My reply from the post on the lens forum....
Howdy from Juneau, Alaska! Boy, 4 days in Lapland would be very, very cool!
I"ve been taking many aurora shots this fall/winter. Here are some of the things I've learned:
1) try and use a reasonable ISO - going above 400 really effects your results. I try and stay ay 200.
2) try and keep your exposure time to a minimum. This is a balancing act between aperture (see below) and setting the ISO. I've found that with my 10D going to over a minute exposure time effects image quality.
3) I try and use an aperture that is stoppoed down at least 1 or 2 stops from completely open so that any foreground objects stand a chance of being somewaht sharp.
4) Go wide! I use both a 15 fish and 17-35 (always at 17).
5) A tripod is a must
6) so is a cable release.
7) if you have a timer with your cable release the previous poster's idea of setting it to automatically take a series of shots at intervals is a great one.
8) don't forget to look around - while you're entranced by lights in front of you, there may be bettr lights in back of you!
9) in terms of composition, it's nice to have foregound objects to set the stage
10) don't trust your LCD preview screen to show you whether you've gotten a decent exposure - always, always check your histogram and make sure everything's not completely bunched at the left side.
11) take the photos in RAW format so you can play with white balance, etc.
12) buy and use Neat Image to get rid of noise
13) be careful of light pollution. lights shining around you will negatively effect your images (potentially leading to washed out photos and playing hell with the white balance).
14) dress very, very warm.
15) take a headlamp or flashlight/torch so you can see what your doing
16) frequently check your lens for frost build-up - try to keep the lens cover on to aviod frost when not shooting (lens shades work well too).
17) don't forget that batteries die quickly in the cold.
18) Use more than one camera if possible so you get more shots!
19) Have fun!
Here are a few sample images and a URL to some of my images:
http://www.pbase.com/akclimber/northern_lights
