Supplementary electronic flash unit for photographic camera - has gating circuit switched between two modes by decision circuit responsive to uncovering of main flash for automatic intensity control

摘要

A capacitor (2) is charged from a voltage source (5) and discharged (4) through the flash tube (1) by a trigger circuit (15) incorporating a detector (17) of emission from the integrated flash unit. A photometer (7) operates an electronic swtich (3) to terminate the flash in dependence on the selected screening values (11) and the sensitivity of the film. The dual-mode timed gating circuit (12) between the photometer (7) and switch (3) operates on attainment of a predetermined min. quantity of light. ADVANTAGE - Correct exposure is achieved automatically over wider range of distances achievable with supplementary flash unit.