Shooting in the Dark
Astro photographer Adam Woodworth discusses the art of capturing the night sky
Landscape astrophotography is one of the most popular and fast-growing forms of photography these days, and with today’s cameras and lenses it’s pretty easy to shoot high-quality images of the night sky. You’ll need a crop or full-frame camera, a fast (low f-stop) wide-angle lens, a sturdy tripod and an intervalometer or remote timer for your camera.
Most of the time there simply isn’t enough light to get the landscape and the sky both well exposed in the same shot at night, so shooting landscapes under the stars often requires using multiple exposures. You can then blend the photos in Photoshop to create your final result. For the sky, the goal is to get a shot where the stars appear as pinpoints and not as trails. Shooting at 14mm on a fullframe camera, I aim for 20 seconds and use an ISO that has a balance of getting a brightenough exposure but not a ton of noise. On the Nikon D850, for example, I’ve found that even ISO 12,800 or 25,600 is fine for a sky exposure, just make sure you aren’t blowing out the stars to pure white. The longer the focal length, the shorter an exposure you will need to reduce star trails.
For the foreground I usually use ISO 1600 and whatever shutter speed is necessary to capture enough light to see detail in the landscape. This can be as little as 30 seconds when shooting with a lot of ambient light, or as long as 20 or 30 minutes. If there’s enough ambient light I might stop down the lens to f5.6 to get more in focus, but otherwise I usually shoot multiple foreground shots at f2.8 and at different focus distances, then stack them with the sky shot in Photoshop.
You might be wondering, how in the world am I supposed to focus in the dark? If you aren’t concerned with focus stacking for the foreground, you could go out in the daytime and focus on something very far away to find the infinity focus spot on your lens. Don’t trust the infinity mark on your focus ring though; it’s often not accurate and humidity, temperature and age of the lens can change infinity focus. When you find infinity you can tape the focus ring to your lens so it won’t move, and then you should have the stars and distant landscape objects in focus. Or, use Live View at night and aim your camera at a bright star, then manually focus the lens until the star appears as small and sharp as possible. This way you can focus for the stars, change focus for the foreground, then refocus for the stars throughout the night.