I used a great tutorial that I found on the web. I took images for 4 hours (30 second each) and then processed them as described in the tutorial. A couple of learnings:
- you don't really import the images in Adobe Bridge, you just navigate to the folder
- when editing the photos, choose "Raw photo editor" - that doesn't load Photoshop but just the editor
- press "Done" not "Save" when done!
- import all the images to photoshop as layers takes 5+ hours!!!
- flattening the layers takes another 5+ hours!!!
- I tried to save first (before flattening) but that takes hours too (and might fail as the file gets too big)!
- my first try was way too bright:
the combined image will get significantly brighter because you use the brightest pixels from each image.
Overall, I'm quite happy. Should do these more often when I'm at dark sites.