Walls and Provin state in the book _A Manual of advanced celectial photography_ Page 36 and 37
"A final aspect of the fork mount design concerns the declination trunnions that join the tube assembly to the arms of the fork."
...
"The trunnions themselves should be as large in diameter as design and materials will allow in order to maximize stability. Again, the rule calling for bearing diameters equal to roughly one-half the aperture of the telescope that they will support will serve well in this application"
Do they mean (2) 4 Inch diameter bearings, or (2) 2 Inch diameter bearings?
Now, I'm planning on using 1 and 7/16 Inch bearings as my declination trunnions on an 8 Inch diameter scope. I really think that this will be fine, but I'd like some more assurance from people that have used fork mounted scopes.
I already have one comment that I should be fine from someone I trust on this list.
Does anyone think 1.4375 Inch bearings are NOT enough to do a good job supporting a 100 pound tube assembly.
I will be doing long exposure photography (Yes with film) with this scope.
I haven't finished the design of the polar axis yet. It will be much larger.
-Alan Kilian