this is a very special theme. I took 6h exposure from the Gulf of Mexico in NGC 7000. The first image is 18x 20 minute subframes. The second image is 3x 120 minutes subframes. So you can compare long time subs and short time subs. Total exposure time is the same. Processing for both images: Calibrate, Align, Data Reject, Median Combine in CCDStack. Histogram Transfer and HDRMultiscale Transform in PixInsight. Topaz Adjust in Photoshop with the same parameters for both images. Neat Image for a little bit of noise reduction.
I think long time has less noise and the very faint details are better. Contrast in brighter regions looks better in short time.
I am very interested in your opinion.
Long time subs
short time subs