How to Photograph the Aurora Borealis – Northern lights

Yesterday I wrote about finding aurora borealis, today how to actually photograph them. 

Tripod
The main requirement is a tripod.  Your exposures will be at least 10 seconds and possibly more, there is no way to hand hold the camera and get decent results.

Lenses
You also want to use the fastest wide angle lens you own.  Most consumer wide angle zoom lenses are f/3.5, this is barely fast enough. A f/2.8 or f/2.4 is much better.  Many SLR cameras come with a 50mm prime lens that most people quickly replace with a more convenient zoom lens.  If you still have an old 50mm prime lens laying around, dig it out – it will probably be the fastest lens you own.  I have an old f/1.8 that works great.  The problem with a 50mm lens is that it isn’t wide enough to capture the full band in most auroras, you usually need a wider lens – more like 28mm or wider.  Serious aurora photographers usually own at least one f/1.4 wide angle prime lens.  These can be somewhat expensive, and very specialized since most nature photographers don’t need fast wide angles because they are stopping down to maximize depth of field for landscape photography.

Shutter Speed
The idea behind using a fast lens is to reduce the shutter speed by as much as possible.  Auroras can have lots of interesting details in their bands and rays, but these details are largely lost with exposures in excess of 30 seconds – the wonderful color is still there, but longer exposures turns the details in to blobs of colors.

ISO Settings
Another way to reduce the shutter speed is to increase the ISO settings on digital cameras, or use higher speed film.  Today most people seem to use digital cameras, so my discussion will focus on these.  Higher ISO settings on digital cameras lead to increased image noise, especially in dark areas, I would use the highest ISO setting that you can live with noise wise.  I have no problem using my Canon 5D at 400 ISO, and wouldn’t hesitate to go to 800, above that, things get fairly noisy.  Because of the lack of detail in auroras, these type of images do respond well to noise reduction efforts in Photoshop.  I may try 1600 ISO my next night out.

Focus
Since the Aurora is far away, you can set focus on infinity and forget about it.  Test your lens in advance in daylight, some lenses need to be backed off slightly from full infinity for proper focus.

Noise Reduction 
I talked about image noise from using high iso settings, but there is another kind of noise to be concerned about during long exposures with digital cameras, and that is sensor noise.  Sensor noise is basically stuck pixels (all cameras have them) on your camera’s sensor that will show as white dots in your image.  To avoid this, you need to make sure the noise reduction feature on your digital camera is turned on.  With noise reduction on, your camera will take a second totally black exposure of equal time to your original capture, and then the camera uses this exposure to block out the stuck pixels.  This does double your total time for every image, but it is a necessary step for long night exposures.  See your manual for more info, on Canon cameras this is typically set with custom function 2.

Exposure
OK, you have a tripod, lens opened all the way, iso set high, focus at infinity and noise reduction on – now you are ready to start shooting.  I typically start with about a 20 second exposure and adjust from there based upon what I’m seeing on the histogram.  The top photo for reference was 10 seconds at f/2.8 and 320 iso.  Exposures can really vary widely depending on the brightness of the aurora and moon, and this is why I rely heavily on the histogram.

Moon Light
Speaking of the moon, a moon lit night can be very helpful at lighting up the surrounding countryside not only adding to the composition possibilities, but the moon makes it much easier to shoot and for walking.  It does take a pretty good aurora to compete with the light from a full moon. 

Other tools
A headlamp can be very valuable when shooting at night.  Be sure to turn your headlamp and any car lights off before taking your photo, as stray light can be a problem with long exposures.  A shutter release can be helpful as it reduces camera shake, I often use my two second timer instead.  Since auroras are often found in the winter, this entry on winter photography tips may also be helpful.

Composition
Including a mountain, tree or other subject matter can help aurora photos.  It is nice to have a reference point for scale.  Experiment, horizontal and vertical, include the moon and leave it out, including the surroundings, even shoot straight up, anything goes. 

Patience
The biggest secret to Aurora photography is patience.  Good aurora photographers spend many nights out in the cold sitting, waiting and even sleeping in their vehicles.