Elmar-C 90 focus adjustment

[Stein K S]

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Hi

 

I just bought a mint Elmar-C incl original front & rear caps, rubber hood, filter and also original (?) Leitz leather pouch. Seems to be more or less unused really and quite fun to have.

However, I know that C-lenses do suffer from focus inaccuracy on M bodies... and so does mine on my M10 (quite some backfocus).

 

My question is: can the Elmar-C 90mm be focus adjusted as other M lenses can?

 

 

[R6M6]

Lenses for the CL have a different thread pitch then M-lenses and therefore especially 90mm is difficult to use. I am not aware if the pitch can be adopted.

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[TomB_tx]

I believe the "C" lenses have the same effective pitch (since M lenses work fine on the CL), but use an angled cam surface instead of a parallel surface. My 90 C is fine on my M9. I've heard the M10 has different geometry to the cam follower linkage, so it tracks an angled cam differently. If so the combination may not be compatible.

[R6M6]

During my last visit in WZ I discussed this with somebody from Service. He explained that for wide angle lenses it is not a problem because of depth of field but for "tele" lenses it may provide some difficulties. But he confirmed the different pitch. I had in the past some problems with my M-Elmarit 90 on the CL. If I remember well Osterloh wrote about it in his M-books also.

[lct]

According to the Leitz leaflet 120-50/Engl, « Screw-mounted Leica lenses and lenses for the Leica M models have a differential helical focusing movement, i.e. the rear focusing barrel bearing against the rangefinder coupling roller moves only in and out. For a more compact and lightweight design, the 40mm Summicron-C f/2 and 90mm Elmar-C f/4 for the Leica CL have instead a direct rear focusing cam ».

Edited September 5, 2017 by lct

[luigi bertolotti]

My question is: can the Elmar-C 90mm be focus adjusted as other M lenses can?

About your original question , I tend to doubt, given what lct has clearly reported :

 

"...the 40mm Summicron-C f/2 and 90mm Elmar-C f/4 for the Leica CL have instead a direct rear focusing cam".

 

This would mean that there is not an adjustable coupling between the rotating barrel and the (directly linked) rotating coupling cam (sloped/inclined, to move the RF roller).

 

But I can be wrong... maybe the Elmar C 90 can be (professionaly) dissassembled and reassembled with some small variation of the angular position of the rotating barrel.... otherwise... filing/rectifying the original cam is surely a VERY delicate job..

 

Of course, as for the Elmar C 90, one could act, conversely, on the adjustment of the roller cam itself... but this would impact the coupling of his other lenses.

Edited September 5, 2017 by luigi bertolotti

[luigi bertolotti]

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Yes.. but can one really adjust it for a "fine tuning" ? How ? is there, for instance, a provision for shimming, somewhere ?

[lct]

Hi Luigi sorry for having cancelled my post above but i was referring to the Summicron 40/2, not the Elmar 90/4 i have no experience with.

[mdemeyer]

My 40mm, an M-Rokkor version, focuses fine on the M10. Don't own the 90mm.

[Stein K S]

Hi and thanks all

 

The decsription by ICT below explains the core of the challenge as I understand it. The only way seems to be to find a copy that just works. This is, however, MY third copy of this lens without succeeding. It is just a pitty though, since it is very small & handy and I think it has a nice & charming ¨glow¨. 

 

This would mean that there is not an adjustable coupling between the rotating barrel and the (directly linked) rotating coupling cam (sloped/inclined, to move the RF roller).

 

Thanks!

Edited September 5, 2017 by Stein K S

[lct]

I have no experience with the Elmar-C 90/4 sorry. I chose the M-Rokkor 90/4 for Minolta CLE instead (below with the "thin" Tele-Elmarit) and never regretted it. It is one of my least flare prone 90's if not the least BTW. Can be found second hand for little money so i would not hesitate to order one if i were you. The M-Rokkor 40/2, at least my version for Minolta CLE, has a normal focus cam. Neither it nor my 3 copies of the Summicron-C 40/2 have had the least focusing problem on either film or digital M bodies. Same on mirrorless cameras. FWIW.

 

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[Stein K S]

Hi ITC

Do I understand it right if you suggest that the focus cam construction of the Rokkor 90 is different from the C 90 (and equal to M cams)?

[lct]

Minolta CLE lenses like the M-Rokkor 90/4 have cams that are fully compatible with M cameras. As for the Elmar-C, i have no experience with it but i tend to believe what Joel Matherson wrote here.