Zoom lens

Abstract

The invention relates to a zoom lens which, albeit being of simplified construction, makes sure brightness and holds back fluctuations of astigmatism, and facilitates making sure being fast and the angle of view and the zoom ratio at the wide-angle end. The zoom lens comprises a first group Gof positive power, a second group Gof negative power and a third group Gof positive power, with a stop S between the second group Gand the third group G. Upon zooming from the wide-angle end to the telephoto end, the first group G, the second group G, and the third group Gmoves; the second group Gmoves toward the object side after moving toward the image side; the first group Gand the third group Gare positioned on the object side at the telephoto end with respect to the wide-angle end. The first group Gcomprises one negative lens and one or two positive lenses, and the second group Gcomprises a first negative meniscus lens convex on its object side, a second negative lens wherein the image side surface is larger in the absolute value of a curvature than the object side surface, and a third positive lens wherein the object side surface is larger in the absolute value of a curvature than the image side surface. Upon focusing from a far distance to a near distance, the second group Gmoves.