| 摘要 |
A wide angle projection lens consists of a Gnp lens group having positive refractive power and a Gf lens group having positive refractive power in the order from a large conjugate side toward a small conjugate side, and further the Gnp lens group consists of a Gn lens group having negative refractive power and a Gp lens group having positive refractive power in the order from the large conjugate side toward the small conjugate side, while satisfying -1.8<fn/f<-1.1, 3.2<fp/f<5.5, 1.2<Dnp/f<2.4 and 2.8<ff/fnp<4.4, where f: focal length of the whole lens system, fn: focal length of the Gn lens group, fp: focal length of the Gp lens group, Dnp: air spacing between the Gn lens group and the Gp lens group, fnp: focal length of the Gnp lens group and ff: focal length of the Gf lens group. With this constitution provided are a projection lens capable of wide angle projection which can be applied to a projector of off-axis projection system and a projection display device mounted with the projection lens.
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