Patent ID: 8144402

Claim:
A zoom lens comprising: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power, wherein the first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially from an object side to an image side, wherein each of the distances between the first lens group, the second lens group, the third lens group, and the fourth lens group varies during zooming, wherein the first lens group comprises a doublet lens comprising a negative lens and a positive lens, and the third lens group comprises a first positive lens, a second positive lens, a negative lens, and a third positive lens, and satisfies 1.4 ≦wfno≦ 2.5, where wfno is a minimum F-number (FNO) at the wide-angle position.