Originally posted by wtlwdwgn I'm not getting the results like you especially the colors. So far I just get more pinpricks of light for longer exposures and the brighter stars become less distinct.
Likely a sign of light pollution and regular pollution interacting but even in great areas you will still get a brightening of the black sky from noise buildup and because the night sky isn't actually perfectly black. I get similar things when first stacked in DSS (Deep Sky Stacker) but then go and do more processing to get the blacker sky, better colors, and bring out the details in things. One of the regular posters in the astrophotography group had a post that contained a links to the tutorials he used to learn how to process astro pics. I can't ever seem to find that post from Pete_XL but I saved the links and included them below. Originally I found some tutorials from other people and the results were less than stellar but I thought I was doing well. I asked for feedback, got it, learned, and got pointed in the right direction.
A series on basic DSO processing The full series on astro image processing
If you want to see an unprocessed but stacked image of what I am currently getting for the sky in my backyard here is one I took at about 2:00 AM on Sunday. It is a stack of 14 10 second (14x10s) exposures at ISO 800 using a 17mm SCM fisheye Takumar wide open. I stacked the image using DSS and did no additional processing. Granted the sky glow is exceptionally bad in this photo but my house is in a high
Bortle 8 area and there was a lot of haze from the humidity plus the smoke from the Canadian wild fires. Vertically this covers an area from just above the tree line in the park behind my house to past the zenith (the tree at the top of the picture was actually behind me). The bright dot at the bottom in the middle is Mars.
Since your series of 3 images at 120s, 120s, and 150s haven't really been processed but are basically straight out of the camera I would say you are doing pretty damn good and have a nice dark area to work in with lower humidity and less pollution than I have. So much of getting good pictures from astrophotography is in the processing of them with learning and mastering that.
My suggestions for you on how to improve would be:
1. Start stacking (get DSS it is free and will work with the raw DNG files), it will help with noise and will also allow you the chance to bring out more detail
2. Learn how to process astro pictures. I'm still not great but getting better.
3. Decrease the individual exposure time to have less astrotracer error as well as digital noise but increase the number of stacked images.
4. Combine
dark and
bias frames in DSS.
5. If you don't have photoshop for astro processing, I would suggest using Gimp instead as it is free and the current version will actually allow you to work with the 32bpc tiff that DSS produces.