| 摘要 |
PURPOSE:To shorten time required for focusing as compared to a conventional case and to attain rapid focusing by immediately stopping the movement of a focusing lens at a time when the focusing lens reaches a just focusing position. CONSTITUTION:A prescribed high frequency component of a video signal S1 obtained from an image pickup means 7 is extracted as a focus voltage E and the focus voltage E in each point based upon the movement of the focusing lens 1 is sampled to find out a differential voltage DELTAE between two points. The focusing lens 1 can be converged on a just focusing position P by controlling the movement of the lens 1 on the basis of the differential voltage DELTAE. The differential voltage DELTAE obtained when the lens 1 reaches the position P is previously found out, and when each differential voltage becomes equal to the set value, the movement of the lens 1 is stopped. Consequently, focusing can be rapidly and surely attained. |
