I am trying to assemble a lighting kit and I wanted to know if there is a spec that I can compare hot shoe flash power vs typical studio strobe? For example, I see that the Alien bee B1600 can deliver 640 true wattseconds + 1600 effective wattseconds, but I do not see similar stats on the Nikon Sb-900. Basically, I want to be able to compare how much more power the studio strobe has over hot shoe flashes. Hope this makes sense... Thanks in advance.