| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens which has a wide field angle and little variation in color aberration upon zooming and gives good optical performance over the entire zoom range.SOLUTION: The zoom lens includes, successively from an enlargement conjugate side to a reduction conjugate side, a first lens group that is immobile upon zooming and has a negative refractive power, a plurality of movable lens groups, and an immobile final lens group having a positive refractive power. In the plurality of lens groups, a final movable lens group disposed closest to the reduction conjugate side has a positive refractive power and moves toward the enlargement conjugate side upon zooming from a wide angle end to a telephoto end. The final movable lens group includes one or more cemented lenses; the final movable lens group includes one or more negative lenses and one or more positive lenses; and an average refractive index nn and an average Abbe number &ngr;n of the material for one negative lens in the final movable lens group, and an average refractive index np and an average Abbe number &ngr;p of the material for one positive lens in the final movable lens group are appropriately determined. |
