Star trail photos can be dramatic, gorgeous depictions of the cosmos. They show how the sky moves as the Earth rotates, and how the stars above us vary so greatly in brightness and color. They also serve brilliantly to fill a frame when it’s not quite dark enough for a great shot of the Milky Way. Plus, they’re like catnip to the social media crowd.
But capturing great star trail images involves a bit more than just opening up your camera’s shutter and then sitting back and sipping beers at the campsite. It takes planning and some diligent, but relatively simple, processing on the back end. I spoke to photographer Harun Mehmedinovic, creator of the Skyglow Project, and British journalist and photographer Jamie Carter, author of A Stargazing Program for Beginners: A Pocket Field Guide, about how to snag epic star trail shots. With their combined insights, you, too, will be able to harness the power of the Earth’s movement for photographic glory!
“The easiest and cleanest way to create a star trail is to concentrate on producing one good long-exposure night-sky image, which, crucially, has something interesting in the foreground.”
As for the old-school single-exposure tactic, both photographers agreed that doesn’t always cut it. As Carter explained, most star trail shots in the old days actually were achieved by opening the camera and keeping it open for hours at a time. “With digital cameras, however, that strategy is much more complicated,” Carter said. “The sensors heat up so much that you get a lot of noise or too much light taken in.”
If you do wish to take a crack at the single-exposure approach, Mehmedinovic suggested setting the camera on a tripod at a dark-sky site (as free of light pollution as possible) during a moonless night. You can set the camera to 100 to 400 ISO, somewhere between f2.8 and f5.6, all depending on the level of light pollution in the area you’re shooting. “Make sure the battery is full, make sure the tripod is fully locked off and set into a place with no vibration — so away from roads, earthquake prone areas, objects that cause vibration, et cetera — and just take a 1-2 hour exposure on ‘bulb’ mode,” he said. “This method requires no post-work on the computer to accomplish star trails, so it’s a good first step, provided conditions are met.”
Although that method can work, by far the best approach — and the one invariably used by the astrophotographers you’re seeing on Instagram these days — is to “stack” multiple exposures into a single image via some specialized software. Here’s how to approach the challenge.
1Find clear skies — and something in the foreground. Obviously, you should have a cloud-free view of the night sky, with as little light pollution as possible (though it is also possible to get good results in cities and suburban areas). “The easiest and cleanest way to create a star trail is to concentrate on producing one good long-exposure night-sky image, which, crucially, has something interesting in the foreground,” Carter said. If you’re in the northern hemisphere, he said, point your camera in the general vicinity of Polaris, near the Big Dipper. This will generate star trails in a circular pattern, as the sky rotates around that spot. If you want elongated curves, point your camera to the south.
