portocar Posted April 13, 2007 Share #1 Posted April 13, 2007 Advertisement (gone after registration) Yes…Leica uses a 6-bit coding system for their lenses. However, we have seen many proofs of concept that the coding can be done at home with a marker and you only need to mark the locations corresponding to the black dots. So, if I send a non-coded lens to a machine shop, to have the recesses created for the 6-bit coding, why not just have them make the small holes corresponding to the black dots and ignore the white ones. I can then fill in the holes with black paint. One further benefit, for those wanting to use zeiss lenses, is that the zeiss mounts just happen to have a screw on one of the locations where a hole for one of the dots in the 6-bit code should be. If you only concern yourself with the black dots, you may never need to trouble yourself with the position of the screw on the Zeiss mount. Link to post Share on other sites More sharing options...
Advertisement Posted April 13, 2007 Posted April 13, 2007 Hi portocar, Take a look here Why six holes on the lens mount. I'm sure you'll find what you were looking for!
robsteve Posted April 13, 2007 Share #2 Posted April 13, 2007 I think there are only a few Leica mounts in the new lines of lenses, so having all six coding indents in the mounts allows Leica to use the same mount on a number of lenses. As for just coding the black, I have done that on all my Leica lenses and it seems to work fine. I wouldn't send the lenses to a machine shop, just the mounts. If they machine the mount while on the lens you may risk damaging the lens, or at the least getting grit into the exposed focusing helical threads. If you get the mounts taken off, some lenses have focus adjustments related to the mount, so a Leica familiar technician should do it. Robert Link to post Share on other sites More sharing options...
DaveEP Posted April 13, 2007 Share #3 Posted April 13, 2007 One further benefit, for those wanting to use zeiss lenses, is that the zeiss mounts just happen to have a screw on one of the locations where a hole for one of the dots in the 6-bit code should be. If you only concern yourself with the black dots, you may never need to trouble yourself with the position of the screw on the Zeiss mount. Some of my lenses actually required some white marker (tipex) to make the white contrast enough with the bare metal (usually in the screw holes). The camera was obviously seeing the metal as black and not white. So in this case, you may need both black and white holes. Link to post Share on other sites More sharing options...
portocar Posted April 13, 2007 Author Share #4 Posted April 13, 2007 Robert, are you confirming my speculation? When you get your lenses coded, you only have them drill/dremel the locations on the lens mount corresponding to the black dots. You do not bother with the white? If that is the case, I won't need to bother with the nasty screw that gets in the way when I get the Zeiss 21mm and have it coded. By the way thanks for the tip. And, yes, I'm having a qualified technician execute the operation. Link to post Share on other sites More sharing options...
robsteve Posted April 13, 2007 Share #5 Posted April 13, 2007 Robert, are you confirming my speculation? When you get your lenses coded, you only have them drill/dremel the locations on the lens mount corresponding to the black dots. You do not bother with the white? If that is the case, I won't need to bother with the nasty screw that gets in the way when I get the Zeiss 21mm and have it coded. By the way thanks for the tip. And, yes, I'm having a qualified technician execute the operation. Yes, all my Leica lenses were coded, just doing the black dots. I just did it this way because I was lazy. If you are paying somebody, they might as well do all six and fill in the white. Link to post Share on other sites More sharing options...
billh Posted April 13, 2007 Share #6 Posted April 13, 2007 .......some lenses have focus adjustments related to the mount... Robert Robert, Will you please elaborate/explain? This may be the answer to why some of our lenses focus OK on the M8, while other have a considerable back focus problem. Does, for example, the 50 f1.4 ASPH have an adjustable mount, and if so, how is this done? To code, what sort of work must the machine shop do? Is there a schematic or instructions? I think I am one of many who have not sent lenses away for coding because we do not want to be without them for an extended period of time. Is it possible to buy a blank (or coded) mount and simply install it yourself? Thanks! Link to post Share on other sites More sharing options...
jlm Posted April 13, 2007 Share #7 Posted April 13, 2007 Advertisement (gone after registration) if someone wants to send me a leica M mount for machining recesses, I'll give it a go. I won't be "coding" it, only providing the recesses. I've already machined the recesses on several of the the Leica thread-bayonet adapters. jm@milich.com Link to post Share on other sites More sharing options...
jaapv Posted April 13, 2007 Share #8 Posted April 13, 2007 One further benefit, for those wanting to use zeiss lenses, is that the zeiss mounts just happen to have a screw on one of the locations where a hole for one of the dots in the 6-bit code should be. If you only concern yourself with the black dots, you may never need to trouble yourself with the position of the screw on the Zeiss mount. 'fraid not... The camera sees the screw as one or two black dots. It must be filled with white paint and if needed a black dot on top. It can be treated as an indentation. Link to post Share on other sites More sharing options...
robsteve Posted April 13, 2007 Share #9 Posted April 13, 2007 Robert, Will you please elaborate/explain? This may be the answer to why some of our lenses focus OK on the M8, while other have a considerable back focus problem. Does, for example, the 50 f1.4 ASPH have an adjustable mount, and if so, how is this done? To code, what sort of work must the machine shop do? Is there a schematic or instructions? I think I am one of many who have not sent lenses away for coding because we do not want to be without them for an extended period of time. Is it possible to buy a blank (or coded) mount and simply install it yourself? Thanks! Bill: I cannot explain fully, just the Noctilux was one where the mount was held on by screwing the screws into a backing plate that affected the focus alignment, not the focus cam adjustment. This backing plate was just a brass ring free floating behind the back part of the lens. It was possible to put the mount on and not have the infinity aligned properly. It took me some trial and error to get it set right. This was not focus cam related, just the overall alignment of the lens in regards to infinity. I think the Noctilux is one of the few lenses with an adjustable cam. From talking to a Leica tech regarding adjusting this, there was mention of Midland using too much loctite and it being difficult to adjust. On a lot of the other lenses they just used shims under the mount to adjust. They can adjust these lenses by altering the shims. I suppose the distance between the cam and the lens flange face is a standardized distance and they just measure this and shim accordingly. John Milch posted a PDF showing the specs of the coded mount. If you ask, he may post it again, or try searching the forum. I used this PDF to code my own lenses. Robert Link to post Share on other sites More sharing options...
billh Posted April 13, 2007 Share #10 Posted April 13, 2007 Thanks Robert. The Noctilux info is interesting. My Noctilux now has this infinity focus issue, and when it was new it was OK, so something changed or slipped. I do have the codes PDF form. Bill Link to post Share on other sites More sharing options...
robsteve Posted April 13, 2007 Share #11 Posted April 13, 2007 Thanks Robert. The Noctilux info is interesting. My Noctilux now has this infinity focus issue, and when it was new it was OK, so something changed or slipped. I do have the codes PDF form. Bill Bill: When I meant infinity focus, I meant putting the lens on the infinity stop and taking a picture of a distant object. Not to be confused with the rangefinder aligning at infinity. This whole discussion of focus issues can get confusing. Both the M8 and the DMR are much more critical of lens setup. I would assume that people who have problems have lenses within spec for film, but the spec should be finer for digital. Incidentally, the Noctilux mount was the only mount that seemed to have been finely machined/lapped on the rear side. I think this may mean the tollerances were quite fine in these lenses. Robert Link to post Share on other sites More sharing options...
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