Archived posting to the Leica Users Group, 1996/11/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Frankly, When Marc first posted the definition of the LTM as 39mm/26tpi, I was not bothered. This is because inches were in common use in Europe at that time. They may still be in use there even though many of you do not realize it. (As a child, I remember buying nails in inch lengths, etc.) Because I work for an institution that pushes the SI system in the US, I am curious. At the time, was it 26tpi or 1mm? I know that some of the early Japanese copies of Leica lenses did not quite fit. Is this why? I am curious. Tricks like this are not uncommon. For example, Russian ammunition was 76mm as opposed to 75mm. Also, .303 is not quite 7.62mm. I certainly would not try to use 6-inch projectiles in a 155mm gun, and vice versa. By the way, I sometimes like to use the "English" system myself, except when doing physics. There, I like the CGS, which is more natural, but probably not approved by Brussels. Anyway, Marc, we have a good assignment for you. Is it 26tpi or 1mm? Best regards, Chris At 09:22 PM 11/24/96 +0000, you wrote: >On 24 Nov 96 at 11:17, Marc James Small wrote: > >> At 01:06 AM 11/24/96 -0500, Charles E. Love, Jr. wrote: >> >> >Marc, forgive me, but I don't know what "LTM" stands for, so I don't get the >> >connection with OB.--Charlie >> >> >> "LTM" -- Leica thread-mount, the 39mm by 26 tpi thread selected by Barnack >> for use on the Leica. > >Shoot. 39mm by 26 tpi is as much a collision of imperial/metric >worlds as using 255/75R16 for tire size. >It hurts my eyes. Awful!....:-)) > >M39x1mm is the German way of thinking....;-)) > >-- >Bye, > > _/ _/ _/_/_/_/_/ _/_/_/_/_/ > _/ _/ _/ _/ _/ _/ _/ > _/ _/ illem _/ _/ an _/ _/ _/ arkerink > _/_/_/ > > > > The desire to understand >is sometimes far less intelligent than > the inability to understand > > ><w.j.markerink@a1.nl> >[note: 'a-one' & 'en-el'!] > > **************************************************** C.M. Fortunko, Ph.D. Group Leader, Materials Characterization (853.05) National Institute of Standards and Technology Materials Science and Engineering Laboratory 325 Broadway Boulder, CO 80303 Office phone:(303)497-3062 FAX:(303)497-5030 Residence: (303)494-7246 ****************************************************