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Canon LTM 50mm f/1.4 Calibration

canon ltm 50

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#1 vk2109

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Posted 29 May 2013 - 21:12

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Hi I just got a got a Canon LTM 50 1.4 for my M9 for a really good price
with clean glass but i feel the focus is not spot on ! I have tried
first with a kippon adapter but wanted great...then a voigtlander and way better but feel
it's not 100% spot on

is this something normal to expect as adding an LTM btw the mount and body ?
i like using around f/2

or should i just give it for CLA

Thanks

Vadim

#2 luigi bertolotti

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Posted 29 May 2013 - 22:01

Well... it's a 1,4, old... the problem is not a CLA in strict terms... the problem is the calibration of an old Rangefinder Cam when mounted on a modern M Rangefinder body : the LTM adapter adds an element of possible error... in theory it must have a 1mm thickness, with very strict tolerancing... and in this sense isn't surprising that two different adapters give slightly different results.

I do not know if the Canon is a lens that allows a fine calibration of the RF cam, and if there is some lab, in case, able to perform it : by converse, the roller cam of the M rangefinder does have a "tuning" mechanism (some people even dares to adjust it by themselves... you need simply a proper Allen key... you can find references in the forum) , but imho is a risky operation, which can alter the correct focusing of other lenses you have. If you can find a lab that has a specific specialization in Leica rangefinders, go to them, choosing the best adapter you have and forgetting the other ; the only "sure" Do-It-Yourself strategy, I think, is to try paper shimming between adapter and lens... a long patient job which could give indeed an optimal result (I did something similar for a 90mm f2 lens, with success... and after all, paper shimming was done in the '20s by Leitz, before the intro of the "standardized mount" Leicas... :o)
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#3 jc_braconi

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Posted 29 May 2013 - 22:11

.. and after all, paper shimming was done in the '20s by Leitz, before the intro of the "standardized mount" Leicas... :o)

and after...

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#4 vk2109

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Posted 30 May 2013 - 05:40

Well... it's a 1,4, old... the problem is not a CLA in strict terms... the problem is the calibration of an old Rangefinder Cam when mounted on a modern M Rangefinder body : the LTM adapter adds an element of possible error... in theory it must have a 1mm thickness, with very strict tolerancing... and in this sense isn't surprising that two different adapters give slightly different results.

I do not know if the Canon is a lens that allows a fine calibration of the RF cam, and if there is some lab, in case, able to perform it : by converse, the roller cam of the M rangefinder does have a "tuning" mechanism (some people even dares to adjust it by themselves... you need simply a proper Allen key... you can find references in the forum) , but imho is a risky operation, which can alter the correct focusing of other lenses you have. If you can find a lab that has a specific specialization in Leica rangefinders, go to them, choosing the best adapter you have and forgetting the other ; the only "sure" Do-It-Yourself strategy, I think, is to try paper shimming between adapter and lens... a long patient job which could give indeed an optimal result (I did something similar for a 90mm f2 lens, with success... and after all, paper shimming was done in the '20s by Leitz, before the intro of the "standardized mount" Leicas... :o)


Thanks Luigi...yeah I def. don't want to touch to the tuning of the M9, it's working perfectly
fine with my 50lux asph !!! paper will actually make the lens further away from the mount,
what happens if it's actually the oposite needed tomake it closer to the mount.....

#5 luigi bertolotti

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Posted 30 May 2013 - 07:16

Thanks Luigi...yeah I def. don't want to touch to the tuning of the M9, it's working perfectly
fine with my 50lux asph !!! paper will actually make the lens further away from the mount,
what happens if it's actually the oposite needed tomake it closer to the mount.....


... well... :o in this case is the adapter that needs filiing/rectifying... it's little and flat (and, if it isn't a Leitz one, probably neither has engravings on the front face... ought not to be difficult to find a workshop the can make such a job)
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#6 doubice

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Posted 30 May 2013 - 07:20

Vadim,

"Making the lens closer to the mount" should actually be quite simple with the Canon 50mm/1.4. If I recall - there is a concentric retaining ring that you can quite easily access from the back of the lens. When removed, the whole optical assembly including the diaphragm will come out. Most of these lenses had a brass shim between the optical assembly and the focusing unit - this shim could be sanded down to bring the lens to correct register.

Movement of the 50mm lens in relation to rangefinder cam is linear so, if the lens sits 0.3mm (as an example) further than it should, than the shim should be made 0.3mm thinner. That will bring the lens to correct register - but only attempt this if you have the right tools to do the job.

Cheers,

Jan
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#7 chris_livsey

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Posted 30 May 2013 - 09:12

Before embarking on expensive surgery, especially self inflicted:rolleyes: I would try some more adapters. They are cheap, easily re-sold and vary. I have some for the 35mm frame that bring up the 50 and vice versa. It may be at the end best to find one that needs metal removing rather than paper shimming, if that is necessary. In my experience the Leica adapters are the most reliable.
You may find this page, rather long with rather too many examples, interesting. On the M9.

The Japanese Summilux – Canon 50mm f/1.4 LTM
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https://www.flickr.c...s/red_eyes_man/

Fishing for shadows in a pool.

Louis Macneice


#8 janrzm

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Posted 30 May 2013 - 09:29

Before embarking on expensive surgery, especially self inflicted:rolleyes: I would try some more adapters. They are cheap, easily re-sold and vary. I have some for the 35mm frame that bring up the 50 and vice versa. It may be at the end best to find one that needs metal removing rather than paper shimming, if that is necessary. In my experience the Leica adapters are the most reliable.
You may find this page, rather long with rather too many examples, interesting. On the M9.

The Japanese Summilux – Canon 50mm f/1.4 LTM


Hahaha

Well you can't please everyone Chris :)
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#9 chris_livsey

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Posted 30 May 2013 - 09:54

Hahaha

Well you can't please everyone Chris :)


Any publicity is good publicity :D:D
  • vk2109 and janrzm said thank you to this

https://www.flickr.c...s/red_eyes_man/

Fishing for shadows in a pool.

Louis Macneice


#10 doubice

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Posted 30 May 2013 - 15:41

Hi......... but i feel the focus is not spot on ..........


Vadim,

When you say that focus is not spot on - are you referring to the final image? Does infinity in the rangefinder match with the lens being at infinity?

That is where your diagnostics should start and that may determine if the LTM to M adapter may be at fault. I would be more comfortable sanding down a cheap adapter to bring the optical unit closer to film plane (or sensor in your case), than an internal part of the lens.

Best,

Jan

#11 vk2109

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Posted 31 May 2013 - 02:44

Thanks everyone, i have tried adding a piece of paper but looks like more front focusing...
so i would expect i would to make the adapter slimmer right ?

@ Jan/Doubice not fully it looks like i still need to turn the focus ring.....I



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