John A. Lind |
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The following is a consensus of what I found from several sources about shooting Auroras: Timing:
Auroras are often short duration. You have to be set up and ready, and wait patiently for them to occur. Sometimes they happen, sometimes they don't, sometimes they're long (hours), and sometimes they're short (a few minutes). Location:
The common thread is keeping well away from any light pollution, which means well away from a city, usually to the north. You want a clear, very dark sky with no light pollution. As to latitude where you will find them, this varies by time of year, by sunspot activity, and the lower latitude ones are often generated by solar flares. The following NOAA web page has continuously updated polar maps showing likelyhood of aurora phenomena based on the conditions required for them:
http://www.sec.noaa.gov/pmap/pmapN.html
Having watched this for a few days it looks as if they are occurring in only the most northern latitudes of Canada and Alaska right now. Equipment:
A fast (f/2 or f/2.8) wide-angle lens is the most popular. Most are using 24mm to 35mm and it can be done with a fast 50mm. Few are using telephotos. Regardless of focal length, the common thread is nothing slower than f/2.8 lens speed. A sturdy tripod and cable (or remote) release is essential for the very long exposures (see method below). Mirror lockup and manual stopdown are not that important with a wide-angle. If the weather is extremely cold your batteries can poop out on you. If the camera has an electronic shutter and this happens you're in trouble and this has happened to me! One of my two 35mm SLR bodies has a mechanical shutter for exactly this reason (the cells only power the metering). The cells will recover when warmed back to room temperature. Some cameras have an accessory that allows powering it from a battery pack you can stuff in your pocket to keep it warm and a cord that plugs into the camera. If not, then always have an extra set in your pocket. If the batteries poop on you, exchange the cells and warm the cold ones in your pocket. Film:
ISO 100 or 200 is highly recommended. Faster films can get into grain issues with enlargement, and supposedly do not have as much contrast or saturation. Reciprocity failure can be an issue with the long exposure times (see method below). The biggest problem is not adjusting for longer exposure but with color shift, which can be corrected some for prints, but could be a real problem if you're shooting transparecy for projection. Check the film data sheet to see what happens in reciprocity failure. Also, look for any remarks about cold weather performance of the film. Kodak, Fuji and Agfa all provide their data sheets electronically on their web sites. Method:
Recommended f-stop is shooting at f/2 if possible and no slower than f/2.8. Shutter speed is highly variable depending on intensity of the aurora, but usually falls between 15 and 30 seconds. Bracketing several shots at several exposure times between 10 and 40 seconds is highly recommended. If the weather is extremely cold, wrap the camera up in a plastic bag before taking it back indoors or inside a warm vehicle. This will keep moisture from condensing on the camera and lens. Let it warm back up to room temperature before removing it from the plastic wrapping. Lastly, a safety tip. Cameras, lenses and metal tripods used in cold weather will suck the heat out of your hands very quickly. If the weather is cold, have a very good set of gloves or mittens, remove them only when absolutely necessary, put them right back on again afterward, and don't have them off for very long. You don't want frostbitten fingers, the first sign of which is numbness, usually in the finger tips. If your fingers go numb, it will take some time to warm them up again! Hope you find a good Aurora Borealis! -- John
September 29, 2000
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