Patent ID: 7133214

Claim:
A zoom lens system comprising in order from an object side to an image side: a first lens unit having a positive optical power; a second lens unit having a negative optical power; a third lens unit having a positive optical power, the third lens unit consisting of, in order from the object side to the image side, a first lens sub-unit having a positive refractive power and including a positive lens element with an object-side surface which has a convex shape, an aperture stop, a second lens sub-unit having a negative optical power and including a negative lens element with an image-side surface which has a concave shape, and a third lens sub-unit having a positive optical power and including a positive lens element; and a fourth lens unit having a positive optical power, wherein a distance between the respective lens units is changed during zooming, wherein the following condition is satisfied: 0.8< Dab/Dbc< 200 where Dab represents a distance between the first lens sub-unit and the second lens sub-unit, and Dbc represents a distance between the second lens sub-unit and the third lens sub-unit, and wherein the following condition is satisfied: 0.64 <( 3 G 3 R 2+3 G 3 R 1)/(3 G 3 R 2−3 G 3 R 1)<1.64 where 3G3R1 and 3G3R2 represent paraxial radii of curvature of the object-side surface and an image-side surface of the positive lens element in the third lens sub-unit, respectively.