From: "Steve B" 
To: 
Reply-To: "Steve B" 


Firstly, thanks all for your replies. Looks like the PVC idea is a no go.

I havn't paid much attention to truss scopes because I never believed I'd
ever build or own one, thinking they would probably house some monster
light bucket to justify the truss design.

The first thing that comes to mind, and forgive me if this sounds obvious,
but what about stray light with a truss design? In a typical dome, mine at
least, I have 2 CRTs going, and quite a few power supply/ equipment LEDs.
The inside of the dome (as yet) is not black and so light, however feeble
still makes it's way to the CCD on long exposures. Do the truss guys strive
for a totally black dome interior or do you strike a compromise between
what you can/can't image because of stray light?

I hadn't thought of the weight issue of a PVC tube. I know this would be
heavy, but no heavier than my rolled galv steel tube 8" Newt.
That scope was overengineered from the ground up almost to the point where
just swapping the OT cradle on the GEM would make it take a 10"
easily.
Vignetting would definately be the problem, so that just about nails it.

Hey....maybe some short FL 10" binocs! :)

regards,
Steve B.

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