[LargeFormat] Compur #1 and Copal #1 for G-Claron 305mm f9

[Clive Warren]

At 00:54 22/01/02 -0600, Michael Briggs wrote:
snip
>It will likely work by directly screwing into any reasonably modern #1 
>shutter.
>If you can measure accurately, measure the total length of the lens in the
>barrel and in the #1 shutter.  If they are the same, it is ok.
>
>According to a datasheet that I have, and confirmed with a measurement, the
>thickness of a Copal #1 press shutter is 20.000 +/- 0.025 mm.  This is the
>distance from the front edge of the thread for the front cell to the back edge
>of the thread for the rear cell.  The other mechanical specs are quite tight:
>these two surfaces are to be parallel to 3 arc min and the centers of the
>threads aligned to 0.03 mm.
>
>S.K. Grimes has drawings of Copal shutters with measurements on his web site.

Thanks Michael - that's clearly the best way of doing it - yes I have 
micrometers that will do that.

Thanks also for the Copal info - will check out the Compur this evening. 
Good to hear that the manufacturing tolerances are fairly tight. The Compur 
shutters generally seem to be pretty good - they are certainly a lot more 
expensive than Copals. The Copals seem to be a little more robust 
though........

Cheers,
            Clive