It’s late. After midnight. I just finished some star trails photography that I began later than I should have. I’ve tried this before with little success, so after some more research I thought I’d give it another shot. All the images below are multiple 30 second exposures stacked on top of each other. The big key to this, which I recently learned, was to turn off the in camera noise reduction basically allowing the camera to immediately start taking a second exposure while the first one is being written to the SD card. This means that there is minimal time in which the shutter is closed and therefore, no gaps in the star trails.
This was just supposed to be an experiment, giving little thought to light painting the foreground or composition. That will be for another night. The lighted tree is from the headlights of a passing car. I wanted to get a sense of how long the star trails were given a set exposure time. Below are 3 examples using the same photos. The first was using 100 x 30 second exposures for a 50 minutes of trails, and the next two were halved then halved again, so 25 minutes and 12 1/2 minutes respectively. Click on the image to enlarge.