[h=1]Obsession with 50mm[/h]Having read the tale of the 55mm f/1.2 lens, did you wonder why the designer stuck to 50mm? That is because normal lenses for the 35mm format have a long history. The focal length of the normal lens was set at 5cm (50mm) by engineers of Ernst Leitz GmbH, notably Oskar Barnack and Max Berek. Then, why did they choose 50mm? There are many stories, typical of which is that the angle of view of 50mm (46 degrees diagonal, 40 degrees horizontal) is the closest to the field of view of the human eye when it is not closely focused. Other theories are that the diagonal distance of the image is close to the focal length (precisely, however, it is not 50mm), that wide lens and telephoto lens characteristics both become least evident at the focal length of 50mm and that lens characteristics are optimum at 50mm (precisely, however, such focal length cannot be limited to 50mm). In any case, only Barnack and Berek, who built this system, know the truth.
The certain fact is that the first 35mm camera of Leitz came with the Leitz Anastigmat (later called Elmax) 5cm f/3.5 as the standard lens. Camera makers of the world all started manufacturing cameras modeled after Leica, together with 5cm (50mm) normal lenses. Because of this historical background, they have been continuing producing 50mm lenses for many long years and developers and users alike have become familiar with the angle of view of 50mm lenses. Based on this history and tradition, 50mm lenses were positioned as normal. Therefore, developers at the time apparently wanted to make standard lenses for SLR cameras with the same angle of view as in the era of range-finder cameras. Designers’ obsessiveness is the seed of progress and development. The development of normal lenses started with 58mm and shifted to 55mm and then to 50mm.