Non-coded lenses.

[SARobinson]

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I've just bought a couple of Zeiss ZM lenses (35mm and 50mm) and I was wondering why I can't specify more than one uncoded lens in the Manual Lens Detection menu. Surely it can tell if it is a 35 or a 50 depending on what framelines are brought up by the lens.

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[250swb]

Why not code them?

Unless they are very old ZM lenses there should be a very fine rebate machined into the lens flange specifically to allow for some paint. Make a coding template and mark in a Leica lens code to suit the lens. But the 35mm and 50mm will most likely not need any corrections anyway.

[SARobinson]

Yeah, I know I can try and code them myself, and I have some matte black paint arriving soon for that very purpose. But I wanted to know why you can't specify three non-coded lenses (say a 28, a 35 and a 50) and then depending on which framelines were brought up, the camera knew which lens was being used and assigned the appropriate profile and EXIF data.

[pedaes]

40 minutes ago, SARobinson said:

why I can't specify more than one

Not sure what you are trying to do. You can only use a Leica lens as a proxy for a uncoded lens and can only mount one lens at once. The camera will revert to last lens manually selected if you dismount a coded lens and have it set to manual lens selection. This can be a pain as it may not be correct and will be in EXIF data for ever! So, if you use this fudge  you need a discipline to reset if necessary.

[SARobinson]

I'm not trying to do anything - I just want to know why it only allows one non-coded lens to be 'stored'. I have a 6-bit coded MATE and the camera knows which focal length is selected, so the lens detection must be based on something other than just the 6-bit coding.

[jaapv]

That is correct, the camera reads the frameline connection as well. This was done specifically for the MATE. This is the reason why a miscoded lens (focal length does not match) will not be recognized. A benefit is that the number of combinations is ~ tripled. A code must be specific to a frameline position; the frameline selection works like an integrated 3-position coding. That is why your idea for uncoded lenses cannot work, as part of the coding is missing..

[SARobinson]

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Thanks Jaap - so you're saying that the frameline 'code' will only work if there is a 6-bit code as well. But it would be possible for Leica to do what I'm saying, wouldn't it?

[jdlaing]

Don’t forget the framelines are in pairs. The six bit code works in conjunction with the frame lines in regard to the MATE. As long as the camera knows the MATE is mounted the frame line selector will identify the focal length. In the case of other lenses the camera would have no way of knowing which lens is mounted without six bit code or selection from the menu. 50 and 35 are two different pairs of frame lines. 50/75 and 35/135 are the pairs.
 

[mujk]

7 hours ago, SARobinson said:

I'm not trying to do anything - I just want to know why it only allows one non-coded lens to be 'stored'. I have a 6-bit coded MATE and the camera knows which focal length is selected, so the lens detection must be based on something other than just the 6-bit coding.

I have proposed almost the same before. There could be a favorites list for uncoded lenses for fast selection. As you propose the camera could also take the framelines (frameline pairs) set by the lens into account.

AFAIK the only way to predefine a few uncoded lens models for (slightly) faster selection is by utilising user profiles, unless you use them for some other purpose. This works also when you have both coded and uncoded lenses. The camera switches automatically between the coded lenses and the most recently selected uncoded one, but I don't think the framelines set by the uncoded lens are used in the selection process. Anyway, in your case you would need to switch user profile every time you change the lens because you have two uncoded lenses.

Edited October 15, 2020 by mujk

[adan]

7 hours ago, SARobinson said:

Thanks Jaap - so you're saying that the frameline 'code' will only work if there is a 6-bit code as well. But it would be possible for Leica to do what I'm saying, wouldn't it?

It would not work consistently.

Imagine a photographer with an uncoded 135 and 35 (or uncoded 90 and 28 - myself, for the moment).

Since each of those pairs of lenses would come up with the identical "meta-code" of "uncoded lens + frameslines set to 135/35 (or 90/28)," there is no firmware logic that can distinguish the lenses further.

The camera would still default to "last lens selected in menu."

[TomB_tx]

Although it would be a clever scheme for Leica to implement this concept, and useful to some users, it would not be in Leica's financial interests. While the basic M mount is no longer protected by patent (without -bit coding) so others make M mount lenses, Leica would much rather you buy new Leica lenses - which are all coded. Likewise, while they do support using older M (&ltm) lenses, and will get some income by coding those where it takes a simple mount change, they would still prefer you to buy new lenses.

I use mainly my film era lenses, and I find their compatibility with them amazing - no complaints. And I'd like Leica to stay in business - which means those that can afford it buying new Leica lenses. My retirement budget limits my involvement in this effort.

[mujk]

19 hours ago, TomB_tx said:

Although it would be a clever scheme for Leica to implement this concept, and useful to some users, it would not be in Leica's financial interests. While the basic M mount is no longer protected by patent (without -bit coding) so others make M mount lenses, Leica would much rather you buy new Leica lenses - which are all coded. Likewise, while they do support using older M (&ltm) lenses, and will get some income by coding those where it takes a simple mount change, they would still prefer you to buy new lenses.

I use mainly my film era lenses, and I find their compatibility with them amazing - no complaints. And I'd like Leica to stay in business - which means those that can afford it buying new Leica lenses. My retirement budget limits my involvement in this effort.

Yes, I know this is probably the reason. But if Leica hadnt been in such a hurry when developing the lens coding system (they needed to be able to make lens-specific corrections in the first digital M, the M8) they could have been more "clever" and added a proprietary chip in the lens and electric contacts instead. After all, the optical coding is quite easy to create afterwards.

[coupdefoudre]

Well... in the meantime you have 4 User Preset options you can use to have EXIF data for your 35 and 50.