As an aurora photographic guide I've seen it so many times, but it still makes me as excited as a kid. Just imagine: those colors in the sky connect us to space and our planet's sun, even during polar night, when the sun does not rise in the Arctic. Here are a few things to consider if you're planning to see it.
Find a good location
You're ideally situated directly below the aurora oval. Tromsø, Norway is a great location - you have a chance to see the aurora directly overhead and the city's position makes it possible to travel in all directions to find clear skies. Do some research into which months are best for viewing (in Tromsø this is from October to March).
Give yourself enough time
I've met so many people who fly into Tromsø for a night or two, hoping to be lucky - many of them are disappointed. The best chance you'll have of seeing the aurora is when you're able to go out for a couple of nights.
Clear skies give you the best chance
Use an aurora forecast tool to monitor activity and scan the weather report to find clear skies (or at least gaps in the cloud cover). Aurora photographers become expert cloud surfers, but even so, the weather report is just a report - sometimes the reality is not what was expected. No one can give you a 100% guarantee that you'll see the aurora, they can only give you an estimation of your chances. All the elements need to be in place: favourable activity, clear skies... and you!
Be prepared for difficult conditions
Icy roads, strong winds and poor visibility are some of the more risky conditions. Check road conditions prior to leaving (click here for Norwegian traffic conditions) and make sure that you're prepared for the worst weather even if the forecast looks favorable. Drive slower than you would in warmer conditions, particularly when driving around corners or on roads that you're unfamiliar with. Icy roads can be extremely slippery and meeting a moose in the middle of the road is not ideal. Have emergency numbers ready. If you're not familiar with the area or weather conditions, strongly consider using a reputable tour guide (I can recommend a company in Tromsø; get in touch with me via the contact form on this website).
The right gear
Make sure you have tyres suited for icy roads, wipers that work well and something to scrape ice off windows. You may return to your car to find that the locks and fuel cover have frozen shut; at local fuel stations you'll find a special liquid to use in this case, but remember to carry it on you - don't leave it in the locked car! Keep a shovel and hazard triangle in your car and check road/snow conditions before you park.
You'll need to be prepared to be outside in cold, windy weather, so make sure you're dressed in multiple layers with clothes that insulate well (like wool or down), a windproof, waterproof outer shell and waterproof boots (the snow may be deep in some areas). Dress properly before stepping outside the vehicle as keeping warm is easier than trying to warm up once you're cold. I recommend a pair of gloves that you won't need to take off to handle the camera with, as the camera becomes extremely cold in sub-zero temperatures and you'll need your fingers to stay warm enough to control the equipment easily. Hand & foot warmers are useful - put them in your gloves or shoes before you get out of the vehicle.
Get to know your camera before you head out
Make sure the camera you take has the functions you need as not all of them do. Auroras can come & go or change intensity quickly, so be sure to find all the settings and know how to adjust them before you set out to see the aurora. You'll need a tripod as you'll use long exposure times to photograph an aurora which is dim or moving slowly. A few extra tips:
Take an extra battery and don't use the camera unnecessarily as batteries run out extremely quickly in cold weather. For the same reason, make sure you keep your mobile phone out of the cold and have a battery bank or car charger available in case of emergencies.
Put your camera in Manual mode (M).
Use a wide angle lens (e.g. 18mm) if you want to bring more of the landscape or sky into the scene.
Focus is tricky as your camera will usually not auto focus on a dark night scene. Put your camera & lens on manual focus. If you want to take aurora landscape images, you need a stable tripod. Zoom in on a star or the moon to bring it into focus. If none of these are a possibility, you can use distant city lights or the red lights on mountain peaks that are located in air traffic zones. You can use the infinity symbol ∞ on your lens if you can see it (not all lenses have one), but keep in mind that cold temperatures can influence the exact point of infinity focus. If you're taking a portrait, you'll need to focus on the person's face.
An aperture f/2.8 is good (or as low as you can go - 3.5 or 4.0 is also ok).
Set a self-timer delay of 2 seconds or use a remote control; this prevents vibrations (caused by pressing the shutter button) from affecting your image sharpness.
White balance is a debatable subject and will vary from daylight settings to somewhere between a Kelvin of 2800 and 4500... there are many factors that influence the choice, so go for what resembles what you saw with your eyes. Shoot in RAW if you usually edit your photos.
Shutter speed and ISO is where it gets more technical - these will vary depending on the aurora's brightness and speed. Start with a low ISO, say 800, and try different shutter speeds. If it's dark even at 30 seconds, go up with your ISO to 1600 or even 3200 (don't go above 1600 unless you have a pro or semi-pro camera). Always use the lowest ISO possible as this gives a better quality image, but if an aurora is moving quickly, you also want to try to keep your shutter speed low so that you can 'freeze' the movement and color on your photo, while still taking care to not lose details in the highlights or shadows. If you're unsure, rather have images that are slightly too dark than auroras that are 'blown out' - this is when the highlights have a burnt white look.
Don't take a camera from a cold temperature directly into a warm one (such as the car or bus) - it will cause condensation in the camera and lens. After your trip, close it in a bag before you get into the vehicle and allow it to warm up slowly.
What the aurora looks like
What you'll see is a combination of the intensity of charged particles released from the sun, atmospheric elements, the earth's magnetic field, your location and the sensitivity of your eyes, but "fairly high concentration of atomic oxygen and higher eye sensitivity in green make green auroras the most common" (Wikipedia).
When light enters your eye, it is sensed by rods and cones, two different cell types located at the back of the eye on a layer of tissue called the retina. Rods (which we use in the dark) are sensitive to changes in light, shapes and movement in dim light, but they aren't sensitive to color and take a while to adjust. Cones are sensitive to color; they are used for color vision and details, but only work in bright light. A very gentle aurora may appear somewhat grey to your eyes if you're picking up on it with your rods - this can be hard to differentiate from a cloud, so you can take a long exposure photograph to help tell the difference (if it's the aurora, your camera should be able to record its color, which is often green). Light pollution from nearby cities can give clouds a yellow or orange color. Some people are more sensitive to light and color and will tend to pick up on the aurora before others can.
Use lights only if absolutely necessary
If you're around a bright light like an electronic device, headlamp or campfire, you'll miss gentle auroras (and so also the opportunity to photograph them). Another reason to keep lights off (at at least on the dimmest setting) is to avoid spoiling photographs: when taking a long exposure image, any light (for example a headlamp) that moves in the scene, even for a second, will put unwanted light and color on the photograph. The bigger the group or the smaller the space, the more difficult it becomes to take a long-exposure photograph without unwanted light in it, especially when people need their headlamps to navigate or to figure out how to work their equipment, so consider that when choosing your position.
What to expect
Long exposure photographs make the aurora look brighter and more saturated than what was seen with the eyes, even without photo editing. I aim for images that resemble what I saw with my eyes. When an aurora is directly overhead and moving quickly, it most definitely does show the mind-bending colors and shapes you see in some pictures. It's important to communicate and appreciate all the nuances of the aurora, otherwise it becomes just another commodity for people to consume. Even when the aurora can't be seen, there are many amazing things to experience: fresh snow on bare trees; animal tracks and sounds; moonlit mountain peaks; the glitter of snow crystals when temperatures are sub-zero; thousands of stars.
Take care of the precious landscape
If you are making a fire, look for an existing fireplace and don't make one directly on the ground (use a fire bowl or basket). Scan the area to make sure your don't leave behind any trash (like toilet paper, cigarette stubs, batteries or packaging)... keep it wild.