The first telescope I bought wasn't a known brand or anything. Optics were always ok, but there were obvious cost-cutting construction bits. I upgraded, but I want to use the old scope as a fun tabletop dobsonian type that the children can also use. It also might not be bad for wider views. I dusted the box off the other day and got to work aligning the optics (that's a big mission, but I'll get it right). When I was tinkering, I remembered that I had tried this before, but couldn't think why I didn't finish. I then found the bit that made me stop - a barlow fitted into the focuser. That's why it's a 1000mm Newtonian only about 500mm long. I took out the barlow and tried to get focus without it. The memories of doing the exact same thing all came back. Oh, and I do want to mention that I would prefer a 500mm scope.
Right, so as it turns out, the focuser needs to be further in than it can be to get focus. That has two problems - obviously it can't focus is the first, but the other is the obstruction of the focuser tube in the OTA itself. I would like to know if it's possible to correct this, and what the easiest (or most practical) way is. If I move the secondary closer to the primary, I also have to move the focuser, but I'm also going to lose aperture (which I suppose isn't the worst thing ever). If I move the primary (cutting the tube is probably the easiest way here), then I guess I only lose a little aperture. But what if I construct a focuser which can bring the eyepiece closer to the secondary?
If there are any other ideas, I'd love to hear them. Maybe I should try turning the barlow around - what effect would that have? I probably couldn't get focus then either. I'll give that a try sometime.