| 摘要 |
PURPOSE:To improve focusing accuracy while the titled device is in zooming by fixing a focus detecting time in zooming, calculating the driving speed of a correction lens and updating the driving speed every approximately fixed time. CONSTITUTION:When a zooming key 11 is turned to the wide angle side at time t0, a variable power lens 2 is moved and the correction lens 3 is driven at a reference speed selected by a microprocessor 10. The processor 10 executes focus detecting operation on the basis of CCD integrating information corresponding to the luminance of an object to obtain a defocused distance D1 at time t1. Then, the processor 10 changes the speed of the lens 2 on the basis of a distance D0 obtained immediately before starting zooming and the obtained speed is held up to time t2. At time t2, information D2 is obtained, the speed of the lens 2 is selected on the basis of D2-D1, and thereafter the driving speed is similarly updated every approximately fixed time. In said constitution, focusing can be always maintained also in zooming without using a coupling material such as a cam ring, the correction lens can be driven at an approximately ideal speed on the basis of distance information obtained every fixed period and focusing accuracy in zooming can be improved. |
