Thanks for the comments.
Thanks also for the tips!
I want to experiment getting more detail from the moving rays and curtains, because on some of my photos with a longer exposure they just come out as a glowing area...
I'd love a lens like that, I'm just using the 18-200 tamron I got with my Canon 550D.
Paul, not sure if you asked? but I live in SE Tasmania, on the Tasman Peninsula, there's some great spots here to get water in the foreground of aurora shots, which gives a nice reflection.
I'm looking forward to the next Aurora now
Ben