| 摘要 |
PURPOSE:To execute accurate measurement by deciding the range of a luminous flux made incident on each photoelectric converting element in a relay optical system when a frequency component is extracted based on the output from the photoelectric converting element and the focus detection of an optical system is executed. CONSTITUTION:The luminous flux transmitted through a quick return mirror 3 is reflected by a sub mirror 4, and the same image as the image on an image pickup surface 5 is formed on a planned image-forming surface 6. The image formed on a position 16 a specified amount away from the planned image- forming surface 6 to an object side and the image formed on the position 17 the specified amount away from the planned image-forming surface 6 to the photoelectric converting elements 14, 15 side are respectively image-formed on the photoelectric converting elements 14, 15 through a condenser lens group 7, mirrors 8, 9, a brightness diaphragm 10, and an image-reforming lens group 11, the frequency component is detected by each output, and a focusing point is found. And the range of the luminous flux made incident on the respective photoelectric converting elements 14, 15 is decided in the relay optical system through the brightness diaphragm 10. |
