| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens which is constituted of three groups having negative/positive/negative power and consists of three or four lenses as a whole, and whose aberration is excellently corrected while realizing miniaturization, lightweight and the reduction of the cost. SOLUTION: The zoom lens is constituted of a 1st negative lens group G<SB>1</SB>consisting of one or two lenses, a 2nd positive lens group G<SB>2</SB>consisting of one lens and a 3rd negative lens group G<SB>3</SB>consisting of one lens in order from an object side, and the 2nd lens group G<SB>2</SB>and the 3rd lens group G<SB>3</SB>are moved on an optical axis at the time of zooming. The zoom lens satisfies following conditional expressions (1) to (3). The conditional expression (1) is 1.9<f<SB>t</SB>/f<SB>W</SB><2.6. The conditional expression (2) is 4.0<TCL<SB>W</SB>/f<SB>W</SB><5.3. The conditional expression (3) is 0.7<Bf<SB>W</SB>/f<SB>W</SB><1.3. Provided that f<SB>t</SB>is the focal distance of an entire system at a telephoto end, f<SB>W</SB>is the focal distance of the entire system at a wide angle end, TCL<SB>W</SB>is a maximum conjugate distance, and Bf<SB>W</SB>is back focus length in a paraxial state in the conditional expressions. COPYRIGHT: (C)2005,JPO&NCIPI
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