Patent ID: 8964301
Filing Date: 2015-02-24
Classification: G02B

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