| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rear-focus system 4-group type zoom lens which is miniaturized in terms of the whole lens system, and which has high optical performance, irrespective of high variable power ratio, and to obtain an optical apparatus using the zoom lens. SOLUTION: The zoom lens includes, in order from an object side, a 1st lens group having positive refractive power, a 2nd lens group having negative refractive power, a 3rd lens group having positive refractive power and a 4th lens group having positive refractive power, The power variation from a wide angle end to a telephoto end is performed by shifting the 2nd lens group to an image plane side, and the image plane fluctuation due to the power variation is corrected by shifting the 4th lens group, provided that the light effective diameter of the lens surface closest to the object side in the 1st lens group is expressed byϕ1F, and the light effective diameter of the lens surface closest to the image side in the 1st lens group is expressed byϕ1R, a conditional inequality of 1.47<ϕ1F/ϕ1R<1.77 is satisfied. COPYRIGHT: (C)2006,JPO&NCIPI
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