| 摘要 |
PURPOSE:To facilitate the focusing by executing smoothly the focusing operation extending from a closest focusing distance to infinity, and also, lowering the sensitivity of focusing in a prescribed range in which focusing is desired in accordance with necessity. CONSTITUTION:By a mode changeover switch, a normal mode and a fine adjustment mode can be switched and used suitably. That is, at the time of normal mode, a voltage signal from a potentiometer 12 is outputted directly to a focus mechanism and a focus lens is moved by being driven electrically. On the other hand, at the time of fine adjustment mode, the voltage signal from the potentiometer 12 is outputted to the focus mechanism through a sensitivity variable circuit. By this sensitivity variable circuit, within a prescribed front-element moving range corresponding to the voltage signal at the point of time switched to the fine adjustment mode, gain of the voltage signal inputted thereafter becomes small, and also, outside of the prescribed front-element moving range, the gain of the voltage signal inputted thereafter becomes large. |
