Auf dem Weg zur allwissenden Fabrik: Vertikale Integration auf Basis kontinuierlicher Datenverarbeitung.

A zoom lens in which fluctuation of lateral chromatic aberration is small has, in succession from the object side, a first group of positive refractive power including at least one positive lens, a second group of negative refractive power including at least one negative lens, and an aperture stop disposed closer to the image plane than the second group. Each of the groups is moved on the optic axis during magnification change so that the distance between the first group and the second group becomes greater and the distance between the second group and the aperture stop becomes smaller as the focal length of the entire system becomes longer. At least one of negative lenses constituting the second group is formed of a material which satisfies the following conditions: nu d+596.7 theta >386.5 nu d>55, where when the refractive indices of the lens material for wavelengths 436 nm (g-line), 486 nm (F-line), 588 nm (d-line) and 656 nm (c-line) are ng, nF, nd and nc, respectively, nu d and theta are defined as follows: nu d=(nd-1)/(nF-nc) theta =(ng-nF)/(nF-nc).