Hi
I just finished doing the full IR mod of 1200D and have to order Baader UV/IR cut filter (or similar) filter to avoid bloated stars with my ED80. This got me thinking about the future improvements, in particular about the light pollution (LP).
I am guessing that there are quite a few people like me that use a DSLR and battle the LP close to the CBD. How "far" is the next step? I have found the following methods and I would like to hear thoughts/recommendations from the more experienced:
1. Dark sky is of course the best but rarely possible. Actually not possible for me ATM.
2. Narrowband/CCD is unfortunately too expensive.
Cost: few $1000s
3. LP filters - I read mixed comments about those, ranging from great to waste of money with some having horrible colour cast which was impossible to fix in post processing.
Cost: $200-$300
(I am about to order DGM NPB filter for visual but I don't think it is suitable for imaging.)
4. HaRGB imaging with a DSLR. The narrowband hydrogen alpha filter is used in front of DSLR as luminance while RGB component comes from the standard DSLR image. The main idea is that the Ha is narrowband, avoiding LP (imaging can even be done during the full moon). Efficiency is 1/4 for Ha on DSLR as only 1/4 of pixels is used unless the camera is debayered.
Cost: $300-$500
5. LRGB with a DSLR where UV/IR filter is used for luminance.
I could be completely wrong here, I saw this mentioned on few places but without a clear description.
Where does the RGB component come from then? The standard DSLR image would give RGB but that would be identical data to the luminance channel? Do they just extract the L channel from the DSLR image and then mix it back with the RGB image.
Anything I missed? How do these methods compare and how much improvement is to be seen over the DSLR images? Any other thoughts?
I know that nothing compares to the dark skies but sometimes that is not an option
Thank for your thoughts
Luka
P.S. As a side question, do I need 2" filters for the DSLR? 1.25" are much cheaper and I believe can be used if I ever move to CCD imaging.