| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which is advantageous in terms of miniaturization when it is collapsed, and easily secures optical performance even when a variable power ratio, brightness and an angle of view are secured, and an imaging apparatus using the same. SOLUTION: The zoom lens includes, in order from an object side, a first group having negative power, a second group having positive power, a third group having negative power and a fourth group having positive power. When fw is set as the focal length of a zoom lens entire system at a wide angle end, ft is set as the focal length of the zoom lens entire system at a telephoto end, and a middle state is set to any zoom state where the focal length of the zoom lens entire system is from 0.9×√(fw×ft) to 1.05×√(fw×ft), the third group G3 satisfies a conditional expression (1):Δ3G(s)/fw≤0 in any middle state. Here,Δ3G(s) is a difference of a position in a zoom state near the middle to a position at the wide angle end of the third group. As to a sign, a positive sign shows a direction to advance to the object side, and a negative sign shows a direction to advance to an image side. COPYRIGHT: (C)2009,JPO&INPIT
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