Compact zoom lens

A compact zoom lens comprising, from front to rear, a first lens group of positive refractive power, a second lens group of negative refractive power, a third lens group of positive refractive power, a fourth lens group of positive refractive power and a fifth lens group of negative refractive power, wherein at least one of the first, second, third, fourth and fifth lens groups are movable in such a manner that when zooming from a wide-angle end to a telephoto end, said first lens group is moved toward the object side, while simultaneously monotonously increasing an air separation between said first lens group and said second lens group, monotonously decreasing an air separation between said second lens group and said third lens group and monotonously decreasing an air separation between said fourth lens group and said fifth lens group, and said zoom lens satisfying the following conditions:

• ##EQU3## where fW and fT are focal lengths of the entire lens system at the wide-angle end and the telephoto end respectively, f5 is a focal length of said fifth lens group, f12W is an overall focal length of said first lens group and said second lens group at the wide-angle end, .DELTA.e34 is a changed amount of the interval of principal points of said third lens group and said fourth lens group at the telephoto end from that at the wide-angle end, and DW is the length of the entire lens system from the first lens surface to the last lens surface at the wide-angle end.