| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens for projection whose entire length is made shorter without lowering optical performance. SOLUTION: This zoom lens 5 is constituted of five groups, that is, a 1st lens group 10 to a 5th lens group 50 having negative, positive, positive, negative and positive refractive power in order from a screen side. The position of the 5th lens group 50 is fixed, and the 1st lens group 10 to the 4th lens group 40 are relatively moved on an optical axis at the time of variable power. By moving the 1st lens group 10 at the time of variable power, the fluctuation of aberration caused with the variable power is restrained, and the entire length of the lens need not be made long.
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