I just put a small album together of my favourite aurora photos from my recent trip to Yellowknife... here is the link:
http://www.huyerperspectives.com/Nat...8401080_4CKTqj

This kind of photography is quite challenging, but when it works out the results can be very rewarding. I rented two wide-angle lenses: The 14 mm f/2.8 L II, and the 24 mm f/1.4 L II. The 24 mm was the best performer, as the f/1.4 aperture really made a huge difference. I could use reasonably short shutter speeds (2-8 seconds), which helped reduce the blur from the fast-moving aurora. With longer shutter speeds, all you get is a big green fuzzball. It is quite important to pre-focus manually with live view, to get the stars as sharp as possible. Simply turning the focus to infinity doesn't work, as Canon intentionally allows you to overshoot infinity (maybe their motto is To Infinity and Beyond?). I had the camera on ISO 800 or 1600, and watched the histogram closely to make sure I didn't blow out the exposures. The aurora can brighten quite suddenly, and you can find yourself with a lot of blown out pictures if you don't adjust things on the fly. If you bring a cable release, you can set the camera to continuous shooting mode and just lock down the shutter button. Then you'll get a series of shots that you can make into a time-lapse movie (however you are stuck at one exposure level).

One of the most difficult things was dealing with the cold. I thought I already had good experience with cold weather photography, but this trip really tested me. Thank goodness for those chemical heat packs.... I stuffed them by the dozen into my gloves, overmitts, and boots. I'm tempted to go back there in the fall... the weather will be more tolerable and I can also try to get reflection shots of the aurora over a lake. But winter is a lot of fun because there is more to do in the daytime, like ice fishing and dogsledding.

The camera survived the cold quite well. I brought two batteries and kept one warm in an inside pocket so I could swap them back and forth when they died (which was about every hour). I also put the camera in a big zip-lock bag before bringing it back indoors, so it wouldn't turn into an ice block. The top LCD display stopped working in the cold, but the main screen still worked fine so I could read the exposure settings on it.

I really think this is a trip that everyone should do. Getting there can be a bit pricey, for sure, depending on where you're coming from. But that doesn't seem to deter the Japanese, who are especially enthralled with the aurora and go to Yellowknife by the plane load just to see them. I'd recommend flying with WestJet rather than Air Canada, since the WestJet planes to Yellowknife have much more overhead storage space for your camera gear. Yellowknife is probably the best place in North America to see the lights, due to the location of the aurora oval and the dry climate with plenty of clear nights. The hotels are very good and once you're there the prices are pretty reasonable.

That's all the technical tips I can think of right now... let me know if you have any questions and in the meantime, please enjoy the photos!