Patent ID: 7782544

Claim:
A zoom lens system, comprising in order from object side to image side: a first lens unit having a negative refractive power; a second lens unit having a positive refractive power, the second lens unit including an aperture stop, a first lens subunit located on an object side of the aperture stop and a second lens subunit located on an image side of the aperture stop; a third lens unit having a positive refractive power, wherein an interval between respective adjacent lens units varies during zooming, wherein the second lens unit is movable to displace an image formed by the zoom lens system within a plane perpendicular to an optical axis, wherein when the image formed by the zoom lens system is displaced within the plane perpendicular to the optical axis, the aperture stop is held, the first lens subunit and the second lens subunit are separately moved in a direction which has a component orthogonal to the optical axis, wherein the following conditional expression is satisfied, 0.03 <Dab/fp≦ 0.21 −0.31 ≦φRt/φP< 3.1 where fp represents a focal length of the second lens unit, Dab represents an interval between the first lens subunit and the second lens subunit, φRt represents a refractive power of the third lens unit at a telephoto end and φP represents a refractive power of the second lens unit, and wherein the first lens unit is the most object side lens unit in the lens system.