Views on the photographic universe by Erwin Puts

Dr. Walter Mandler died on april 21, 2005(april 23, 2005)

Dr. Mandler died on April 21, 2005. Walter Mandler dominated the optical development within Leitz from about 1950 till about 1985. He was 'wissenschaftlicher Mitarbeiter' (science assistant) in the department of Max Berek and had intimate knowledge of the challenges and problems associated with the lenses for the small Leica format. When Leitz decided to set up a new company in Canada, he was asked to structure and manage the optical department there. Already in the fifties, the Leitz designers recognized the fundamental problems of small format and high-speed lenses and on both sides of the Atlantic solutions were created. In Wetzlar it was professor Marx who explored the first attempts of an aspherical design and in Midland it was Mandler who sought the service of the computer to speed up the design process. The period from 1950 to 1970 was one of the most exciting periods for optical designers as new approaches and insights could be explored without cost considerations, because of intense competition.
Optical design is partly pure mathematics and partly pure art. But the most important aspect is manufacturing quality and economy. One can design the most brilliant lenses, but when these creations are too expensive to produce, the design is ripe for the dustbin. In his 1979 dissertation Mandler explored in detail the limits of the Gauss design, carefully balancing optical quality and manufacturing cost. This book is still required reading for anyone who wants to understand the manifold aspects of computer assisted optical design.

Walter Mandler had a strong commitment to high-speed lenses that could be manufactured at reasonable costs. The Summilux 1.4/75 and 1.4/80 are examples as is the famous Noctilux 1/50mm. This lens is a masterpiece of optical design. It is very difficult, if not impossible to improve on this design without the use of exotic glass types and aspherical surfaces. He used the computer to explore all possible options and select the design that suited his requirements best. He was also a daring man: he created the Summilux 1.4/35mm when everybody assumed that such a lens was not possible. Mandler was a pragmatist more than a visionary. His designs are very competent, but he had to work within the restrictions of the Leitz philosophy of lens manufacture. It seems that lenses for 35mm photography were a bit boring for him, as they did not pose the challenge he wanted. This he found in the designs for the military and in the Elcan lenses he could explore more exciting optical limits.
It is a strange coincidence that the famous designers are of German origin, like Bertele and Rudolph and Berek, but all serious optical design programs are American. By location Walter Mandler was more exposed to these programs and their underlying design approach. The Germans on the other hand relied on a more fundamental and theoretical design method. The programs designed in-house by Leitz originated with Professor Marx, who was responsible for the first Noctilux with aspherical elements. Theoretically and from a performance perspective the Marx design was undoubtedly the best, but too expensive and the Mandler design used high index glass types to deliver (almost) the same performance at lower cost.

In the sixties and seventies the Japanese designers made big strides forward with novel techniques, like aspherical surfaces, floating elements and HD glass to push the lens limit to uncharted terrain. In many cases these designs were flawed as the Germans were quick to note, but the Japanese gained valuable knowledge and honed their designs to perfection. Leitz and to a lesser extent Zeiss, focussed on the other part of the lens equation. A good design is worthless, if not supported by adequate manufacturing techniques and here the German industry had definitely the advantage.
There are only a few letters by Mandler in the Leica archives and the contents give the impression of a passionate man, who feels slightly frustrated by the slow progress made by Leitz and the fast improvements made by the Japanese. He clearly saw that without fundamental changes Leica could not compete in the long run. But Leitz was in those days already living on borrowed money. His Elcan designs were by nature less cost oriented and the knowledge gained here could be transferred to the photographic department.
Walter Mandler must have been happy with the optical progress made in the last decade in the Solms design team. Many of his ideas have been developed further and current Leica designs employ the whole range of techniques now available: aspherics, floating elements, a wide selection of glasses, and a focus on the critical aberrations, like the Petzval sum and the correction of the secondary spectrum.
Mandler's study about the Double-Gauss designs is still the definitive analysis of the limits and potential of this class of lenses. The book was published in 1979 and represented the state of the art in optical design at that time. His achievement was the transfer of that theoretical framework to practical design. He did not develop really innovative designs, but his strong point was the exploration of existing limits and to find ways to implement the almost impossible. The Elcan 2.4/75mm and the Noctilux 1/50mm are examples of his craft and his passionate commitment to photographic lenses.
Dr Walter Mandler was 83 years old and lived from may 10, 1922 to april 21, 2005