| 摘要 |
PROBLEM TO BE SOLVED: To provide a real image variable power finder capable of realizing a high variable power ratio exceeding four times while having compact size and high optical performance and an image pickup apparatus. SOLUTION: In the real image variable power finder provided with an objective optical system consisting of a 1st lens group G1 having positive refracting power, a 2nd lens group G2 having negative refracting power, a 3rd lens group G3 having positive refracting power, and a 4th lens group G4 having positive refracting power and capable of correcting variable power and diopter changes following the variable power by moving the 2nd and 3rd lens groups on an optical axis, the following conditional expressions (1), (2) are satisfied when Z2=β2t/β2w and Z3=β3t/β3w. The conditional expression (1) is Z2 Z3>4.0 and the conditional expression (2) is 0.60<¾f2¾/fw<1.00 (provided thatβ2w is horizontal power at the wide end of the 2nd lens group,β2t is horizontal power at the wide end of the 2nd lens group,β3w is horizontal power at the wide end of the 3rd lens group,β3t is horizontal power of the 3rd lens group, f2 is the focal distance of the 2nd lens group, and fw is a focal distance at the wide end of the objective optical system). COPYRIGHT: (C)2005,JPO&NCIPI
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