JP2000155350A - Method and device for controlling flash light of image pickup equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flash light control method suitable to control the flash light quantity for a digital still camera, etc., and to provide the device therefor. SOLUTION: The image pickup equipment provided with an image pickup means for photographing an object image formed through a photographic lens and an illuminating means 15 for illuminating the object is controlled, and prior to photographing, the illuminating means is made to emit light, and also, a 1st received light quantity obtained by directly detecting the light reflected by the object and a 2nd received light quantity obtained by detecting the light from the object through the photographic lens 5 are measured, then, the light emitting quantity of the illuminating means is controlled based on the 1st received light quantity, and the correction quantity is decided based on the 2nd received light quantity, then, in the case of photographing the image of the object by the image pickup means, the light emitting quantity of the illuminating means is controlled based on a 3rd received light quantity obtained by directly detecting the light reflected by the object and the correction quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flashlight dimming method and apparatus for an imaging device used for flash photography in an imaging device such as a general camera or a digital still camera.

[0002]

2. Description of the Related Art Conventionally, in flash photography by a camera, the amount of light reflected from a subject when the flashlight is turned on is measured in order to control the amount of light emitted from the flashlight. As a technique for controlling the light amount of the flashlight, an external light control method and a TTL light control method are known. In the external dimming method, a light receiving element such as an SPD is used to directly receive reflected light from a subject to control the amount of flashlight.

In the TTL light control method, the amount of light emission is controlled using reflected light from a subject which passes through a photographic lens and is reflected on a photographic film surface. TTL
By adjusting the light emission amount of the flashlight using the light adjustment method, the light emission amount of the flashlight can be accurately controlled for all aperture values of the photographing lens having a wide angle of view.

[0004]

The following problems arise when the TTL light control technology that uses light reflected on the film surface for photography for control is directly applied to a digital still camera. For a CCD sensor used in a digital still camera or the like, since no consideration is given to the surface reflection of the CCD sensor, the surface reflected light of the CCD sensor hardly contains a diffuse component. Therefore,
By using the surface reflected light from the CCD sensor, CCD
The amount of light incident on the sensor cannot be measured accurately.

In a camera using a photosensitive film, if a special film having a reflectance greatly different from that of a general film is used, it is difficult to accurately control the amount of light by TTL light control. A TTL photometric technique for detecting light reflected from a shutter curtain near a film position is known. However, when photometry is performed to adjust the light emission amount of the flashlight, it is necessary to open the shutter curtain for photographing, so that light reflected from the shutter curtain surface cannot be detected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flashlight dimming method and apparatus suitable for adjusting the light emission amount of a flashlight of an imaging device such as a digital still camera.

[0007]

According to a first aspect of the present invention, there is provided a flashlight dimming method for an imaging apparatus, comprising: an imaging unit configured to capture an image of a subject formed through a photographic lens; and an illumination unit configured to illuminate the subject. Controlling the device, the illuminating unit emits light prior to photographing, and a first light receiving amount obtained by a first sensor that directly detects reflected light from the subject, and a light from the subject passing through the photographing lens. A second light reception amount obtained by a second sensor to be detected is measured, and a light emission amount of the illumination unit at the time of photographing is calculated based on the first light reception amount, and based on the second light reception amount The calculated correction amount of the light emission amount at the time of photographing is determined, and when the image of the subject is taken by the imaging means, the light reception level of the first sensor is calculated based on the calculated light reception amount and the correction amount. By controlling the said And controlling the light emission amount of the light unit.

According to a second aspect of the present invention, there is provided a flashlight dimming device for an image pickup apparatus, comprising: an image pickup means for photographing an image of a subject formed through a photographing lens; an illumination means for illuminating the subject; and a reflection of illumination light from the subject. A first photoelectric conversion unit for directly receiving light, a diffuse reflection plate disposed in front of the imaging unit and retractable at the time of photographing, and the illumination unit according to the amount of direct light received by the first photoelectric conversion unit. Lighting control means for controlling the amount of light emission of the light source; and preliminary light emission of the lighting means is performed under the control of the illumination control means prior to photographing, and light receiving amount of the preliminary light emission is transmitted via the photographing lens and the diffuse reflection plate. The second photoelectric conversion unit detects the light emission amount of the illumination unit controlled by the illumination control unit when capturing an image of a subject with the imaging unit. Forecast Characterized in that a light emitting amount correction means for correcting, based on the amount of received light.

According to a third aspect of the present invention, in the flashlight dimming device for an imaging device according to the second aspect, at the time of preliminary light emission,
The illumination control means sets the detection sensitivity of the first photoelectric conversion means with respect to the amount of directly received light high according to a predetermined coefficient, and when the imaging means takes an image of a subject, the light emission amount correction means sets the coefficient The light emission amount of the illumination means is corrected in consideration of the following.

According to a fourth aspect of the present invention, in the flashlight dimming device for an imaging device according to the second aspect, the illuminating means is provided for the same period as the light receiving time required for the second photoelectric conversion means to store the amount of light received. A stationary light receiving amount detecting means for detecting a light receiving amount of the second photoelectric conversion means as a stationary light receiving amount while the light is turned off, and the light emitting amount correcting means detects the second light amount at the time of preliminary light emission. The amount of light emitted from the lighting unit is corrected based on a difference between the amount of light received by the photoelectric conversion unit and the amount of received steady light.

According to a fifth aspect of the present invention, in the flashlight dimming device for an imaging device according to the second aspect, a shutter film for controlling light reception and light shielding of a light receiving surface of the imaging means is provided as the diffuse reflection plate. I do. A flashlight dimming method for an imaging device according to claim 6 controls an imaging device including an imaging unit for photographing an image of a subject formed through a photographing lens and an illuminating unit for illuminating the subject. A first sensor obtained by directly illuminating the illuminating means and directly detecting reflected light from a subject by a first sensor.
And the second sensor detects the light from the subject passing through the photographing lens with the second sensor, and measures the amount of light received by the illumination means based on the first amount of light received. Is determined based on the second received light amount, and when the image of the subject is taken by the imaging means, the first sensor can directly detect the reflected light from the subject. The amount of light emitted from the lighting unit is controlled based on the amount of received light and the amount of correction.

(Function) In the method according to the first aspect, the preliminary light emission of the illumination means is performed prior to photographing, and the first received light amount obtained by directly detecting the reflected light from the subject by the first sensor is measured. Then, the light from the subject passing through the taking lens is measured by the second sensor as the second light reception amount. The second sensor is disposed, for example, between the photographing lens and the imaging unit.

By calculating the first light reception amount measured at the time of preliminary light emission, it is possible to estimate the light emission amount of the illumination means required at the time of photographing. However, even if the amount of light emitted from the illuminating unit is constant, the amount of light actually incident on the imaging unit changes depending on the aperture. Therefore, based on the second light receiving amount measured by the second sensor, the correction amount of the light emitting amount required at the time of shooting is determined.

When the image of the subject is taken by the image pickup means, based on the calculated amount of received light and the amount of correction,
The light emission amount of the lighting unit is controlled so that the light reception amount level of the first sensor becomes appropriate. When performing preliminary light emission,
The shutter curtain may be closed and the reflected light from the shutter curtain may be detected. If the shutter curtain is processed in advance so as to have a predetermined light reflection characteristic, the correction amount of the amount of light incident on the imaging means at the time of shooting can be obtained from the second light reception amount detected at the time of preliminary light emission. it can. Of course, a reflecting member other than the shutter curtain may be used.

At the time of photographing, the light emission amount of the illumination means is corrected in accordance with a correction amount predetermined based on the second light reception amount. Since the correction level of the amount of light incident on the imaging means at the time of photographing can be obtained based on the second amount of received light, it is not necessary to detect the amount of received light with the second sensor at the time of photographing. Therefore, even when a solid-state image sensor or the like is used as the imaging means, it is possible to appropriately adjust the illumination of a flashlight or the like based on the correction amount at the time of shooting.

The device according to claim 2 operates as follows. The imaging unit captures an image of the subject formed through the imaging lens. The illumination means illuminates the subject. The first photoelectric conversion unit directly receives reflected light from a subject illuminated by the illumination unit. The diffuse reflection plate arranged in front of the image pickup means is retracted during photographing. The second photoelectric conversion unit performs pre-emission of the illumination unit under control of the illumination control unit prior to photographing, and detects an amount of received pre-emission light through the imaging lens and the diffuse reflection plate. .

The luminous intensity correcting means is configured to detect the luminous intensity of the illuminating means controlled by the illuminating control means when the second photoelectric conversion means detects the luminous intensity of the subject when the image capturing means takes an image of the subject. Is corrected based on the amount of received light. When performing preliminary light emission, the shutter curtain is closed, and light reflected from the shutter curtain is detected. Therefore, if the shutter curtain is processed in advance so as to have a predetermined light reflectance, the correction level of the amount of light incident on the imaging means at the time of shooting can be obtained from the amount of light received during the preliminary light emission detected at the time of the preliminary light emission. Can be. Of course, a reflecting member other than the shutter curtain may be used.

At the time of photographing, the light emission amount of the illuminating means is controlled in accordance with a correction amount determined in advance based on the light reception amount at the time of preliminary light emission. Since the correction level of the amount of light incident on the imaging unit at the time of photographing can be predicted based on the amount of light received by the second photoelectric conversion unit at the time of preliminary light emission, even when using an individual image sensor as the imaging unit, it is possible to directly Illumination such as a flashlight can be appropriately adjusted based on the received light amount and the correction amount.

In the apparatus according to the third aspect, the illumination control means increases the detection sensitivity of the first photoelectric conversion means with respect to the amount of directly received light during the preliminary light emission, so that the amount of the preliminary light emission is suppressed as compared with the time of photographing. . Therefore, power consumption due to preliminary light emission is suppressed. Therefore, it is possible to shift from preliminary light emission to main light emission without requiring recharging of the power supply. When an image of a subject is photographed by the imaging means, the light emission amount correction means corrects the light emission amount of the illumination means in consideration of the coefficient at the time of preliminary light emission, so that the light quantity of illumination necessary for photographing can be obtained.

In the apparatus according to the fourth aspect, the steady light receiving amount detecting means turns off the illuminating means for the same period as the light receiving time required for accumulating the light amount of the light receiving amount of the second photoelectric conversion means at the time of preliminary light emission. During this time, the amount of light received by the second photoelectric conversion means is detected as the amount of steady light received. The light emission amount correction means corrects the light emission amount of the lighting means based on a difference between the light reception amount of the second photoelectric conversion means and the steady light reception amount at the time of preliminary light emission.

The amount of light received by the second photoelectric conversion means at the time of preliminary light emission includes a component of steady light from the subject and a component due to light emission of the illumination means. Therefore, when the light emission amount of the illumination means is corrected based only on the light reception amount of the second photoelectric conversion means at the time of preliminary light emission, the light emission amount of the illumination means at the time of shooting varies depending on the magnitude of the component of the steady light. Occurs. According to the fourth aspect, the light emission amount of the illumination unit is corrected based on the difference between the light reception amount during the preliminary light emission and the steady light reception amount, so that the variation in the light emission amount of the illumination unit at the time of shooting is suppressed.

In the fifth aspect, since the shutter film controls light reception and light blocking on the light receiving surface of the image pickup means, it is easy to control the amount of light incident on the image pickup means. Further, since the shutter film and the diffuse reflection plate are shared, it is useful for simplifying the structure of the imaging device. 7. The method according to claim 6, wherein a preliminary light emission of the illuminating means is performed prior to photographing, a first light receiving amount obtained by directly detecting reflected light from a subject by a first sensor, and the photographing is performed by a second sensor. A second light receiving amount obtained by detecting light from the subject passing through the lens is measured.

Then, the light emission amount of the illumination means at the time of preliminary light emission is controlled based on the detected first light reception amount. Second
The second sensor for detecting the amount of received light is disposed, for example, between the photographing lens and the imaging means. Therefore, a value corresponding to the amount of light incident on the imaging means when the illumination means reaches a predetermined light emission amount is detected as the second light reception amount. Therefore, the correction amount is determined based on the detected second light reception amount.

When the image of the subject is taken by the image pickup means, the light emission amount of the illumination means is controlled based on the received light amount obtained by directly detecting the reflected light from the subject by the first sensor and the correction amount. I do. Since the correction level of the amount of light incident on the imaging unit at the time of photographing can be obtained based on the second received light amount, even when an individual image sensor or the like is used as the imaging unit, it is necessary to use the second sensor at the time of photographing. However, it is possible to appropriately adjust the illumination of a flashlight or the like based on the amount of received light detected by the first sensor and the correction amount.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 1 show an embodiment in which a flashlight dimming method and apparatus of an imaging apparatus according to the present invention is applied to a digital still camera.
This will be described with reference to FIG. This form corresponds to all claims.

FIG. 1 is a block diagram showing a configuration of a main part of a digital still camera of this embodiment. FIG. 2 is a block diagram showing a configuration of a main part of an electric system of the digital still camera of FIG. FIG. 3 is a flowchart showing a part of the operation of the control system of the digital still camera of FIG. In this embodiment, the imaging means, the illumination means,
The first photoelectric conversion unit, the diffuse reflection plate, the second photoelectric conversion unit, the illumination control unit, and the light emission amount correction unit are each a CC.
D sensor 54, flash lamp 15, first light receiving element 1
0, the shutter film 53, the second light receiving element 20, the dimming control unit 40, and the main control unit 30.

The means for detecting the amount of received steady light of claim 4 corresponds to the main control unit 30 (S18 to S21). The digital still camera shown in FIG. 1 includes a camera body 100 and an external flash 200. Of course, the camera body 100 and the external flash 20
The present invention can be practiced even when 0 is integrally formed.

Inside the camera body 100, a taking lens 51, an aperture 52, a shutter film 53, a CCD sensor 5
4, quick return mirror 55, screen 56, pentaprism 57, eyepiece 58, second light receiving element 20
And a main control unit 30. The CCD sensor 54 is a two-dimensional solid-state imaging device. External flash 2
00, a flash lamp 15, a first light receiving element 10, and a dimming control unit 40 are provided. The first light receiving element 10 and the second light receiving element 20 generate electric charges according to the amount of incident light.

Normally, the quick return mirror 55 is
Is arranged at a position inclined by 45 degrees as shown by a virtual line.
In this case, light from the subject that enters the camera body 100 via the taking lens 51 and the aperture 52 is reflected by the quick return mirror 55. That is, the incident light is imaged through the quick return mirror 55, the screen 56, the pentaprism 57, and the eyepiece 58. Therefore, the user can observe the image of the subject to be photographed by looking through the finder.

In the photographing sequence, the quick return mirror 55 is retracted to the position shown by the solid line. in this case,
Light from the subject goes to the shutter film 53 via the taking lens 51 and the aperture 52. When the shutter film 53 is closed, incident light from the subject is reflected on the surface of the shutter film 53. Part of the reflected light is the second light receiving element 2
Incident at 0. When the shutter film 53 is open,
The incident light enters the CCD sensor 54.

The CCD sensor 54 is an area sensor for photographing a two-dimensional image formed on the incident surface thereof. The CCD sensor 54 is composed of a semiconductor integrated circuit such as a CCD. The dimming control unit 40 controls the start / stop of light emission of the flash lamp 15. The first light receiving element 10 detects light directly entering from a subject without passing through the photographing lens 51. The dimming control unit 40 inputs an electric signal corresponding to the amount of light detected by the first light receiving element 10.

The second light receiving element 20 detects light incident from a subject through the taking lens 51. Second light receiving element 2
The main control unit 3 outputs an electric signal corresponding to the amount of light detected by the
0 is input. The main control unit 30 controls the dimming control unit 40 by determining a correction value of the light amount of the flash lamp 15 and instructing lighting.

As shown in FIG. 2, the main control unit 30 includes an amplifier 21, an integrator 22, an A / D converter 23, a D / A
It comprises a converter 25 and a microcomputer 24. The light incident on the second light receiving element 20 is converted into a current by the second light receiving element 20 and input to the amplifier 21. The output of the current amplifier 21 is integrated by the integrator 22. The integrator 22 is an analog integrator. Microcomputer 2
The control unit 4 controls the integrator 22 to start and stop the integration operation, clear the integration value, and the like.

The voltage corresponding to the integrated value of the integrator 22 is A
/ D converter 23. Microcomputer 2
4 detects the integrated value of the integrator 22, that is, the amount of light received by the second light receiving element 20 via the A / D converter 23.
As shown in FIG. 2, the dimming control unit 40 includes the amplifier 1
1, an integrator 12, a comparator 13, and a flash light control circuit 14. The light incident on the first light receiving element 10 is converted into a current by the first light receiving element 10 and input to the amplifier 11. The output of the amplifier 11 is integrated by the integrator 12.

The amplification degree of the amplifier 11 is variable.
The microcomputer 24 controls the gain of the amplifier 11 via the D / A converter 25. The integrator 12 is an analog integrator. The microcomputer 24 of the main control unit 30 controls the integrator 12 to start and stop the integration operation, clear the integration value, and the like.

The integrator 12 outputs a voltage corresponding to the integrated value. This voltage is applied to one input terminal of the comparator 13. A predetermined threshold voltage Vref is constantly applied to the other input terminal of the comparator 13. The comparator 13 is an analog comparator. The comparator 13 compares the integration voltage input from the integrator 12 with the threshold voltage Vref, and outputs a binary signal indicating the magnitude relation between them as a light emission stop signal. This issue stop signal is applied to the flash light control circuit 14 for emission stop control.

The flash light control circuit 14 controls the start and stop of light emission of the flash lamp 15 in accordance with a control signal from the microcomputer 24 and a signal from the comparator 13. The operation of the control system will be described with reference to the operation flow shown in FIG. FIG. 3 shows an operation flow when a release button (not shown) of the digital still camera is pressed. Each step in FIG. 3 is controlled by the microcomputer 24 shown in FIG.

The operation of each step in FIG. 3 will be described below. In step S11, the quick return mirror 55 is positioned at the position shown by the solid line in FIG. 1, and the state of the aperture 52 is adjusted according to a predetermined aperture value. In step S12, the gain (amplification degree) G of the amplifier 11 is determined. Here, the result of multiplying a predetermined reference gain G0 by a constant K is determined as the gain G. Also,
A control signal corresponding to the gain G is applied from the microcomputer 24 to the amplifier 11.

The gain G of the amplifier 11 is adjusted to adjust the detection sensitivity of the dimming control unit 40 with respect to the received light intensity detected by the first light receiving element 10. The constant K is set to a large value with respect to the reference gain G0 at the time of shooting in order to increase the sensitivity at the time of preliminary light emission.

The light emission period of the flash lamp 15 is a period from the start of light emission until the integrated voltage output from the integrator 12 becomes equal to the threshold voltage Vref.
When the gain G of 1 is increased, the lighting period of the flash lamp 15 is shortened. That is, the amount of emitted light and the power consumption are suppressed. If a large amount of electric charges charged in the flash circuit are consumed during preliminary light emission, light emission cannot be performed during photographing. Therefore, it is necessary to minimize power consumption during preliminary light emission. Therefore, the light emission amount of the flash lamp 15 at the time of preliminary light emission is made smaller than at the time of photographing.

In step S13, a control signal is applied from the microcomputer 24 to the integrator 22, and the integrator 2
After clearing the integration value of 2, the integration operation of the integrator 22 is restarted. In step S14, the microcomputer 2
After applying the control signal to the integrator 12 from 4 to clear the integrated value of the integrator 12, the integrating operation of the integrator 12 is restarted. In addition, the flash lamp 15 starts preliminary light emission according to a control signal applied from the microcomputer 24 to the flash light control circuit 14.

In step S15, the flash lamp 1
The elapsed time from the start of light emission of No. 5 is compared with a predetermined time T1. Time T1 is a constant. The time T1 is set to a value smaller than the longest lighting time of the flash lamp 15 in order to secure electric power required for light emission during photographing.
During the period from the start of flash lamp 15 emission to the elapse of time T1, the amount of received light reaches a predetermined amount and the integrator 12
If the output voltage of the flash lamp 15 exceeds the threshold voltage Vref, a signal instructing stop of light emission is applied from the comparator 13 to the flash light control circuit 14, so that light emission of the flash lamp 15 stops.

If the subject is located at a short distance, the emission of the flash lamp 15 ends while waiting for the time T1 to elapse in step S15. When the time T1 has elapsed, the process proceeds from step S15 to S16. Step S16
Then, the control signal is applied from the microcomputer 24 to the integrator 22 to stop the integration operation of the integrator 22. If the amount of received light does not reach the predetermined amount when the subject is at a long distance, the light emission is forcibly stopped.

In step S17, the microcomputer 24 controls the A / D converter 23 to read the integrated value output from the integrator 22 as the photometric value Ix. The photometric value Ix corresponds to the amount of light received by the second light receiving element 20 during steps S13 to S16. The photometric value Ix is the time T1
The light amount component and the component of the steady light by the preliminary light emission of the flash lamp 15 during the period are included. The following steps S18 to S21 are executed in order to detect only the component of the stationary light.

In step S18, a control signal is applied from the microcomputer 24 to the integrator 22, and the integrator 2
After clearing the integration value of 2, the integration operation of the integrator 22 is restarted. In step S19, the elapsed time after restarting the integration operation of the integrator 22 is compared with the time T1. Time T
After 1 elapses, the process proceeds to the next step S20.

In step S20, a control signal is applied from the microcomputer 24 to the integrator 22, and the integrator 2
The integration operation of Step 2 is stopped. In step S21, the microcomputer 24 controls the A / D converter 23 to
The integrated voltage output from the integrator 22 is read as the photometric value Ixn. The photometric value Ixn corresponds to the amount of steady light detected by the second light receiving element 20 during the time T1.

In step S22, the dimming correction amount H is determined based on the following equation. H = Io / (K · (Ix−Ixn)) (1) Io: Reference level determined by assuming a subject having a standard reflectance In the above equation (1), the level was detected at the time of preliminary light emission. By subtracting the photometric value Ixn detected in an environment without illumination from the photometric value Ix, the component of the steady light is removed, and only the received light component due to the emission of the flash lamp 15 is extracted.

In step S23, the gain G of the current amplifier 11 is calculated using the dimming correction amount H obtained in step S22.
To determine. The dimming correction amount H is set to a predetermined reference gain G0.
Is given to the amplifier 11 as a gain G. Further, a control signal corresponding to the gain G is applied from the microcomputer 24 to the amplifier 11. In step S24, the microcomputer 24 controls a shutter control circuit (not shown) to open the shutter film 53. As a result, the incident light from the subject passing through the photographing lens 51 and the aperture 52 enters the CCD sensor 54,
The sensor 54 is operated to photograph the subject.

In step S25, a control signal is applied from the microcomputer 24 to the integrator 12, and the integrator 1
After clearing the integration value of 2, the integration operation of the integrator 12 is restarted. In step S26, the microcomputer 2
4 to instruct the flash lamp 15 to emit light by a control signal applied to the flash light control circuit 14. When the amount of light emitted from the flash lamp 15 becomes an appropriate value, the output of the integrator 12 becomes equal to Vref, and a signal instructing the stop of light emission is input from the comparator 13 to the flash light control circuit 14. The light emission of the lamp 15 stops.

In step S27, the shutter film 53 is closed to block light incident on the CCD sensor 54. Thus, the flashlight photographing operation ends. (Second Embodiment) This embodiment is a modification of the first embodiment. The configuration is the same as that of the first embodiment except that the configurations of the main control unit 30 and the dimming control unit 40 are changed as shown in FIG. 4 and the operation of the microcomputer 24 is slightly changed. The changed part will be described.

In this embodiment, the amount of light emitted from the flash lamp 15 is adjusted by controlling the threshold voltage Vref applied to the comparator 13 instead of controlling the gain of the amplifier 11 in the first embodiment. A D / A converter 25 is provided in the main control unit 30 to control the threshold voltage Vref. The voltage output from the D / A converter 25 is applied to the comparator 13. Therefore, the threshold voltage Vref can be changed under the control of the microcomputer 24.

In this embodiment, the microcomputer 24
Controls the threshold voltage Vref output from the D / A converter 25 instead of the gain control in steps S12 and S23 shown in FIG. With this control, the light emission amount of the flash lamp 15 is controlled as in the first embodiment. (Third Embodiment) This embodiment is a modification of the first embodiment. The configuration of the main control unit 30 and the dimming control unit 40 is changed as shown in FIG. 5, and the operation of the microcomputer 24 is changed as shown in FIG. The changed part will be described.

In this embodiment, as shown in FIG.
The output terminal 3 is connected to the microcomputer 24. Therefore, the microcomputer 24 operates the comparator 13
By monitoring the binary signal output from the flash memory, the timing at which the flash lamp 15 stops emitting light can be recognized. The operation flow of this embodiment will be described with reference to FIG.

In step S15B shown in FIG. 6, the microcomputer 24 monitors the signal output from the comparator 13 and waits until the flash lamp 15 stops emitting light. In step S16B, the integration operation of the integrator 22 is stopped, and at the same time, the difference between the time when step S14 is executed and the time when step S16B is executed is detected as the preliminary light emission time T2.

In step S19B, the process waits until the time T2 has elapsed in order to detect the component of the steady light having the same time as the preliminary light emission. In this mode, the second
The integration time for detecting the amount of light received by the light receiving element 20 is reduced. Therefore, it is possible to shorten the waiting time from when the release button is pressed until when the photographing operation is actually performed.

(Fourth Embodiment) This embodiment is a modification of the first embodiment. In this embodiment, as shown in FIG. 7, the components of the optical finder are eliminated. Instead, a liquid crystal monitor 60 for electronically observing the image of the photographing target is mounted. The operation of the microcomputer 24 is changed as shown in FIG.

On the liquid crystal monitor 60, a two-dimensional image detected by the CCD sensor 54 is displayed. Further, in order to use the CCD sensor 54 as a component of the electronic finder, the timing of opening and closing the shutter film 53 is changed. That is, as shown in FIG. 8, when the power is turned on, the shutter film 53 is opened in step S08. Also,
When shooting by pressing the release button fully,
In step S10, the shutter film 53 closes. Then, immediately before photographing, the shutter film 53 is closed only until the shutter film 53 opens in step S24.

While the shutter film 53 is closed, the image of the object cannot be monitored on the liquid crystal monitor 60. Therefore, it is desirable to close the shutter film 53 only when the amount of received light is detected by the second light receiving element 20 as in this embodiment. (Fifth Embodiment) This embodiment is a modification of the first embodiment. This form of digital still camera
As shown in FIG. 9, the optical finder according to the first embodiment and the electronic finder according to the fourth embodiment are both mounted. Other configurations and operations are the same as those of the first embodiment.

In this embodiment, the user can selectively use the optical viewfinder and the electronic viewfinder as needed. In each of the above embodiments, the second
The case where the light receiving element 20 detects the reflected light from the shutter film 53 has been described. However, the light from the reflection member other than the shutter film 53 may be received by the second light receiving element 20. For example, a diffusion type liquid crystal device that switches between a transparent state and a state in which incident light is diffusely reflected by electrical control can be used instead of the shutter film 53.

In each of the above embodiments, the case where the present invention is applied to a digital still camera has been described. However, a camera using a photosensitive film, or a composite image pickup device in which the camera and the digital still camera are integrated. It is also possible to apply the present invention. Also, in any of the above-described embodiments, the present invention can be similarly implemented by integrally configuring the camera body 100 and the external flash 200.

[0061]

According to a first aspect of the present invention, there is provided a method for detecting a second light emitted during a preliminary light emission.
It is possible to predict the level of the amount of light incident on the imaging means at the time of shooting based on the amount of received light. Therefore, even when using an individual imaging device or the like as the imaging means, at the time of shooting, based on the first received light amount and the correction amount. Lighting such as a flashlight can be appropriately adjusted.

(Claim 2) Since the level of the amount of light incident on the image pickup means at the time of photographing can be predicted based on the second received light amount detected at the time of preliminary light emission, even when an individual image pickup element or the like is used as the image pickup means. At the time of photographing, the illumination such as a flashlight can be appropriately adjusted based on the first received light amount and the correction amount.

(Claim 3) Since the light quantity of the preliminary light emission is suppressed as compared with the time of photographing, the power consumption by the preliminary light emission is suppressed. Therefore, it is possible to shift from preliminary light emission to main light emission without requiring recharging of the power supply. (Claim 4) Since the light emission amount of the illumination means is corrected based on the difference between the TTL preliminary light reception amount and the TTL steady light reception amount, variation in the light emission amount of the illumination means at the time of photographing is suppressed.

(Claim 5) It becomes easy to control the amount of light incident on the image pickup means. Further, since the shutter film and the diffuse reflection plate are shared, it is useful for simplifying the structure of the imaging device. (Claim 6) Since the level of the amount of light incident on the image pickup means at the time of photographing can be predicted based on the second light reception amount detected at the time of preliminary light emission, even when an individual image pickup device or the like is used as the image pickup means, at the time of photographing Illumination such as a flashlight can be appropriately adjusted based on the first received light amount and the correction amount.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of a digital still camera according to a first embodiment.

FIG. 2 is a block diagram showing a configuration of a main part of an electric system of the digital still camera of FIG. 1;

FIG. 3 is a flowchart showing a part of an operation of a control system of the digital still camera in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of a main control unit and a dimming control unit according to a second embodiment.

FIG. 5 is a block diagram illustrating a configuration of a main control unit and a dimming control unit according to a third embodiment.

FIG. 6 is a flowchart showing a part of an operation of a control system of the digital still camera according to the third embodiment.

FIG. 7 is a block diagram illustrating a configuration of a main part of a digital still camera according to a fourth embodiment.

FIG. 8 is a flowchart showing a part of the operation of the control system of the digital still camera according to the fourth embodiment.

FIG. 9 is a block diagram showing a configuration of a main part of a digital still camera according to a fifth embodiment.

[Explanation of symbols]

 Reference Signs List 10 first light receiving element 11 amplifier 12 integrator 13 comparator 14 flash light control circuit 15 flash lamp 20 second light receiving element 21 amplifier 22 integrator 23 A / D converter 24 microcomputer 25 D / A converter 30 main control unit Reference Signs List 40 Dimming control unit 51 Photographing lens 52 Aperture 53 Shutter film 54 CCD sensor 55 Quick return mirror 56 Screen 57 Pentaprism 58 Eyepiece 60 LCD monitor 100 Camera body 200 External flash

Claims (6)

[Claims] 1. An imaging apparatus comprising: an imaging unit configured to capture an image of an object formed through an imaging lens; and an illumination unit configured to illuminate the object. A first received light amount obtained by a first sensor that directly detects reflected light from the camera and a second received light amount obtained by a second sensor that detects light from a subject passing through the photographing lens are measured. Calculating a light emission amount of the illumination unit at the time of photographing based on the first light reception amount, determining a correction amount of the light emission amount at the time of photographing calculated based on the second light reception amount, When capturing an image of a subject, the amount of light emitted from the illumination unit is controlled by controlling the level of the amount of light received by the first sensor based on the calculated amount of received light and the amount of correction. Imaging device flash Light dimming method. 2. An imaging device for photographing an image of a subject formed through a photographing lens, an illuminating device for illuminating the subject, and a first photoelectric conversion device for directly receiving reflected light of illumination light from the subject. A diffuse reflector disposed on a front surface of the image pickup unit and retractable at the time of photographing; an illumination control unit for controlling a light emission amount of the illumination unit according to a direct light reception amount received by the first photoelectric conversion unit; A second photoelectric conversion unit that performs preliminary light emission of the illumination unit prior to the control of the illumination control unit and detects a received light amount of the preliminary light emission through the imaging lens and the diffuse reflection plate, When capturing an image of a subject with an imaging unit, the light emission amount of the illumination unit controlled by the illumination control unit is set to the second
A flash light dimming device for an imaging device, comprising: a light emission amount correction unit that corrects based on a light reception amount of preliminary light emission detected by the photoelectric conversion unit. 3. A flashlight dimmer for an image pickup apparatus according to claim 2, wherein said illumination control means determines in advance the detection sensitivity of said first photoelectric conversion means with respect to the amount of directly received light during preliminary light emission. A flash light for an imaging device, wherein the light emission amount correction means corrects the light emission amount of the illumination means in consideration of the coefficient when the image of the subject is taken by the imaging means. Light control device. 4. The flashlight dimmer for an imaging device according to claim 2, wherein the illuminating unit is turned off for the same period as the light receiving time required for the second photoelectric conversion unit to store the amount of received light. Means for detecting the amount of light received by the second photoelectric conversion means as the amount of received steady light while the light is being emitted, and the second photoelectric conversion means when the light emission amount correction means performs preliminary light emission. A flash light dimming device for an imaging device, wherein the light emission amount of the illumination unit is corrected based on a difference between the received light amount of the light source and the steady light received light amount. 5. A flashlight dimming device for an image pickup apparatus according to claim 2, wherein a shutter film for controlling light reception and light blocking of a light receiving surface of said image pickup means is provided as said diffuse reflection plate. Flash light dimmer. 6. An imaging apparatus comprising: an imaging unit configured to capture an image of a subject formed through a shooting lens; and an illumination unit configured to illuminate the subject. A first sensor measures a first light reception amount obtained by directly detecting reflected light from a subject with a sensor, and a second sensor measures a second light reception amount obtained by detecting light from the subject passing through the photographing lens with a second sensor. Then, controlling the light emission amount of the illumination means based on the first light reception amount, determining a correction amount based on the second light reception amount, when photographing an image of a subject with the imaging means, The first
A flashlight dimming method for an imaging device, comprising: controlling a light emission amount of the illumination means based on a light reception amount obtained by directly detecting reflected light from a subject with a sensor and the correction amount.