>Hey guys! SO I just picked up a D5100 and want to purchase 3 >speed-lights. trying to figure out the most affordable way to >do this. I was thinking a SB700 as my master and two SB600's >for off camera? Does that sound right or what other options >should I consider? > >Thanks!
Be careful with the term 'CLS', because it does not mean wireless. 'Wireless' is a subset of CLS called Advanced Wireless Lighting or AWL. Some CLS flashes cannot be used wirelessly. The SB-400 is an example of a CLS flash that cannot be used wirelessly. It can only be used in the hot shoe, and it has no Commander function. Another is the CLS flash inside your D5100. It is CLS but has no Commander function.
Some CLS flashes have Commanders that can control Remote CLS flashes and some do not.
If you want to take full advantage of the CLS wireless system, you will need a CLS Commander in the hot shoe and three external CLS Remotes.
The SB700 can be used as a Commander, but it will only control two CLS Groups wirelessly. This means that you can't have a Main flash, a Fill flash, but no hair light. Of course, if you are experienced, you can use a reflector for the Fill light and use the 2nd group as a hair light, but that is hard to do.
Therefore, I recommend one of the flashes that has a Commander that can control three groups: Main, Fill, and Hair lights. These are the SB-800, SB-900, or SB-910. These flashes all have a 3-Group Commander plus a flash that can be used for additional Fill.
Or, you can use an SU-800, a 3-Group Commander without a flash. The problem with this unit is that its head doesn't tilt or rotate, meaning it sends out its command signals in only one direction, and sometimes it won't fire Remotes that are set too far back beside it. It works fine as long as there is sufficient reflection off the walls and ceiling in your studio, but it doesn't work well outdoors at all. With the other Commander flashes, you can attach a diffuser and point the head straight up and they will fire CLS Remotes in all directions.
The SB-600 is an excellent CLS flash that will work as an CLS Remote, but it does not have a Commander.
The SB-800 and SB-600 are both out of production, but can be purchased used for reasonable prices from online auction sites, and sometimes right here on Nikonians.