This star trail photograph is a stack of 58 images. Nikon D90 with a Tokina 11-16mm wide angle set on infinity focus, f/4. Exposure 30 seconds, one second in between. Stacked using StarStax software. I used the “Comet” setting to see what it would do. It is a pleasing effect as a novelty. I used an intervalometer, set the camera up on the roof, and went to bed. I was planning for a much larger stack but the cheap third-party battery gave out. You’ll have this. I’m always excited to see the colors of the stars become evident. I have boosted the colors a little in post-processing. For a larger version, see my Flickr album.