Curtains of light
What’s the effect? This time segment is probably my favourite as the images created at these shutter speeds are the stuff that Doctor Who is made of. Capturing the psychedelic skies of an aurora borealis is something that every photographer should experience.
I’m lucky to experience this spectacle every year when I lead workshops in the Lofoten Islands in Norway. It’s never a sure thing as it relies on the amount of solar activity and clear skies. Checking the aurora forecast tells me if there is a chance of a decent show. The Kp-index is a global geometric storm index with a scale of 0 to 9. The higher the number, the better the aurora. You don’t have to travel to the Arctic to see an aurora, though, as they are becoming frequent as far south as northern Europe.
What’s the time? There is a particular procedure for capturing auroras. The normal exposure times are around 15 secs to 30 secs. The shapes of the auroras change quickly, so they would blend together and the stars would start to elongate during longer exposures.
There is also a formula for figuring out how long an exposure you can make before the stars start to trail due to the Earth’s rotation. It’s called the 500 rule, and basically you divide 500 by the focal length of your lens. For example, if you’re using a focal length of 24mm on a full-frame camera, divide 500 by 24 and you’ll get 21, meaning that going no longer than 21 secs will ensure the stars will be sharp points of light.
Use a wide-angle lens with the aperture set to its widest aperture. Focus manually and set it to infinity. The hash mark should be set to the middle of the infinity mark on the lens. I always make an exposure then check the focus at 100 per cent on the LCD. The ISO setting can be anything from ISO400 to ISO4000 or more, depending on the amount of moonlight. I’ve used ISO400 with a full moon where it lights the landscape. No moon will allow the aurora to show up better, but I like to have some detail in the landscape. The usual go-to ISOs are ISO1600 to ISO3200. These give a short enough exposure time to capture the aurora.
When deciding where to photograph your aurora, look for a landscape feature that will complement them. I shot this image from a beach; the wet sand captured the reflections of the mountain and aurora perfectly.