| 摘要 |
<p>PURPOSE:To prevent exposure from being affected by a subject brightness value by irradiating a photodetecting element with both subject light and light from a light emitting element superposedly and storing its quantity of light and comparing the quantity of light that is irradiated to the photodetecting element with the stored quantity of light after the start of exposure and monitoring the aperture area rate of a subordinate stop aperture. CONSTITUTION:The rays of light from LED 26 is superposed upon the subject light during strobe photography to irradiate an SPD 22 and the output of an optical amplifier 30 when the aperture area rate Ss of the subordinate stop aperture is, for example, 0.5 is stored in when shutter blades 3 and 4 begin to open a main aperture 1a, the aperture area Ss of the subordinate stop aperture also increases associatively and the output value of the optical amplifier 30 also increases. Then, a comparison part 37 compares the output value of the optical amplifier 30 with the output value of an arithmetic part and applied a trigger signal to a strobe circuit 38 when the both coincide with each other to let an internal xenon discharge tube, etc., emit light. Consequently, a strobe is synchronized at the timing where an optimum F value is obtained.</p> |
