| 摘要 |
A projection lens includes a first lens having at least an aspheric surface, a second lens having a concave surface facing the reduction side of the projection lens, and having negative refractive power, a third lens, a fourth lens, a fifth lens, a sixth lens having a convex surface facing the reduction side, and having positive refractive power, and the like, which are sequentially arranged from the magnification side of the projection lens. Further, the following formulas (1) and (2) are satisfied: 3.5<Bf/f<7.5  (1); and 1.2<|fa/f|<2.0  (2), where f: focal length of the entire system of the projection lens, Bf: back focus in air of the entire system, and fa: combined focal length of lenses from the second lens to a most-reduction-side lens.
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