Patent ID: 7554746

Claim:
A zoom lens, comprising: in order from an object side, a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a positive refracting power; and at least the first lens group and the third lens group being moved to the object side such that an interval between the first lens group and the second lens group increases, an interval between the second lens group and the third lens group decreases and an interval between the third lens group and the fourth lens group increases during changing a magnification from a wide angle end to a telephoto end, wherein the first lens group comprises one negative lens and two positive lenses, the fourth lens group consists of one positive lens, and a focal length of an entire system at the wide angle end, fw, and a curvature radius of the object side surface of the positive lens comprising the fourth lens group, r4F satisfy the following condition: 1.6 <r 4 F/fw< 4.0. (11)