| 摘要 |
PROBLEM TO BE SOLVED: To provide a new zoom optical system for projection that can achieve a wider angle of view.SOLUTION: A zoom optical system for projection has six or seven lens groups and an aperture stop, and has a first lens group G1 to a sixth lens group G6 or the first lens group G1 to a seventh lens group G7 arranged in order from an enlargement side to a reduction side. The first lens group has a negative refractive power; a second lens group has a positive refractive power; a third lens group has a negative refractive power; a fourth lens group has a positive or negative refractive power; a fifth lens group has a positive refractive power; and the sixth or seventh lens group arranged closest to the reduction side has a positive refractive power. In the variation of magnification from the wide angle end to the telephoto end, the first lens group and the lens group closest to the reduction side are fixed and the rest of the lens groups move therebetween. |
