| 摘要 |
PURPOSE:To perform a high-precision and stable automatic focus control by changing the extent of aperture of stop part, which is provided in an auxiliary optical system for focus detection, in accordance with the focusing state to detect the focus of a main optical system and to discriminate the direction of the mismatching state. CONSTITUTION:The light from an object 1 is made incident to an image sensor 10 through the main optical system consisting of a focus lens part 2, a zoom lens part 3, a stop part 4, and a relay lens part 5. A part of the light is led to the auxiliary optical system by a beam splitter prism 8. The suxiliary optical system controls the focus of the focus lens part 2 and consists of a system from a stop part 21 to a focus detecting sensor part 30. The output of the focus detecting sensor 30 is inputted to an automatic focus control part 40, and a degree of focusing is detected by a contrast ratio, and a control signal is outputted. The auxiliary optical system is so controlled that a large extent of aperture is given to the stop part 21 in case of mismatching state and a small extent of aperture is given to the stop part 21 in case of approximation to the focus. |
