| 摘要 |
<p>This specification discloses a photoflash circuit for modulating the flash output of a photoflash device in accordance with the focus setting of a camera. The circuit includes an energy storage device, a triggering circuit to supply the energy to the photoflash device and an energy dissipating resistor in series with the flash tube to limit its light output. The circuit includes a control means comprising an electronic switching means to shunt the energy dissipating resistor out of the photoflash device circuit to increase the light output from the flash tube and a timing circuit to produce a triggering signal to energize the switching means. The timing circuit includes an adjustable resistor mechanically coupled to the camera focus controls for varying the triggering time of the switching means and the time the resistor remains in the flash tube circuit.</p> |
