Archived posting to the Leica Users Group, 1997/08/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 02:34 PM 08-08-97 -0600, you wrote: >LUGs and Rolleis, > >Last night, I did a little thinking about the so-called standard focal >lengths. It is widely thought that 50mm is the standard, or normal, length >for 35mm cameras and 80mm is standard, or normal, for 6-by-6 (cm) cameras. >This is curious since using the normally-accepted calculation, the standard >focal length for 35mm leads to something like 43mm. Leitz produced the 40mm >lenses only for the CL and, possibly, on some plastic cameras. Yet, I find >this focal length to be more natural. I would make the same comment about >the 75mm lens on the Rolleiflexes. > >Does anyone know why 80mm is considered preferable for the 6-by-6 format? I >believe that 50mm became a de-facto standard, because it was first used by >Oscar Barnack before WWI and later in most Leica TM cameras. Maybe it all depends on what you mean by standard. My understanding is that a focal length is considered "standard" if a print made from it has normal looking perspective. If the viewing distance of the print = VD, then normal perspective occurs when MAG = VD/FL where MAG = magnification of negative FL = focal length of lens For example, a 50 mm lens will be "normal" for roughly 5x7 inch prints held at a distance of 10 inches. 8x10 inch prints held at a distance of 10 inches will have a decided telephoto perspective. etc., etc. Dan C.