Vari-focal objective lens of short total length

摘要

An objective lens comprising a front lens unit and a rear lens unit with the separation between the two lens units being varied to vary the focal length of the entire system, wherein the front lens unit has a positive refractive power and consists of a positive lens of strong convex curvature toward the front, a negative doublet lens of a negative lens and a positive lens cemented together in this order from the front, and a positive lens sub-unit, and the rear lens unit has a negative refractive power and comprises a positive lens and a negative lens. Particularly the double lens is so designed that the comatic aberration in the intermediate zone of the image frame is stabilized throughout the entire range of variation of the focal length, and the halo in the intermediate zone in the telephoto end is well corrected.