There seems to be a lot of misunderstanding about wide angle lenses. Here is how they are categorized. There are two large categories; one being symmetrical and the other being reversed telephoto(asymmetrical). Within the symmetrical category are lenses like the Biogon and Wild Aviogon. These are used on rangefinders and view cameras where there is no mirror box to clear and can be placed very close to the film. The advantage is that they have no distortion and automatically have a flat field. The reversed telephotos are asymmetrical and are used for SLRs and need to be removed from the film due to the mirror box. They all use negative front elements(sometimes combined with positive ones)and have positive rear groups. There are three sub-types. They are the Retrofocus, the thick element type and the thin element type. The Retrofocus was invented in France in 1950 by Angenieux and is characterized by a large negative meniscus lens element up front followed by four or five small elements in the rear. The 75mm f/4.5 is such a design. The thick element design originated in Germany but has been used by many designers worldwide. It is characterized by thick center elements and thinner outside elements. The 45mm, second version 55mm and 75mm shift are all of this design. The last of the reversed telephoto designs is the thin element type. This is a Japanese design as far as I can tell and is characterized by thin elements throughout. The new version 55mm is of this type.

-- Steve Rasmussen (srasmuss@flash.net), February 26, 1999

Answers

Thanks Dr. Hoeller, I had no idea we had people from Zeiss reading this forum. Welcome. SR

-- Steve Rasmussen (srasmuss@flash.net), April 19, 2001.

One comment : The Biogon and Aviogon systems are based on the Hypergon design from Hoegh. The main advantage of these systems is that they are free from distortion and coma, which is the most critical aberration for wide angle systems. To my opinion it is not true, that they are free from curvature of field by principle. This can be achieved, but it is not necessarily the case.

-- dr.frank hoeller (hoeller@zeiss.de), April 17, 2001.