Importance

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Abstract

A zoom lens for projection substantially consists of a first lens-group having negative refractive power, and a second lens-group through a fifth lens-group having positive refractive power, arranged in this order from a magnification side. The zoom lens is configured to be telecentric on a reduction side. The first lens-group and the fifth lens-group are fixed while the second lens-group through the fourth lens-group move during magnification change. The fourth lens-group includes at least three positive lenses, and a most-magnification-side lens in the fourth lens-group has a convex surface facing the magnification side. Further, when a focal length of an entire system at a wide angle end is fw, and a focal length of the fourth lens-group is f4, and a full angle of view at a wide angle end is 2ω, conditional formulas (1) and (7) are satisfied:

description='In-line Formulae' end='lead'7.5<f4/fw<14.5  (1); anddescription='In-line Formulae' end='tail'

description='In-line Formulae' end='lead'70°≦2ω  (7).description='In-line Formulae' end='tail'

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First Claim