| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens which has comparatively high variable magnification, is compact, attains low cost and is most suitable for a lens shutter camera or the like. SOLUTION: In the zoom lens which has a positive first lens group and a negative second lens group in order from an object side and which performs variable magnification by changing air spacing of respective lens groups, the first lens group comprises a positive lens, a negative lens and a positive lens from the object side and the second lens group comprises a positive lens and a negative lens from the object side. Further in an optical system, average refractive index of all positive lenses, average refractive index of all negative lenses and focal length of the first lens group respectively satisfy predetermined criteria. COPYRIGHT: (C)2005,JPO&NCIPI
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