Patent ID: 8503098
Filing Date: 2013-08-06
Classification: G02B,G03B

Abstract:
1. A zoom lens for projection, 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; and a fourth lens group having positive refractive power, which are arranged from the magnification side of the zoom lens for projection in the order mentioned above, wherein the first lens group and the fourth lens group are fixed during zooming, but the second lens group and the third lens group move on the optical axis of the zoom lens toward the magnification side, based on an operation for operating the zoom lens from a wide end to a tele end, in such a manner that a distance between the second lens group and the third lens group changes, and wherein the following formula (1) is satisfied: F fw: focal length of entire system at wide end.