Patent attributes
The present invention is directed to provide a telecentric zoom lens capable of attaining a small numerical aperture, a wide angle of view, reduced distortion, high resolution, reduced chromatic aberration, small aperture, and yet avoiding a cost increase and also to provide the telecentric zoom lens that shows a unified imaging ability relative to a varied distance to the screen and has a minimum projection distance to the screen got shorter. The telecentric zoom lens is comprised of a first group of lenses negative in power, a second group of lenses positive in power, and a third group of lenses positive in power, and a focal length fw at a wide angle of view can be given in relation with focal lengths f1, f2 and f3 of the first, second and third groups of lenses respectively, as follows:2.5≧|f1/fw|≧1.5,4≧f2/fw≧2.5, and13≧f3/fw≧3.
