I managed to find the following advertisements on this specific lens and Compur shutter in Burke & James catalogs from 1931 and 1933.
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I managed to find the following advertisements on this specific lens and Compur shutter in Burke & James catalogs from 1931 and 1933.
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Sent from my iPhone using Tapatalk Pro
Sent from my iPhone using Tapatalk Pro
And this one from George Murphy Inc catalogue 1931
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The Xenar D 3.5/150mm ist mounted in a shutter type Compur 2-Tube 5/I
The pitch of the thread is not 0.9mm it is 29 1/13 per inch and the angle of the thread is not 60° it is 50°
It has only a metric diameter but an imperial pitch and an uncommon thread angle.
I ground special tools to cut mounting rings for this shutters because with 50° angle you canīt buy it, DIY is the only way.
When you donīt find a mounting ring please feel free to contact me. I have a Xenar 3.5/150 as well in my collection and I can turn a ring for it.
Also according to Grimes, who knew his work, the pitch is continental M0.9 - I have 5 of these (Compurs bought in Germany) and have measured them; all have the M0.9 pitch - may be the shutters made for Bausch & Lomb and other US manufactures had imperial thread pitches although UN and UNF have also 60° angle and whitworth has 55°.
>edit> I have two Compound shutters nr 2 (one is of the oldest type) and two nr 3; and these all have M0.9 thread pitch.
Last edited by Ron (Netherlands); 1-Dec-2021 at 05:46.
I can thoroughly recommend Jose at Custom Photo Tools. As well as the stock range of adapters he will manufacture custom items. I've had flanges and adapters in both metric and imperial threads, and the work is excellent.
(No association, just a happy customer )
If you go to this reference: http://www.tontrennung.de/assets/doc...ur_shutter.pdf
Scroll down a bit to "Section 2 Specifications" then scroll a bit more to the specifications for the rimset No. 2 Compur you can see the mounting thread is described as having a pitch of 29 1/13 threads per inch (T.P.I.) with the angle of the threads being 50š. Then just a bit further the No. 3 and No. 4 Compound shutters are described as having the same 29 1/13 threads per inch pitch with an angle of 50š. The SK Grimes website describes these shutters as having a mounting thread pitch of 0.9 mm.
Doing the arithmetic 29 1/13 threads per inch works out to be a metric pitch of 0.874 mm which does round off to 0.9 mm.
Incidentally I have a circa mid-1960's Schneider brochure on their Componon and Comparon enlarging lenses. It shows the 180, 210, and 240 mm Componons and the 210 and 300 mm Comparons as having a mounting thread with the 29 1/13 threads per inch pitch (thread angle not given.)
David
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