| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact low-cost autofocus adapter which can be attached to existing photographic lenses in general. SOLUTION: The autofocus adapter is equipped with: a photographing side adapter optical system 10A arranged on the optical axis Z1 of a photographic lens 20 when it is attached; and a focus state detection side adapter optical system 10B arranged on an optical axis Z2 different from the optical axis Z1 of the photographic lens 20 when it is attached. The photographing side adapter optical system 10A has: a light dividing prism P1 dividing subject light passing through the photographic lens 20 to subject light for photography and subject light for focus state detection; a first lens group L1 having negative power as a whole and arranged on an object side relative to the light dividing prism P1; and a second lens group L2 having positive power as a whole and arranged on an image side relative to the light dividing prism P1. The focus state detection side adapter optical system 10B has a positive lens group L3 having the same lens constitution as the second lens group L2 in the photographing side adapter optical system 10A. COPYRIGHT: (C)2008,JPO&INPIT |
