I’ve been playing with two SB800s in wireless iTTL mode, experimenting with CLS. Last night I did the following test. First I set-up a small tabletop still life set against a neutral wall and photographed it in ambient light (i.e. without any flash). This gave me what I called the “base exposure/histogram”. Next I photographed it with two SB800s without any compensation on either of the flashes or on the D2x itself. Additionally, I was well within the range of the flashes (a few feet) and was shooting at f/2.8. I set the camera on manual exposure and chose a shutter speed that would ensure that none of the ambient light would be recorded (but less then the sync speed). I expected this dual flash exposure to be close to the base exposure, but it was not. It was significantly underexposed (about 1 to 1 1/3 stops). I thought CLS was supposed to use iTTL to calculate the correct exposure as well as balance the light between the SB800s. Why was this not the case?