Quote:
Originally Posted by Dr Nick
I also mount an IR filter on the nosepiece of the DSI Pro II for all of my shots (including the colour shots).
Thanks again.  |
As I am only just finding out myself, Nick, there are diiferent rated IR filters. Then there are IR/UV filters. Then there are different methods of IR filtering. Not as Cut & Dry as I thought it would be! IR can be filtered by 2 different methods, reflective or absorbtion. Reflective is the better.
I am at the moment about to order a Baader IR/UV Cut filter as it has an extremely Sharp Cutoff at 690nm (leaves all the visible red, including the important 656nm H-alpha emission line).
and a sharp cutoff below 400nm which eliminates violet halos around bright stars (more effectively than simpler so-called Minus Violet photographic filters). These nm cut-off levels allow colour through, not just Blue, and is reflective, not absorbive.
As for the Star Spikes, may I suggest Noel Carboni's set of Photoshop actions:
http://actions.home.att.net/Astronom...l_Version.html
One click and many actions are done for you
