| 摘要 |
PURPOSE:To prevent a motor driving member from sharp change of a driving speed by changing a restriction current value by a current restriction circuit in accordance with the mounting/dismounting of an additional optical system into the optical axis of a lens. CONSTITUTION:When a front type teleconverter or wide converter is fitted to the head part of a motor type lens structure, the fitting is detected by a sensor 5, a relay driving circuit 4 is actuated, a relay 3 is switched, and resistors R1, R2 are connected with each other in parallel. Consequently, the restriction current value of the current restriction circuit 10 is increased and the reduction of a control speed to be generated due to the increase of a motor load caused by the fitting of the additional optical system, e.g. the front type teleconverter or wide converter, to the head part of the motor type lens structure is not generated because of the increase of the current value, so that the motor driving member can be always controlled at an approximately constant driving speed independently of the use of the additional optical system. |
