Automatic focus adjustment for optical system

摘要

A follower region adjustment device (11-20) variably adjusts object follow regions at a signal scan plane. A calculator (21-40) determines the difference of data over the difference of a predetermined signal component of an image signal between an internal and an external part of an object follower region selected by the adjustment device. This difference data indicates a sharpness adjustment parameter. An ascertaining device determines the position of an object in the scan corresp. the calculated difference and a sharpness adjuster displaces the sharpness measurement region to the position of the object on the scan plane by means of the ascertaining device. The adjustment device divides the region into n times m fields using each as a displacement parameter.