On 10/20/2010 8:46 PM Alan Browne spake thus:

On 10-10-20 14:11 , Cheesehead wrote:

Big brass beast. No aperture or focal length markings.
Rear glass diameter is right at 3 inches.
Uses Waterhouse stops, but none included.

Can you make your own stop plates out of metal or plastic?

I'd assume you could start with a nominal diameter and measure a
constant light source with an incident meter on the ground glass and
then work up a bunch of plates for any stop you may want.

I think Richard Knoppow can tell us how to actually determine the
correct hole size for a given stop, by calculation using such things as
the entrance pupil size, focal length (which I guess is still unknown in
this case), etc.

Though you could probably get inside the ballpark with your method ...


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