| 摘要 |
PURPOSE:To implement excellent auto focus operation by setting properly a range finding frame in response to the content of an object. CONSTITUTION:A contrast component of a video signal Y is fed to a hold circuit 8, in which a range finding frame is set by a controller 7. The hold circuit 8 gives a maximum value (evaluation value) in the range finding frame and data of a position of a screen at which the evaluation value is obtained to the controller 7. The range finding frame for a large and a small frame is set and a lens 1d is moved by a very small distance (DELTAx) to detect a change (DELTAy) of the evaluation value. When the change (DELTAy) in the evaluation value is detected for the small frame, the small frame is used for the range finding frame. When the change (DELTAy) is not detected in both small and the large frames, no focus adjustment is implemented. When the change (DELTAy) is detected in a large frame only, while the focus is adjusted based on the evaluation value of the large frame, the frame excluding the position at which the evaluation of the large frame is obtained is set, and when the change (DELTAy) is detected in the frame and it is not coincident with the change (DELTAy) of the large frame, a frame in which the evaluation value is obtained at a more middle position in both frames is used for the range finding frame. |
