Patent ID: 7561344

Claim:
A zoom lens system comprising, in order from an object side to an image side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power, wherein a distance between the first lens group and the second lens group becomes the smallest at a halfway point during zooming, wherein the first lens group is positioned closer to the object side at a telephoto end than at a wide-angle end, wherein the first to fourth lens groups move in such a manner that a distance between the second lens group and the third lens group is smaller and a distance between the third lens group and the fourth lens group is larger at the telephoto end than at the wide-angle end, wherein the second lens group consists of, in order from the object side to the image side, a negative lens element and a positive lens element, and wherein the following condition is satisfied: 10<( d 1 t−d 1min)/( d 1 w−d 1min)<90 where d 1 w and d 1 t denote distances between the first lens group and the second lens group at the wide-angle end and at the telephoto end, respectively, and d 1 min denotes the smallest distance between the first lens group and the second lens group at a halfway point during zooming.