| 摘要 |
PURPOSE:To determine the moving quantity of a focusing lens in a variable power optical system with good accuracy by detecting the out-of-focus quantity of the variable power optical system by a focus detector provided in an optical device on a camera side, then making prescribed computations by the utilization of the out-of-focus quantity of the variable power optical system and the intrinsic various optical numerical values provided to the memory part of the variable power optical system. CONSTITUTION:A zoom position detecting part 41 and the memory part 3 are provided on a part of the variable power optical system. The zoom position is detected by the zoom position detecting means 41. The prescribed coeffts. to be used by the focus detector 2 in the camera body 10 mounted with the variable power optical system are previously stored in the memory part 3 and are transmitted, at need, to the inside of the camera body 10 where the prescribed computations are made from the out-of- focus quantity detected by the focus detector 2 and the prescribed coeffts. and the moving quantity of the focusing lens is thereby determined with good accuracy. The variable power optical system which is capable of moving the focusing lens to the prescribed position with the smaller number of times than in the conventional method and allows automatic focusing with high accuracy is thus obtd. |
