Patent ID: 7139130

Claim:
A zoom lens, arranged in order from an object side to an image plane side, comprising: a first lens group having a positive optical power, fixed with respect to an image plane; a second lens group having a negative optical power, movable in a direction parallel to an optical axis for performing a zooming action; a third lens group having a positive optical power, including a movable lens element having at least one aspherical surface and movable in a direction perpendicular to the optical axis for compensating for a blurred image; and a fourth lens group having a positive optical power, movable in the direction parallel to the optical axis for adjusting a focus, the zoom lens satisfies the following conditional expression: 0.006 <|dsagi/CL|< 0.02 wherein CL is an effective lens diameter of the at least one aspherical surface, and dsagi is an amount of asphericity at the effective lens diameter, wherein the third lens group comprises at least two lens elements, and wherein the third lens group includes a meniscus convex lens element and the following conditional expression is satisfied: 0.50 <f 31 /f 32 <1.00 where f 31 is a focal length of the first lens of the third lens group, counted from the object side, and f 32 is a focal length of the second lens of the third lens group, counted from the object side.