FOCUS DETECTING DEVICE AND OPTICAL EQUIPMENT USING THE SAME

摘要

PROBLEM TO BE SOLVED: To have sufficient operation limit subject luminance characteristics and to perform focus detection at an arbitrary point in a photography range with high precision by properly setting the respective elements of an optical means for focus detection provided on the image plane side of an objective (photographic lens). SOLUTION: A 1st reflecting mirror 4 is an elliptic mirror and a 2nd reflecting mirror 6 and a 3rd reflecting mirror 10 are plane mirrors. The light incidence side of a reimaging lens block 9 is formed in a single concave spherical surface having its center on the optical axis of the objective deflected by the 1st reflecting mirror 4 and the projection side is formed in two couples of convex lens surfaces 9e to 9h which are eccentric in the mutually opposite directions. Further, the center of the concave spherical surface is set in almost equal to the paraxial image formation plane 5 of the objective lens formed by the 1st reflecting mirror 4 and the centers of two pairs of lens parts 9e to 9h are set in almost equal to nearby a stop aperture 8. The power of the lens is thus arranged to enable high-precision focus detection in plural areas in a photography range over a wide wavelength range.