[5ash (Philip)]

I was up early one morning last week and captured a few shots of M42 with my unmodified 60D through a SW ED120 with a baader UHC-S broadband nebula filter. The stacked picture was the result of 6 X6min exposures @ iso800 with darks and flats , didn't have time for more, it shows some nice red in the running man but also a slight pink colour cast in stars.I was not sure how you process this out and as my skills at PS are limited i tried experimenting using a feature of "astronomy tools" that i've used in the past to remove dark rings around stars captured with a video camera. I used astronomy tools to select bright stars then used select/modify/expand to increase the size of the 'selecting rings' around stars. Then went to Image/adjustments/hue saturation and adjusted the saturation and lightness of the stars.Then deselected the stars and a reduction in colour cast was apparent. The pictures below are before and after , i will have to experiment with this a little more. Thought i'd pass this on for those using photoshop ,all you need to get is Noel Carboni's astronomy tools action set . I bought it 7-8yrs ago and have found it very easy to use ,You can download it for a small price .Well worth it.
regards philip