sentences:  Erwin Puts wrote in an essay about Zeiss lenses that "The great revolution in optical designs occurred during the sixties and seventies, when Dr. Glatzel (Erhard Glatzel) of Zeiss introduced new methods of lens design.In the Leica-centric view of the world, one often assumes that well-known Leica designers, like Dr. Mandler, are in the front rank of the world's best optical designers.In fact this is not the case.