I removed the bowed Beatte and we installed a new linhoff ground glass w/o fresnel (for the moment).
I decided to test the new rig.
I have a test setup using books with clear text each set up about 3 inches deeper than the previous. I focus carefully on the center book and shoot a polaroid (55).
The test was with a 150 f5.6 at about 10 feet away to target. Lens wide open, close in giving a fairly shallow dof.
it appears the camers is about 6 inches back focusing. What is acceptable?