Zoom lens system

A zoom lens system comprising at least three lens groups including a first lens group having a positive focal length, a second lens group having a positive focal length and having at least one negative lens element, and a third lens group having a negative focal length, in this order from the object side, wherein upon zooming from the short focal length extremity toward the long focal length extremity, all the lens groups are moved toward the object side, and the distance between the first and second lens groups increases and the distance between the second and third lens groups decreases, and wherein said zoom lens system satisfies the following conditions (1) and (2):

• -0.3<f.sub.W /f.sub.1G +f.sub.W /f.sub.2G +f.sub.W /f.sub.3G <0(1)
• 1.845<N.sub.2Gn ( 2)
• wherein
• f.sub.W designates the focal length of the entire optical system at the short focal length extremity,
• f.sub.1G designates the focal length of the first lens group (f.sub.1G >0),
• f.sub.2G designates the focal length of the second lens group (f.sub.2G >0),
• f.sub.3G designates the focal length of the third lens group (f.sub.3G <0),
• N.sub.2Gn designates the average refractive index of all the negative lens elements of the second lens group.