| 摘要 |
PROBLEM TO BE SOLVED: To obtain a real image type variable power finder that can easily have a specified power variation ratio and makes it possible to observe an excellent finder image over the entire power variation range. SOLUTION: An object image formed through an objective system which has a power varying function and positive refracting power is inverted into an erect image through an image inversion optical system P and the erect image is observed in the variable power finder through an ocular system Le. In the variable power finder, the objective system 10 has three lens groups which are a 1st group L1 with positive refracting power, a 2nd group L2 with negative refracting power, and a 3rd group L3 with positive refracting power. When the power is varied from the wide-angle end to the telephoto end, the 2nd group L2 moves having a trace which is convex to an observation side, and the 3rd group L3 moves toward the object while decreasing the air gap formed with the 2nd group L2. The finder satisfies a condition of 1.0<m3/f3<2.0, where the difference in position of the 3rd group L3 at the telephoto end from the wide angle end is m3 and the focal length of the 3rd group L3 is f3. COPYRIGHT: (C)2006,JPO&NCIPI
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