| 摘要 |
PROBLEM TO BE SOLVED: To reduce the diameter of a front lens in size and shorten the entire length of a lens system in the direction of an optical axis while retaining high optical performance in a zoom lens. SOLUTION: The zoom lens includes four lens groups, which are the first lens group G1 to the fourth lens group G4. On zooming, the first lens group G1 and the third lens group G3 are fixed and the second lens group G2 is moved to zoom. The fourth lens group G4 is moved for correcting the position of an image plane and focusing accompanied by the zooming operation. The first lens group G1 includes three lenses which are negative, positive, and positive refractive powers. The second lens group G2 is composed of four lenses including a negative lens that has an aspherical face. The zoom lens satisfies conditional expression (1) 6.0<f1/fw<8.0 and (2) 0.10<H2f/fw<0.20, wherein f1 is the focal distance of the first lens group, fw is the focal distance of the entire system at a wide-angle end, and H2f is a distance on an optical axis from the object side face of a lens closest to the object in the second lens group to the object-side principal point of the second lens group. COPYRIGHT: (C)2010,JPO&INPIT
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