I am building a 10" F6 newt and I'm not sure about secondary size. Of course I want to keep it as small a possible. right now I am planning on using a 1.83" but not sure if I can go smaller. Any quick and not so dirty methods out there to calculate the proper size? Thanks, Vince
calculating seconday size
Started by vbert, 09/22/2004 07:16PM
Posted 09/22/2004 07:16PM
Opening Post
Posted 09/22/2004 07:29PM
| Edited 09/22/2004 07:29PM
#1
Download Newt 2.0. Do a google search for it, it is a free program by Dale Keller. Depending on your tube size and focuser, 1.83 is probably about right for general use. You could get away with one size down (1.52" I think) if you use a relatively narrow tube or UTA and a low profile focuser, but you may notice some vignetting in low power wide field eyepieces. If you plan to really concentrate on planets it might be worth it, but 1.83 is already below 20% so it will still do well on planets with that (and I have a 10" f5.6 with a 1.83" scope that does quite well on planets).
Jarad
Jarad
Funding Member
