PROGRAMMIERTER BLENDENVERSCHLUSS

摘要

In a program shutter including a forwardly/reversely rotatable step motor for opening and closing a shutter blade to effect automatic exposure, a drive pulse number and an interpolation quantity are set in first and second counters. A step drive pulse is generated by the first counter to start opening the sectors. After a final pulse is generated, the second counter is started, and at the timing when the time corresponding to the interpolation quantity is elapsed, the step motor is reversely rotated thereby to fractionate a gap between steps and obtain a proper exposure quantity.