Small-sized zoom lens

A zoom lens comprising in the following order from the object side:

• a first lens group with a positive refractive power;
• a second lens group with a negative refractive power;
• a third lens group with a positive refractive power;
• and
• a fourth lens group with a negative refractive power;
• wherein in a refractive power varying operation from a wide-angle end to a telescopic end, said first lens group and said fourth lens group are moved toward the object side, the distance of an air space between said first lens group and said second lens group is increased and the distance of an air space between said third lens group and said fourth lens group is decreased, and if the refractive power of said third lens group is .psi.3, the refractive power of said fourth lens group is .psi.4, the axial distance between the air space between said third lens group and said fourth lens group in the wide-angle end is dw34, the axial distance between the air space between said third lens group and said fourth lens group in the telescopic end is dt34, an effective focal length of the whole zoom lens system in the wide-angle end is Fw, an effective focal length of the whole zoom lens system in the telescopic end is Ft, and a radius of curvature of a lens surface of said fourth lens group located closest to the image side is r4, the following condition is satisfied:
• 1.47<(dt34-dw34).multidot..psi.3.multidot..psi.4.multidot.(Ft-Fw)<2.00, Fw/r4<-0.1.