| 摘要 |
PROBLEM TO BE SOLVED: To obtain a compact zoom lens which is suitable for an imaging system using a solid-state imaging device, has a reduced number of lenses, has small diameter and high variable power ratio, and is excellent in optical performance, and to provide an optical apparatus using the zoom lens. SOLUTION: The zoom lens comprises, in order from an object side, first, second, third and fourth groups having positive, negative, positive and positive refractive power. When varying power from a wide angle end to a telephoto end, the groups move so that space between the second group and the third group is decreased and space between the third group and the fourth group 4 is increased. When varying the power from the wide angle end to the telephoto end, the first group moves on a part of a locus which is convex to an image side. The second lens group has a negative lens and a positive lens, and the third group has an aperture stop, a positive lens 31 and a negative lens 32. A radius of curvature R32a of an object-side lens surface of the lens 32, a radius of curvature R32b of an image-side lens surface thereof, a focal length f3 of the third group, and a focal length f32 of the lens 32 are properly set, respectively. COPYRIGHT: (C)2011,JPO&INPIT
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