Leica Summicron 40mm f2 6-bit coded reversal

[xveruskax]

Advertisement (gone after registration)

Hello,

 

I'm wondering if this is even possible. I purchased a 40mm Summicron lens that was 6-bit coded to read as 35mm lens on Leica M digital bodies. However, I actually need to use the lens as a 40mm lens on a Minolta CLE. Because the lens is modified, it does not give the 40mm framelines on the CLE but instead as a 28mm lens which is the default if the lens is not "read". For the life of me, I cannot find any information on how to reverse the "modification" or to learn if it is even possible. If you can point me in the right direction, that would be much appreciated.

From picture you can see current 6-bit code registers as a Summicron-M 35mm f/2 (IV).

IMG_5002.heic

[jaapv]

You have to replace the mount as it was filed down.  The CLE reads the focal length mechanically. The coding is irrelevant. 

[adan]

To expand a bit on jaapv's correct answer:

The lens sets the framelines automatically and mechanically by way of the physical length of one of the 4 flanges on the lens mount. Remember that the frameline-setting system for the M and C mount predates the existence of 6-bit coding by about 52 years!

Whoever converted your lens to show 35mm framelines, changed the length of that flange by removing metal from it with a file, to make it shorter.

Pretty much a one-way street.

The only way to reverse that is to add metal back, by soldering or welding some fresh brass onto the too-short flange you have, and then adjusting that with a file to the correct length to set 40/50mm lenses. A non-trivial exercise.

Or by getting an entire original replacement mounting ring to mount on the lens. Which is only slightly less trouble, since you'd have to get one with the right number and pattern of holes for the mounting screws, as well as the correct flange length for 40/50mm. Probably one cannibalized from another Summicron-C 40mm.

[pegelli]

I don't think the mount is filed down in case it brings up the 28 mm framelines as the "tab" on the M-mount to bring up the 28/90 mm framelines (as is happening in the OP's case) is the longest of the three possibilities, 50/75 mm is the middle one and 35/135 mm is the shortest one.

So if indeed the 28 mm framelines are brought up the tab on this lens can be filed down a little bit to bring up other framelines. However in case it's not the 28 mm framelines but the 35 mm framelines that show up when the lens is mounted jaapv and adan are right and only a mount replacement can solve your problem.

Edited August 3, 2023 by pegelli

[a.noctilux]

4 hours ago, pegelli said:

I don't think the mount is filed down in case it brings up the 28 mm framelines as the "tab" on the M-mount to bring up the 28/90 mm framelines (as is happening in the OP's case) is the longest of the three possibilities, 50/75 mm is the middle one and 35/135 mm is the shortest one.

So if indeed the 28 mm framelines are brought up the tab on this lens can be filed down a little bit to bring up other framelines. However in case it's not the 28 mm framelines but the 35 mm framelines that show up when the lens is mounted jaapv and adan are right and only a mount replacement can solve your problem.

You are correct for Leica M,

but we are talking about Minolta CLE which framelines are different from Leica M, only possible using 28/40/90 lenses and framelines,

28mm lines in CLE are always visible.

[pegelli]

32 minutes ago, a.noctilux said:

You are correct for Leica M,

but we are talking about Minolta CLE which framelines are different from Leica M, only possible using 28/40/90 lenses and framelines,

28mm lines in CLE are always visible.

Thanks, I didn't know that. That's indeed a different situation  and it's unlikely the lens still has the "long" notch, if it had it would probably bring up the 90 mm frameline as well.

[lct]

Advertisement (gone after registration)

8 hours ago, jaapv said:

You have to replace the mount as it was filed down

+1

[250swb]

Assuming the mount is brass underneath the plating I'd have thought it would be fairly easy to take the mount off and  build up the flange with solder before filing it down again to bring up the 40mm framelines. The OP should be able to see where its been filed down.

[Kwesi]

11 hours ago, xveruskax said:

Hello,

 

I'm wondering if this is even possible. I purchased a 40mm Summicron lens that was 6-bit coded to read as 35mm lens on Leica M digital bodies. However, I actually need to use the lens as a 40mm lens on a Minolta CLE. Because the lens is modified, it does not give the 40mm framelines on the CLE but instead as a 28mm lens which is the default if the lens is not "read". For the life of me, I cannot find any information on how to reverse the "modification" or to learn if it is even possible. If you can point me in the right direction, that would be much appreciated.

From picture you can see current 6-bit code registers as a Summicron-M 35mm f/2 (IV).

IMG_5002.heic 655.44 kB · 10 downloads

The smart thing to do here is to return the lens to the seller and acquire an unadulterated Summicron-C. 
if that’s not possible then sell it and get one that hasn’t been filed down. All these other options of opening up an ironsmithing shop so you can use it on the camera it was intended for seems like an unnecessary hassle to me. These lenses are cheap plentiful and awesome. It should be incredibly easy to sell. A lot of first time M users buy them as an affordable option to the Leica 35/2 hence the modification. 

[jaapv]

It would have to be silver solder. Otherwise it will wear down in no time. Even silver is on the soft side.  

[jaapv]

There was a seller on eBay selling flanges. A 50 mm one would be OK. It might be possible to bring up the correct framelines by pushing the button and over-rotating the lens. On a 40 that will result in a minor rangefinder error, though. 

[wizard]

Folks, did anybody check which framelines an unmodified Summicron 40mm lens will bring up on a Minolta CLE? The fact that the Summicron 40 brings up the 40mm framelines on a Leica CL does not mean it will bring up the same framelines on a Minolta CLE, the more so since I believe the 40mm framelines on a Leica CL were permanent, with the 50 and 90mm framelines only appearing upon mounting a respective Leica lens. And which framelines does the unmodified Summicron 40 bring up on a regular Leica M? 35 or 50?

A solution to the OP's problem may only be found once the answers to the above questions are known. Possibly, however, there is no solution, as a 40mm Summicron was never designed to work with a Minolta CLE in a fully compatible way.

[xveruskax]

8 hours ago, adan said:

The only way to reverse that is to add metal back, by soldering or welding some fresh brass onto the too-short flange you have, and then adjusting that with a file to the correct length to set 40/50mm lenses. A non-trivial exercise.

I contacted a camera/lens repair person who can "add metal back". He's done this kind of thing before apparently. The glass on the lens is in excellent shape so I'd rather keep this lens and "fix it" than have to go through the trouble of selling it and finding a comparable lens.

Thanks to everyone for their responses. I'm a huge fan of the 40mm focal length and wish it were more common. The Minolta CLE only has 28/40/90mm framelines. When the camera can't "read" the lens, it shows 28mm framelines by default.

Edited August 3, 2023 by xveruskax

[Kwesi]

43 minutes ago, xveruskax said:

I contacted a camera/lens repair person who can "add metal back". He's done this kind of thing before apparently. The glass on the lens is in excellent shape so I'd rather keep this lens and "fix it" than have to go through the trouble of selling it and finding a comparable lens.

Thanks to everyone for their responses. I'm a huge fan of the 40mm focal length and wish it were more common. The Minolta CLE only has 28/40/90mm framelines. When the camera can't "read" the lens, it shows 28mm framelines by default.

That is great news. I remember years ago using my 28/2 v3 on an aps-c camera and falling in love with 40mm effective focal length. Funny though that years later when I bought the summicron c for the m9 or 240, I couldn’t handle that it brought up the “wrong” frame lines and ended up returning it despite it being fantastic optically. 

[a.noctilux]

1 hour ago, xveruskax said:

I'm a huge fan of the 40mm focal length and wish it were more common

Strange that you bought modified 40mm Summicron-C.

I'm fan of 40mm and CLE user myself for decades.

So in your case, the best choice would be M-Rokkor 40mm.

I have one 2/40 modified to bring 35mm (on M) and good news I can use it on CLE, just (when I need to see the right framelines) push the lens release and turn the lens further to see "40" framelines and if doing nothing the "28" is always visible.

 

...as side note, the rangefinder of C lens is slanted and may not be accurate on CLE,

permanently using "C" lens as I used M-Rokkor (flat RF coupling) would not be good idea

so remodified to bring 40 framelines should be better idea.

Edited August 3, 2023 by a.noctilux

[xveruskax]

11 minutes ago, Kwesi said:

That is great news. I remember years ago using my 28/2 v3 on an aps-c camera and falling in love with 40mm effective focal length. Funny though that years later when I bought the summicron c for the m9 or 240, I couldn’t handle that it brought up the “wrong” frame lines and ended up returning it despite it being fantastic optically. 

Right, so apparently this modified 40mm lens would possibly sell well since it does show 35mm framelines on a Leica M digital body. But I don't want to go through the trouble now of finding an unmodified 40mm Summicron and selling this one as well. From what I can tell on the mount, I can see where it was filed down to read as a 35mm.

I had been trying to guess the 40mm framelines when the CLE just read it as a 28mm by default since it was a modified lens. It was a nightmare and I kept cropping feet and cutting off the head on a subject. Getting the wrong framelines is too much to handle, I agree.

[lct]

There are no 35mm framelines in the CLE's viewfinder, only 28, 40 and 90mm. 28mm framelines are always visible whereas 40mm and 90mm framelines are visible only when their respective lenses are mounted. Any 40mm M-mount lens will then bring up 40mm framelines in the CLE's VF, be it a Summicron-C 40/2 or a M-Rokkor 40/2 v1 or v2, provided the flange of the lens has not been modified. What the OP needs is thus a flange of Summicron 40 that has not been modified or that has been repaired to the same effect. I would rather ask Leica or a good repair shop before i embark on DIY exercises but it's me.

[pippy]

2 hours ago, xveruskax said:

...I'm a huge fan of the 40mm focal length and wish it were more common...

Glad to read that you know a good repair man, xveruskax; they are getting hard to find!

As far as the bit quoted goes I have noticed a fairly sizeable group here in the LUF who are fans of the 40mm f/length and I count myself amongst their number (my own favourite being the 40mm f1.4 Voigtlander Nokton which is, in its rendering-style, the slightly Bigger Brother of the much-loved-and-similarly-flawed Leitz 35mm Summilux v2).

It would be interesting to see whether there would be much market-interest in Leica re-issuing the 40mm Summicron as part of their 'Heritage' line-up but perhaps the number of likely candidates within the target audience is too small and/or the ensuing profit-margins too low?

Philip.

Edited August 3, 2023 by pippy

[250swb]

2 hours ago, xveruskax said:

Right, so apparently this modified 40mm lens would possibly sell well since it does show 35mm framelines on a Leica M digital body.

No, anybody with even a half ass comprehension of the job can file a bit off the flange, it isn't a unique selling point as if it adds value. You definitely don't need to send it to a camera tech guy who may charge actual money to do it.

Edited August 3, 2023 by 250swb

[Advertisement]

Hallo,

Look here: Leica M

[lct]

Filing off a flange is one thing but adding metal to it is another story.
That's what a repair shop has done on this Rokkor 28/2.8 of mine but i don't know whom.

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!