Voigtlander Color Skopar M lenses to L39/LTM, is there such a flange?

[Smudgerer]

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I would like to change my two Voigtlander Color Skopar VM lenses, 21mm & 25mm, to L39/LTM mount, is there such a flange? Is this possible to do?

I have been looking everywhere but so far coming up empty handed. Any pointers would be appreciated, thanks!

[Ecar]

Not that I know of. Besides, you would need to reduce the length of the barrel by 1mm, which doesn't seem feasible.

[earleygallery]

No. You can fit LTM lenses to an M with an adapter but not the other way around.

[Carlos cruz]

2 hours ago, Smudgerer said:

I would like to change my two Voigtlander Color Skopar VM lenses, 21mm & 25mm, to L39/LTM mount, is there such a flange? Is this possible to do?

I have been looking everywhere but so far coming up empty handed. Any pointers would be appreciated, thanks!

You can buy older versions of these lenses in ltm

[dg4mgr]

The flange on Leica M lenses is just 1mm thick, so mounting another flange with 1mm less is impossible. Voigtländer might have a thicker flange as they offered also M39 versions of some lenses. 

Edited November 16 by dg4mgr

[Smudgerer]

40 minutes ago, Carlos cruz said:

You can buy older versions of these lenses in ltm

Thanks Carlos, sure I do know that but I would like to see if I could put my existing lenses to use first.

[Smudgerer]

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18 minutes ago, dg4mgr said:

The flange on Leica M lenses is just 1mm thick, so mounting another flange with 1mm less is impossible. Voigtländer might have a thicker flange as they offered also M39 versions of some lenses. 

Sorry, perhaps being somewhat thick myself here but I would like to see if it was possible to change the M flange for a M39 flange, are you saying that this would not be possible because the m39 flange would have to be less than 1mm, ( obviously impossible ), or what?......Thanks anyway.

Edited November 16 by Smudgerer

[FrozenInTime]

https://en.wikipedia.org/wiki/Flange_focal_distance

[dg4mgr]

vor 5 Minuten schrieb Smudgerer:

are you saying that this would not be possible because the m39 flange would have to be less than 1mm, ( obviously impossible ),

The M39 flange must be 1mm less thick than the M flange. So it is only possible if the M flange that is on the lens ist thicker than 1mm. On Leica made lenses the flange is exactly 1mm.

[Smudgerer]

Ok, thanks!

[lct]

There is only one way i'm ware of, but it is not with a CV lens. It is with the Summaron 35/2.8 "Dual Mount" which includes a built-in LTM to M adapter. An M lens that becomes a LTM when you remove the adapter.

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[adan]

On 11/16/2025 at 2:31 AM, Smudgerer said:

Sorry, perhaps being somewhat thick myself here but I would like to see if it was possible to change the M flange for a M39 flange, are you saying that this would not be possible because the m39 flange would have to be less than 1mm, ( obviously impossible ), or what?......Thanks anyway.

It is really the cameras that are different - thus requiring different lenses.

M39 cameras are 1mm thicker.

When Leica designed the M cameras, they reduced the camera flange distance by one 1mm, exactly so that a legacy M39 lens plus adapter thickness of 1mm would work like the native M lenses.

But native M-mount lenses cannot be retrofitted in the other direction, for use on M39 cameras. Except for the few (as lct notes) that had a dual-mount built right in at the factory (long before Cosina came along).

M39 lenses can be "stepped up" 1 mm (via adapter) to use on M cameras.

M lenses cannot be "stepped down" 1mm to use on M39 cameras. No such thing as an adapter with a negative thickness (less than zero 😉 ).

Technically, if you are willing to permanently grind several mm of metal off the back of the M-mount C/V lens(es) - and then permanently mount an M39 thread-mount - and calibrate it, and bench-test the result for correct focusing - and pay a machine-shop for the service, that might be possible.

Otherwise, it is an "one-way street."

(Canon had the reverse problem with the change from FD-manual to EOS-EF-autofocus lenses. No way to "grandfather" FD lenses to fit on an EOS body, without losing the ability to focus all the way to infinity - they become macro-only lenses. Except via an adapter that is also a 1.26x or 1.4x teleconverter, where the glass can compensate for the back-focus mismatch. Probably not something you want with super-wides, which would lose much of their "wideness.")

[Smudgerer]

Thank you Adan, I was having a senior / dumb moment when I posted that Topic Question..........about an hour later I worked it out for myself, it's quite obvious really. But your idea of a "negative thickness" adapter is a good one, if only..............

[farnz]

On 11/20/2025 at 12:56 PM, Smudgerer said:

it's quite obvious really. But your idea of a "negative thickness" adapter is a good one, if only..............

I saw a negative thickness adapter for sale on Craig's List in a package deal with a Bell Unringer and a time machine although the time machine was advertised "as is" so it wasn't clear if it was working properly. 

I offered a swap for my Combustion Reverser and a 1952 iPod but unfortunately the seller already had both.  I'll keep my eye out though.

Pete.

[Smudgerer]

32 minutes ago, farnz said:

I saw a negative thickness adapter for sale on Craig's List in a package deal with a Bell Unringer and a time machine although the time machine was advertised "as is" so it wasn't clear if it was working properly. 

I offered a swap for my Combustion Reverser and a 1952 iPod but unfortunately the seller already had both.  I'll keep my eye out though.

Pete.

Wish I saw that before you did..........

[dg4mgr]

When looking at pictures of the Voigtländer Skopar M lenses, it looks like their M flange is like 2 mm. So for the Voigtländers, it might be possible to make an M39 flange. 

Edited November 22 by dg4mgr

[Smudgerer]

I solved the problem the old fashioned way. Sold my 25mm and 21mm VM Voigtlander Skopars and bought the new 28mm /2.8 Color Skopar L39 ASPH and the 40mm / 2.8 Heliar L39 ASPH both of which will match my "new", restored and repainted Leica 1F perfectly...........Job done. Thanks for all the imput above.................

Edited Sunday at 09:20 AM by Smudgerer

[farnz]

That's lucky because it turns out that the time machine won't be working until the 16th Century, something to do with a clash between the Julian and Gregorian calendars.  (You'd think it'd be simple enough to travel back in time and fix it but the seller says he doesn't pass his time driving licence until 2090 so he can't.)

Pete.

[LocalHero1953]

My technical manager tells me that when she was teaching maths to student trades people ('Meat One' and 'Plasterers Two', for fans of Tom Sharpe), she had to teach imaginary numbers to electricians and electronics engineers. Applied to optics, perhaps this would help fit a M lens to a LTM mount. 

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Hallo,

Look here: Leica M