sentences: "Reginald P. Jonas and Michael D. Thorpe, in the article quoted, also present a valuation of Mandler's significance.Mandler was Head of Optical and Mechanical design at Leitz Canada for 20 years "during which time he was involved in the design of over 400 lenses, including many photographic objectives, as well as lenses for movie taking, movie projection, laser scanning, and other speciality optics.