| 摘要 |
PURPOSE:To always ensure a proper exposure, by varying the constant of an exposure calculating circuit for a prescribed period of time at an optional time point within the exposure time and producing an exposure end pulse in anticipation of a mechanical time delay of the shutter. CONSTITUTION:A shutter 24 is opened when a release button 26 is pushed, and at the same time a synchronous signal is produced. Then a diaphragm 40 is removed out of the optical path of a light source. When the synchronous signal is fed to a timer 58, a pulse is produced from the timer 58 for a prescribed time duration Tp during which the mechanical operation delay is compensated for a light source shutter 42 and with a prescribed time delay corresponding to the mechanical operation delay of the diaphragm 40. As a result, a switch 60 is opened for the time Tp. An integrating circuit 72 integrates previously the voltage signal corresponding to an overexposure and according to the mechanical delay of the shutter 42. In such constitution, an output pulse is produced from a level detector 86 in anticipation of the excessive photographing light. Thus a proper exposure is always assured for a film 20. |
