I need to purchase a speedlight for my d40. I want it to experiment with creative lighting techniques, and I plan on using it off camera quite a lot. I was looking at the SB-600 but then I heard that the D40 doesn't have a commander mode to operate it wireless. What do I need to purchase to make this work for my camera? Whatever it is, would it be cheaper/worthwhile to just sell my D40 and then spend a little extra to buy a more advanced body? What other options are there? Also out of curiosity, how do you mount a speedlight to a tripod? They aren't threaded as far as I am aware.