Paul - Thank you for your reply. That was my initial plan, but the SB-600 does not do SU-4 othewise I would be all over that. Am I better to save for a 900 and use that?
Jampat - I photographing 1 person inside. These are very low power yes and the recycle time does bother me. I have heard good things about the Alien Bees and I think they are close to my price range. What is your opinion on them? Am I better to buy another SB-900 instead of B-800 or B-1600?
Thanks for the help!
For 1 person inside, don't use a 1600, it will be way to powerful. A 400 will be more than enough (an 800 will probably work and give you some room to expand in the future). If I remember correctly the guide number of the 1600 is something like 4 times that of a 580EXII, but a direct comparison is flawed as the 1600 does a giant area at that number while the 580 does a small patch. I think in terms of total light output, a 1600 would be ~8 580's at full power (my memory could be flawed here). If you are only buying 1 for now, in most situations, I believe an 800 is the most flexible.
I haven't used Nikon flashes, so I can't comment on specifics, but I use speedlights and strobes quite differently. Speedlights are fast and easy to setup, but slow to recycle (unless there are battery packs on all of them which is expensive and slower to setup). The strobes are slow to setup, but fast to recycle. For static poses of 1 person, speedlights will work. For fast moving action or large areas of light needed, I use strobes. ie. For weddings, I use strobes for group shots and dancing shots and speedlights for individual shots (normally, sometimes I set up strobes to do proper portraits if time and space allows as the shorter recycle times and lack of batteries makes life easier).
Don't some of the Nikon flashes have optical triggers built in? How about using the 600 on an off-camera cord (or sync cord) providing fill and using the 900's on optical trigger mode? Or buy peanuts and optical trigger everything. I have sometimes used the pop-up flash on very low power to trigger the optical slaves without affecting the picture (much, sometimes adds another catchlight, it depends on the shot). This gets you the shot with minimal equipment investment.
For studio shooting, I recommend either strobes or cheap manual flashes. Automatic flashes are expensive and I never use them on auto in controlled shoots. You already have two nice flashes for on camera use, the manual ones are worth a look.
My next light purchase will likely be a Q-flash (or something similar) to allow me to be much more portable than the AB+Vagabond, but still have more light than normal speedlights. They can be pricey, but are a good balance of light and portability.
As for a review of AB's, they just work. everytime we pull them out they work reliably and we have never had a problem. My only criticism is that the sync cord is hot (it has AC power present, I haven't metered it, but it feels like 120V if you touch the plug while pulling it out). It is a pain in the ass having to run extension cords to every light, but that isn't a fault of AB. At full power, recycle time is 2s on the 1600, 0.5 seconds on the 400. Basically I can shoot as fast as I want and rarely get ahead of the lights. Typically, in studio we trigger one light using a wireless trigger and let the rest slave, for weddings, I use wireless triggers on everything. If you want something to drool over, check out the CyberCommander, wireless remote power control and scene memory. I don't have one yet, but it is definitely under consideration (Pocketwizard also just came out with something similar, it's not as sexy and has fewer features, but it does remote power control).
