| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and bright zoom lens of which F-number at the telephoto end is 3.5 or less and of which zoom ratio is approximately 3. SOLUTION: The zoom lens comprises a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power which are arranged successively from the object side. The zoom lens performs zooming from a wide-angle end to a telephoto end by moving the second lens group G2 to the image surface side, corrects the image point position resulting from the zooming by moving the fourth lens group G4, wherein the first lens group G1 is formed by a first lens 1 having negative refractive power and a second lens 2 having positive refractive power, and the focal distance fw at the wide-angle end in the lens system, and the focal distance fG1 of the first lens group G1 satisfy the conditional expression 0.07<fw/fG1<0.15. Thereby, the compact and bright zoom lens of which F-number at the telephoto end is 3.5 or less is obtained. COPYRIGHT: (C)2008,JPO&INPIT
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