I think that it is almost impossible to take a decent photo of an Aurora. These things can fill the sky with pulsating colours from the entire rainbow. They are magical and captivating, and only come out at the most inconvenient times - when it's dark, which is to say cold, and usually at four o'clock in the morning or some similarly inconvenient moment. Here are my efforts at capturing this majestic natural phenomenon. In the first three you can see the ACB at the bottom of the frame, the fourth, my favourite, is from my first field trip in April 1994.
This was taken with the camera sitting on a sledge. I tried many different exposures from 10 seconds to several minutes. I can't remember how long this one was, but there were many black frames before this one appeared.