Thanks - yes I want it mainly for lunar and white light solar (and if it seems okay I'll get it a camera tripod so I can keep it handy) - and the zoom ep it came with was rubbish. I've just had a go with the projection, though it's not something I've done before. I shone a bright desk lamp down it and used 20mm and 32mm plossl eps, with some thin paper wrapped over the top of the ep to form a screen - it looked pretty circular I'm afraid. Did you try it before removing the prism? also, does flexing the cardboard adapter make any difference? btw I may borrow your adapter idea - I think maybe I could make something cheap and usable with discs of plywood.