| 摘要 |
PURPOSE:To convert a defocusing quantity into a driving quantity with simple constitution by finding information of a deviation in the focusing point of a focus lens group in the direction of the optical axis first and then finding the driving quantity of the focus lens group when the defocusing quantity is converted into the driving quantity of the focus lens group. CONSTITUTION:This device is provided with an information detecting means 1 which detects the quantity of the deviation between the image formation plane of subject light passed through a photographic lens 5 and a film surface and the direction of the deviation, an extension quantity detecting means 4 which detects the quantity of the extension of the focus lens group of the photographic lens from a reference position, and a focus group deviation information determining means 2 which determines the quantity and direction of the deviation in the extension quantity in the optical axis direction about the focusing position of the focus group according to the deviation information. Then an arithmetic means 3 determines a driving quantity required for the focusing of the focus group from the output of the extension quantity detecting means 4 and the output of the focus group deviation information determining means 2. Consequently, the deviation in focus can be converted into the driving quantity with the simple constitution. |
