Before someone is called a liar and a soundly tar'd-n-feather'd, I thought I'd do some simple measurements, and see why my 90M Elmarit fits very tight on the M6TTL, and just fine on the M4-2.

These are quick measurements and subject to error, but according to my Mitutoyo calipers this morning...

Across the widest part of the lens flange on the 90M Elmarit is 1.715 inches. On the 35 Summicron Asph its 1.709 inches, or about .006 inches less in diameter.

When I say the 90M Emarit is tight - I mean its a wiggle fit into the body, AND you have to rotate it with a decent amount of speed to get the release to snap into position. If you try to turn it slowly, it sometimes will not lock, or locks poorly (I think the frame selector is "bottoming out" ie, cut too long).

Given what I found on my equipment - I can see tolorance problems being great enough to not allow lenses to fit, or fit well like in my instance.

-- Charles (cbarcellona@telocity.com), May 10, 2002

Answers

Charles - measuring is good - more people should do it if they have access to accurate equipment and can use it properly. They may be suprised at what they find though! I have stated before that most of the Hexar/Leica 'wrangle' could be settled with a few basic measurements - but that's another story. Back to your measurements - although you have found a (large) difference in size it may not be related to the tightness issue. It is possible that the lens flange may be slightly bent on body or even the lens. Have you measured the flanges (body and lens) at different points to check for roundness? Engineers use a thin film of ink like substance (engineers blue) to see where parts are tight - a felt tip pen is a good substitute - mark the flange contact surfaces on either the lens or body and fit them together a few times - where the pen is rubbed that is where it is contacting. I use a marker pen and then removed the ink with lighter fluid.

-- Johann Fuller (johannfuller@hotmail.com), May 10, 2002.

Can't say that I've put calipers on them as Charles has done, but I can say that, in my experience, there clearly does appear to be some differences in tolerances or specs among different M bodies and/or lenses.

I've got a new M6TTL with 3 new lenses (28/50/90) -- all fit snugly and smoothly into the bayonet mount . . . it "feels" right. I also have an M3 (recently CLA'd) and those same three lenses are a VERY tight fit on that body. As Charles said, you have to rotate the lenses with some authority to get them to snap into place. The older Leica lenses I previously had for the M3 all fit smoothly onto that body -- you didn't have to apply any exceptional torque.

A limited data set, I'll admit, but the specs and/or tolerances for the bayonet mount on M bodies and lenses would seem to have changed a bit over time.

-- Jim Reed (jimreedpc@aol.com), May 10, 2002.

Charles; Bravo on taking some actual measurements! Johann's idea on using bluing is good also. I have 3 Leica Thread Mount to M mount adapters. The Leitz Wetzlar one fits my M3 perfectly; the Voigtlander is abit tight, but still ok; the "no-name" adapter tends to get stuck on the body, abit too tight for my liking....(The different adapters key the rangefinder's field frames differently) Kelly

-- Kelly Flanigan (zorki3c@netscape.net), May 10, 2002.

Ditto to Jim Reed's post. All my current generation lenses fit fine on my M6 TTls, but are a 'tight' fit on my M3.

-- Richard Fulco (calcinc@mn.rr.com), May 10, 2002.

This is part of what has been discussed here for some time; QC. I have 16 AI Nikon lenses. They all fit the same on my original F [As you will notice I never sell anything; no meters on most of these older Nikons]as they do on the newest Nikon.

Having said that I have 4 M lenses. I see no difference in fit between the M3 and the M6. Maybe I just got good ones. ;<)

Art

-- Art (AKarr90975@aol.com), May 10, 2002.

Humm. Perhaps the LTM is better than the M. Wobble? Just tighten it down a bit, to oh, say 68 foot pounds of torque...

Tony

-- Tony Oresteen (aoresteen@mindspring.com), May 10, 2002.

More testimony to 'variable' mounting smoothness:

90 Tele-Elmarit - fine on the M4-2, a little stiff to mount on the 4-P; in between on the new M6TTL. Also even stiffer to REMOVE from the M4-P than to mount.

21 Super-Angulon - fairly stiff on all bodies, with a tendency to not want to lock on the M4-2.

28, 35, 90 f/2 lenses, and 15 with screw-mount adapter - no tightness, no wobble, just a nice crisp 'click' into place.

The oldest lenses are the ones with the most tightness (in this tiny sample) so it may just be small dings and chips to the mount surfaces from 25-30 years of use.

But that doesn't explain the variability among bodies, nor the fact that lens A is stiffer on body C than D, while lens B is stiffer on D than C.

-- Andy Piper (apidens@denver.infi.net), May 11, 2002.

Once in a while (do it every 1-2 yrs, according to lensuse) I put a tiny bit of grease on the lensflanges, rub it off again, so that an even tinier amount remains there.

If those metal parts are too >dry< this might also add to the fitting problem.

Best regards

-- K. G. Wolf (k.g.wolf@web.de), May 11, 2002.