View Full Version : LTM to M adapter problem. plesae measure

02-01-2006, 13:15
Dear fellow RRF members.

I have a slight problem (admittedly a luxury problem as all Leica problems are).
I already owned a Voightlander adapter which works fine on my M6TTL.
I decided to buy a second adapter to use with a second LTM lens (the CV 12mm I bought from Scekiat). I bought one on the bay, and it does not work.

It looks original Leica, and I have no reason to doubt it is not. It mounts fine on the lenses :) , but refuses to mount on the camera. I can insert it, but it will not turn :confused: .

Out came the caliper and I measured both adapters. They differ in one main dimensions: the distance between the ring and the notch :bang:.
The New (Leica) one has 5,05mm
The Old (Voigtlander) one has 5,25mm
I have measured all my M mount lenses, and these are all 5,25 mm as well.
0,2 mm is a tiny difference, but it may be just enough to cause the problem.

To correct this I can either trim the notches by 0,2mm, or the ring by 0,2mm.
If I touch the ring it influences the focal plane of the lens (which is more critical as the focal length reduces and this lens is a 12mm!)
To make a choice I measured the thickness of both rings:
New (Leica): 1,15mm inner ring, 0,90 mm outer ring
(Inner ring is the slighty raised part directly under the notches)
Old (Voigtlander): 1,0mm inner ring, 0,90mm outer ring.
So it seems the inner ring is too thick.
There is an other clue; the inner ring is the same silvery colour as the rest of the adapter. In many pictures of the adapter, it seems to be bronse colour. Mayby if I start shaving the inner ring it will turn out that under the silvery coating there is a bronse base (could this be an unfinished sample??)

Before touching (destroying?) it (I do not have a clue yet of how to do this) I would like to ask if some of you could measure your own adapters to confirm my conclusion.
- Has anyone experienced similar problems?
- Has anyone a Leica adapter of which the inner ring is silvery in colour?
- What is the distance between inner ring and notch?
- What is the thickness of your inner ring?

Thanks in advance for your input,


02-01-2006, 13:37
We had a long discussion of this some time back on the R-D 1 forum; you may want to search that out.

I'm not sure I understand your terminology about the "ring" and the "notch," but if I understand correctly, it sounds as if your new ring is 'way too thick.

On a genuine Leitz-brand adapter (no longer manufactured) the bearing surface -- the one that determines the distance between the lens mount and the body flange -- should measure 0.98mm to 0.99mm.

I assume this is the same part as what you call the "inner ring," so your old Voigtlander adapter sounds as if it is the correct thickness; the distance between my 0.99mm measurement and your 1.0mm measurement could be a tolerance difference between your adapter and mine, or a slight difference between how our calipers read.

The other one that measures 1.15mm, though, is MUCH too thick. The thickest ones I've encountered were in the range of 1.04mm, and that was enough to throw off infinity focus.

You note that the inner ring is silvery color, meaning that it has chrome plating on it. On a genuine Leitz adapter, this surface is brass-colored; I believe Leica first plated the brass part, then milled the back edge of the ring until it was exactly the right thickness. It sounds as if this step was skipped on your adapter.

I am only guessing, but my guess is that this extra thickness also may be what keeps your adapter from seating on the lens mount. It suggests that either you got one which was very poorly made, or which was bent or otherwise damaged sometime after manufacturing.

Although it's possible to try to file or sand down this rear surface until you get it the correct thickness, I don't know that it would be worth the bother -- you also need to keep it extremely flat and parallel, and that's difficult to do when working with hand tools. I have succeeded in thinning down a slightly too-thick adapter by sanding the front face against a flat surface, but this is only practical for reducing it by 0.01mm - 0.02mm. Also, it would not help your problem of the adapter not mounting on the camera, because that problem is caused by excessive thickness on the BACK edge.

I suspect that the new adapter you got on eBay is simply no good, and you should either return it to the seller and ask for a replacement (and measure it before using it) or get a refund and apply it toward a known-brand adapter that has a better chance of being made correctly.

If you can post photos or sketches showing what points you want measured, I can take more measurements tonight when I am home from work. But if your adapter is out of spec for thickness (the most critical dimension) I suspect it's going to be out of spec all over.

02-01-2006, 15:07
As requested 3 pics of the adapter

second indicates the inner ring I mentioned
third the distance to measure

Gabriel M.A.
02-01-2006, 16:15
When you say "new", do you mean that you just acquired it, or you actually bought it new, in its original box, from a dealer, or something like that?

I don't know, but this adapter doesn't look like an original Leitz adapter to me. My 35mm Leitz adapter has a red dot where yours shows a hole, and the letters are painted, where yours are not, just engraved. :confused: :(

Gabriel M.A.
02-01-2006, 16:17
There is an other clue; the inner ring is the same silvery colour as the rest of the adapter.
Mine has a "brass" color to the ring you're describing

02-02-2006, 01:48
The thickness of the ring (1.15mm) is suspect. Isn't the difference in flange-film plane distance supposed to be exactly 1mm between the LTM and M Leica's?

It looks indeed like that the ring hasn't been machined to that thickness on the inside.

All my adapters show bronze where they're machined. See attachment.

02-02-2006, 05:51
don't worry about brassing, eletro-plating are usually measure in microns, the thickness of the adapters (like the 0.1mm difference you found) have a bigger effect.

Buy a desent/good one, it will save you from spending again. My LTM to M (50mm) was given to me when I brought a lens, brassing everywhere but I am not complaining. If I have to buy one, I would get a CV one just to be safe.



02-02-2006, 23:36
I have the same adapter (M2 21-35, M3 135). Yours appears to be the genuine part, but incomplete in manufacture. First, the engraving should be ink-filled. Second, the "inner ring" should show the underlying brass as illustrated by Peter. Correct thickness of this surface looks essential for happy mating with the camera, and yours is too thick (gauging your pics by eye).

A properly-working adapter bayonets onto the body in a smooth, effortless fashion.

02-03-2006, 16:21
Sorry to say this, but I think Mad_Boy got stuck with a forgery. The genuine Leitz adapters are worth more than no-name versions on the used market, so there would be a strong incentive for an unscrupulous machine shop to increase the value of a no-name adapter by engraving the Leitz name on it.

I'm attaching two pictures of a genuine Leitz adapter. Notice that the style of lettering on it is completely different from that of the adapter in Mad_Boy's pictures -- the lettering is upper-and-lower case, rather than all capitals, and the style of the letters is more subtle.

Also, as someone else pointed out, the lettering on the real adapter is filled with black enamel paint, a time-consuming extra step that adds to the cost. (Also, while it's not visible in the photo because of the way I lit it, the round orienting index dot is filled with red paint.)

On the back-side picture, note that the seating area of the adapter -- where it rests against the camera flange -- has been machined to the exactly correct thickness, an operation which removed the chrome plating and left the natural brass surface visible.

I measured this adapter from the inside of the bayonet prongs to the seating area, and got a measurement of 5.33mm. The comparable dimension on Mad_Boy's adapter is 5.05mm as quoted above. So it's no wonder it's difficult to mount his adapter on a camera -- the fit is just too tight! (The measured difference between his Voigtlander adapter, with 5.25mm, and my 5.33 is almost certainly small enough that the springs on the camera's bayonet lugs can adjust to the difference.)

As we've discussed previously, the thickness of my adapter at the seating area is 0.98mm, while the suspect adapter was measured at 1.15mm, which would be 'way out of tolerance.

So, apparently Mad_Boy has discovered a new thing of which we have to be careful -- counterfeit Leitz adapters! As if the marketplace weren't already a jungle...

Gabriel M.A.
02-03-2006, 16:27
Yep, that's what I thought too. That makes me think... I do have a "cheap" 50mm LTM-to-M adaptor. I should go ahead and measure that one or compare it to the one that, well, apparently, is the "real" thing.

02-04-2006, 05:21
Dear fellow RFF members,

many thanks for your support and answers.
I agree with you conclusions. The ring is too thick and this probably because it is a couterfeit eitem :bang:

That is a disapointment. Now I have to either bin it, or have some-one with the propper tool (CNC milling machine) and skills correct it.

I will not sell it off again. I would hate to sell an item I know is not working.
Unless any one of you is interested:
- Like new adapter :angel:
- Has never been used :p :D
- 100 Euro only :rolleyes:
(plus packing 20 Euro :) )
(plus insurance 20 Euro :p )
(plus paypal charge and commission 5% :D )

Have a good week-end ;)


02-04-2006, 07:15
There are people who collect counterfeit Leica cameras. Maybe one of them would like to expand into counterfeit Leica adapters!

02-04-2006, 07:32
Great! then I can increase the asking price :D

02-06-2006, 22:20

Your adaptor is a repo but...
Take a coarse triangular stone and work it all over the backside of adaptor on the mating surface then a fine stone.
After about 30 minutes of careful polishing it will fit your camera.
BTW it is always easier to mount ring AND lens together rather than ring alone.

02-21-2006, 14:35
I have contacted the seller with the conslusions of the discussion above.
It is either fake, or a half-finished product.

He stated that He knew for sure it was real (bought it at Wetzlar) and promised to do some research.

Now he came back with the following interesting story:
In the 60's some adapters were indeed sold as semi finished product to proffesionals.
These could then mount the adapter to their lens, measure the exact ideal thickness and then have the ring dimension reduced to the ideal size for that specific lens.
Aparently leica (Leitz at the time) would also provide this service for the pro's when they send in their lenses.

The seller has offered me to take back the adapter and to have it machined to whatever thickness I would whish it to be.

Has anyone of you heard this story before???


02-21-2006, 15:40
ummmm,sounds like bull.

always buy leica

02-21-2006, 19:35
Now he came back with the following interesting story:
In the 60's some adapters were indeed sold as semi finished product to proffesionals.
These could then mount the adapter to their lens, measure the exact ideal thickness and then have the ring dimension reduced to the ideal size for that specific lens.
Aparently leica (Leitz at the time) would also provide this service for the pro's when they send in their lenses.

I'd hate to tell someone to his face that he's a liar, but that certainly sounds like a fishy story to me! I've never heard anything like it before, nor seen it in my admittedly sparse collection of Leica reference books.

And it seems out of character for Leitz in the '60s to think it would have told its customers, in effect, "We can't make this part precisely enough to work right, so we'll sell you an unfinished one and let you figure out how to fix it." I think they had too much hubris for that!

Even if you want to believe the part about the "semi-finished" adapters, it doesn't explain why Leitz also would go to the bother of engraving the lettering in a completely different style, then omitting to fill it with paint.

If you really think the guy is sincere, and want to continue to pursue this, I'd say take him up on his offer: Tell him you want the back flange milled to exactly 0.98mm thickness. Assuming he can get a good job done at this (correct thickness and parallelism) then you've not only got a usable adapter, but an interesting curio that's either a virtually unknown Leitz accessory or a particularly blatant forgery.

02-22-2006, 02:15
100 Euro is a surprisingly high price for an adapter (if that really is what you paid for it....),even if it were ok. I'd stick with Cameraquest in the future if I were you.And as for that Leica story: Is the sellers name von Münchhausen by any chance?

02-22-2006, 13:18

I did not pay 100 for it, not by far.
It is my asking price :p since this is a collectible item now :angel: .
A forgery of a semi finished Leica adapter :D . Ha, must be the only one in the world!
I should ask 200 at least thinking about it.

I think that I will indeed send it back to the seller.
Worst that can happen is that he does not return it, but then it was not working anyway.

to be continued.....