Zoom lens

Abstract

The present invention is directed to a “negative lead type” zoom lens advantageous for downsizing the entire lens system, which has a high zoom ratio and provides superior compensation for aberration, retaining a predetermined back focal distance. The zoom lens has at least a first or leading lens unit of negative refractive power and a second or succeeding lens unit of positive refractive power in this order from the view point closer to a photographed object. The first lens unit is of two positive lens pieces and three negative lens pieces while the second lens unit provides an aspherical surface, having a positive lens piece in the second foremost position closer to a photographed object. During the zooming from a wide-angle view to a tele-photo view, a separation between the first and second lens unit is reduced. The first lens unit serves as a focusing lens, and the zoom lens satisfies requirements as expressed in the formulae 3.0<ft/fw<4.9 where fw is a focal length at the wide-angle view end, and ft is the focal length at the tele-photo view end.

Dependencies are inferred from the claim text.