US Patent 7139130 Zoom lens, and optical apparatus using the same

A zoom lens includes, arranged in order from an object side to an image plane side, 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 predetermined conditional expression.