Automatic focusing system for use in cameras having zoom function.

摘要

There is disclosed herein an automatic focusing system including an optical system having a focus lens, a zoom lens and an image pickup device for converting a light beam from an object into a corresponding electrical signal. The automatic focusing system comprising a filter for deriving a predetermined component of the electrical signal, a detector for detecting a focus voltage of the predetermined component and a drive circuit for moving the focus lens and zoom lens in the directions of the optical axis of the optical system. Also included in the focusing system is a control unit which moves the focus lens through the drive circuit to bring the focus lens into the focus position and, when the focus position is not taken in a predetermined movable range, moves the zoom lens toward the wide-angle side before again moving the focus lens so as to take the focus position.