> Well maybe. At RTMC this year I was looking thru Jerry Logan's
> 10" folded Schupmann at a 1.5 sec double star. I could not split it.
> Jerry turned on a fan at the bottom of the tube. The air enters at
> the top of the tube around the lens cell and is expelled at the bottom
> of the tube. As soon as the fan was turned on the double split with
> a dark space between the stars.
I have noticed that more and more close-tubed designs use fans to force laminar flow around the window/corrector/front lens (like Ceravolo's 8.5" Mak-Newtonian). My friend has cut few openings on his homemade 8" Maksutov-Cassegrain tube and that SIGNIFICANTLY improves the seeing after some experimenting of which holes to open. (Incidently this has finaly removed any of the advantages I enjoyed when comparing my 8" Newtonian in rapidly falling temperature conditions - now little Mak holds its own all the time). Has anyone got any more data on this ? Have you seen one of Ceravolo's Maksutov-Newtonian setups ? Is it possible to contact Jerry Logan via e-mail ?
Bratislav