Photographing the aurora

While there are some general guidelines for photographic the aurora, much of it is still trial-and-error. This is primarily due to the fact that the aurora can vary significantly in brightness and the speed in which it evolves.

Equipment

In this discussion, I will assume you are using a 35mm SLR camera. If you are using a larger format, you will have to adjust this information to compensate. Digital cameras often work just fine if they have the capability to do long exposures and you can set them at a high ASA number. However, I don't own a digital camera so I can't really talk about them with any authority.

Camera body

The main requirement here is that your body has a "B" setting so you can do long exposures. You will find that a long session of aurora photography, especially in cold weather, will sap your batteries. The options are to carry a spare set of batteries in a warm place (the cold batteries will sometimes still work well after you warm them up), or use an old body with a mechanical shutter. The latter option has an advantage in that you could by a cheap, used camera and a couple of lenses to dedicate to aurora photography and other astrophotography. You will also want a cable release that allows you to open and close the shutter without touching the camera.

Lenses

While a relatively a long focal length lens like an 85mm, 100mm or 105mm could be used to get a close-up on a particular ray or other feature, usually you will use a shorter lens. Fortunately, the standard 50mm (or 45mm, or 58mm, etc.) lens that usually comes with a camera will work fine. However, aurora displays can cover a lot of real estate in the sky and at some point you will want to get a lens in the 24-35mm focal length range. You want the lens to be relatively "fast", that is it should have a small f/ratio like f/2.8 or smaller. An f/4 lens can work, but you will be collecting half as much light. Fortunately, lenses in the 35mm to 58mm range are almost always f/2.8 or faster. Zoom lenses can also work, but often they are not of as high of optical quality as a fixed lens, and they are usually relatively "slow" lenses.

Film

Certain astronomical objects give off light at very long red wavelengths that modern films sometimes have trouble with. However, that is generally not the case with the aurora, and normal "off the shelf" films seem to work just fine. But, you will want to use film with an ASA rating of 400 or higher, and 800 or 1000 is better. I generally try to always have a roll of ASA 800 film (usually Fuji) on hand at all times. I have used professional films at times, which require refrigeration because they are perfectly "ripened", but that's really not necessary, and I have shot great photos on consumer grade film. I do recommend that you consider buying the consumer grade films that are sold in a camera shop as opposed to a department store, supermarket, etc. For example, for Fuji films in 2004, that means getting "Superia" as opposed to things like "Super HQ". It is still cheaper than professional films, while probably being nearly as good.

Technique

Sky quality

In short, if you are clearly seeing an auroral display, you can photograph it, and even if you only see a hint of the aurora, a long exposure should bring it out even better. However, it's best to get as far from city lights as convenient. For obvious reasons, the north side of your town or city can be a great place to shoot unless there's another city to your immediate north.

Equipment settings

I said earlier that you want to have a fast lens. However, expecially with faster lenses, consider stopping them down an f-stop for at least some of the photos to get a sharper image. For instance, an f/2.8 lens could be shot at f/4, or an f/1.7 lens would be shot at f/2.8. But, this depends on the lens quality, too. Just understand that night-sky photography is one of the most demanding tests of a camera lens due to having bright point sources in the field and having to shoot at small f-ratios. In any case, the f/ratio is the single most important number that tells you how bright of an image you will get on the film for a particular auroral display. At f/4, for a great display, and ASA 800-1000 film, I recommend a 15-30 second exposure. For a mediocre display you may need a 60 second exposure to get anything. However, the aurora is a dynamic feature and long exposures will blur details. In addition, the longer exposures will reveal trailing of the star images as the Earth rotates. At f/2.8 you can try exposures as short as 5 seconds to "freeze" a great display. As always with nature photography, taking a lot of photos with a range of camera settings is essential.

Composition

One problem with displays at middle latitudes is that even a great display might only extend up to about 45-60 degrees above the horizon. A more normal display might only go up to 15-30 degrees. For this reason, you usually do not want anything in the way. However, if practical, one can shoot a great display over the light of a city. If there is a Moon in the sky you might be able to catch a light-colored landscape along with the aurora. In particular, a snow-covered field makes a good foreground and gives that "arctic" feel to the scene. If you have a lake nearby, try to catch the aurora along with it's reflection. Don't forget that a vertical composition will sometimes work better than a horizontal composition.

Processing

If your favorite film processor is not familiar with astrophotography, they may improperly print your photos. Options include finding a magazine or book with aurora photos and loan it to the processor, shooting a "normal" scene at the beginning of the roll and tell them to use those color settings for the aurora photos, or shooting a "grey card" illuminated by direct sunlight at the beginning of the roll for proper color balance. This is a situation where patience can pay off; find a film processor that will work with you and eventually they will get used to your "weird" photos and consistantly do a good job. Of course, you may be lucky and another astrophotographer will have the technicians properly "trained", saving you the work!

Note that I've implicitly assumed that you will be taking your film to a photo shop and not a department store, supermarket, etc. A local shop will probably be more expensive but also will probably be worth it in the long run. You could also have the film inexpensively developed, and if the prints don't come out well, you can take the negatives to a good photo shop and have them make good prints out of the best negatives. Remember, it's the print-making part of the equation that is tough, the developing of the negatives is the same no matter what you have taken pictures of.


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