jimdesu Posted December 3, 2004 Share Posted December 3, 2004 I keep finding different sources of information on LTM; is it: M39x26tpi@28.8mm, or M39x25tpi@28.8mm ? Need to figure out what to tell the machinist.... =) Link to comment Share on other sites More sharing options...
al_kaplan1 Posted December 3, 2004 Share Posted December 3, 2004 James, I think that your problem might be in attempting to use "Threads Per Inch" for a metric measurement. I'm pretty sure that one inch equals 25.4mm. The 39 is the diameter of the threads and 28.8mm is the distance from the front surface of the camera's lens flange to the film plane. What are you conjuring up? What great new lens or accessory are you going to proudly announce to all of us eager Leicaphiles, and perhaps even a few Leicaphobes, all inexplicably drawn here against our better judgement? The suspense is unbearable! Make sure that the machinist is properly attired in an Al Kaplan T-shirt, and get some good shots of him (or her) while working on the gizmo! Link to comment Share on other sites More sharing options...
jonathan_stark Posted December 3, 2004 Share Posted December 3, 2004 Schneider says it is 26tpi. Interesting little write-up here on their web site: http://www.schneideroptics.com/info/faq/photo_enlarging/#q3 Link to comment Share on other sites More sharing options...
al_kaplan1 Posted December 3, 2004 Share Posted December 3, 2004 Can't argue with that, Jonathan. Thanks for the link! So why did Schneider then pick a smaller size hole for their own enlarging lenses? Link to comment Share on other sites More sharing options...
shambrick007 Posted December 3, 2004 Share Posted December 3, 2004 What you working on Hue..uh...I mean James? ;-) Link to comment Share on other sites More sharing options...
dan flanders Posted December 3, 2004 Share Posted December 3, 2004 I can't argue with any authority, but it's a bitch to cut on my little Atlas which doesn't like Metric standards. I finallly found a gear for the lead screw, but the thread indicator doesn't cooperate so I have to stop, reverse, and back out before each successive cut. Link to comment Share on other sites More sharing options...
paul t Posted December 3, 2004 Share Posted December 3, 2004 Is <a href="http://www.a1.nl/phomepag/markerink/mounts.htm" >this site</a> helpful? <p> Personally, I'm extremely confused by how many people refer to M39 mount as a Leica mount, when I thought it was L39... and that M39 is a Soviet SLR mount. Anyway, this site has been mentioned by people who seem to know what they are doing (unlike me), Link to comment Share on other sites More sharing options...
EricM Posted December 3, 2004 Share Posted December 3, 2004 Hue, James? huh? Link to comment Share on other sites More sharing options...
jim_mcbride Posted December 3, 2004 Share Posted December 3, 2004 He means Huw, as in Finney. Link to comment Share on other sites More sharing options...
EricM Posted December 3, 2004 Share Posted December 3, 2004 excuse the typo Huw/James. Link to comment Share on other sites More sharing options...
ronald_moravec1 Posted December 3, 2004 Share Posted December 3, 2004 Metric threads are specified in diameter and distance from peak to peak in mm. There is no inch specification in the description. Give the machinest a screw thread lens and have him measure it and make a mount to match. The female half needs certain clearances so they will actually screw together and not have an interference fit. Therefore you need to furnish a mate for trial fit in any case. The mount holes for the flange need to be in certain places so the lens orients properly. S k Grimes will know without all the hassle. Link to comment Share on other sites More sharing options...
huw_finney Posted December 4, 2004 Share Posted December 4, 2004 I am only Huw Finney (the world couldn't cope with more), to answer I am working on a VC Focomat bulb for another forum member. Details to be posted soon. Link to comment Share on other sites More sharing options...
huw_finney Posted December 4, 2004 Share Posted December 4, 2004 Story goes Leitz used 26TPI to confuse the competitiors. Link to comment Share on other sites More sharing options...
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