obtained in S209 and S215 is“ 3.75 ”. At this time, the guide number obtained in S219 is the same as S209. Since the guide number is larger by two or more steps than the guide number obtained in S215, the guide number of the second light emission is "7.5" which is two steps higher (the light amount is four times) than the guide number obtained in S209 and S215. And S2
The guide number obtained in 15 is the so-called DV dimming method,
This is a method for obtaining a proper exposure when the reflectance is about 18%. If it is necessary to shine two or more steps brighter than this, the reflectance of the subject becomes 4% or less. This is a rare case for a subject, so it was judged that the photometry by the first flash could not be accurately measured because of the poor scene, and the upper limit of the brightness of the flash was obtained by the DV dimming method. Put a limit up.

From the guide number for the second light emission obtained as described above, the light emission time of the second light emission can be reduced by using the “guide number and light emission time table” representing the strobe characteristics shown in FIG. It is calculated by the control / calculation unit 9 (S22
2). At this time, if the guide number for the second light emission exceeds the maximum value in the table, the excess is calculated and the gain of the imaging signal processing circuit 5 is increased by that amount. However, considering the influence of noise and the like, the maximum is increased by one step. As a result, there is an advantage that the reach distance of the strobe is up to 1.4 times as much as the normal case. This is particularly effective when the power of the strobe is small, for example, when the capacity of the main capacitor is reduced due to downsizing or the like.

Then, the main exposure is started (S225), and a strobe trigger pulse is sent to the strobe light emitting unit 15 under the control of the overall control / arithmetic unit 9, and the strobe 15 starts the second light emission in synchronization with this pulse. When the light emission time obtained in S222 elapses, light emission is stopped at that moment (S22
6).

When the exposure is completed (S227), the image signal processed and output by the imaging signal processing circuit 5 through the solid-state imaging device 4 is A / D-converted by the A / D converter 6 and passed through the signal processing unit 7. The data is written into the memory unit 10 by the overall control / arithmetic unit 9. After that, the data stored in the memory unit 10 is stored in the recording medium control I / O under the control of the overall control / arithmetic unit 9.
Removable recording medium 1 such as a semiconductor memory passing through F section 11
2 is recorded.

Next, the timing of strobe light emission according to the present embodiment having the above configuration will be described with reference to the timing chart of FIG.

When the first switch of the release switch 14 is turned on (t1), the lens position of the AF lens is driven to a required position (t2), and the imaging signal processing circuit 5 and A / D
The power of the imaging signal processing circuit system such as the converter 6 is turned on. The overall control / arithmetic unit 9 opens the diaphragm 3 (t3), and sets the subject based on data obtained by converting the signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4 by the A / D converter 6. The overall control / calculation unit 9 calculates the amount of reflected light from the camera. As a result of this photometry, if it is determined that
The operation unit 9 sufficiently charges the light emitting capacitor constituting the strobe light emitting unit 15 (t4), and controls the aperture (t5).

Next, based on the signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4, the overall control / arithmetic unit 9 calculates the distance to the subject. Then, the lens 2 is driven (t6) to determine whether or not the lens is focused. If it is determined that the lens is not focused, the lens is driven again to measure the distance. When measuring the distance to the subject, when it is determined that the surroundings are dark or when the contrast of the subject is uniform, the overall control / arithmetic unit 9 sends a signal prompting light emission to the auxiliary light emitting unit 16 and sends the signal to the auxiliary light emitting unit 16. Reference numeral 16 irradiates auxiliary light (t7).

After focusing, the operation waits until the second switch which is turned on in response to the second stroke of the release switch 14 is turned on. When the flash mode is on, the second
Is turned on (t8), the aperture is controlled to the aperture value obtained from the distance information (t9). Next, exposure is performed before the first light emission, and this is set as a first photometric value. Subsequently, a strobe trigger pulse is sent under the control of the overall control / arithmetic unit 9, and the strobe light emitting unit 15 performs the first light emission in synchronization with the rise of this pulse (t11). When the first light emission ends, the electronic shutter is turned off to end the exposure, and this is set as a second photometric value. A signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4 by the first light emission is converted by the A / D converter 6 and reflected light from the subject based on data input to the signal processing unit 7. Is calculated by the overall control / calculation unit 9. The light emission time of the second light emission is determined from the result of the photometry.

Subsequently, the main exposure is started, and a strobe trigger pulse is sent under the control of the overall control / arithmetic unit 9. In synchronization with the rise of this pulse, the strobe light emitting unit 15 starts the second light emission ( t12). When the predetermined time has elapsed, the light emission is stopped instantly (t13). When the second light emission ends, the electronic shutter is closed, and the main exposure ends.

As described above, according to the present embodiment,
Photographing can be performed at an optimal light control level according to the presence or absence of an object, a range, and the like in each photometry block. In addition, it is possible to shoot at an appropriate dimming level without being affected by external light and without being affected by an extremely bright subject.

(Embodiment 2) The hardware configuration of a "still video camera" according to Embodiment 2 is the same as that of Embodiment 1, and the description is omitted.

The flash emission operation during photographing will be described with reference to the flowchart of FIG. In addition, FIG.
Steps that perform the same operations as those in the flowchart of FIG.

When the barrier 1 is opened, the main power is turned on, then the power of the control system is turned on, the lens position of the AF lens is driven to the reset position, and the AF switch is turned on according to the first stroke of the release switch 14. First
Wait until the switch is turned on. When the first switch is turned on (S201), the lens position of the AF lens is again driven to a predetermined position, and the imaging signal processing circuit 5 and the A
The power of the imaging system circuit such as the / D converter 6 is turned on.

The overall control / arithmetic unit 9 opens the diaphragm 3 (S202), and the signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4 is converted by the A / D converter 6 and then processed. Input to the unit 7. Exposure calculation is performed by the overall control / calculation unit 9 based on the data (S203).

The brightness is determined based on the result of the photometry (S204), and the overall control / arithmetic unit 9 is operated according to the result.
Controls the aperture (S206). In addition, when it is determined that the light is dark, when the backlight is determined, or when the external operation member for strobe forced light emission is pressed, a flag is set, and the strobe light emitting unit 1 is controlled by the overall control / calculation unit 9.
When the light emitting device 5 emits light, the capacitor for storing energy is sufficiently charged (S205). In other cases, the charging is not performed without setting the flag.

Next, based on the signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4, high-frequency components are extracted and the distance to the subject is calculated by the overall control / calculation unit 9 (S209). At this time, when it is determined that the contrast difference between the subjects is small or dark (S207), the auxiliary light emitting unit 16 emits auxiliary light (S208). afterwards,
The lens is driven to determine whether or not focus is achieved (S210). If it is determined that focus is not achieved, the lens is driven again to perform distance measurement.

After focusing, if the flag is set in S205, it is determined that the flash mode is set (S211).
If not, the process waits until the second switch that is turned on in response to the second stroke of the release switch 14 is turned on (S212). When the second switch is turned on, main exposure is performed (S213), and photographing is performed. finish.

If it is determined in S211 that the flash mode is set, the operation waits until the second switch of the release switch 14 that is turned on in response to the second stroke is turned on (S214). S when the second switch is turned on
The aperture is controlled based on the distance information obtained in step S209 (S21).
5) The first photometry is performed (S216), and the photometry result is stored.

In the photometry, different from the first embodiment, as shown in FIG. 3A, the photometry is performed for each area obtained by dividing the photographic field of view into 64 areas of 8 * 8. Further, the electronic shutter speed is set to the same shutter speed as S218 described later.

The aperture control in S215 is performed in S217.
When the first light emission always emits light with a constant light amount, control is performed such that reflected light that changes depending on the distance to the subject and the reflectance enters the solid-state imaging device 4 with an appropriate light amount. The aperture value at that time can be expressed by equation (1).

Av = 2 * Log ₂ (D / L) + Y (1) Av: aperture value L: distance information D, Y: predetermined value D and Y shown in the equation (1) are predetermined values. It is not necessary to change the light emission amount of one light emission if it is constant, but the aperture control amounts D and Y may be switched depending on the mode so that the reflected light from the subject enters the solid-state imaging device 4 with a more appropriate light amount. . For example, a macro mode for shooting at a close distance, a document mode for shooting paper with high reflectance, a day / day mode forcibly emitting light in a backlight, a black and white mode for expressing with contrast, and the like may be provided and switched. Needless to say, the modes may be combined to set a more detailed mode for switching.

Thereafter, the first light emission is performed (S217).
At the same time when the light emission ends, the electronic shutter is closed (S21).
8). At this time, the first light emission is performed in a maximum of 4 to 5 steps at the time of full light emission because the charging energy for the second light emission is not reduced as much as possible and the light emission amount necessary and sufficient for photometry can be sufficient. The amount of light emission that falls is good. In this case, the voltage drop of the charging capacitor due to the first light emission is about 7 to 10% of the full charge, and the remaining charge voltage after the first light emission has a substantially constant value. Also, the electronic shutter speed is such that the first light emission time is about 20 [μsec].
Therefore, the shutter speed is set to about 1/10000 to 1/15000 seconds, which is about one horizontal period. By releasing the electronic shutter, the amount of exposure due to external light during the time when the strobe is not emitting is not accumulated as compared with the case where the exposure is continued for one field, so that the effect of improving the photometric accuracy of the strobe light in photometry 2 (S219) is improved. is there.

The following S701 and S702 are the flows added to the flow of the first embodiment.

The integrated values detected in all the 64 divided areas in photometry 2 are compared with a predetermined value (S
701). As a result, a point equal to or higher than a predetermined value (FIG. 3C)
It is determined that there is a subject at the lower left of the area group, and the position of the center of gravity of the area group is obtained. Centering on the center of gravity,
A photometric block A is set up to 2 * 2, a photometric block B is set up to 4 * 4, and a photometric block C is set up to 6 * 6. If the photometry block is out of the shooting angle of view by matching the centers, the end is adjusted to the edge of the shooting angle of view (FIG. 3D), and the position of the photometry block for calculation is determined (S702). If all the areas are smaller than the predetermined value, the photometric block for calculation is set at the center of the angle of view (FIG. 3).
(B)). The area ratio of the photometric block B is about three times and that of the photometric block C is about five times based on the photometric block A.

As described above, by performing photometry before and after the pre-emission, the presence or absence of the subject can be determined based on the presence or absence of reflected light of the strobe light, and as a result of the calculation, the position of the photometry block is set at the center of the subject. It becomes possible. Therefore, the calculation accuracy is improved, and the second light emission can be performed at a more appropriate level.

In the photometry 1 and photometry 2 (S219), the signal output from the imaging signal processing circuit 5 through the solid-state imaging device 4 is converted by the A / D converter 6 and the data input to the signal processing unit 7 is Control over the amount of reflected light from the subject
Calculation is performed by the calculation unit 9 to obtain a photometric value. Then, a difference (ΔEv) from the appropriate level is obtained from the photometric value by the following method.

First, the difference from the reference value for each block is obtained by the equation (2) (ΔA, ΔB, ΔC) (Equation (2) describes only the block A. The blocks B and C are similarly obtained).

ΔA = Log ₂ (Pre_A−Prepre_A) / (Ref−Prepre_A) (2) Prepre_A: photometric value of photometric 1 Pre_A: photometric value of photometric 2 Ref: reference value At this time, the solid in photometric 2 The output from the image sensor 4 is a mixture of strobe light and external light. In order to obtain the light amount of only the pure strobe light with respect to the appropriate value, the result of photometry 1 which is a photometry value of only external light is subtracted from the result of photometry 2 in which the strobe light and the external light are mixed. As for photometry 2, as described in S218, the effect of external light is reduced by cutting the electronic shutter speed quickly, and the result of photometry 1 which is a photometry value of only external light exposed at the same shutter speed is subtracted. Thus, it is possible to know the exact amount of only the strobe light by the first light emission.

Further, although the required level of the strobe light changes depending on the brightness of the external light, the required level of the strobe light is changed by subtracting the photometric value of photometry 1, that is, the external light component from the reference value. Can be determined accurately.

Next, ΔA, ΔB,
From ΔC, a difference ΔEv from the appropriate level is obtained by equation (3).

ΔEv = (a * ΔA + b * ΔB + c * ΔC) / (a + b + c) + d (3) where the coefficients a, b, c, and d in the expression (3) are compared with predetermined values as described later. Classify according to the result.

The coefficients are a = 3, b = 1, c = 4, d = 0
Is the default value.

In the comparison, .DELTA.A, .DELTA.B, and .DELTA.C are compared with a predetermined value X. If they are larger than the predetermined value, the coefficients (a, b, c) are used as default values.

If it is smaller than the predetermined value, the coefficients (a, b,
c) is set to “0”. However, if all are smaller than the predetermined value, all the coefficients are left as they are.

In this case, the presence or absence of a subject in each photometric block is checked based on the amount of reflected light, and when the amount of reflected light is smaller than a predetermined value, it is determined that there is no subject, and the information of the block is not used. However, if all are smaller than the predetermined value, all information is used.

As a result of the comparison, it is divided into the following cases.

Case 1 where all are smaller than a predetermined value ∴ a = 3, b = 1, c = 4, d = 0 Case 2 ΔC is larger than a predetermined value 値 a = b = 0, c = 4, d = 1. 74 Case 3 When ΔA alone is smaller than a predetermined value ∴ a = 0, b = 1, c = 4, d = 1.32 Case 4 Other than Case 1 to Case 3 ∴ a, b, c are d = 0 as in the comparison result. Each correction term is added to the calculation result, and a guide number (GNo.) Required for final main light emission is obtained from equation (4).

[0081]

(Equation 2)

The correction term 1 is a term that changes according to the brightness of external light, as shown in FIG. In addition, various scenes can be handled by changing the pattern that changes as shown in FIG.

The correction term 2 is a term that can be set flexibly, such as when it is desired to make fine adjustments to ± appropriate steps.
For example, when the photographer wants to emit strobe light brighter by +0.2 steps, it is possible to cope by setting β = 0.2 by setting the operation member to +0.2 steps.

Here, the guide number required for the second light emission obtained in S219 is calculated by using the distance measurement information obtained in S209 and S2.
The guide number obtained from the aperture value set in 15 is compared (S220), and the guide number obtained in S219 is compared with S20.
If the guide number obtained in steps S209 and S215 is larger than the guide number obtained in steps S209 and S215 by two or more steps, the guide number of the second light emission is used (S221). In the case of two or less stages, it is left as it is.

For example, the guide number obtained in S219 is "8", and the distance measurement result obtained in S209 is "1.5".
[M] ”, when the aperture set in S215 is“ f = 2.5 ”, the guide number obtained in S209 and S215 is“ 3.75 ”. At this time, the guide number obtained in S219 is the same as S209. Since the guide number is larger by two or more steps than the guide number obtained in S215, the guide number of the second light emission is "7.5" which is two steps higher (the light amount is four times) than the guide number obtained in S209 and S215. And S2
The guide number obtained in 15 is the so-called DV dimming method,
This is a method for obtaining a proper exposure when the reflectance is about 18%. If it is necessary to shine two or more steps brighter than this, the reflectance of the subject becomes 4% or less. This is a rare case for a subject, so it was judged that the photometry by the first flash could not be accurately measured because of the poor scene, and the upper limit of the brightness of the flash was obtained by the DV dimming method. Put a limit up.

From the guide number for the second light emission obtained as described above, the light emission time of the second light emission can be reduced by using the “guide number and light emission time table” representing the strobe characteristics shown in FIG. It is calculated by the control / calculation unit 9 (S22
2). At this time, if the guide number for the second light emission exceeds the maximum value in the table, the excess is calculated and the gain of the imaging signal processing circuit 5 is increased by that amount. However, considering the influence of noise and the like, the maximum is increased by one step. As a result, there is an advantage that the reach distance of the strobe is up to 1.4 times as much as the normal case. This is particularly effective when the power of the strobe is small, for example, when the capacity of the main capacitor is reduced due to downsizing or the like.

Then, the main exposure is started (S225), and a strobe trigger pulse is sent to the strobe light emitting unit 15 under the control of the overall control / arithmetic unit 9, and the strobe 15 starts the second light emission in synchronization with this pulse. When the light emission time obtained in S222 elapses, light emission is stopped at that moment (S22
6).

When the exposure is completed (S 227), the image signal processed and output by the image signal processing circuit 5 through the solid-state image sensor 4 is subjected to A / D conversion by the A / D converter 6 and passed through the signal processing section 7. The data is written into the memory unit 10 by the overall control / arithmetic unit 9. After that, the data stored in the memory unit 10 is stored in the recording medium control I / O under the control of the overall control / arithmetic unit 9.
Removable recording medium 1 such as a semiconductor memory passing through F section 11
2 is recorded.

Since the operation timing of this embodiment is the same as that of FIG. 6, the description of the timing chart is omitted.

As described above, according to the present embodiment,
Shooting can be performed at an appropriate dimming level according to the position of the subject.

[0091]

As described above, according to the present invention,
You can shoot with the proper dimming level.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first embodiment.

FIG. 2 is a flowchart showing the operation of the first embodiment;

FIG. 3 is an explanatory diagram of a photometry block.

FIG. 4 is an explanatory diagram of correction light.

FIG. 5 is a diagram showing a table for obtaining a light emission time;

FIG. 6 is a timing chart illustrating the operation of the first embodiment;

FIG. 7 is a flowchart showing the operation of the second embodiment.

[Explanation of symbols]

 4 Solid-state imaging device 9 Overall control / arithmetic unit 15 Strobe light emitting unit

Claims (8)

[Claims] An imaging unit that captures an optical image of a subject from a solid-state imaging device; a light emitting unit that performs first and second light emission for irradiating the subject; and a signal processing unit that processes a signal sent from the imaging unit. And a photometric unit that obtains photometric information from a plurality of photometric areas, wherein the plurality of photometric areas are divided into a plurality of photometric blocks smaller than the number of photometric areas, and a predetermined weight different for each of the plurality of photometric blocks. And a photometric result of the first light emission in the plurality of photometric blocks is compared with a reference value, and the weighting factor of each of the plurality of photometric blocks is different from the predetermined weighting factor according to the comparison result. And a control unit for calculating the brightness of the second light emission based on the coefficient, and controlling the brightness of the second light emission based on the calculation result. Imaging device for. 2. The imaging apparatus according to claim 1, wherein a predetermined weighting coefficient assigned to each of the plurality of photometric blocks is different for each area. 3. An image capturing means for capturing an optical image of a subject from a solid-state image sensor, a light emitting means for performing first and second light emission for irradiating the subject, and processing a signal sent from the image capturing means. In an imaging apparatus having photometric means for obtaining photometric information from a plurality of photometric areas, a position of a subject is assumed by comparing photometric values of the plurality of photometric areas by the first light emission with a predetermined value, and the assumed position Centering around, dividing the photometric area into a plurality of photometric blocks less than the number of photometric areas, giving a different predetermined weighting coefficient for each of the plurality of photometric blocks,
The photometric results of the first light emission in the plurality of photometric blocks are compared with a reference value, and the weighting coefficients of the plurality of photometric blocks are changed to coefficients different from the predetermined weighting coefficients according to the comparison result. An image pickup apparatus comprising: a control unit that calculates the brightness of the second light emission according to the following formula, and controls the brightness of the second light emission based on the calculation result. 4. The imaging apparatus according to claim 3, wherein a predetermined weighting coefficient given to each of the plurality of photometric blocks is made different for each area. 5. The control device according to claim 1, wherein when calculating the brightness of the second light emission, the control device removes the influence of the external light by using a photometric value of only the external light from the photometric device. 1
The imaging device according to claim 4. 6. A distance measuring means for calculating a distance to a subject, wherein the control means determines the brightness of the second light emission calculated based on the light measurement result of the first light emission as a result of the distance measurement by the distance measuring means. The brightness of the second light emission is limited to within the predetermined times when the brightness exceeds a predetermined times the brightness obtained by the method according to any one of claims 1 to 4. Imaging device. 7. An imaging method in an imaging device for converting an optical image into an electric signal by an imaging unit using a solid-state imaging device, wherein a first step of performing preliminary light emission and photometry by the imaging unit in the first step are performed. An imaging method, comprising: a second step of examining the presence or absence of a subject in each photometric block based on a result; and a third step of performing main light emission based on the examination result in the second step. 8. A storage medium storing a program for realizing the imaging method according to claim 7.