dugnsuz
07-01-2007, 12:00 AM
Hi all,
I've been image processing a whole batch of stuff taken recently with Pentax 135mm f3.5 and 200mm f4 lenses. After stacking, some of the brighter stars have objectionable purple halos.
Couple of qu's...
1. Is it better to use a filter on the lens to try and combat CA - say a good quality 2" violet reduction filter with a 49-48mm step down ring on the 135mm lens (52-48 on the 200mm) or use image processing software (such as Astronomy Tools Photoshop actions) to work on the image afterwards.
2. Bert also recommended using an UHC filter to combat CA - would this reduce the violet fringes and enhance nebular detail in one go?
What is/are others experiences???
Got to try something! It's driving me mad!!:P
Can't afford APO lenses either!!!!!!!!!
Cheers
Doug:thumbsup:
I've been image processing a whole batch of stuff taken recently with Pentax 135mm f3.5 and 200mm f4 lenses. After stacking, some of the brighter stars have objectionable purple halos.
Couple of qu's...
1. Is it better to use a filter on the lens to try and combat CA - say a good quality 2" violet reduction filter with a 49-48mm step down ring on the 135mm lens (52-48 on the 200mm) or use image processing software (such as Astronomy Tools Photoshop actions) to work on the image afterwards.
2. Bert also recommended using an UHC filter to combat CA - would this reduce the violet fringes and enhance nebular detail in one go?
What is/are others experiences???
Got to try something! It's driving me mad!!:P
Can't afford APO lenses either!!!!!!!!!
Cheers
Doug:thumbsup: