| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom projection lens. <P>SOLUTION: A zoom projection lens comprises, in the order from a projection surface to an imaging surface thereof: a first lens group with negative refraction power; a second lens group with positive refraction power; a third lens group with positive refraction power; a fourth lens group with negative refraction power; and a fifth lens group with positive refraction power. The first to fourth lens groups are movably positioned along an optical axis, the fifth lens group is immovably positioned, and the zoom projection lens satisfies the following conditional expressions: 1.0<¾F1/Fw¾<1.2; 2.5<¾F3/Fw¾<2.7; 2.81<¾F5/Fw¾<2.83; and 0.21<¾F2/F4¾<0.24, where F1, F2, F3, F4, and F5 respectively represent effective focal lengths of the first, second, third, fourth, and fifth lens groups, and Fw represents an effective focal length at a wide angle end of the zoom projection lens. <P>COPYRIGHT: (C)2012,JPO&INPIT |
