A zoom lens system includes a negative first lens group, a positive second lens
group, and a positive third lens group. The negative first lens group includes
a negative meniscus lens element having the convex surface facing toward the object,
and the positive third lens group includes a positive biconvex lens element. Upon
zooming, at least the negative first lens group and the positive second lens group
are moved. A diaphragm is provided on the object side of the positive second lens
group, and moves integrally therewith. The zoom lens system satisfies the following
conditions: 0.25R1/D10.55 . . . (1); 0.25f2/TL0.45
. . . (2) wherein R1: the radius of curvature of the image-side surface
of the negative meniscus lens element; D1: the distance between the negative
first lens group and the positive second lens group at the short focal length extremity;
f2: the focal length of the positive second lens group; and TL: the distance
from the most object-side surface the negative first lens group to the most image-side
surface of the positive third lens group, at the short focal length extremity.
