I had planned the trip to coincide with new moon, so that we would have pitch dark nights with lots of stars. By the end of the tour we had managed to try it at three different locations. And even if you don't like star trails (you know who your are, it's still a lot of fun to try - being out there in the darkness, fiddling around with your buttons and settings, and not to forget the excitement a few hours later, or sometimes even the next morning: did it all work? Or: ehm, where was it that I put my camera last night? :-)
When we returned the next morning, everything worked out, and we spent our time in the bus to stack the whole lot in PS to see the results. If you're interested, please have a look on my blog to see the images from the rest of our group.
For this shot of a dead camelthorn tree I made a 58 second exposure for the master image, during which I painted the tree and the foreground with a small torch and a warm-up gel. There was still some afterglow on the dunes in the background. During the night the camera took little over 80 shots, each four minutes long.
I would have liked the center of the star trails to be more to the left, but to get this view of the tree, with all the branches perfectly separated, this was the only position that worked - and believe me, I tried. :-)
As I was shooting with a D3X, I converted the star shots to jpeg after raw conversion before stacking them in PS, to keep the file size manageable.