Zoom lens, and electronic imaging system using the same

Abstract

The invention provides a zoom lens that comprises a reduced number of lens elements, is compact and simplified, and has high image-formation capability, thereby achieving thorough size reductions in video cameras or digital cameras, and an electronic imaging system using the same. The zoom lens comprises a first lens group G1 of negative refracting power, a second lens group G2 of positive refracting power and a third lens group G3 of positive refracting power. Upon zooming from the wide-angle end to the telephoto end of the zoom lens, the second lens group G2 moves toward the object side alone of the zoom lens, and the third lens group G3 moves while the spacing between the third lens group G3 and the second lens group G2 varies. The second lens group G2 is composed of a front subgroup and a rear subgroup. The front subgroup is composed of a doublet component consisting of, in order from its object side, a positive lens element having an aspheric surface and a negative lens element, and the rear subgroup is composed of one positive lens component. The third lens group G3 then satisfies condition (1) with respect to the axial radii of curvature of the surfaces located nearest to the object and image sides of the third lens group G3.

Dependencies are inferred from the claim text.