| 摘要 |
PROBLEM TO BE SOLVED: To provide a bending variable power optical system having a first positive group having a reflection member and fixed when varying power, and a second group moving when varying power, and made high in variable power and short in entire length, and a device such as an imaging apparatus using the same. SOLUTION: The bending variable power optical system has the first positive group G1 fixed when varying power, and the second negative group G2 moving when varying power. The first positive group G1 has a negative single lens, the reflection member P and a positive lens group in order from an object side. The optical system satisfies a condition (1): 1<f<SB>1</SB>/¾f<SB>2</SB>¾<2.8, for arranging the position of an entrance pupil so as to restrain the variation thereof, a conditional expression (2): 0.1<f<SB>1</SB>/f<SB>t</SB><0.65, concerning the focal length of the first group G1 and a conditional expression (3): 1.8<R<SB>2</SB>/f<SB>w</SB><10, for adjusting the shape of the negative single lens of the first group G1, wherein f<SB>1</SB>is a focal length of the first position group having a reflection surface, f<SB>2</SB>is a focal length of the second negative group , R<SB>2</SB>is an on-axis radius of curvature of an image-side surface of the negative lens at the outermost object side of the first position group, f<SB>w</SB>is a focal length of the entire system at a wide-angle end and f<SB>t</SB>is a focal length of the entire system at a telephoto end. COPYRIGHT: (C)2007,JPO&INPIT
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