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Anthony RS

Should I use CLS-CCD for Galaxies in Bortle 4 Skies?!

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I've modified my Canon 500D (t1i) following Garry Honis' video; however, I did not replace the IR cut filter with a clear glass filter. I just removed the IR filter and put back together all the other filters. I'm using a Newt. with the Skywatcher Aplanatic coma corrector.

Here's my issue, I already have the Astronomik CLS-CCD filter which is a light pollution filter as well as an IR blocking filter but I will be shooting M81/82 in bortle 4 skies this weekend so I'm not sure if using the CLS-CCD is a good idea. First, I'm in relatively dark skies with low light pollution, second, I'm shooting a galaxy, which as far as I know, and please correct me if I'm wrong, the CLS-CCD will do more harm then good blocking probably some of the details or requiring much longer exposures to get the same details as without the filter. I could remove the filter since i'm not worried about light pollution, but would that cause bloated stars since I'm using a coma corrector? or are the remaining filters in the DSLR enough to block IR?

If removing the CLS-CCD does mean I'm going to get bloated stars, the question is can I remove the filter to get as much detail as possible from the galaxies and deal with the stars in processing, or is keeping the filter not that detrimental to galaxies?

Appreciate any insights and opinions especially if you have any experience with this.



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From my understanding the CLS CCD is ok for galaxies as well as nebulas whereas the UHC is not. I use it for galaxies and although I'm no expert and my colours are not always right I always use the CLS CCD as I have full spectrum like you a modified Canon 550d. I don't think it will affect the galaxy too much it just removes a lot of yellow which can be adjusted afterwards. 

One of mine from earlier this year with the same filter. 



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I think the CLS-CCD will take out too much light in Bottle 4 skies, but with a full spectrum conversion you'll need a IR-UV cut filter to control bloat.

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