Spectacular star trails
Use these straightforward techniques to record the movement of the stars across the night sky
Traditionally, shooting star trails with film-based cameras relied on shutter speeds of minutes or even hours to capture the movement of the stars across the night sky. But these exposure times will produce too much noise on digital cameras. As such, it’s better to shoot a sequence of images using a much shorter shutter speed and then combine them later. The other big advantage with this technique is that unlike many other creative options for shooting the stars, you can get great star trails images even when there is some light pollution.
1 Take POLE POSITION
Fix the camera in position, focused on the stars – and ideally pointed close to the pole star (see Step by step). You can either use continuous drive mode and just lock the shutter release on your remote, or you can use an intervalometer to take a sequence of images.
2 Capture the Trails
To capture significant trails with a wide-angle lens, you’ll need to keep shooting for at least 15 minutes, which works out at 30 exposures of 30 seconds each. The longer you shoot for, and the more exposures you take, the longer the star trails will be in your final image.
Once you’ve completed your sequence of star trail images, you also need to take a final ‘dark frame’. This is a shot taken using exactly the same shutter speed, ISO and aperture as your main images, but with the lens cap in place. This dark frame is used when you come to combine the shots in software; it will help to reduce noise and the visibility of any ‘hot pixels’, which appear as white dots in long-exposure images. For this to work successfully, the dark frame needs to be taken immediately after you’ve shot the final image in your star trail sequence.
3 Combin e the images
Once you’ve taken your sequence of images, plus a dark frame, you need to combine them. Load each star shot as a separate layer in Photoshop (or your preferred photo-editing software), then change the blending mode of all layers, apart from the bottom one, to Lighten. Load the dark frame on top of the Layer stack, and change its blending mode to Difference.
This process is fine for a few images, but if you’ve taken 30 or more shots it’s a bit slow. The easiest way to combine lots of shots is to use software to automate the process. A popular option is Startrails for Windows, available to download in the Software section at www.startrails.de. Alternatively there’s StarStaX, which is available for both Windows and Mac OS X via the Software section at www.markus-enzweiler.de.
Look for a stationary foreground detail, such as this rock formation in Arches National Park, USA, to add interest and drama