[ATM] Building a 6" f/5, would like some input

[Jay Kirkland <jaykirk2@compusmart.ab.ca>]

A 6" f5 is one of the best scopes you can have, something that you will 
love having for the rest of your life. Your diagonal will depend on both 
what you want to use the scope for and what eyepieces you have. I 
started out with a 1.8" secondary for the full field of view with 2" 
eyepieces. Because the scope is light and small and easy to pull out and 
use whenever you want, I was using it in less than ideal conditions, 
like twilight. The 1.8" secondary in less than ideal conditions REALLY 
creates a secondary shadow, a big black hole in the centre of your field 
of view. It isn't noticable in the dark when your eye is fully dark 
adapted but it made it impossible to enjoy the scope for  a quick grab 
and look in the backyard. I scaled the secondary back to 1.5" (or 1.45 
or something) and that has helped hugely. Still can't use the scope in 
bright twilight or daylight. And everything still looks fine in 2" 
eyepieces, no noticable loss of light. Since these small secondaries are 
so inexpensive, you could probably get two or 3  that you could 
interchange for different purposes - a 1.25" for best planetary viewing 
(you'd be amazed at how much detail can be had with high power in a 6") 
to a 1.8" for  full illumination from a dark sky location. 1.5" is my 
compromise.
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