Re: ATM Defining Super-Planetary

[beck <rbeck@gate.net>]

Hi Mel,

Bullseye. For casual, visual planetary viewing build a long focus
Newtonian, or use a mask and save big bucks. 

Combining your 'prescription' for a super planetary scope with 
'amateur telescope making' was my goal when I built my 8" f10
Dob/Newt. It produces awesome images and was cheap to build.  It 
uses a .75" secondary (on half circle spider) for high contrast with
no diffraction spikes. 
I recommend a project like this to all ATM's who are tired of hearing 
that planets are best (visually) using only high priced commercial
refractors or schiefspeiglers. That is a bunch of hooey.
However, you can't buy a scope like this, it must be custom made.
Two design 'caveats': 
1) A long Newt. optical tube assembly obviously needs solid mounting. 
2) and staying on target at high power gets tiring even for
   the most dedicated Dob pusher. The images are so outstanding that
   it is tempting to spend more and get/make a heavy equatorial mount.

I wouldn't build this kind of a specialized scope if it were my only
scope, though. I prefer my 20" for dark sites, and my 12.5" for being
slightly more portable. Yet, the 8" f10 gets used most, because the moon,
planets and double stars are easy targets from light polluted suburb patios.

Isn't the ATM hobby great...make a scope for every purpose. 
Regards, Bob