JPS62180339A - Daylight synchronizing flash control method - Google Patents

Abstract

PURPOSE:To perform proper daylight synchronizing flash photography by starting the emitting of an electronic flash when the integrated quantity of light reaches a 1st specific value and starting shutter closing operation when the integrated quantity reaches a 2nd specific value. CONSTITUTION:When a release pulse 32 is inputted to a CPU 16, the CPU 16 outputs a reset pulse 18 to reset an integration output 8 and a timer 17. When the integration output 8 reaches the 1st specific value 12, the 1st detection output 14 is obtained and the CPU outputs a light emission ON pulse 23 and the electronic flash 26 starts emitting light. Then an increment in the quantity of exposure of an image formation part 5 becomes large in this light emission period, so the integration output 8 varies as shown in a figure and when it reaches proper exposure or the 2nd specific value 13 set in the vicinity of it, the 2nd detection output 15 is obtained. The CPU 16 on receiving the outputs a light emission OFF pulse 24 to stop the light emission of the electronic flash 26 and also outputs a closing command 21 to close a shutter 3, thereby completing the exposure in daylight synchronizing flash mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a daytime synchronization control method for a camera using a lens shutter.

Conventional technology Cameras that use a lens shutter use a daytime synchronization control method that starts the shutter opening operation, then starts the shutter closing operation when the integrated amount of light transmitted through the lens reaches the appropriate exposure amount, and simultaneously fires the strobe at full capacity. It is used.

Problems to be Solved by the Invention However, in the above-mentioned method, processing is not performed in accordance with the brightness of the peripheral area of the subject, so it is difficult to obtain an appropriate amount of exposure for the subject image.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides that the integral amount of light transmitted through the lens and shutter after the start of the shutter opening operation, or the integral amount of light that changes equivalently, is determined by the shutter opening operation. When the strobe light emission reaches a first predetermined value set as a function of the elapsed time after the start, the strobe light emission is started, and the integral amount is set as a second predetermined value.
When the shutter speed reaches a predetermined value, the shutter starts closing and the flash stops emitting light.

By means of this method, proper daytime synchronization becomes possible regardless of the brightness of the surrounding area of the subject.

Embodiment FIG. 1 is a block diagram for explaining a daytime synchronization control method according to an embodiment of the present invention.

The reflected light from the subject 1 passes through a lens 2, a shutter that also serves as an aperture (lens shutter) 3, and a half mirror 4, and then reaches an imaging unit 5.
image is formed. Further, a part of the reflected light from the half mirror 4 enters the photometry section 6, and the light that changes equivalently to the amount of light incident on the imaging section 6 is photometered. Information converted from light into electrical signals by the photometer 6 is input to an integrating circuit 7, and its integrated output 8 is sent to the first .
It is input to the second comparison circuits 9 and 1o. The first comparison circuit 9 compares the integral output 8 with a first predetermined value 12 that is less than or equal to the appropriate exposure amount 11, and the second comparison circuit 10 compares the second predetermined value 13 that is set at or near the appropriate exposure amount. Compare the integral output 8 and obtain the 1st. The second detection outputs 14 and 15 are input to the CPU 1e which is in charge of overall control.

The timer 17 is reset by a reset pulse 18 that resets the integral output 8 of the integral circuit 7, and its output is
The predetermined value 12 is used as the address of the ROM table 19 to be created.

The shutter and drive circuit 19 receive an opening command 2 from the CPU 16.
0. The shutter 3 is opened and closed according to the closing command 21.

The strobe light emission control circuit 22 controls the light emission from the CPU 16.
A light emission pulse 25 having a width corresponding to the interval between the N pulse 23 and the light emission OFF pulse 24 is output, and the strobe 26 is dimmed. Further, the light beam 27 is emitted toward the subject 1.

The mode selector switch 28 is a switch for switching between a daytime synchro mode 29 and a normal mode 30, and its mode signal 31 is input to the CPU 16, and a release pulse 32 that requests exposure is similarly input to the release switch 33. be done.

FIG. 2 is a waveform diagram showing waveforms of various parts of the block diagram shown in FIG. This waveform diagram shows the mode selector switch 28.
shows the case where the daytime synchronization mode 29 is selected, and the normal mode 30 is omitted because it has no direct relation to the present invention.

When the release pulse 32 is input to the CPU1e, the CPU
16 outputs a reset pulse 18 to reset the integral output 8 and timer 22.

Next, the CPU 1s outputs an opening command 2o and starts an opening operation in which the opening amount 36 of the shutter 3 increases as shown in the figure. Therefore, the first predetermined value output from the ROM table 19, which is addressed by the integral output 8 and the output of the timer 17, also increases as shown in the figure, and when the integral output 8 reaches the first predetermined value 12, the first detection output 14 is obtained, the CPU outputs the light emission ON pulse 23, and the strobe 26 starts emitting light. During this light emission period, the increase in the exposure amount of the imaging section 6 becomes large, so the integral output 8
changes as shown in the figure, and when it reaches a second predetermined value 13 set at or near the appropriate exposure, a second detection output 16 is obtained. Upon receiving this output, the CPU 16 outputs a light emission OFF pulse 24 to stop the strobe 26 from emitting light, and also outputs a close command 21 to close the shutter 3 and complete the exposure in the daytime synchro mode.

Daytime synchronization is a method to prevent the subject image from being exposed darkly when the brightness of the surrounding area is higher than that of the subject 1, but there are cases where the elapsed time until the first detection output 14 is obtained is short. Since the brightness of the surrounding area is high and low when it is long, the first predetermined value 12 becomes smaller as it approaches the opening command 18 as shown in the figure, that is, the luminance period of the strobe 260 is lengthened and the integral amount of the luminous flux 27 is increased. The camera is configured so that the exposure of the subject image and its surroundings is harmonized.

The photometry pattern of the photometry section 6 has a larger area in the center of the imaging section 5,
Center-weighted metering is normally performed with less exposure to the periphery, but the fact that the gain of the photometer 6 differs depending on the ratio between the center and the periphery must of course be corrected, but in addition to this correction, the following Make corrections.

Figure 3 shows the case where the photometric ratio between the center and the periphery is made the same in each case when the brightness of the center and the periphery is the same, the periphery remains unchanged, and the brightness of the center is low. , is a principle explanatory diagram showing how the integral value of the photometry output differs when the central part is concentrated compared to the peripheral part.

As is clear from the figure, when the elapsed time until the first detection output 14 is obtained is the same, if the ratio of photometry in the central area to the peripheral area is high, the brightness in the peripheral area will be high, and in the opposite case, it will be low. Therefore, in the former case, the first predetermined value 12 is set smaller than in the figure, and in the latter case, it is set larger to obtain a strobe light flux 27 that matches the brightness of the peripheral area.

In the above description, the lens measures the light that has passed through the shutter 3, but the same operation can be performed by measuring the light that changes equivalently.

With the configuration described above, proper daytime synchronization is possible regardless of the brightness of the peripheral area of the subject.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining a daytime synchro control method according to an embodiment of the present invention, FIG. 2 is a waveform diagram thereof, and FIG. 3 is a diagram illustrating its principle. 1...Subject, 3...Shutter, 6.
...Imaging section, 6...Photometering section, 8...
... Integral output, 9... First comparison circuit, 1o.
...Second comparison circuit, 12.Old..First predetermined value, 13.....Second predetermined value, 16.Old..CPU
. 17...Timer, 18...ROM table, 19...Shutter drive circuit, 2o/old/
・Open command, 21...Close command, 22...
... Strobe light emission control circuit, 25 ... Light emission pulse, 26 ... Group strobe, 38 ... ROM table output, 39 ... ROM table output, 4
o...Third predetermined value. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] A first predetermined value, in which the integrated amount of light transmitted through the lens and shutter after the start of the shutter opening operation, or equivalently changing light, is set as a function of the elapsed time after the start of the shutter opening operation, which is less than the appropriate exposure. When the value is reached, the strobe starts firing, and when the integral amount reaches a second predetermined value set at or near the appropriate exposure, the shutter close operation is started and the strobe stops firing. Medium synchro control method.