| 摘要 |
PURPOSE:To maintain the specified moving speed of a focusing lens and to allow stable operation by changing the zooming speed according to focal distances when zooming is executed with the rear focus zoom lens. CONSTITUTION:Regions f1, f2, f3 are set and the distance where the focusing lens is required to move is trisected at the time when the focal distance moves from a W end to a T end at 1.2m shortest distance so that the moving speed of the focusing lens is kept constant in correspondence to the change in the focal distance. A microcomputer 8 receives the signal from a potentiometer 2 and outputs the signal to rotate a zoom motor 1 at a high speed at the focal distance corresponding to the region f1. The motor is rotated at a middle speed in the region f2 and at a low speed in the region f3. The focusing lens moves at the constant speed when the focal distance is changed by zooming the lens in this way and, therefore, the stable operation is assured. |
