On a large stage that isn’t lit to one particular area you will need both cameras as close together as you you can, this is due to light spilling over the same area at different angles. One camera reads one light temperature and the other camera reads a different light temperature. Use a white card or a white piece of paper because this will give you the flattest whitest source you can get. Make sure the light is shining on the card evenly. Whatever you white to the cameras are essentially saying "What ever color there is most of on the screen that is what I am going to call white." When you white it to a cyc chances are they use the gray shadowy area inbetween your white white and everything else. Turning the stage lights on and the house lights off is good, but make sure that you have only the stage lights that have no gels on them. This includes cookies if they are used. You don’t want any shadows or colors hitting your white card. Finally, a little tip that I use is in the broadcast industry they use a spectrometer to measure the colors the camera sees. White is usually set at 90%. The GL2s have an option to adjust your zebra stripe. I changed mine so that I start seeing zebras at 90% so that when I white my camera I iris the camera to the point where I just start seeing zebras. That way I know that the camera will be using as much of the CCDs as it possibly can, Not only that but then you know that both cameras are receiving the same amount of light iris wise.
