| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens and a projecting optical system using the same capable of projecting picture information displayed by a liquid crystal display element on a screen surface while maintaining high optical performance. SOLUTION: A variable power optical system is provided with a 1st lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, a fifth lens group and a sixth lens group having positive refractive power in order from a first conjugate point side at a longer distance; and three or more lens groups out of the second to the fifth lens groups are moved in the case of varying power from a focal distance at a wide-angle end to a focal distance at a telephoto end and the first lens group and the sixth lens group are fixed in the midst of varying power. In the optical system, one or more lens groups out of a plurality of lens groups are provided with one or more diffraction type optical elements rotationally symmetric with respect to an optical axis. |
