Abstract: An exemplary zoom lens for use in projection technology includes, in this order from the magnification side to the minification side thereof, a first lens group having negative refraction of power, a second lens group having positive refraction of power, a third lens group having positive refraction of power, a fourth lens group having negative refraction of power, and a fifth lens group having positive refraction of power, wherein the zoom lens satisfies the formulas: ?1.5<F1/Fw<?1.3, 1.5<F2/Fw<1.8, 1.8<F3/Fw<2.2, ?10<F4/Fw<?5, and 2.3<F5/Fw<2.8, where F1, F2, F3, F4, F5, and Fw respectively represent the effective focal length of the first lens groups, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the shortest effective focal length of the zoom lens.

Abstract: An exemplary imaging lens includes, in this order from the object side to the image side thereof, a first lens of positive refraction power, a second lens of negative refraction power, a third lens of positive refraction power, and a fourth lens of negative refraction power. The imaging lens satisfies the formulas of: (1) 1<T/F<1.29; (2) R3/F>15 and (3) R7>0, R6<0, where T is the overall length of the imaging lens, F is the effective focal length of the imaging lens, R3 is the radius of curvature of the object-side surface of the second lens, R6 is the radius of curvature of the image-side surface of the third lens, and R7 is the radius of curvature of the object-side surface of the fourth lens.