View Single Post
  #2  
Old 06-09-2018, 06:34 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Quote:
Originally Posted by Lee View Post
Another 'image' from last night.... unfortunately not much from the big end of the scope. This is something I've noted before in the PHD window.

Scope is 8" f/4 Bintel Newt. OAG and lodestar.

Is this astigmatism? - it has never seemed to bother PHD much, but I suspect it is an amplified version of what is happening in the main CCD.....

A bit of astigmatism mixed with coma. That's pretty standard on the edge of the field of a fast newt. Coma can be dealt with by spacing the corrector, astigmatism by rotating the primary mirror. PHD doesn't care.
Reply With Quote