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View Full Version : Rodenstock Geronar 210mm 6.8 rear flange diameter



Darcy Cote
11-Oct-2010, 11:06
Hi Looking for the diameter of the rear lens flange. Can someone tell me/measure? I am building a 6x9cm camera and need a portrait lens that fits in a homemade helical.
Thanks
Darcy

Mark Stahlke
11-Oct-2010, 15:31
I have a Caltar II-E 210/6.8 (Calumet re-branded Geronar) in a Copal 1 shutter. I'd be happy to measure it for you but I'm not sure what measurement you're looking for. Can you clarify?

Larry H-L
12-Oct-2010, 05:24
I also have the Caltar version in a Copal 1, the lens board hole size would be approximately 42mm.

Bob Salomon
12-Oct-2010, 06:53
The 210mm Geronar is in a Copal 1 shutter. The mounting thread for a Copal 1 shutter is 39 x 0.75mm. The brand or model of the lens is not a factor in the mounting. What is a factor is the flange focal length of the lens and the focal length of the lens which together determines the thickness and throw of the helical and the distance betwwen the film plane and the collapsed helical for infinity focus. The 210mm Geronar in Copal 1 had a flange focal length of 195.3mm at infinity.

Darcy Cote
12-Oct-2010, 13:47
Thanks for your replies. They all help. Darcy