Patent ID: 7242533

Claim:
A two-unit zoom lens system comprising, in order from an object side to an image side: a first lens unit having a negative refractive power; and a second lens unit having a positive refractive power, wherein during change of magnification from a wide-angle end to a telephoto end, the first lens unit and the second lens unit are moved so as to reduce a space between the first lens unit and the second lens unit, the first lens unit comprises, in order from the object side, a negative sub-unit G 1a and a positive sub-unit G 1b , the second lens unit comprises, in order from the object side, a first positive lens L 21 , a second negative lens L 22 , and a third positive lens L 23 , the two-unit zoom lens system further comprising: an aperture stop disposed in an air space which comes into contact with the first positive lens L 21 , the following conditions (A), (B) being satisfied: −1.5<( r 21a +r 21b )/( r 21a −r 21b )<−0.87 (A); and −1.0<( r 22a +r 22b )/( r 22a −r 22b )<−0.28 (B), in which r 21a denotes a paraxial radius of curvature of an object-side surface of the first positive lens L 21 , r 21b denotes a paraxial radius of curvature of an image-side surface of the first positive lens L 21 , r 22a denotes a paraxial radius of curvature of an object-side surface of the second negative lens L 22 , and r 22b denotes a paraxial radius of curvature of an image-side surface of the second negative lens L 22 .