Archived posting to the Leica Users Group, 2000/11/30[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
At 12:27 AM 11/30/2000 +1100, A.H.SCHMIDT wrote: >The pitch for Leica screw mount lenses was always 0.977mm. To be precise, the pitch for LTM has always been 26 turns-per-inch Whitworth, which equates to .977mm but the slope of the threads is not metric but Whitworth, a carry-over from Leitz' microscope origins. This has been bolluxed by a number of manufacturers, most notably FED in the 1930's and Canon after the end of the Second World War, both of whom thought the pitch ought to be 1.0mm even. Thus, early FED and Canon gear might not be completely compatible with true LTM. Also, Canon got the chamfer on the lens-mount wrong at first, though this had minimal effect on compatibility. Marc firstname.lastname@example.org FAX: +540/343-7315 Cha robh bas fir gun ghras fir!