[Leica] How did 50mm become the "normal" lens for 35mm cameras?

[oliverbryk at comcast.net (Bryk Oliver)]

In 1953 I was a student in the US Army Signal Corps Photography School in 
Ft. Monmouth, NJ. After passing still photo school (4x5 Speed Graphic) I was 
selected for ?Combat Cameraman? class (35mm b&w cinematography) using the 
Bell & Howell ?Eyemo? handheld newsreel cameras well as Mitchell and Maurer 
studio cameras. 50mm was the normal lens for these 35mm cameras.

A booklet ?Instructions for the use of the Leica Camera Models c, f & g? 
(referring to the Leica III series) published by Hove Books Ltd. states that 
?THE STANDARD LENS OF THE LEICA is the world famous ELMAR having a maximum 
aperture of f/3.5 and a focal length of 50mm?.

In the book ?Leica M Advanced Photo School? by G?nther Osterloh, 2nd English 
ed., published by Lark Books in 2005 (the original German edition was 
published in 2002) is a section ?Normal focal lengths?:

"Lenses with focal lengths that correspond approximately to the diagonal of 
the negative format are called normal lenses. In the 35mm format of 24 x 36 
mm the diagonal measures about 43 mm. For practical reasons and for reasons 
of better quality, however, more than 75 years ago Leitz decided to use a 
standard focal length that is nearly 10 mm longer. And that is still the 
case today; standard lenses for Leica cameras have a focal length of 52 mm. 
This holds true even when the engraving around the front element of the lens 
reads only 50 mm.?

?For the novice, taking pictures with this lens is easy because its angle of 
view of about 45 degrees most closely corresponds to the natural coverage of 
the human eye.? 

Respectfully submitted,

Oliver