I had decided to try galaxy shooting again from my light polluted backyard last year. Equipment issues put a stop to that and I decided to try and get some RGB and Ha data as my basic mono Lum stack looked fairly decent.

I processed this while being very sleep deprived and had planned on reprocessing it from the ground up. I still might do that and while it's far from the best M51 ever, it turned out pretty decent.

*Notes a friend asked me about my workflow that I'll share here.

I used batch process script to calibrate and stack everything.

I had previously stacked all my Lum from last year. I used that as my reference for stacking.

I then stacked Red, Green, Blue and Ha. I then stacked ALL subs as a master Lum. Not sure if that is ideal or not. But it seemed to look ok. I made a copy of the master Lum and stretched it to death to do my DBE plotting. (of course crop all your stacks before this)

channel combine for the RGB. I think I did linear fit first.

NRGB combine to get the Ha blended in. The stock settings (with putting the proper filter bandwidth) worked pretty well.

used arcsinh stretch for the color data as it preserves the color pretty well.I did the photometric color calibration (wasn't perfect but a good starting point)Then I did a small touch up with the histogram stretch. LRGB combine with the below Lum data. Then a few passes of curves just to tweak the color/saturation.

As for Lum I did MultiscaleLinearTransform with an inverted mask (so the NR goes to the background) I found these settings are a good start and aren't too strong.

Layer 1 Threshold: 2 Amount :0.50 Iterations 1Layer 2: Threshold 1, amount 0.5Layer 3 Threshold 0.5, amount 0.5Layer 4 0.25, amount 0.5dynamic PSF/deconvolution I found a dering of aorund 100-200 works well. You want to mask this too, only effecting the galaxy and bright strars.

Histogram stretch here. Sometimes for lum I use arcsinh stretch too, but for some reason this didn't look as good with that, so I went with the basic histogram stretch.

Masked local histogram eq. This seems to work well on getting some of the knotty looking dust lanes and clumps to really pop. I have been heavy handed with it before so now I try to go where I think it looks good, then back it off a tad.