Exposure timing circuit for automatic photoflash camera - has potentiometer adjustment to set, or alter exposure time, with manual override

摘要

The automatic photo flash control for a camera has the reflected light from the object monitored and the signal compared with a reference signal calculated from the exposure details and e.g. film speed. This generates a timing signal for the exposure speed. The control also provides a signal to indicate that the photoflash is ready. A manual override is provided to set a determined exposure speed, whose signal is fed into the comparator and operates the exposure irrespective of the lighting conditions. No additional circuitry is required, other than a potentiometer operated by the manual control. This provides a manual exposure speed, or modulates the automatic exposure speed.