JPH06160946A - Camera and its control method - Google Patents

Abstract

PURPOSE:To adjust the emitted light quantity of a stroboscope so that appropri ate exposure may be attained. CONSTITUTION:Emitted light quantity data for fixing the emitted light quantity of a discharge tube 45 is decided based on a distance to an object and a diaphragm value. When a power source switch 21 is turned on and photographing by the stroboscope is performed, a main capacitor J13 is charged. When a shutter release button 22 is depressed at a first stage, a switch circuit 47 is turned off and the main capacitor 43 is inhibited from being charged. The elapsed time from depressing the button 22 at the first stage till depressing it at a second stage is measured by a timer 6. The emitted light quantity data for fixing the emitted light quantity of the stroboscope is corrected based on the elapsed time. The corrected emitted light quantity data is given to an emitted light quantity control circuit 30 and the emitted light quantity of the discharge tube 45 is fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera for irradiating a subject with stroboscopic light for photographing when the subject brightness is low and for backlighting, and a control method thereof.

[0002]

[Background Art] When the subject brightness is low, such as at night or indoors, or when the subject is backlit even during the daytime, stroboscopic photography is generally performed because proper exposure is not performed. The amount of light emitted from the strobe is generally determined according to the aperture value and the distance to the subject. The smaller the aperture value or the greater the distance to the subject, the greater the amount of emitted light.

However, when a long time elapses before strobe light emission after the charge of the capacitor included in the strobe light emitting device for stroboscopic photography is completed, the electric charge accumulated in the capacitor is naturally discharged.

For this reason, stroboscopic light emission is not performed by the amount of light emission determined, resulting in insufficient exposure.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to make it possible to adjust the amount of strobe light emission so that proper exposure can be performed regardless of the time elapsed until the strobe light is emitted after the charging of the capacitor included in the strobe light emitting device.

According to the present invention, in a camera provided with a charging circuit for charging a stroboscopic light emitting capacitor, and a charging prohibiting means for prohibiting charging of the capacitor by the charging circuit in response to the start of photographing processing, Control amount setting means for setting a control amount for determining the discharge time of the capacitor for firing the strobe according to the distance to the aperture and the aperture value, from the prohibition of charging of the charging circuit by the charging prohibition means to the shutter. .Timer for measuring the time until the trigger signal is output for strobe emission in response to depression of the release button, and the longer the time measured by the timer is, the longer the discharge time determined by the control amount is. Correcting the control amount set by the control amount setting means based on the time measured by the time measuring means In response to the control amount correction means and the trigger signal, the discharge of the capacitor is started from the time when the trigger signal is output to cause the strobe to emit light, and the discharge time based on the control amount corrected by the control amount correction means. It is characterized in that it is provided with a stroboscopic light emission control means for stopping the discharge of the capacitor when the time has elapsed.

The camera control method of the present invention comprises a charging circuit for charging the stroboscopic light emitting capacitor, and a charging prohibiting means for prohibiting charging of the capacitor by the charging circuit in response to the start of the photographing process. In the camera, the control amount for setting the discharge time of the capacitor for causing the strobe to emit light is set according to the distance to the subject and the aperture value, and the charging prohibiting means prohibits the charging of the charging circuit. By measuring the time until the trigger signal output for strobe emission in response to pressing the shutter release button is measured, the discharge time determined by the control amount becomes longer as the measured time becomes longer. Corrects the set control amount based on the measured time and responds to the trigger signal by outputting the trigger signal Luo to initiate the discharge of the capacitor is electronic flash, characterized in that discharge is stopped the capacitor when the discharge time has elapsed based on the control amount corrected by the control amount correction means.

According to the present invention, since the charging of the charging circuit is prohibited in response to the start of the photographing process, the shutter release,
The time until the trigger signal is output for strobe emission in response to the pressing of the button is measured. The longer this time is, the larger the spontaneous discharge amount of the stroboscopic light emitting capacitor becomes, and the amount of stroboscopic light emission based on the control amount representing the discharge time determined from the distance to the subject and the aperture value causes insufficient exposure.

According to the present invention, the control amount is adjusted so that the discharge time by the stroboscopic light emission becomes longer as the measurement time becomes longer, so that the exposure becomes insufficient even if the spontaneous discharge amount of the stroboscopic light emitting capacitor increases. Can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a digital still camera will be described below in detail with reference to the drawings.

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

The imaging optical system includes a diaphragm 2, an imaging lens 3,
And a CCD 4 as a solid-state electronic image sensor (image sensor). A mechanical shutter is provided if necessary, but generally the shutter function is achieved by an electronic shutter realized by the control of the CCD 4. The image pickup lens 3 forms a subject image on the CCD 4,
It is moved by the imaging lens driving device 25 controlled by the CPU 5 and positioned at the in-focus position.

The digital still camera is provided with a power switch 21 and a shutter release button 22, and a signal indicating the input of the power switch 21 and the depression of the shutter release button 22 is given to the CPU 5. The shutter release button 22 is of a two-stroke type, and is pressed down in the first stage to perform photometry and distance measurement, and pressed down in the second stage to perform actual shooting of the subject.

The CPU 5 includes a timer 6, and the timer 6 measures the time from the first-step depression of the shutter release button 22 to the second-step depression thereof.

The digital still camera is provided with a photometric sensor 26 for preliminary photometry, and photometric data is given to the CPU 5. The CPU 5 controls at least one of the aperture value and the shutter speed on the basis of the photometric data obtained from the photometric sensor 26 so that the exposure amount to the CCD 4 falls within an appropriate range.

After the rough exposure amount adjustment based on such preliminary photometry, preliminary photographing is performed. By this pre-shooting, the photometric value is calculated and precise exposure control is performed using the video signal obtained from the CCD 4. These high precision exposure controls will be described in detail later.

The digital still camera is also provided with a distance measurement sensor 27 for distance measurement, and distance measurement data representing the distance to the object is given to the CPU 5. CP
U5 positions the image pickup lens 3 at the in-focus position via the image pickup lens driving device 25 based on the distance measurement data from the distance measurement sensor 27. The CPU 5 further determines the amount of light emitted from the strobe device based on the distance to the subject and the aperture value, as will be described later.

The digital still camera is for indoor photography,
As will be described later, a strobe device is included so that an appropriate exposure amount can be obtained when auxiliary light is required. The digital still camera can set prohibition of stroboscopic photography. When stroboscopic photography is prohibited, stroboscopic photography is not performed, and when stroboscopic photography is not prohibited, the strobe device is driven by the power supply 41.

The strobe device is a discharge tube (strobe) 45
And a charging circuit 40 for charging the electric charge given to the discharge tube 45.
And a light emission quantity control circuit 30 for controlling the quantity of strobe light emission, and a stop circuit 46 for stopping the light emission of the discharge tube 45.

The charging circuit 40 includes a switch circuit 47 for inhibiting the accumulation of charges in the main capacitor 43.
The switch circuit 47 is controlled by the charge permission signal output from the CPU 5, and while the charge permission signal is at L level, the switch circuit 47 is turned off and the main capacitor
Charging to 43 is prohibited. Power switch for charging permission signal
When the shutter release button 22 is turned on and the shutter release button 22 is not pressed, the H level is set, and when the shutter release button 22 is pressed, the L level is set.

When the switch circuit 47 is turned on, the voltage of the power supply 41 is boosted by the booster circuit 42 and the main capacitor 43 is charged. The charging voltage of the main capacitor 43 is detected by being applied to the A / D port of the CPU 5 through an appropriate voltage reducing circuit or voltage detecting circuit. This gives C
The PU 5 can know that the main capacitor 43 has been charged.

Since the CPU 5 can detect the charging voltage of the main capacitor 43, the charging voltage of the main capacitor 43 before the discharge tube 45 emits light and the main capacitor 43 after the discharge tube 45 emits light.
It is also possible to detect each of the charging voltage and the charging voltage and to calculate the amount of light emitted from the discharge tube 45 from the difference between these voltages.

The strobe light emission is performed by giving a strobe light emission command X ON to the trigger circuit 44. When the strobe light emission command X ON from the CPU 5 is given to the trigger circuit 44, the trigger circuit 44 is driven, the electric charge accumulated in the main capacitor 43 is discharged through the discharge tube 45, and strobe light emission starts.

The amount of stroboscopic light emitted is determined according to the distance to the subject and the aperture value. The CPU 5 creates the emission light amount data so that the flash emission light amount is determined according to the distance to the subject and the aperture value. The emitted light amount control circuit 30 includes an electronic volume circuit (EVR) 31 including a D / A converter 31A, and emitted light amount data output from the CPU 5 is given to the EVR 31 and converted into a voltage for output. .

The emission light amount data determined according to the distance to the subject and the aperture value is corrected according to the elapsed time from the first-step depression of the shutter release button 22 to the second-step depression thereof. It This correction is performed so that the amount of strobe light emitted by the strobe light emitting device increases as the elapsed time increases. Also included is a differential amplifier circuit 36 for providing a stop signal to stop circuit 46.

Further, the emitted light quantity control circuit 30 includes a reference power source 32.
And a capacitor 34 is included. The output voltage of the EVR 31 is given to the capacitor 34 via the resistor 33. A switch 35 for discharging the charge of the capacitor 34 is also provided. A reference power supply circuit is provided at the negative input terminal of the differential amplifier circuit 36.
The reference voltage output from 32 is applied, and the differential amplifier circuit 36
The terminal voltage of the capacitor 34 is applied to the positive input terminal of the.

The switch 35 is normally turned on, and CP
It is turned off when the flash emission command X of U5 is given. When the switch 35 is turned off, the EV
Charging of the capacitor 34 is started based on the voltage output from R31.

A voltage is output from the EVR31 and the switch 35
When is turned on, a predetermined charge is accumulated in the capacitor 34. When the terminal voltage of the capacitor 34 becomes equal to the reference voltage output from the reference power supply 32, a stop signal is output from the differential amplifier circuit 36 and is given to the stop circuit 46, so that the discharge tube 45 stops emitting light.

In the CCD 4, interlace photographing is performed by the substrate extraction pulse, the A field vertical transfer pulse, the B field vertical transfer pulse and the horizontal transfer pulse, and the A field and B field video signals (GRGB
Color sequential signals) are alternately generated every one field period and sequentially read out. The driving of the CCD 4 (imaging and reading of a video signal) is performed at least at the time of photographing, and for precision photometric processing and distance measuring processing prior thereto.

The video signals of the A field and the B field representing the subject image output from the CCD 4 are given to the color separation circuit 8 through the correlated double sampling circuit 7, and the three primary colors, G (green), R (red) and It is separated into B (blue) color signals.

The color signals G, R and B are given to a variable gain amplifier circuit (hereinafter referred to as GCA) 9. In Figure 1, GC
Although one block is shown as A9, GCA is actually provided for each of the R, G, and B signals. In this GCA 9, after correction of variations in light transmittance of the color filters provided in the CCD 4 between filters (hereinafter referred to as color filter variation correction) and white balance adjustment are performed, the gamma correction circuit 10
Given to.

The output color signals R, G, B of the GCA 9 are gradation-corrected by the gamma correction circuit 10 and input to the clamp and resampling circuit 11.

The clamp and resampling circuit 11 is
The three color signals R, G, B are clamped and re-converted into color sequential signals of GRGB ... Which match the color filter arrangement in the CCD 4. This color sequential signal is input to the gain control and blanking circuit 12. The gain control and blanking circuit 12 amplifies the color sequential signal to an appropriate level for recording and adds the blanking signal to it. The output signal of the gain control and blanking circuit 12 is applied to the A / D converter 14 and is recorded on a memory card or the like via a recording processing circuit (not shown).

Before the main photographing, the precise photometric processing (exposure control) is performed as described above. The photometric processing is performed by utilizing the low frequency component of the video signal obtained from the CCD 4 by the preliminary photographing.

In order to take out the low frequency component of the video signal representing the image in the photometric area (described later) provided in the photographing area of the CCD 4 for the photometric processing, the Y _L synthesizing circuit 15,
A gate circuit 16, an integrating circuit 17, an amplifying circuit 18, and an A / D converter 19 are provided. The output data of the A / D converter 19 is given to the CPU 5.

The main photographing is performed after the photometric processing, the exposure control (control of the diaphragm and the shutter) based thereon, and the focus control (positioning of the image pickup lens 3). CCD by actual shooting
The video signals obtained from 4 are the circuits 7, 8, 9, 1 described above.
Input to A / D converter 14 via 0, 11 and 12
The data is converted into digital image data by the / D converter 14, processed by an image data processing circuit (not shown) such as Y / C separation and data compression, and then recorded on a recording medium such as a memory card. become.

The photometric processing (and exposure control based on it) prior to the main photographing will be described.

The photometric processing is performed by the Y _L combining circuit 15, as described above.
This is performed using the gate circuit 16, the integration circuit 17, and the amplification circuit 18. The Y _L synthesizing circuit 15 outputs the output color signal R of the GCA 9,
G and B are given.

The CPU 3 outputs a window signal WIND1 for controlling the gate circuit 16 and a reset signal HLRST1 for resetting the integrating circuit 17. These signals WI
The timing of ND and HLRST will be described later.

The color signals R, G and B output from the GCA 9 are added by the Y _L synthesizing circuit 15 to generate a relatively low frequency luminance signal Y _L (hereinafter simply referred to as luminance signal Y _L ). The luminance signal Y _L passes through the gate circuit 16 while the window signal WIND1 is applied during the required horizontal scanning period. The integrator circuit 17 has a reset signal HLRS.
It is reset when T1 is given, and then the luminance signal Y _L input from the gate circuit 16 is integrated. Integrator circuit 17
The integrated signal of is amplified by the amplification circuit 18, and then the integration circuit 17
Immediately before being reset, the data is input to the A / D converter 14 via the change-over switch 13, converted into digital integrated data for photometry by this A / D converter 14 and taken into the CPU 5.

In the photometric processing of this embodiment, average photometry (hereinafter referred to as A
V metering) and spot metering (hereinafter referred to as SP metering) for measuring the brightness of the main subject in the field of view. The SP metering is useful when the brightness of the main subject and the background in the field of view are different and it is necessary to set an appropriate exposure condition accordingly.

Further, in this embodiment, the integration by the integration circuit 17 and the A / D conversion operation and addition processing by the A / D converter 19 are alternately performed every horizontal scanning period.

FIG. 2 shows the AV photometric area and the SP photometric area set in the photographing area 50 of the CCD 4.

The AV photometric area is basically set over almost the entire photographing area 50. In this embodiment, the AV photometric area is set for a period of 40 μs after the lapse of 16 μs from the trailing edge of the horizontal synchronizing signal HD (the start point of the horizontal scanning period) in the horizontal direction, and the 35th horizontal scanning in the vertical direction. 24th from the line
It is set up to the 6th horizontal scan line.

The SP photometric area is set as a small area at an arbitrary position within the photographing area 50. In this embodiment, the SP metering area is set at the center of the photographing area 50, and the horizontal direction is the 87th horizontal scanning line in the vertical direction during the period of 15 μs after 28.5 μs has elapsed from the fall of the horizontal synchronizing signal HD. From the 194th
It is set up to the second horizontal scan line.

The memory associated with the CPU 5 is provided with a photometry area and a distance measurement area. AV metering area data area and SP metering area data
There is an area.

When AV photometry is performed, integration is performed every other horizontal scanning line in the AV photometry area.
The above integration is performed every other horizontal scanning line for A / D conversion, reset integration of the integration circuit, and data addition processing.

As shown in FIG. 3, in AV photometry, between the 34th horizontal scanning line and the 246th horizontal scanning line, the gate circuit 16 is provided with 16 μs after the fall of the horizontal synchronizing signal HD. A window signal WIND1 having a pulse width of 40 μs is applied. Then, the integrating circuit 17
Integration of the luminance signal Y _L , A / D conversion of the integration signal in the horizontal scanning period subsequent to the horizontal scanning period in which this integration operation is performed, reset of the integration circuit 17 and AV of the memory.
The addition of integrated data to the photometric area data area is alternately repeated for each horizontal scanning period.

When SP photometry is performed, a pulse width rises 28.5 μs after the fall of the horizontal synchronizing signal HD in the gate circuit 16 between the 87th horizontal scanning line and the 194th horizontal scanning line. A window signal WIND1 of 15 μs is provided.

Also in SP photometry, when the window signal WIND1 having a pulse width of 15 μs is given to the integrating circuit 17 and the luminance signal Y _L is integrated, the integration is performed in the horizontal scanning period next to the horizontal scanning period in which the integration operation is performed. A / D conversion of the signal, reset of the integrating circuit 17, and addition of the integrated data to the SP photometric area data area of the memory are performed.

When AV photometry is performed, the CPU 5 adds integrated data for one horizontal scanning line obtained based on the window signal WIND1 having a pulse width of 40 μs in the AV photometry area data area for one field period by the procedure described later. Then, the AV photometric value is calculated.

When SP metering is performed, the CPU 5
The integrated data for one horizontal scanning line obtained based on the window signal WIND1 having a pulse width of 15 μs is added in the SP metering area data area for one field period by the procedure described later to calculate the SP metering value.

In this digital still camera, focusing control is performed based on the distance measurement data from the distance measurement sensor 27. The lens driving device 25 is driven based on the distance information to the subject obtained from the distance measurement data, and the lens driving device 25 is positioned at the in-focus position.

In general, when the image is out of focus and blurred, the high frequency component contained in the video signal obtained from the CCD by photographing is small. When the image comes into focus, the high-frequency component of the video signal increases, and the high-frequency component contained in the video signal becomes maximum at the correctly focused position. Focusing control can also be performed based on such a fact.

In this case, a gate circuit for passing the output signal of the gain control and blanking circuit 12 for a certain period, a bandpass filter for extracting high frequency components, a detection circuit, an integration circuit and an amplification circuit are provided. Then, the distance measurement data is calculated, and focusing control is performed based on this data.

FIG. 4 shows the aperture value F according to the distance to the subject.
No. and a guide number GNo. Showing the amount of light emitted from the strobe light emitting device. FIG. 5 is a table showing the correspondence between the guide number GNo., The light emission amount data EVR value and the output voltage of the EVR31. 6 is a table showing the relationship between the correction data of the emitted light amount data according to the elapsed time from the first-step depression of the shutter release button to the second-step depression thereof. Data of various tables shown in FIGS. 4 to 6 are stored in the memory of the CPU 5.

FIG. 7 is a time chart at the time of shooting, and FIG. 8 is a flow chart showing a processing procedure of shooting.

When the power switch 21 of the digital still camera is turned on at time t ₁ , it is checked whether or not the flash photography prohibition mode is set (step 61). If the flash photography prohibition mode is not set (NO in step 61), a charge permission signal is output from the CPU 5, the switch circuit 47 is turned on, and the main capacitor 43 is charged (step 62). If the flash photography prohibit mode is set (YES in step 61), CP
The charging permission signal is not output from U5 and the main capacitor 43 is not charged (step 63).

When the shutter release button 22 is depressed in the first step at time t ₂ (E in step 64)
S), the output of the charging permission signal output from the CPU 5 is stopped. This turns off the switch of the charge prohibition circuit 47 and prohibits the charging of the main capacitor 43 (step
65).

At time t ₂ , when the output of the charge permission signal is stopped and charging of the main capacitor 43 is prohibited, CU5
The operation of the timer 6 is started (step 66).

When the shutter release button 22 is depressed at the first stage at time t ₃ , the distance measuring sensor 27 measures the distance to the object (step 67), and the photometric sensor 26 performs preliminary photometry and the circuit. 15, 1
Photometry is performed by 6, 17 and 18 (step 6
8). The lens driving device 25 is driven according to the distance to the subject, and the imaging lens 3 is positioned at the in-focus position (step 69).

When the shutter release button 22 is pressed in the second step (YES in step 70), it is determined whether or not the flash photography is performed according to the photometric value and the setting status of the flash photography prohibition mode. (Step
71).

If the flash photography prohibit mode is set, or if the photometry value is such that flash photography is unnecessary, the subject is photographed without firing the flash (NO in step 71, 72).

If the flash photography prohibition mode is not set and the photometric value is low enough to require flash photography, the process shifts to flash photography (YES in step 71).

First, it is stored in the memory of the CPU 5,
From the calculation table of aperture value and guide number GNo. Shown in Fig. 4, the aperture value and guide number are calculated according to the distance to the subject.
A number is set for each (step 73). The aperture stop 2 is driven so that the aperture value is determined (step 7).
Four). Further referring to FIG. 5, the EVR value is calculated from the determined guide number GNo.

When the shutter release button 22 is depressed in the second stage at the time t ₃ , the time counting operation of the timer 6 ends (step 75).

Subsequently, the correction value of the EVR value is calculated from the time measured by the timer 6 and the selected guide number GNo. With reference to the correction table shown in FIG. 6 (step 76). The EVR value calculated by this correction value is subtracted from the EVR value determined by FIG. 5 and corrected. The photographer may be warned when the elapsed time exceeds a certain time (for example, 30 seconds).

When stroboscopic light emission is performed by the discharge tube 45 (step 77), shutter control in the CCD 4 is performed and the subject is photographed (step 78).

When the EVR value is corrected, the strobe 45 emits strobe light, so that the corrected EVR value is output from the CPU 5 as the emitted light amount data and given to the EVR 31. It is converted into an analog voltage value in the D / A converter 31, and the stop circuit 46 is changed according to the magnitude of the analog voltage value.
Stops the flash firing (step 79).

When the photographing of the subject is completed, the video signal is read from the CCD 4 (step 80) and the circuits 7, 8, 9
Recording is performed on the memory card through steps 10, 11, 12 and 14 (step 81). Subsequently, aperture 2 is returned to the home position.

When the shutter release button 22 is released at time t ₄ (step 83), the digital still camera is in the initial state.

Next, the guide number, EVR value, etc. will be described with reference to specific examples.

Distance to subject (step 67) is 1.5 m
, The aperture value is 5.6 and the guide number GNo. Is 8.5 (step 7).
3). If the timer 6 measures 25 seconds as the elapsed time from the first-step depression of the shutter release button 22 to the second-step depression thereof, the correction amount of the EVR value becomes 15. The EVR value when the guide number GNo. Is 8.5
Therefore, if the correction amount 15 is subtracted from the EVR value 45, the corrected EVR value becomes 30.

The CPU 5 outputs the emitted light amount data representing the EVR value 30 and supplies it to the EVR 31. The voltage value corresponding to the EVR value 30 is 600 [mV] from FIG.
Output a voltage of 600 [mV].

As a result, stroboscopic light emission is performed in consideration of discharge due to the lapse of time after completion of charging of the main capacitor 43, and a subject is photographed.

In the above description, the EVR value that gives the guide number GNo. Determined according to the distance to the subject is corrected, but it is corrected by changing the aperture value of the aperture 2 without correcting the EVR value. You may do it. In this case, the aperture set in step 74 of FIG. 8 is changed again according to the time measured by the timer 6.

In the above-mentioned embodiment, the embodiment in which the present invention is applied to the digital still camera has been described, but the present invention is not limited to the digital still camera, but is recorded on a still camera for recording on a magnetic disk or a silver salt film. It can also be applied to cameras that do.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a digital still camera.

FIG. 2 shows a photometric area.

FIG. 3 is a time chart when photometry is performed.

FIG. 4 is a table for calculating an aperture value and a guide number from a distance to a subject.

FIG. 5 shows a correspondence relationship between a guide number and an EVR value.

FIG. 6 is a table for calculating a correction value of an EVR value.

FIG. 7 shows a shooting time chart.

FIG. 8 is a flowchart showing a processing procedure of photographing.

[Explanation of symbols]

 2 Aperture 5 CPU 6 Timer 27 Distance measuring sensor 30 Emission light intensity control circuit 40 Charging circuit 41 Power supply 42 Booster circuit 43 Main capacitor (strobe emission capacitor) 45 Discharge tube 46 Stop circuit

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

Claims (2)

[Claims] 1. A camera provided with a charging circuit for charging a stroboscopic light emitting capacitor, and a charging prohibiting means for prohibiting charging of the capacitor by the charging circuit in response to the start of a photographing process. A control amount setting means for setting a control amount for determining the discharge time of the capacitor for firing the strobe according to the distance and the aperture value, from the prohibition of charging of the charging circuit by the charging prohibition means, to the shutter release. .Timer means for measuring the time until the trigger signal is output for strobe emission in response to the pressing of a button, and the longer the time measured by the timer means, the longer the discharge time determined by the control amount A control amount compensator for correcting the control amount set by the control amount setting means based on the time measured by the time measuring means. In response to the positive means and the trigger signal, the discharge of the capacitor is started from the time when the trigger signal is output to cause the strobe to emit light, and the time when the discharge time based on the control amount corrected by the control amount correction means elapses. And a flash emission control means for stopping the discharge of the capacitor. 2. A camera provided with a charging circuit for charging a stroboscopic light emitting capacitor, and a charging prohibiting means for prohibiting charging of the capacitor by the charging circuit in response to the start of a photographing process. According to the distance and the aperture value, a control amount for setting the discharge time of the capacitor for firing the strobe is set, and the shutter release button is pressed after the charging prohibiting means prohibits the charging of the charging circuit. The time until the trigger signal is output for the strobe emission in response to is measured, and the discharge time determined by the control amount becomes longer as the measured time becomes longer, based on the time measured by the time measuring means. Corrects the set control amount and responds to the trigger signal to start discharging the capacitor from the trigger signal output point. A method of controlling a camera, wherein the strobe is caused to emit light and the discharge of the capacitor is stopped when the discharge time based on the corrected control amount has elapsed.