Photographing the aurora borealis

Aspectacular Northern Lights display is something to behold. It moves, changes color, and changes intensity constantly, and when it fills the sky it takes your breath away. At the same time, it makes you feel small and insignificant in the grand scheme of things.

Photographing the aurora is easy once you understand the settings. You have to first realize that because the lights move, exposures that are too long will cause a loss in definition. In other words, the shape and design of the celestial light pattern may be lost and you end up with nothing but a large green glow. If this is the first image of the Northern Lights you’ve ever taken, even that will be exciting. But very soon you’ll be looking for something more.

My exposure for the image below was 10 seconds. I would recommend making this your longest exposure. As you can see, the curves of light patterns are nicely defined. That’s what you want. The lens aperture I used was f/2.8, and my ISO was only 800. You have to use the largest lens aperture available -- the larger, the better. F/4 is the smallest aperture I’d use; otherwise, you’ll be forced to raise the ISO or length-

en the exposure. Post-production software to mitigate noise, like Topaz DeNoise and Neat Image are both superb, but noise does show up prominently in the shadows. And night skies are full of shadows.

For the image below I used a 15 second exposure, and you can see some movement in the patch of green color in the upper right quadrant. A 25 or 30 second exposure would produce just a glow in the sky without any form.

Note how the colors vary. I didn’t alter the colors in post-processing at all. This is how a digital sensor reacts to the lights. I typically use a white balance between 3000 and 4000 degrees Kelvin. This has to be set manually.

The biggest challenge with shooting the sky -- and this includes the Milky Way as well -- is, believe it or not, focusing. As good as autofocus is today, the camera can’t delineate a subject in a night sky even if the aurora borealis is bright. There are two things you can do.

First, you’ll be using a wide angle lens. I suggest 16mm or wider. Lenses with a super wide focal length go to infinity at approximately their focal length . . . in feet. So, for example, a 14mm lens focuses to infinity at about 14 feet. That means you can focus on a distant window light, street lamp, car headlight, or even a flashlight that’s at least -- let’s say for insurance -- 25 feet away or more. Sometimes if you are shooting in a remote area specifically to get away from the lights of a city, there aren’t any manmade lights to be seen. In that case, use a flash. Have a friend hold the light for you or simply rest it on the ground or on anything else. Walk away and when you are about 25 to 30 feet away, focus on it. You can focus manually or use the AF function. However, once fo-

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cused, switch to manual focus mode and don’t touch or jar the lens in any way. Now, when you shoot the sky, you’ll be in focus.

If you want to include the aurora behind an illuminated building or city skyline, like you see with the church photo on page 13, it can’t be done with a single shot. The lighting on the architecture is much brighter than on the aurora, and the exposure discrepancy is too much for a digital sensor. You have two choices:

1. You can take an HDR sequence in which the longest shutter speed permits a good exposure on the sky. In this case, I’d recommend exposure increments of 2 f/stops and take 7 frames in the sequence.

2. Take two separate shots in which you first expose correctly for the architecture, and then second you take the correct exposure for the Northern Lights. Then, in Photoshop, composite them together. This is what I did to create the photo of the church.

Including landscapes at night with a sky illuminated by the aurora can be quite dramatic. With the ligh gathering of a long exposure and a large aperture, landscapes can look virtually like a daylight exposure. This gives form, perspective, and interest to the image. You can also paint foregrounds with a flashlight, and this, also, makes for dramatic images.

I captured all the images in this article in Iceland during winter trips there. You never see the aurora in the summer because the sky is never dark enough. §