1Ds MkIII star trails

Beautiful, I really love it so I am going to try to do something similar.
What were the parameters you used? ISO? and exposure mainly.

Also which lens did you use? I could use the 17-40, the 50mm, the 100mm or the 70-200 zoom.
Which one wold you recommend? My camera is the 1 Ds Mark II.
Oh and you did quite a nice job pointing at the North star...
Thanks,
Simon