Zoom lens

Abstract

Disclosed is a zoom lens comprising at least three movable lens units. The zoom lens comprises a first lens unit disposed closest to an object side and having positive refractive force. The first lens unit includes a positive cemented lens constituted by a positive lens element and a negative lens element, with a concave side of the cemented surface facing the object side. The zoom lens also comprises a last lens unit disposed closest to an image side. Upon zooming from a wide angle end to a telephoto end, at least the first lens unit and the last lens unit move toward the object side so as to increase an air gap between the first lens unit and a lens unit adjacent to the first lens unit on the image side but to decrease an air gap between the last lens unit and a lens unit adjacent to the last lens unit on the object side. The zoom lens satisfies the following condition: 0.7<f1/(fw.multidot.ft).sup.1/2 <1.4 where f1 is the focal length of the first lens unit, fw is the focal length of the entire lens system at the wide angle end, and ft is the focal length of the entire lens system at the telephoto end.

Dependencies are inferred from the claim text.