Patent ID: 7167318

Claim:
A zoom optical system comprising, arranged along an optical axis in order from the object side as follows: a first lens group having negative refractive power and consisting of three lens elements; a stop; and a second lens group having positive refractive power and consisting of three lens elements; wherein both the first lens group and the second lens group move along the optical axis during zooming; the object-side lens element of said second lens group has positive refractive power and has at least one aspheric surface; said second lens group includes, arranged along the optical axis in order from the object side, as follows said object-side lens element; a fifth lens element having negative refractive power and a meniscus shape with its concave surface on the image side; and a biconvex sixth lens element; said three lens elements of said first lens group are arranged along the optical axis in order from the object side as follows: a first lens element having negative refractive power and a meniscus shape with its concave surface on the image side; a biconcave second lens element; and a third lens element having positive refractive power.