JPS62163026A - Exposure control device for stroboscopic photographing - Google Patents

Abstract

PURPOSE:To prevent the titled device from the generation of a miss due to day photographing using a stroboscope as auxiliary light by delaying the output time of a close control signal based on exposure data when the aperture of a lens is so small as to photograph at the emitting of the stroboscope. CONSTITUTION:When the maximum aperture of the lens is Fm and the aperture of the lens is Fs, the step difference Fs-Fm of the lens aperture which is calculated by a step difference arithmetic circuit 13a based on exposure data and opening data is inputted to a correcting value determining circuit 13b and converted into a time signal proportional to the stop difference Fs-Fm and the time signal is inputted to the 1st time constant circuit 4. The circuit 4 delays an output time T3 of an aperture close control signal determined by exposure data obtained from an exposure arithmetic circuit 2 by a correction value DELTAT determined by the step difference Fs-Fm. A sector is transferred to a closing process at a time T4 delayed from the time T3 determined from the guide number of the stroboscope found out by an aperture value arithmetic circuit 7 only by a correcting value DELTAT. Consequently, the aperture of a shutter is increased and the aperture appropriate for stroboscopic photographing is formed to obtain exposure proper to a main object.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exposure control device that adjusts a lens aperture during daytime flash photography to an aperture value suitable for strobe photography.

(Prior art) Even if the average field of view is sufficiently bright, the main subject is
2, l'7'' R intersection 1 The entire F area is a supplementary location (photography using this, so-called daytime synchronized photography, is being carried out.

By the way, in a camera using a program shutter in which the exposure amount is determined by combining the lens diaphragm and the aperture time depending on the aperture shape of the sector, the first timer circuit determines the shutter closing timing according to the brightness of the subject. and a second time setting circuit that determines the flash emission timing of the strobe according to the distance to the main subject, and is configured to cause the strobe device to emit light based on the first output signal. When synchronized photography is performed during the day with a camera using such a shutter, if the brightness of the main subject is too low, the signal of the first specific circuit, that is, the shutter opening/closing control signal determined by the subject brightness, is activated very early. Since this output causes the strobe to fire, there is a problem in that the aperture value when firing the strobe becomes too small, resulting in underexposure of the main subject and causing a photographic error.

(Purpose) The present invention has been made in view of such problems, and its purpose is to automatically correct the exposure jl to the excessive side when the lens aperture is too small for the main subject, and to An object of the present invention is to provide an exposure control device capable of adjusting the exposure m for daytime synchronized photography to an appropriate value.

(Example) The details of the present invention will be described below based on illustrated examples.

FIG. 1 shows an embodiment of the present invention, and reference numeral 2 in the figure is an exposure amount calculation circuit, and a circuit for detecting subject brightness information from a photometry circuit 1 to which a light receiving element 1a is connected and a film sensitivity detection circuit. The film sensitivity information from 3 is input, and an exposure amount suitable for the subject brightness is calculated. Reference numeral 4 denotes a first timing circuit that determines the timing to close the shutter in the open state based on the exposure amount, and outputs a shutter opening/closing control signal using a signal from the aperture value correction circuit 13 (described later) during flash photography. It is configured to delay the time. 7 is an aperture value calculation circuit configured to calculate a lens aperture suitable for strobe photography based on film sensitivity information, guide number information from the strobe guide number detection circuit 5, and distance information from the distance detection circuit 6. has been done. Reference numeral 8 denotes a second time constant circuit which outputs a light emission trigger signal when the sector opens to the aperture determined by the aperture value calculation circuit 7. Reference numeral 9 designates a strobe light emission control circuit, which outputs a signal from either the first timer circuit 4 or the second timer circuit 8 which is input via the OR circuit 12 when the strobe switch 10 is in the N state. The strobe is configured to emit light based on the signal received. 1
Reference numeral 3 denotes the aperture value correction circuit described above, which calculates the difference in the number of steps in the lens aperture between the exposure data from the exposure amount calculation circuit 2 and the aperture data from the aperture value calculation circuit 7, based on the exposure data from the exposure amount calculation circuit 2 and the aperture data from the aperture value calculation circuit 7. It consists of a circuit 13a and a correction value determining circuit 1.3b which delays the output point of the aperture closing control signal from the first timing circuit 4 if the difference in the number of stages is large enough to be inappropriate for strobe photography. ing. Note that reference numeral 14 in the figure indicates a shutter opening/closing control circuit that outputs a signal for closing the opened sector.

In this embodiment, in order to take a picture using the strobe light as auxiliary light, the strobe drawing guide number is set and the strobe switch 10! When turned ON, the strobe control circuit 9 becomes operable and the correction value determination circuit 13b enters a standby state. When you point the camera at the subject and press the release button (not shown) to the first stage, the exposure calculation circuit 2 calculates exposure data based on the subject brightness and film sensitivity information, and the aperture value calculation circuit 7 calculates the guide number information, The optimum aperture value for photographing the main subject with strobe light is calculated based on the subject distance and film sensitivity. These exposure data and aperture data are input to the step number difference calculating circuit 13a, and the step number difference Fs-Fm between the maximum aperture Fm of the lens that forms the exposure t determined by the subject brightness and the lens aperture Fs determined by the guide number is calculated. Ru. As a result, if there is no problem with strobe photography, the step number difference calculation circuit 13
No correction signal is output from. In this state, when the photographer further presses the release button to perform flash photography, the shutter (not shown) is activated and begins to open. 1st
The time setting circuit 4 calculates the output timing of the shutter opening/closing control signal based on the exposure data, and the second time setting circuit 8 calculates the output timing of the strobe trigger synchronization signal based on the opening data. In this way, the strobe is caused to emit light at time T1 when the strobe trigger synchronization signal is output (
Fig. 2 1), then the time T when the opening closing control signal is output.
Close the sector with 2. Needless to say, the difference in steps between the maximum aperture value of the shutter, which is determined by the subject brightness, and the aperture value at the time the strobe fires has been determined in advance and has been confirmed to not pose a problem for photography, so the main subject should be the center of the image. The exposure will be carried out.

On the other hand, if the main subject is located farther away and the subject brightness is higher, the maximum aperture Fm of the lens based on the exposure data will be smaller, so the aperture determined by the guide number and distance will be smaller. The step number difference Fm-Fs from the data lens aperture Fs becomes extremely large. The step difference Fs-Fm of the lens aperture calculated by the step difference calculating circuit 13a based on the exposure data and aperture data is input to the correction value determining circuit 13b and converted into a time signal proportional to the step difference Fs-Fm. It is converted and input to the first time constant circuit 4. Upon receiving this time signal, the first time setting circuit 4 adjusts the output time point T3 of the aperture closing control signal determined by the exposure data from the exposure amount calculation circuit 2 (FIG. 2 II), and adjusts the correction amount determined by the step number difference Fs-Fm. Delay by ΔT. The sector shifts to the closing stroke at time T4, which is delayed by six correction amounts from time T3, which is determined by the strobe guide number determined by the aperture value calculation circuit 7. As a result, the aperture of the shutter increases and the entire subject becomes slightly overexposed, but since the aperture suitable for strobe photography is formed for the main subject, exposure suitable for the main subject can be obtained.

FIG. 3 shows a second embodiment of the present invention, with reference numeral 15 in the figure.
1 is a subject condition determination circuit into which subject brightness information from the photometric circuit 1 and distance information from the distance detection circuit 6 are input, and according to this embodiment, subject conditions can be input. .

(Effects) As explained above, according to the present invention, exposure data based on subject brightness, aperture data based on distance information, and the difference in the number of lens aperture steps are detected, and the lens aperture at the time of flash emission is determined to be unsuitable for photography. In cases where the exposure level is small, the output point of the closing control signal based on the exposure amount data is delayed, so that the lens aperture suitable for strobe photography is formed regardless of the brightness of the main subject, and the strobe fires. This allows you to avoid mistakes when taking photos during the day when using a strobe as fill light.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention;
FIG. 2 is a waveform diagram showing the operation of the above snowmaking operation, and FIG. 3 is a block diagram showing an embodiment of the present invention. 13...Aperture value correction circuit

Claims (1)

[Claims] step difference detection means for calculating the step difference in lens aperture between exposure data based on subject brightness and aperture data based on the distance to the subject, and a reference level representing a step difference unsuitable for photographing being set in advance; A strobe photographing exposure control device comprising a correction means for delaying the output point of a shutter opening/closing control signal when a step number difference signal outputted from the detection means exceeds the reference level.