Compact high vari-focal ratio zoom lens system

Claim 1

A compact high vari-focal lens system comprising, in the order from the object side, a first lens group having positive refractive power, a second lens group having positive refractive power and a third lens group having negative refractive power, so adapted as to perform zooming by shifting the first lens group integrally with the third lens group along the optical axis and shifting the second lens group in a different locus in conjunction with the shift of the first lens group and the third lens group, and so designed as to satisfy the following conditions (1), (2) and (3): 0.2<φ.sub.1 /φ.sub.W <0.9 (1) 1.1<φ.sub.12.sub.W /φ.sub.W <1.9 (2) 1.5<β.sub.3.sub.T /β.sub.3.sub.W <2.8 (3) wherein the reference symbol φ W represents refractive power of the zoom lens system as a whole at the wide position thereof, the reference symbol φ 1 designates refractive power of the first lens group, the reference symbol φ 12 W denotes total refractive power of the first lens group and the second lens group at the wide position, the reference symbol β 3 W represents lateral magnification of the third lens group at the wide position, and the reference symbol β 3 T designate lateral magnification of the third lens group at the tele position.