Patent ID: 7688520

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, the first lens unit consisting of a positive lens element and a negative lens element; a second lens unit having a negative optical power, the second lens unit consisting of three negative lens elements and a positive lens element; a third lens unit having a positive optical power; and a fourth lens unit having a positive optical power, wherein a distance between the first lens unit and the second lens unit is longer at a telephoto end than at a wide angle end, a distance between the second lens unit and the third lens unit is shorter at the telephoto end than at the wide angle end, and a distance between the third lens unit and the fourth lens unit is different at the wide angle end and at the telephoto end, and wherein the following conditions are satisfied: 8.0< f 1 /fw< 13.0 1.0<| f 2| /fw< 1.7 where fw represents a focal length of the zoom lens system at the wide angle end, f 1 represents a focal length of the first lens unit, and f 2 represents a focal length of the second lens unit.