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
Last edited by 5ash; 19-10-2013 at 12:38 PM.
Reason: addition
Nice images Phillip, either one is very good. The colour cast you mention is noticeable but I don't find it distracting, so I would be very happy with either image.
Thanks Kevin , Bryan and Rex for your comments , will try to get several hours of exposure at 10 minute exposures to bring out the extended nebulosity as you have in your pics Rex. Am happy with the increased redness with this filter.will experiment more with the technique I described .
Regards philip
