Photographing star trails

Night sky can give a lot of opportunities to take wonderful images. One of them is photographing the trails caused by the apparent movement of the stars on the sky due to the Earth rotation around its axis.
The image below gives an example of star trail photography, being taken in front of a hotel during a weekend at seaside.

Star trails (15 min exposure, f5.6, 17mm,  ISO200)
Star trails (15 min exposure, f5.6, 17mm, ISO200)

What do you need to photograph star trails:

  • DSLR camera;
  • remote control or cable  release for the shutter;
  • tripod;
  • wide lens;
  • fully charged camera battery.

The key of capturing the star trails is of course long exposure. Depending on  how long do you want  the trails  to be, the exposure time can e between 15 minutes to several hours. It is important that the sky is as dark as possible, with no moon and no light pollution as you find in a city for example. Also the other settings of the camera should be adjusted to eliminate the background light during the long exposure.

To keep  the camera shutter open for  so long you will need to enter in bulb mode, where you can start and stop the exposure using a remote control.  Check your camera manual on how to activate bulb mode and use the remote control to start and stop  the exposure. It is very important that your battery is fully charged so it doesn’t discharge completely during the exposure. Also if you have a long exposure noise reduction function  on the camera, processing time is usually greater than the exposure time so if you don’t like to wait, make sure you disable that function from the camera menu prior to taking the shot.