> I not sure I'm following this advise. It would not seem that a optical
> window would complicate the use of the scope and would address the main
> bugaboo to optimum newtonian performance - tube currents. The complexity is
> in the construction is it not? If that is the case why not build the scope
> and put it in use without the optical window and then go to work on the
> later. It would seem little would be involved in retrofitting once and if
> the project is completed. Personally Texaru's discription of the benefits
> has long made me wonder why more have not been made.
There is single most important factor in planetary telescope - quality of optics. With a simple Newtonian you've already got not that simple task of making primary paraboloid to a very high degree of precision (assume that you can buy a decent secondary). Let's NOT forget the percentage of trully excellent mirrors outside - it is _very_ small. With a window, you suddenly have more than tripled the difficulty. Your primary and secondary have to be of even higher standard (there is another optical element). The glass for the window has to be absolutely first class, and contrary to popular beleief, it is NOT that easy to make a good window. I want to make myself clear : it IS possible to do it, but please read Texerau again when he talks about the windowed telescope. The term he uses when describes makers and uses of this telescope type is "elite", and probably not without the reason.
Bratislav