| 摘要 |
PROBLEM TO BE SOLVED: To provide a finder adapter which has a continuous diopter adjusting function, which is small in size and which has good optical performance. SOLUTION: A finder adapter Ga is to be mounted at the back of an eyepiece optical system Gf in a finder optical system and comprises a first lens group G1 having negative refractive power and a second lens group G2 having positive refractive power in the successive order from an object side. The finder diopter is continuously corrected by moving the first lens group in the optical axis direction and the following conditional equations (1), (2) and (3) are satisfied, i.e., (1) 2.5<f1+f2<5.0 (2) 150<¾f1xf2¾<600 and (3) ¾f1/f2¾>0.8 where f1 is the focal distance of the first lens group and f2 is the focal distance of the second lens group. COPYRIGHT: (C)2005,JPO&NCIPI
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