Patent ID: 8169712

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 through fourth lens groups are sequentially arranged from an object side to an image side, the third lens group comprises a first positive lens, a doublet lens including a second positive lens and a third negative lens, and a fourth positive lens sequentially arranged from the object side, the first through fourth lens groups are moveable when the zoom lens is zoomed from wide angle position to telephoto position, and the zoom lens satisfies the following equation: −0.6 <f 2/( ft/fw )<−0.2, where f2 indicates the focal length of the second lens group, fw indicates the focal length of the zoom lens at wide angle position, and ft indicates the focal length of the zoom lens at telephoto position.