[Blondeb3 (Geoff)]

wow, what a bunch of great replies! Thanks for all the information guys it's great getting such a good range of responses, now I've got some serious reading to do starting with the rooftop design stuff, thanks Trevor, and then Brendan's Pier Design stuff. I think I'll start with viewing from the front verandah just on a tripod - I bought a Meade ETX105 for starters and then I might get more serious with a dob but no plans for astrophotography yet. I'm still considering the ceiling space thing but lots of factors to take into account from what I see here, so I doubt peeling back some roof and installing a flip up panel is going to give me good results in an old timber house. My other thought is to build something on top of our concrete water tank since it has a concrete roof supported by a good diameter pillar up the centre. Should be stable and strong enough to build a practical structure on top, I think the pillar up the centre is about 12" in diameter from memory - does that sound practical, on top of a concrete water tank for a small backyard structure?