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Shooting star trails


Something I like to do when the sky is clear at night is to get out and shoot some star trails.  The results can be quite dramatic and guaranteed to make all your friends go ‘wow!’. 

And all it takes is a sturdy tripod, a remote shutter release and a bit of patience.

The method
By far the most effective means of obtaining a successful result that I know of is to take a series of exposures and stack them together.  The advantage of using a series of short exposures over one long exposure is that even in the suburbs, you can get good results without the sky becoming over exposed.  Stacking the images can be done in photoshop or in specialist software like StarTrails.exe, which can be downloaded from http://www.startrails.de/html/software.html for free.  NOTE: this website is often down, so just keep trying.

The settings
Using the widest lens you have, set the camera up using the following settings:

  • manual mode
  • 30 seconds
  • f/4
  • ISO400
  • mutishot mode

Set the camera to manual focus mode and focus the lens at infinity.  Point the camera in the direction you want to shoot and press the shutter button to take a test shot.  Check the test shot in the camera’s viewer, you should at least be able to see a few stars.  If all looks good, lock the shutter button down on your remote switch.  Your camera should now start taking a series of 30 second exposures, so sit back and enjoy the night view for a while.  After about 30 minutes, you will have a good series of exposures to work with.  Of course, the longer you leave the camera running, the longer the star trails will be.  If you are out in the country and away from all the city lights, try setting the ISO to 800 or 1600, you will get more and brighter stars.

Why use a high ISO?
The stars themselves are not very bright, so you need to increase the sensitivity of the camera’s sensor in order to capture their light.  Usually in photography, when we want to shoot a dark subject we lengthen the exposure time to get more light.  However, because the stars are constantly moving, lengthening the exposure won’t make them brighter, it just makes the star trails longer.  Increasing the ISO will increase the sensitivity of the camera’s sensor and get you brighter stars.

So armed with a little info, why not step out the back door, into the yard and have a go at it tonight?

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