Coded lenses on M240, Some detect, some don't. Why?

[Huss]

OK, another update for those out there who might be interested:

I did a couple of "experiments" to see what I could learn. It was educational and perhaps others will find it useful.

I decided to start with an LTM lens that has an adapter (LTM -> M) with coding pits milled in it. I believe I got this adapter from ebay (Chinese?) but its been a few years now, so don't remember the exact source.

The lens/adapter was not detected by my M240 at the beginning of my experiments.

BTW, the lens is a Canon 50/1.4 and I coded it as a summilux (100000). No need to explain to me that there's a difference in the performance of these lenses

I used Testor's brand model paint. The white is labeled just "White", and Black is "Flat Black". I put paint in the coding pits and waited for them to dry (goes quick right now with 90-100F heat and low humidity). Tried out the adapter/lens on the M240 and ----- no go.

So, I decided to really fill in the pits. I placed paint in each pit so that it "mounded" with surface tension. When the mounds dry, the paint collapses down into the pit. I waited for my first set of mounds to dry, then mounded again with more fresh paint. After the second mound dried, the pits were clearly "filled" with paint, not just colored. They still dried to be a bit sunken and not even with the surface of the flange.

Tried this lens/adapter on the M240 and ..... 1.4/50. Detected! Hmmm.

I am coming to the conclusion that the M240 is picky in both the precision of the milled pits (location, size and shape), and the quality of the paint filling them. I believe the white paint needs to be very reflective, in particular in the near infra-red range. The black paint needs to be the opposite. Flat Black is considered much more absorptive than Gloss Black (I think that's common knowledge). In fact, I think black Sharpie ink is somewhat reflective. I think this because of an experience I had coding for my M9 and M8. Back then, I remember trying to code a lens with a no-name black marker I found in the drawer. It didn't work no matter how much I tried to apply the ink. Then I found a Sharpie and applied that to the lens, and it worked. Interesting. However, over the years I've found that not all Sharpies will work for coding either. The thin-point black Sharpies would never work, no matter how much I applied ink. A brand new Sharpie I bought at the office supply store would not work, but my old Sharpie that I bought years ago would work fine for coding. I think this variation in coding success is related to variation in the reflectivity of inks.

To reinforce some of what I've learned, I did one last experiment with another LTM -> M adapter. Again, I attempted to code it for Summilux. That code has 5 white pits and one black pit. This time, I only applied mounds of black paint in the black pit and left the remaining pits "blank" (which would be a silver color). That did not get detected by the M240. OK, that's interesting. Then I put thin coats white paint in the blank pits and tried again. No detection. OK again. So now I mounded the white paint just like I did in the previous experiment described above......and it was detected (however, I did need to "jiggle" the lens to get it to detect. I think that's because of the precision of the frameline lug. I didn't get the 50 frameline without the jiggling either).

My conclusions: It seems quite possible to code lenses for M240. Its just harder than before with the M9 and M8. Parameters include: precision of the milled pits and frameline lug, paint type/characteristics, and paint quantity.

Now I'll leave with yet another consideration for folks interested in coding their own lenses. Replacement flanges vary in thickness, as do factory Leica flanges. If you want to retain focus accuracy, you will want to address this. I did so by measuring the thickness of my original flange and matching it to the thickness of the replacement flange (I have a micrometer, you'll need one too). This means ordering a few or several of the replacement flanges. If there's no match among the replacement flanges, I will use a thinner flange and shim it. However, this is not easy because the shim often needs to be quite thin. For example, a piece of typing paper was much too thick for my last lens coding attempt. Scotch tape is a little thinner and I eventually found a combination of replacement flange and Scotch tape that would work. Effort intensive, eh? I think I learned about Scotch tape from Brian S. who is quite a lens hacking genius.

I hope I've helped someone.

Wow, thanks for all that information! I had just used Sharpies.

 

[pyeh]

Rfaspen, thanks for the meticulous testing of home-coding. Your findings are pretty much as I expected, but it's great to have a demonstration. Like you, I also found different marker pens had different ink gloss or transparency, which would affect the readers on my M9s as well. Thanks again.

 

[Bill Blackwell]

... I found that only factory coded lenses were readable, while Sharpie coded Voigtlander and Zeiss lenses that worked on my M9s would not, nor even Sharpie coloured milled coding pits on an LTM-to-M adapter. It's possible, even probable, that matt black and white enamel paint would have made those lenses readable but I didn't go so far as to try that idea. I dd though get as far as buying tiny tins of flat enamel and a sable brush.

This has not been my experience at all! If the lens is coded properly (make sure any after-market lens is coded with the proper framelines of the lens you want on the exif data) an M/MP-240 will read it.

... from memory the Not-M10 does not have codes for M lenses that were produced after the introduction of the M8, so you can't manually code in a new M lens. That's assuming that some of Rfaspen's unsatisfactory lenses are uncoded versions of post-2007 Leica M lenses.

This is absolutely untrue! Any 6-bit (properly) coded lens will work on an M10.

 

[pyeh]

Bill Blackwell, you'll have to share your secret in getting hand coded lenses to work on the M Typ 240. You did well.
I think you misunderstand me on my second point: yes a properly coded lens will be read by the M Typ 240, but any lens that has been designed after the advent of 6-bit coding, will not have its code listed in the camera menu. If you wanted to manually enter that code for an uncoded lens, you won't be able to select it. Your recourse is to code your lens of course.

 

[Bill Blackwell]

Bill Blackwell, you'll have to share your secret in getting hand coded lenses to work on the M Typ 240.

I always have my flanges milled (I used to have a direct source for that, but now go through DAG). Fill with water-based model paint (acrylic black and white). Again, as long as the coding is correct with the proper framelines, you'll be golden.

I've never even tried using the sharpie method.

 

[Bill Blackwell]

Now that I think about it, there was one occasion that my 90mm Elmarit-M was picked up as a Summarit on my MP-240. After dismounting and blowing off the 6-bit code, it read correctly once remounted to the camera. This is the only time anything like this has happened to me.

 

[rfaspen]

All seems to confirm what I've found, which I hope is useful to others.

1. Coding pits should be accurately placed (and I think pits are really necessary instead of just marking a flat mounting flange).
2. Frameline selector bayonet lug needs to bring up the correct framelines. If your lens mount doesn't, lets be hopeful you can get there with careful, judicious filing. Otherwise, if the lug doesn't turn far enough, a new mount is needed.
3. Coding pits need to be filled with paint. Perhaps not completely full to the "rim", but more than just a coating on the bottom of the pit. I was a little surprised this made a difference. More than one round of paint-filling may be necessary to build up enough paint in the pit.
4. Paint needs to be "good quality" in that the black paint doesn't reflect light and the white paint is reflective. You must have both black and white coding present for the M240. We could get away with just the black markings on M9 and M8. Not with the 240, the white paint portion is required.
5. Sharpie and similar ink markings don't work with M240. They appear to be too reflective. And the M240 might even be sensitive to the kind of paint used in the pits. I used "flat" model paints and they worked. Testor's brand, commonly available in the U.S.

Best luck to everyone. I have successfully coded all the lenses I need coded for the time being...

 

[Doug]

I agree with the 5 points above. And add that nail polish has worked well.
I had most of my lenses coded and adjusted by DAG, who sent the flanges to John Milich for machining the pits.

 

[Gregm61]

5. Sharpie and similar ink markings don't work with M240. They appear to be too reflective. And the M240 might even be sensitive to the kind of paint used in the pits. I used "flat" model paints and they worked. Testor's brand, commonly available in the U.S.

I do not think it is a coincidence the M-coder kit Match Technical used to sell was discontinued shortly after the introduction of the M240, then the M262. My M262 has never read the M-coder markings that my M9 always did. I think Match Technical figured out pretty quickly their system had been "defeated" by Leica with the new bodies, requiring a more permanent solution for the camera to read.

 

[umcelinho]

Got an MP240 this week. I'm using a Voigtlander Nokton, tried using a posca pen to code it before finding forum posts about the M240 being more picky. Would anyone have a seller on ebay that they'd recommend for buying 6-bit pits flanges? I'm based in the UK but as long as it's a reliable seller it would work out. Trying to avoid buying a codeable flange only to discover the lens won't focus properly! I reckon using a paper template and using nail polisher or other enamel paint (any recommendations?) to paint the 6-bit coding wouldn't work out, right?