Max Berek joined the Ernst Leitz Company in 1912 as the first permanent professional scientist. The 1914-1918 war interrupted Berek’s work and it was only after he returned from the war that the emphasis of his work shifted more and more into the realm of optics.
The low film sensitivity at the time meant that the f/4.5 lens used by Barnack had to be faster, but not too fast, to preserve the great depth of field of the modestly fast focal length of the lens. On the other hand, even at tenfold enlargement, the image should be sharp to the edges. This would not have been possible with the higher apertures designed at the time in accordance with the old rule “focal length equals image diagonal”.
At the time, a focal length of 43.3mm was not yet possible using a variation of a triplet lens, and Barnack insisted that the camera and lens fit into a coat pocket. So how did the 50mm lens become the accepted lens format for the Leitz 24×36 camera?
If you are thinking that 50mm was chosen because it is the natural way the human eye happens to see and corresponds to the image angle by a 50mm lens – you would be wrong.
The Book, “Oscar Barnack-From the Idea to the Leica” explains in detail the events that resulted in the standard 50mm lens. I have found this and other tidbits in this book both fascinating and educational. You will too.
Richard is the Executive Director of LHSA - The International Leica Society and a part-time professional photographer. He is also a classically trained pianist, writer and published author. His book, "What Music Means to Me" is available from Hal Leonard Corporation.