| 摘要 |
PURPOSE:To put even a long-focus lens in accurate focusing operation by provid ing a position detecting device for a focus ring and abstracting a focus phase difference which is impossible in consideration of the position information of the detecting device. CONSTITUTION:An image of a subject is formed through an optical system on a photodetection part 30 which has plural pairs of photodetecting elements, and output analog signals of the photodetecting elements are led out and inputted as digital signal to a microprocessor 36 through an analog signal processor 32 and an A/D converter 34. A focus ring position detecting device 38 detects the current position of the focus ring and inputs it to the microprocessor 36. The microprocessor 36 performs focus phase difference detection arithmetic in consideration of the position information on the focus ring so that the focus phase difference which is impossible at some position of the focus ring, is obstracted, and a motor 42 for focal length control drives the focus ring on the basis of the arithmetic result. |
