Archived posting to the Leica Users Group, 1996/11/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Marc, I believe you to be right. It is likely that some of the machines used by Leica at the time used "English" units. This was not uncommon. The Industrial Revolution started in England. Then, it invaded Germany. Alan Bearden told me how he "measured" the pitch. Unfortunately, his methods are not accurate. Measurement is a science and one should not always believe what the instruments one has at hand read. I learn new things every day. Did you know that most of the bolts on my 1978 Volvo also are also "English". (NO, I DO NOT DRIVE A PORSCHE!) Barnack was a genius mechanic and a great photographer. Cheers, Chris At 11:49 PM 11/24/96 -0500, you wrote: >At 02:04 PM 11/24/96 -0800, Alan Bearden wrote: > >>The Leica screw mount is 39mm x 1mm (thread); not 26 tpi. I just measured >>several using a comparison microscope. > >Well, the bulk of my references are at the office, and I'm at the house, so >a quick scan could only locate one. Peter Dechert, the great scholar of the >Canon RF cameras (and also a scholar of things Leica), wrote on p. 15 of his >CANON RANGEFINDER CAMERAS 1933 - 1968, in explanation of why early Canon and >Nikon LTM lenses will sometimes not mount on Leica cameras: > > ... both Canon and Nippon Kogaku engineers believed that the Leitz > flange pitch was exactly 1.0mm, when in fact it is 26 threads to the >inch. > >I have a copy of the original Leica lens-mount patent, somewhere, and >Barnack set out therein that the mount was 39mm by 26 tpi. I believe Emil >Keller has a picture of it in his HISTORY OF THE 35mm CAMERA. > >Marc > >msmall@roanoke.infi.net FAX: +540/343-7315 >Cha robh bas fir gun ghras fir! > > >