I want to expand just a little on Mr Barker's point. You will most likely not get the attributes in a small 2x AA battery unit that would be as capable as a larger unit with variable fill flash abilities. If you are shooting a "7" say for portraits, in many instances you'll be farther back due to the fact that you would normally use a longer lens for better perspective. It may also be true that you'll often want to do full length or 3/4 shots of multiple people. A 2x unit can have some power, (the 20BC-6 Metz I recommended has 3x AA and has a GN of 66ft aT 100ISO, but most flashes of the smaller size will not have variable abilities except thru your attached diffusion in manual mode and your need to utilize your mental calculator. On "auto" you'll suffer the abilities of the unit as pertains to it's engineering which may or may not be to your requirements; I.E. variable fill in. You might check the SB15 Nikon. It was one I seriously considered in the past, is small, and doesn't sit high.