I was invited a few weekends ago to join a couple of astronomy enthusiasts up in the mountains (Amiantos area) for some night-sky watching. After recently having read a couple of tutorials on star trail techniques, I was itching to give it a try.
For this first picture, I located the North Star (Polaris) just before it got completely dark. I set my camera with my Canon 24-70 F2.8L lens on my trusty tripod and took a couple of pictures to make sure my composition was correct. After being satisfied that I had everything where I wanted them to be, I set my camera to Manual mode and dialed my settings to ISO 400, F2.8 with a 30 sec exposure. What followed was an excruciating hour and a half, where I manually took 140 consecutive pictures using my remote cable release (guess who just ordered an intervalometer!). These images were later stacked together using a simple freeware program I downloaded from www.startrails.de and then imported the image into Photoshop for some minor touches (contrast and sharpness).
The second picture was taken facing South East – same settings, slightly less painful shooting procedure as I only took about 75 images.