| 摘要 |
PURPOSE:To obtain a correct automatic dimming flash, by triggering only stand- by light emission, when a shutter release button is depressed to the first stroke position, in an automatic dimming flash device whose dimming level is controlled by the stand-by light emission. CONSTITUTION:To an electric power supply 1, a DC-DC converter 3 is connected through an electric power supply switch 2, and a photographing main discharge tube 13 and a range measuring subdischarge tube 7 are connected through rectifying diodes 4, 5. When a shutter release button which is not shown is a figure is depressed to the first stroke position. constant-voltage is applied to a terminal (a) through a shoe of a camera, and is applied to a comparator 51 through a buffer circuit 54. An output of the comparator 51 triggers a one-shot circuit 130 through an AND gate 128. Accordingly, a triggering circuits 8 is triggered, and stand-by light emission of the discharge tube 7 is started. In this case, since a light emission trigger signal is not applied to a synchro terminal C, dimming capacitors 58-60 are not operated, and prior to main light emission, an aperture value can be confirmed by LEDs 105-107. |
