Get into position on a clear dark night and set up your tripod and compose your frame. If you want to line up with the North Star, do this now. Using a wide lens will let you get as much sky in the frame as possible!
Set up the camera.
Next, set your camera onto manual, and on manual focus. Focus the lens to infinity to get the sharpest possible trails.
Set the ISO fairly high, somewhere around 1600, the aperture as wide as possible and then the shutter speed to bulb if using Triggertrap Mobile or the longest possible duration if using a normal intervalometer.
Take a frame at 30 seconds and see how it looks. If the stars are nice and bright, this will probably do. If it is too dark, increase the exposure time until you’re happy.
Set up your intervalometer or Triggertrap Mobile.
Plug in your intervalometer or Triggertrap Mobile kit and set it up. Open up the Star Trails mode in Triggertrap Mobile and set it to your desired exposure time, with a two second interval and the desired number of frames. You can set this to a really high number and stop after 30-45 minutes if you’re not sure how long you want to go for.