View Single Post
  #195  
Old 12-03-2015, 03:24 PM
Rac's Avatar
Rac (Raymond)
Registered User

Rac is offline
 
Join Date: Dec 2012
Location: Whangarei, New Zealand
Posts: 120
Quote:
Originally Posted by frankly1 View Post
Hi all, after 9 months work, I have just finished a 19 inch mirror at f4.5. It appears to be very good on the foucault tester for the central 18 inches, then things go down hill outside of that. But that's OK as I treat the lost inch as a 1/2 inch support ring for the 18 inches remaining of the mirror. I will paint the edge black, and all will be well. I will report back with a pic after the scope build.
cheers, Frank
Is the edge rolled off on Figure XP. It can get a little confusing out there and when you do what you think is right it only seems to get worse - been there!

I've got my own little mirror project going on right now, an 18" f3.3 and it's been a challenge to say the least.
Reply With Quote