M Flanges and 6-bit coding

[LCL999]

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Apart from the $300 Leica service, one way to get lenses coded is to replace the flange, or send it away for coding to a third party. This led me to do some research on flanges.

There is a Chinese vendor offering what I call Type I flanges, and also Type II ones.

Here is what I found out.

 

Note that:-

All measurements in degrees clockwise from the centre of the key as viewed looking at the rear of the lens.

Measurement are approximate and have been rounded to what appears to be the nearest whole number.

All flanges come in three variations for 28/90, 50/75, or 24/35 viwefinder frame lines.

 

6-bit code

start 115

finish 142

 

Type I flanges

These appear to be on all digital era lenses as the screws don't invade the code area.

Six screws at

40 80 160 210 275 340

 

Type II flanges

Examples I have seen include

Product Year

11815 1982 Summilux 75mm f/1.4

11800 1973 Tele-Elmarit 90mm f/2.8

11134 1991 Elmarit 21mm f/2.8

Six screws at

60 72 36 72 72 36

Note that the second screw sits right in the 6-bit code area and looks like a "1" to the sensor.

Thus uncoded lens with type II flange looks to have code 000100.

Which is great if it is the 90mm above, but a problem elsewhere.

 

Type III flanges

I have only seen one.

Product Year

11817 1968 Summicron II 50mm f/2.0

Five screws at

45 135 225 270 315

Again, the second screw sits right in the 6-bit code area and looks like a "1" to the sensor.

Worse though, if that screw is omitted, there will be a full 180 degrees without one.

I'm not sure if the flange would stay flat and square under such circumstances.

 

Type O flanges

I call them this as they have no screws at all in the face of the flange

This makes it difficult to remove.

I think all the early lenses were made like this

Examples are

Product Year

11631 1955 Elmar 90mm f/4.0

11870 1967 Summilux 35mm f/1.4 - (this has screws around the edge of the flange)

11118 1953 Summicron (I) 50mm f/2.0

11850 1961 Elmar 135mm f/4.0

16464 OTZFO M-mount for Visoflex lens heads

also the Voigtlander 12mm Ultra-Wide Heliar (are all Voigt. flanges screw-free?)

 

I hope this helps.

Edited March 3, 2013 by LCL999
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[devonbuy]

My attempt on 6-bit coding my Summicron-M 50mm f/2 version V may be found here at https://www.devonbuy.com/how-to-6-bit-code-leica-m-lens/.

I have also provided a colour-coded table of 6-bit codes for other M lenses as well as a step-by-step picture guide of the process.

Hopefully it will be of some assistance to those who wish to attempt the same.

Thank you.

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[tobey bilek]

Having pondered this for a long time,  I decided to use only factory coded lenses or those that can be set manually.

If I wanted to code over a screw,  I would drop some wax or tape over the screw.   Then fill with black paint.   This keeps the lens repairable.

[farnz]

I have successfully coded some of my lenses with pre-pitted flanges bought over the internet.  

A word of warning though: I did the same with my 50/1 Noctilux v4 only to find that when I removed its flange there were shims beneath and the pre-pitted flange wouldn't fit properly so I was unable to attach the lens to an M-mount camera that I'd used it on previously.  It took an extreme amount of laborious work to refit the lens's original flange so that focus wide open is still spot on.  

Pete.

[rsolomon]

Farnz

thats exactly what I’m afraid of......then not having confidence to get it back to working order

[thecat]

Hi,

I would like to share my very bad experience coding my Apo-Summicron-M 1:2/90 ASPH myself with one of those shitty chinese flanges.
Months after having changed the flange, I noticed that all my pictures taken in front of the sun, around F11 and F16 showed incredible diffraction, V or X shaped. Since I has also bought a brand new Leica M10, the confusion was maximum. I made many tests, and I didn't have the problem with other lenses, I had the same problem on my old M8.2, but NOBODY could tell me how this phenomenon was possible. And then I remembered that I had change this flange... Its interior is shining, while the Leica original is matte black. I installed the original flange, and the problem was gone.

So be extremely careful ! I do not say it would happen on all lenses, but on the Apo-Summicron-M 1:2/90 ASPH specifically, it just doesn't work !

Hope it helps.

 

Philippe.

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[jaapv]

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Yes, it does look like flare due to an internal reflection. Not too problematic, though, to apply a bit of flat  black paint.

[AndreasG]

vor 32 Minuten schrieb jaapv:

Not too problematic, though, to apply a bit of flat  black paint.

Before disassembling the flange and painting I would attach inside the flange a small stripe of black adhesive tape, simply to test the approach.

[Ecar]

I've had a few lenses coded (usually in conjunction with a CLA) by Leica during the good old M8 times.
Since then, and also because I often use vintage lenses these days, I have made it an automatic routine to set the code (if any at all) manually when swapping lenses.
In addition, if my experience with literally dozens of LTM to M adapters of various types and brands is an indication, I wouldn't want to go through the time and expense required to replace an original M mount with one made by the same eBay sellers, only to find that the lens doesn't focus quite as accurately as it used to.
Given the manufacturing tolerances of even the *best* CN-made flanges available on eBay, replacing the original mount with one of these (especially on focus-critical lenses such as the 50/1.0, 75/1.4 or 90/2) is a recipe for disaster IMO. Unless, of course, one values lens recognition more than RF focus accuracy...

[mediumformula]

Does Leica still offer 6-bit coding on old lenses and does it still cost $300?  I have a 50 Summicron v4 that I'd like to code.  I can't find any flanges on ebay that could be screwed into the back of my lens to replace the un-coded flange.  

[rsolomon]

Best to call and talk to them, ensure they have the new flange in stock. Also this time of year July - August you might be leaving your lens a long time for a simple upgrade by leica.  
 

ps: I would only use Leica services (or DAG)

[mediumformula]

Basically, no one on the internet sells replacement flanges anymore for DIY coding.

[Gregm61]

I have noticed Leica Store Miami selling in their used department recently, numerous lenses that date well back in time that have been sent to Leica repair centers for servicing, including 6 bit coding.

I purchased a Canadian version IV 50mm f2 Summicron from them dating from the 80’s and I’ve seen 90mm f2 pre-APO, 28mm f2.8 version 3 Elmarit-M (they have one of those right now), even a 90mm f2.8 Thin Tele Elmarit-M the last several weeks.

I also would not doubt DAG would perform this service, just as well and substantially faster than a Leica repair center.

[lct]

16 hours ago, mediumformula said:

Does Leica still offer 6-bit coding on old lenses and does it still cost $300?  I have a 50 Summicron v4 that I'd like to code.  I can't find any flanges on ebay that could be screwed into the back of my lens to replace the un-coded flange.  

This eBay store might interest you possibly. I bought a couple of 6-bit coded flanges from them in the past but none for 50/2 v4 sorry.

[mediumformula]

1 hour ago, lct said:

This eBay store might interest you possibly. I bought a couple of 6-bit coded flanges from them in the past but none for 50/2 v4 sorry.

Thank you.  I'll try writing them.  I think I need the Type 1 adapter for the 50/2. 

[lct]

26 minutes ago, mediumformula said:

Thank you.  I'll try writing them.  I think I need the Type 1 adapter for the 50/2. 

I don't remember the type but the code number of the 50/2 v4 is 11819 in black and its flange has 6 screw holes. Native flange below.

Edit: There is no adapter properly speaking here. It is just the native flange of the lens that you will remove and replace with a replacement flange milled for 6-bit coding. All you need is a screwdriver fine enough not to damage the screw heads of the lens.

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Edited July 16, 2023 by lct

[mediumformula]

 

28 minutes ago, lct said:

I don't remember the type but the code number of the 50/2 v4 is 11819 in black and its flange has 6 screw holes. Native flange below.

Edit: There is no adapter properly speaking here. It is just the native flange of the lens that you will remove and replace with a replacement flange milled for 6-bit coding. All you need is a screwdriver fine enough not to damage the screw heads of the lens.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Thank you.  I just wrote the seller and asked about a replacement flange with 6-bit indents for the 50/2. 

[DadDadDaddyo]

I tried one of these aftermarket flanges with unpainted pits for 6 bit coding, once. 

It aligned and fit onto the lens alright (it was a 90 if I recall right) but when I tried it on a body, there was clear and unusual resistance and binding while cautiously turning the lens to lock it into place. Something about the machining of the bayonet was funky. I turned it no further, removed it, and put the original, ancient, German flange back on, and everything was butter-smooth again. I vowed to go down that path no more. 

So then I found a printable template for the back of the original flange showing the locations of the 6 bit pits. I darkened the appropriate spots using dots marking with the tip of a Sharpie; they were just simple dots, not even as big as the original marks would have been, but they were centered in the correct locations....

.... and it worked. This was my one attempt at hand-coding an unencoded lens.

Since then I've gone the way of the probably-overly-chicken, and when adding to my collection of M lenses, have added only factory-encoded lenses. 

My suggestion for most folks, certainly any who might be concerned about fit, or shims, would be to give the Sharpie method a try. Or, simply enter a lens profile manually. If you confine your unencoded lenses to one per session or trip and enter its profile manually, the camera, set to detect coding, will revert to that profile the next time it sees an unencoded lens, so it's workable that way. 

There were aftermarket kits at one time that included a plastic template with holes to guide marking an unencoded lens. These still show up from time to time on EeeekBay.

And perhaps it's helpful to remember that our ancestors managed to produce workable images on film with bodies completely incapable of attempting software correction of distortion or vignetting. Simplicity is a gift. 

[lifeandmylens]

DAG will 6 bit code a lens with a removable flange for $325 using a 6 bit factory flange.  Or 6 bit code a flange where it's part of the focusing system (older lenses with no screws on the flange) for $300 via milling it and painting it.  I've done several lenses with him using both methods.  Very happy with them.  

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[lct]

6 minutes ago, DadDadDaddyo said:

My suggestion for most folks, certainly any who might be concerned about fit, or shims, would be to give the Sharpie method a try [...]

Fine on recent CV or ZM lenses that have a recessed area for coding but not that much on Leica lenses that have no recessed area and will cause the coding marks to erase by friction soon or late, unless by butchering the flange with a dremel tool  Also, sharpies are not dark enough to avoid reading errors in my experience. I may use one to mark the coding dots in the first place but i apply some black paint (or black ink) over those marks afterward and it works perfectly this way. FWIW.