Re: [ATM] Banishing the diagonal

[Ken Lowther <hermit@outofoptions.org>]

Quoting Gary Fuchs <gary@rcn.com>:

>  >> Is the original poster still reading this thread?
>
> Yes, I'm still reading it. The tangential discussions are quite interesting.
>
>  >>What was your goal?
>
> To understand more about the effects of changes to the secondary size
> and placement. I've been going on the assumption that secondary size
> could be varied somewhat, provided the overall design, f-ratio, etc.,
> allowed it, without compromising the apparent quality of the view - what
> I'm realistically going to be able to discern. I'd like to know how much
> variation I could get away with, and if adding a lens might be a
> workable way to manage a significantly smaller secondary obstruction
> while maintaining the quality of view.

Well, some acomplished observers on the list say that a 20% obstruction 
is good
enough in real life.  The Newtonian Reflector is still a very good performer
for most needs without the need to obsess about things you read about on the
list.   You really do run into dimisinishing returns and adding lenses just
becomes a trade off.

My main purpose of entering this thread is to provide a reality check for new
comers.   Sir Isac did a fine job with the original concept.  The main
improvement has been in materials such as using glass with aluminum 
coating and
methods like measuring during figuring.  But the original concept is still
pretty solid.  And the question really does become how are you going to 
use the
scope and what will be the measure of any 'improvment' you can make on the
design?


Hermit, holed up in Youngstown, Ohio
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