Photographing the Northern Lights

There is no more appropriate subject to photograph than the Aurora borealis to remind one that the word photography literally means to draw with light. 

The Aurora of the north (Aurora Borealis) and the Aurora of the south (Aurora Australis) occur when charged particles emitted from the sun penetrate the earth’s magnetic shield and collide with atoms and molecules in the atmosphere. Witnessing this phenomenon is out of this world, but the process of photographing it need not make your head spin.

Since the word photography literally means drawing with light, let’s begin by thinking of your camera’s sensor (or film plane) as a canvas. Without any exposure, the image you begin with is black. Slowly over time you allow light to enter the lens of your camera which paints your canvas with light. But how does one expose for light from outer space? In the same way you do anywhere else except that you will allow the exposure to be longer than with ordinary day to day photography. 

The first thing I always do is set my camera ISO for the aurora between 400 and 3200 depending on how strong it is. Then I put the camera on aperture priority and take a picture. The camera picks a shutterspeed authomatically and makes an exposure. Your camera’s meter is balanced to average out light. As such if you were to point it at a black wall it would make it grey. If you point it at a white wall it would make it grey. So pointing it to a dark sky with lights will often result in an undesirable overexposed exposure. Take the picture and see what happens. Switch to manual mode and adjust the shutter speed accordingly. 

Here are the steps. 

1. Mount camera on on tripod, frame up your image. 

Yes this can be difficult in the dark but you will take several exposures and can adjust as you go. 

2. Select your base ISO setting. 

I like to start with 400ISO which has very little noise but more speed than 200 or 100. Depending on your camera and on the amount of light present on the night you might go 200 or you might need 3200. 

3. Select your aperture. 

If you are not concerned with depth of field pick an aperture either the lowest your lens offers, or for best image quality the sweet spot on your lens. This is usually two stops down from the lowest. So if your lens is at 3.5, it would go 4.0 then 5.6. If you want to have more depth of field pick a higher number like f 8.0. 

4. Put the camera on A (aperture priority) and take a test shot. 

This will force the camera to pick your shutter speed for you. Note what shutter speed the camera picks when on the Aperture priority setting and how dark or light the image is. 

5. Switch the camera to M (manual mode). 

Double check the aperture is the same as your test shot and set the shutter speed accordingly. If your camera gave you 14 seconds but it is way too bright try halving the time. So 7 seconds. If it is just right note the shutter speed and set it to manual anyhow. This way you will have that exposure as a base reference and the meter will not jump all over the place as the aurora flares up and down.

You will need to use your judgement and experiment with trial and error. Even more so if you are not practiced at metering. You can control it yourself judging the light and what you are getting. Remember you are painting with light and your results can vary greatly depending on the settings above. Have fun and experiment. I usually bring something warm to drink and some very good mitten gloves. The aurora tends to be visible when the skies are clear and the weather is cold.

The following five principles will control what your image looks like.

Stability (tripod)

Before we make an exposure we must make sure we are stable. The Aurora moves but generally your camera should not. Usually a tripod is the best solution for this but sometimes we are places where we can rest the camera and restrict movement. You will be using a very slow shutter speed, in some cases one which is several seconds long to capture the dancing lights.

White Balance

If you are shooting RAW images as opposed to JPEGS this is not as critical. However I like to keep my RAW files as clean and more importantly as consisitent as possible. Therefor I do not shoot with the AUTO WB setting. That can have your images varying from shot to shot which makes for more work in post.  I pick a setting which looks good and stick to it. With JPEG it is critical you get the image’s colours to look as good as possible on each image.

Sensitivity (ISO - the higher the number, the more grain and noise)

This is usually a number ranging from 50 to 128000. The higher the number the less light you need to make a picture but the more noise you get. I like to shoot the lights at 400ISO or 800ISO and try not to get above 1600ISO. This will vary from camera to camera.

Aperture or F-stop (Depth of field or amount of image in focus from near to far)

The aperture can be varied if there are other elements in the foreground you wish to have in focus. For this image I used a F1.8 which is a very low aperture allowing the maximum amount of light in but also having the least depth of field. That means that if I wanted a mountain or river in the foreground to be in focus as well I might have to change this number. We’ll get to that later. So for now I am using the lowest number my lens has which is the largest opening. Remember it is a fraction so it is 1/1.8. 1/22 or f22 is a very small hole with a lot of depth of field and not very much light let in.

Shutter Speed (how long the iris of the camera is held open to expose your canvas to light)

Generally this will be lower than 1/30th of a second at most ISO. I do not think about trying to ‘stop’ the lights in motion but prefer to photograph their motion as in the example above. You can vary your shutter speed accordingly. In the image above the shutter speed was 14.0 seconds. I was using LIVETIME to watch the image develop over time and ended the exposure at 14.0 seconds, but you can program your camera to have a shutter speed of 14.0 seconds or a number of others. Experiment by setting all the other variables and take a guessed exposure.