#1. "RE: D5000 and SB-900 - can it be done wirelessly or not?" In response to In response to 0 Sun 07-Feb-10 05:44 PM by greenwing
You'll need to set the SB-900 into SU-4 mode, and you may need or want to have the camera's flash in manual. Manual flash is probably best, as the SB-900 will be adding a lot of light that the camera wasn't expecting when it calculated the exposure. I don't know off-hand whether the SU-4 mode of the SB-900 ignores pre-flashes.
You might be better with an SB-600 or an additional SB-900 (or an SB-800 if you can find one) than an SU-800.