| 摘要 |
PURPOSE:To adjust exposure even by a photographer as well with a simple configuration by providing a bias circuit for impressing a prescribed bias voltage at a gain control terminal corresponding to the changeover of a switch. CONSTITUTION:When it is desired to make an object bright, the photographer changes a switch SW1 to a position B (backlight correction mode). At this time, an iris lamp 11 amplifies the output signal of a window circuit 6 with a gain-6dB. As a result, the control signal of a comparator output changes from a low level to a high level, and a driving IC 5 decelerates the speed of a shutter pulse. Therefore, the object can be made bright, and visibility can be improved. Thus, by operating the switch SW1, the photographer can manually adjust exposure. On the other hand, since only a bias circuit 12 equipped with the switch SW1 is added to a conventional general electronic iris circuit, it can be easily constituted. |
