Patent ID: 6906869

Claim:
A zoom lens optical system having a zoom ratio of 3 or greater and comprising, in order from an object side thereof, a first lens group having positive refracting power and a second lens group having negative refracting power in which, for zooming from a wide-angle end to a telephoto end of the zoom lens optical system, the respective lens groups move toward the object side with a decreasing spacing between the first lens group and the second lens group, wherein: said first lens group consists of, in order from an object side thereof, a first lens component (U 1 ) that has negative refracting power and in which a surface located nearest to an object side thereof is concave on the object side, a second lens component (U 2 ) having positive refracting power, a third lens component (U 3 ) having negative or positive refracting power and a fourth lens component (U 4 ) having positive refracting power, wherein the respective lens components in the first lens group consist of a single lens or a doublet and satisfy the following conditions: 0.5 <|f G1 /f 11 |<3 (7) 0.4 <f G1 /f 13 <0.1 (8) where f G1 is a focal length of the first lens group, f 11 is a focal length of the first lens component, and f 13 is a focal length of the third lens component.