Patent ID: 8878982

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit having positive refractive power; a second lens unit having negative refractive power; an aperture stop; a third lens unit having positive refractive power; and a fourth lens unit having positive refractive power, wherein the second lens unit, the aperture stop, and the fourth lens unit move during zooming from a wide-angle end to a telephoto end, wherein the third lens unit includes, in order from the object side to the image side, a first lens sub-unit having positive refractive power, and a second lens sub-unit having negative refractive power, wherein the second lens sub-unit is movable in a direction having a component perpendicular to an optical axis to change an image forming position in a direction perpendicular to the optical axis, and wherein, when a distance between the aperture stop and the third lens unit at the wide-angle end is denoted by Ds 3 w , a composite focal length of the first lens unit and the second lens unit at the wide-angle end is denoted by f 12 w , a focal length of the first lens sub-unit is denoted by f 3 a , and a focal length of the second lens sub-unit is denoted by f 3 b , the following conditions are satisfied: 0.9 <Ds 3 w/|f 12 w|< 3.0 0.8 <|f 3 b|/f 3 a <2.0.