Guest wisewoman Posted February 5, 2012 Share Posted February 5, 2012 Hi there, I have been messing about for ages trying to get perfect concentric rings in my cheshire. I've ended up with something exactly like the image on the right here with the secondary offset slightly and more black shadow showing on the right then the left (hence not perfectly concentric): http://stargazerslou...dry-quandry.jpg now I understand that fast scopes naturally end up a bit offset but my 200P is an f6 (1200cm length, 200cm diameter) - should I be able to get perfect concentric rings or not? Thanks, Melissa Link to comment Share on other sites More sharing options...
Guest Kheldar Posted February 5, 2012 Share Posted February 5, 2012 Not, f6 is still relatively fast compared to f12 say The beauty of the offset issue, is you don't actually have to worry about it. So long as the steps before are done right, and the crossharis line up with the centre spot, the offset is always right. I think ... Link to comment Share on other sites More sharing options...
Guest wisewoman Posted February 5, 2012 Share Posted February 5, 2012 Right thanks for that Kheldar - I was contemplating trying to fiddle with the focusser housing but I shall leave it for now and star test tonight hoping for perfection! The board will be hearing from me if it's not! Melissa Link to comment Share on other sites More sharing options...
Doc Posted February 5, 2012 Share Posted February 5, 2012 The offset is figured into the secondary mirror you do not need to worry about it. Link to comment Share on other sites More sharing options...
Rusty Strings Posted February 5, 2012 Share Posted February 5, 2012 (edited) This offset used too bother me until, as Mick says, I found out it's naturally in with the secondary. Edited February 5, 2012 by Rusty Strings Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now