| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detection optical system that includes a small number of components, has a short full length, is compact, and detects the focus without causing a focus detection error by reducing the variation between the cores of separator lenses by ambient temperature variation. SOLUTION: This focus detection optical system includes a condenser lens 10 positioned behind an expected image plane 11 of a photographing lens, an auxiliary lens 20 positioned behind the condenser lens along the optical axis thereof, and a separator lens 30 including at least a pair of lenses behind the auxiliary lens. The focus detection optical system images an object image on the expected image plane on a pair of areas on a sensor 40 again. The auxiliary lens is one resin-made lens having a negative refractive power. The separator lens is a glass lens or a hybrid lens consisting of a glass substrate and the resin having a curved surface. Each surface of the auxiliary lens establishes a predetermined conditional expression related to the imaging magnification. COPYRIGHT: (C)2011,JPO&INPIT |
