Method and apparatus for detecting focusing in an image pickup device

摘要

Apparatus for adjusting the focus of an optical system comprising an image pickup device providing an image detection plane where the image of an object is focused via the optical system to be adjusted and a circuit for processing the analog video signal provided by the pickup device to control the focus. The circuit comprises a means for forming a time and level shifted version for comparison with the unshifted analog video signal and means for shifting the focus to minimize the length of time during which this comparison exceeds a prescribed threshold level.