Optical imaging system with movable solid-state imaging device for focus control

摘要

An image pickup optical system for use in a magnifying endoscope or the like in which focus control is effected by moving a solid-state image pickup device. When a simultaneous solid-state image pickup device is used, color shading is suppressed satisfactorily, and flare-preventing measures are taken satisfactorily. Further, the center of the field and the center axis of the endoscope are allowed to coincide with each other at a reduced cost. The optical system is capable of being focused at a plurality of object distances by moving a solid-state image pickup device. The optical system is provided with a field lens by which light rays whose incident angle varies in accordance with focus control are made telecentric.