| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens system of high variable power and high performance which has a variable power ratio of about five times to twenty times and a half-angle view at a wide angle end of about 35°or more, and is superior in compactness. SOLUTION: The wide-angle high variable power zoom lens includes a positive first lens group G1, a negative second lens group G2, a positive third lens group G3 and a positive fourth lens group G4. When zooming from the wide-angle end to the telephoto end takes place, at least the first lens group G1 and third lens group G3 move to the object side so that the interval between the first lens group G1 and second lens group G2 is increased, and an interval between the second lens group G2 and third lens group G3 is decreased. The zoom lens satisfies conditional expression (1), expressing the angle of view, conditional expression (2) expressing the variable power ratio, conditional expression (3) defining the refractive power of the first lens group G1; conditional expression (4) expressing the refractive power ratio of the second lens group G2 to that of the third lens group G3; and conditional expression (5) defining the proportion of the second lens group G2 to the third lens group G3 in variable power from the wide angle end to the telephoto end. COPYRIGHT: (C)2008,JPO&INPIT
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