Re: A Schiefspiegler as first telescope (was Re: ATM 3-Vane or 4-Vane Spiders)

[mjc5 <mjc5@psu.edu>]

It's a bell shaped curve. The mirrors in the middle of any focal length
are usually the easiest to do. Then as they work away from the middle,
they become progressivly harder. This is a generalization, but basically
true.

	What happens is that the fast mirror is harder to parabolize, due to
more glass removal to take it away from spherical to paraboloid. The
slower mirrors are a much shallower sphere, and harder to bring to a
sphere, and parabolization is more difficult.

	I don't want to scare you away from parabolization though, because it
really isn't as difficult as many new workers think.

	And the last thing is if you are really really set on the schief or
other exotic, you *can* do it as a first scope. It will be plenty hard,
but you can. My first scope was a 12.375 f5.9. I'm as pleased as can be
with it. But I probably should have made something smaller to start
with.

	- Mike -

Charvell wrote:
> 
> So a long focal lengh mirror is actually harder to do than a medium focal
> lengh? Am I getting this correctly? Long=hard, medium=easier, short=very
> hard. So where is the very easiest place to start and would a 10" be OK for
> a first time mirror or should I try a smaller? I want the easiest option to
> start with. I don't have anyone I can get to come over and bail me out  :)