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toast
18-Aug-2017, 08:49
Hi everyone!

I'm just getting into ULF, and recently acquired a great Rodenstock Apo-Ronar 600mm F9 lens (the older version, not the CL). The only thing I don't have is a flange for it, however, it was just too good of a deal to pass up. I've looked on some other threads here and know that SK Grimes can make a custom one, but I want to see if I can find something that will work before going that route. Anyone have any ideas for finding a flange? Alternatively, is there a lens board that would work? After doing some other research, I think the non-CL 600mm that I have uses a M90x1 threaded flange of overall diameter 121 mm. Please correct me if I'm wrong! Thanks for any suggestions!

Dan Fromm
18-Aug-2017, 09:24
Look in the R'stock documentation here: http://www.largeformatphotography.info/forum/showthread.php?138978-Where-to-look-for-information-on-LF-(mainly)-lenses

Dan Fromm
18-Aug-2017, 13:06
I failed to mention that not all Apo-Ronars conform to the documentation. Klimsch Apo Ronars (so badged) in particular. I have a couple of 150 mm KARs. Mechanically they're nothing like the documentation.

Emmanuel BIGLER
19-Aug-2017, 02:38
Hello from old Europe!

This is the documentation I have for the 600 mm Apo Ronar (thanks again to Jörg Krusche)
The older version needs a threaded ring @ M90x1 ; The CL version needs M110x1 (http://www.cjoint.com/c/GHtjE1pQkyk)

Hence the documentation confirms that you probably have a M90x1 version.

In both cases this is simple to manufacture for somebody equipped with a lathe accepting metric measurements ;)

Not kidding, taking into account the weight of this lens (2.5 kg = 5.5 lbs.) a metallic threaded ring is the best fixing method.
Either you fix the lens on a lensboard through a hole of diameter 93.5 mm (as specified in the fiche techique for the older, non-CL model) and you'll need a retaining ring with an inside thread M90x1 with the same shape as required for mounting all LF lenses on a lensboard (the threaded part of the lens should not touch the inside of the lensboard hole, see attached diagram); or you use a simple flat threaded ring with 3 or 4 peripheral screws and firmly secure the threaded ring in front of a lens board of your choice.


And if by bad luck your model needs neither M90x1 neither M110x1, a competent craftsman will measure the thread for you and fabricate the matching ring accordingly.

toast
20-Aug-2017, 10:55
Dan, thanks for the link to those resources! Definitely some good information in there.

Emmanuel, after measuring my lens again, this documentation looks correct. Thank you for sending that over! Time to start hunting for a M90x1 flange!