| 摘要 |
PURPOSE:To perform a focusing operation with higher accuracy by integrally displacing all lens groups along an optical axis, after completion of the focusing operation, in corresponding relation to an optical distance error between all lengs groups retained by a lens retainer means during the focusing operation and a photographing means. CONSTITUTION:On the basis of a photograph object distance data calculated from the output signal of a distance measuring means 15, the rotational direction and quantity of a focusing motor 12 are calculated by a system controller 16, or are selected from the previously stored data, whereby a drive signal is outputted to a motor drive circuit 17. As a result, the motor 12 starts rotation. With the rotation of the motor 12, a retainer frame 3 is rotated via a gear 13, whereby the retainer frame 3 and a first lens group 1 are displaced along an optical axis through helicoid coupling thereof with a moving member 4. Thus, focusing is performed. Next, the respective positions of the first lens group 1 and second lens group 2 having a high focus sensitivity are sensed by high resolution position sensors 20, 21. Subsequently, the amount of error of the focusing plane, as measured along the optical axis, corresponding to the amount of error of each lens group as measured from a specified position, is determined. Then, a fixed cylinder 8 is driven by the amount of error toward the optical axis to cause focusing operation with high accuracy. |
