1:2.8/18cm Olympia Sonnar on a Leica M?

[UliWer]

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The first examples of the famous 1:2.8/18cm Olympia Sonnar from 1936 for the Zeiss Ikon Contax could be coupled directly to the camera. These versions are extremely rare, probably less than a dozen examples of this first version were made, so there is no realistic hope to find one on the second hand market. Usually the Sonnar is coupled with the Flektoskop, a reflex housing which was also very useful to control the focus of the lens with it's very shallow DOF.  With an Contax-to-Leica-M-adapter the Flektoskop can be attached to an M-body, which allows to use the Sonnar with or without EVF (if the Flektoskop still works, which is not guaranteed...) Unfortunately the Flektoskop is a very cumbersome device, no comparison to the Ploot or Visoflex. The combination of the lens and the housing weighs approx. two kilos which is no great motivation to use the lens.

It might be very helpful if the lens - which can be unscrewed from the Flektoskop - could be attached to a bellows or other devices which fit the Leica standards. Unfortunately again, the large lens has a very large diameter for it's thread to unscrew it. I measure 77mm. The max. diameter of an adapter for the bellows is 52mm (16572 for the 12.5cm Hektor). Even if you used the inner thread of the bellows directly you'd have to squeeze the lenses thread to 64mm. 

Of course there are reducing rings usually used for larger filters on smaller lenses. Next problem: the thread to screw in the Sonnar is not at it's rear end but rather centered. I measure 2.4cm from the thread's lower edge to the lense's edge. So a reducing ring will not allow you to fit the large rear end into the opening for a bellows. You would need a large conic device to achieve this.

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Last problem is the lenses very fine thread pitch: I am not sure but I think it's 0.5mm, it looks and feels certainly finer than the usual thread pitch for Leica devices.

Anyone has an idea how all these problems could be solved? 

[UliWer]

Ha, one problem might be solved. My Sonnar came with two extension rings (Zeiss Ikon 543/86). Attaching one of them gives me a thread (still with 77mm) almost at the lenses edge. Now and assembly of reducing rings might work to go down to 64 or 52 mm for the bellows, or even to 39mm for the Leica M mount together with an LTM-to_M adapter. (https://www.kentfaith.de/SKU0629_18in1-filteradapter-set-step-up-ring-step-down-ring?gclid=EAIaIQobChMImeXfhYuq9AIV3pBoCR3B8gkZEAQYASABEgI7W_D_BwE) 

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[zeitz]

The Flektoskop thread is 77mm diameter x 0.75mm pitch; the flange to focal plane (registration) is 114.7mm.  The Flektometer thread is 70mm x 1.5mm pitch; the registration is 100.0mm.  These are as I measure them with calipers and a pitch gauge.  The Panflex mount is the Contax Outer Bayonet Mount; the registration is 99.35mm.  This number is calculated because I can't tell where the reference flange is on the complicated Contax camera lens mounts.

I will take pictures of the Carl Zeiss Jena Flektometer to Visoflex adapters that I have in a day or two.  The Flektometer reflex housing was introduced about the same time as the Visoflex I (1951).  I will also make a sketch with dimensions of a nice adapter that any machinist should be able to make.

When I need special purpose adapters, I have S K Grimes in Rhode Island make them for me.  S K Grimes' prices are very reasonable.  Production times are roughly 1 month, but the lead time can vary.

[UliWer]

Here you can see the first version of the 18cm Sonnar with direct coupling to the camera. It gives an idea how the adapter should be shaped:

https://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/RF-Nikkor/Contax_RF/ContaxRF180mmf282.htm

I hope you are right about the 0.75 thread pitch. This would solve another problem.

[zeitz]

Uli, here is how you can check the thread pitch without a thread pitch gauge.  The thread you show on your lens in your original posting is 10mm long.  Count the number of threads.  Just counting from your picture there are about 13 threads.  10mm / 13 = 0.769mm.  A really critical count would find that there are actually 13.33 threads.  10mm / 13.33 = 0.75mm

[zeitz]

Attached are pictures that should illustrate the various versions of the Carl Zeiss Jena 18cm f2.8 Olympia Sonnar for Contax Flektoskop and Flektometer reflex housings.  Note that when attached to a Visoflex as decribed, the lens focuses correctly to infinity.  There are many combinations of lens and reflex housings, so I didn't prepare a sketch of the adapter that would be needed.  If there is a particular combination of interest, I will make the sketch.

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[luigi bertolotti]

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Just as a curiosity... what about the version for Pentacon Six ? I see it's rather easy to find; is it the same design ? I mean : do all the Olympia Sonnars cover 6x6 ?

 

Edited November 22, 2021 by luigi bertolotti

[zeitz]

1 hour ago, luigi bertolotti said:

Just as a curiosity... what about the version for Pentacon Six ? I see it's rather easy to find; is it the same design ? I mean : do all the Olympia Sonnars cover 6x6 ?

This lens was made for such a long period and in so many configurations that it is hard to know what was changed over time after the Flektometer was discontinued.  I believe you are specifically referring to versions of the Olympia Sonnar that have leather or "zebra" bands around the front of the lens and are conically shaped at the rear and that date to the mid-60's into the 70's.  I do not have one to examine.

I wish I had a collimator to check the image circle.  Maybe the sun will be out tomorrow so that I can try to see the image circle of one of  my lenses on a piece of paper.

[luigi bertolotti]

8 hours ago, zeitz said:

This lens was made for such a long period and in so many configurations that it is hard to know what was changed over time after the Flektometer was discontinued.  I believe you are specifically referring to versions of the Olympia Sonnar that have leather or "zebra" bands around the front of the lens and are conically shaped at the rear and that date to the mid-60's into the 70's.  I do not have one to examine.

I wish I had a collimator to check the image circle.  Maybe the sun will be out tomorrow so that I can try to see the image circle of one of  my lenses on a piece of paper.

Yes, many I see that have that distinguishing zebra banding... a finishing that DDR lenses used on other items too... but some are different (ebay example : 184397534633 )

Edited November 23, 2021 by luigi bertolotti

[zeitz]

4 hours ago, luigi bertolotti said:

ebay example : 184397534633

Luigi, that is what I referred to as leather bands around the front of the lenses.

I think Enna started zebra banding for Corfield lenses and then for its general production.  Some Japanese lens companies briefly used similar zebra designs.