Archived posting to the Leica Users Group, 1997/08/08

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Subject: Standard Focal Lengths
From: Chris Fortunko <fortunko@boulder.nist.gov>
Date: Fri, 08 Aug 1997 14:34:17 -0600

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.

I believe that the 75mm focal length is normal, because Rolleiflex negatives
are cropped for printing to fit something like 8-by-10 or similar standard
format in Europe and elsewhere. If we assume the same for the 35mm format,
then there is an even stronger argument for the 40mm lens being considered
normal, particularly for snapshots.

Best of Light,

Chris