| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-variable-power zoom lens which is made small in collapsing thickness and has high performance, and an imaging apparatus using the same. SOLUTION: The zoom lens constituted of four groups is equipped with a first group G1 having positive refractive power, a second group G2 having negative refractive power, a third group G3 having positive refractive power, and a fourth lens group G4 having positive refractive power. In the case of variable power from a wide angle end to a telephoto end, the first group G1 to the fourth group G4 are each moved so that an air space between the first group G1 and the second group G2 may be increased, an air space between the second group G2 and the third group G3 may be decreased, and an air space between the third group G3 and the fourth group G4 may be increased. The first group G1 includes one negative lens and one positive lens in order from an object side, the second group G2 includes two negative lenses and one positive lens in order from the object side, and the third group G3 includes four or less lenses. The zoom lens satisfies a conditional expression; 0.3<f<SB>3</SB>/f<SB>4</SB><1.4, and n<SB>d</SB>≥1.90, wherein f<SB>3</SB>and f<SB>4</SB>are the focal distances of the third group and the fourth group respectively, and n<SB>d</SB>is a refractive index at the d-line of the material of the negative lens of the first group. COPYRIGHT: (C)2011,JPO&INPIT
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