| 摘要 |
PURPOSE:To eliminate the need to measure a range and to extend an electronic flash photographic range by comparing the aperture value of a lens shutter with a photometric value at the time of electronic flash light emission and determining the quantity of light emitted by an electronic flash. CONSTITUTION:The lens shutter 2 is given a specific shutter speed and an aperture position with a signal from a CPU 1 and an encoder 3 outputs a voltage corresponding to the aperture value, so that the voltage is impressed to the negative terminal of a comparator 6 through a converting circuit 4. Then the CPU 1 sends a light emission start signal to an electronic flash control circuit 7 and a control signal to a photometric circuit 8 to open a switch 9, and a capacitor C is charged with the output of a light receiving element 10; and a photometric output voltage rises and is inputted to the positive terminal of the comparator 6 and compared with the voltage at the negative terminal. Then when both voltage becomes equal to each other, the control circuit 7 is turned off with a high-level output from the comparator 6, so that the light emission is stopped. |
