| 摘要 |
PURPOSE:To facilitate an automatic focus adjustment, by securing the shift of a photographing lens even in the pretravelling range at the outside of the range of a prescribed shift corresponding to the effective photographing distance range of a camera. CONSTITUTION:The barrel 2 of a photographing lens 1 is set at the short distance side smaller than the shortest photographing distance and detained by a detaining lever 4. When the lever 4 is pressed, a focusing detector starts its operation. Thus an electromagnet 6 is energized to hold a lever 5. When the lever 4 is further pressed, the engagement is disenaged between the barrel 2 and the lever 4. Thus the barrel 2 moves to the long distance side. When the focusing signal is delivered from the focusing detector, the energization of the magnet 6 is cut off. Then the right edge 5a of the lever 5 rises up by a supring to engage to a ratchet 2a, and the barrel 2 is locked. In such way, a position control system is realized for a photographing lens with a simple and assured operation. The shifting speed is stable by setting a pretravelling range to facilitate a focus adjustment. |
