| 摘要 |
PURPOSE:To execute auto-focusing of both a regular distance range and a macro-area, by changing a moving range of a master lens position by opening or closing a push-button switch. CONSTITUTION:An image to be photographed, which is made incident to a zoom lens 1 becomes a video signal in a camera circuit 2, and is inputted to a focal quantity detecting circuit 3. The circuit 3 outputs the quantity of a high band frequency component of the video signal to a difference detecting circuit 4 at every period of one sheet of picture. By an output of this circuit 4, a motor driving circuit 5 is controlled, and a focusing structure of the lens 1 is moved by a motor 6. In this state, in case when the auto-focusing operation is executed within a regular distance range by a push-button switch 10, the moving range of a position of the lens 1 for covering the regular distance range can be set to a small value by setting the focal distance of the lens 1 to the minimum. Subsequently, in case of opration as an auto-focusing device of the macro-area, by the switch 10, the moving range of the lens 1 of a moving range calculating circuit 8 is set to a range within which the focal distance becomes the maximum. In this way, auto-focusing up to the shortest distance can be executed. |
