Projection Lenses

A projection lens includes a first lens group and a second lens group, all of which are arranged in sequence from a projection side to an image source side along an optical axis.

The first lens group is with positive refractive power. The second lens group is with positive refractive power and includes a first lens, a second lens, a third lens and a fourth lens, wherein the first lens is with negative refractive power, the second lens is with positive refractive power, the third lens is with positive refractive power and the fourth lens is with positive refractive power.

The first lens and the second lens are cemented together to form a cemented lens, the cemented lens is with negative refractive power. The first lens satisfies: −0.579≦f1/f≦−0.4 wherein f1 is an effective focal length of the first lens and f is an effective focal length of the projection lens.