The other night I wanted to test out a new technique I learned for photographing "star trails" over a period of time. When I took my first photographs up north in September, I kept the shutter open on my camera for 30 minutes and then had to wait 30 more minutes for the camera to process that huge amount of data. I stumbled across another photographer that has the same exact camera and lenses that I have that makes beautiful star photos. He sets his camera to take shorter exposures - 10 to 15 seconds each - in rapid succession and then merges them together. The foreground stays the same and the background stars move across the sky. In the photo above, I took 45 minutes worth of photos, every 10 seconds, without having 45 minutes of processing time. The merged photo is much sharper than if I left the shutter open for half-an-hour. The really bright smudge across the sky is the crescent moon. This was photographed in our church parking lot just after sunset, so the sky was not that dark yet and the lights of passing cars shows up very brightly.
Here is a time lapse of the same photos that I used to merge into the photo above: