I picked up the ASI183MM Pro before the holidays and have been taking a few images with it. I decided to give NB imaging a shot, even though I'd be far short of the minimum exposure time to exceed the camera's read noise. My scope is an f/6.5 scope under Bortle 6 skies and there was virtually no lunar illumination in the skies that night. My calculations gave a theoretical exposure time of 30 minutes for an H-Alpha image. From my perspective, that is way too long for a sub. Instead, I decided on 10 minute exposures and put a huge pedestal in during the calibration processing. This actually seemed to work out fairly well and the total noise in the stacked H-Alpha image was around 8e-5.
The image came about from the following subs:
57 x 50s Lum frames at gain 53
27 x 90s Blue frames at gain 111
27 x 90s Green frames at gain 111
17 x 140s Red frames at gain 111
9 x 600s H-Alpha frames at gain 178
I took a few different processing approaches from the norm:
1) Normally, I really boost the red for the H-Alpha contribution but decided to go light on it. It essentially gives a more purplish tint to the H-Alpha region. Still wondering if that was a good effect or not.
2) I also went lighter on the noise reduction than normal. In some ways, it keeps the details sharper but when I start pixel-peeping, it definitely shows some granularity in the background. Technically, I guess most people aren't pixel-peeping the image. The noise is probably more obvious in the full sized astrobin version: https://astrob.in/385445/0/
3) I left the mean background much higher than normal in the final image. Normally, I raise the black point pretty high but decided against it. I suppose this is somewhat subjective.
I feel like in general, it is not a bad image. Any comments from anyone? I've been staring at it for a couple days and hard to be objective at this point.