Patent ID: 8514498

Claim:
A zoom lens comprising, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; and a fourth lens unit having a positive refractive power, wherein the second lens unit and the fourth lens unit move during zooming, wherein the third lens unit includes at least one positive lens and at least one negative lens, and wherein, when Rnf and Rnr are radiuses of curvature of surfaces on the object side and the image side respectively of one negative lens of the second lens unit, Rpf and Rpr are radiuses of curvature of surfaces on the object side and the image side respectively of one positive lens of the second lens unit, the following conditions are satisfied: 3.4<( Rnf−Rnr )/( Rnf+Rnr )<4.4 −0.7<( Rpf−Rpr )/( Rpf+Rpr )<−0.5.