| 摘要 |
PURPOSE:To perform reliable focus detection at any time even if the contrast distribution of an object is directional by setting two couples of area on a lens in two orthogonal directions and performing the focus detection in the two directions. CONSTITUTION:A visual field mask 2 which ha a cross opening is arranged on the front surface of a condenser lens 6 and the mask surface is set on the expected focal plane of a photographic lens 1 at a position equivalent to the film surface of a camera. A reprojection lens 8 forms the image of the surface of the visual field mask 2 on an image sensor 10. Images of the same part of the object are formed on X1 and X2, and the reprojection images on the X1 and X2 come closer to each other in a front-focus state and leave each other in a rear-focus state. For the purpose, the line image sensor 10 is arranged in such a direction that the X1 and X2 are put over the other; and the video signal of the object image on the X2 is shifted, bit by bit, to the video signal of the object image on the X1 through processing operation as to video signals and the quantity of shifting where the correlation between the video signals in the overlapping direction is maximum is detected. Further, Y1 and X2 are the same. |
