Creative Lighting System Question

Discussion in 'General Technical Discussion' started by jklofft, Oct 12, 2005.

  1. 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?
     
  2. cwilt

    cwilt

    Apr 24, 2005
    Denver, CO
    Jeff,

    I would bet money you were using matrix mode? When using matrix, CLS tries to balance flash exposure with ambient light.

    This may sound strange, but I use a gray card to set flash exposure when I don't have a meter with me. First set your camera to the exposure you want. Spot meter a gray card at the subject and use FV lock. Flash exposure will be locked until the light meter in camera goes off.

    Hope this helps.
     
  3. Yes, I am using Matrix. I'll have to try wait you suggest. Thanks.
     
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