Re: ATM Eight inch F8 Design

[Brad Davy <bdavy@bigdog.fred.net>]

At 06:44 PM 6/17/97 -0400, John D. Gwinner wrote:
>Folks:
>
>  I had been planning on a 1.52" diagonal, or maybe a 1.83, but it seems
>like if I go with the longer focus, a smaller diagonal would be better for
>planetary use (I later plan on going with a 12" thin mirror after I finish
>the 8", so I'm planning on 'starting' with a 'planetary scope' so I won't
>feel like I've wasted the time doing the 8").

I went back and searched the archives on secondary size.  Boy what a can of
worms this opens! After looking at these messages, I think I need to take
Mels advice and use two secondaries.  My 8"f8 currently has a 1.05"
secondary, which from everything I've read is great for high power
planetary work.  One night last week, I did manage to see the polar caps on
Mars.  I've not yet had a good morning to get up and look at Jupiter and
Saturn.

In the interim, I turned to Deep Sky.  Looking at the Great Cluster and the
Ring Nebula were impressive.  But looking for other objects has proved
frustrating.  I'm wondering if a larger secondary (1.3-1.5") would make it
easier to see fainter objects and add more to views of the objects I can
see.  

If this has been discussed ad nauseum, feel free to reply e-mail rather
than to the list.

Thanks.
Brad
bdavy@fred.net               http://www.fred.net/bdavy/home.html
bdavy@nox.cs.du.edu