When shooting stage performances, don't trust your meter. Stage lighting is artistic and beautiful, but it is not uniform. Spot lights on performers often leave dark backgrounds, and unless you are using spot mode, the meter readings can be inaccurate. Spot mode metering is one approach, but you can also use the LCD monitor on the back of the camera to gauge how well your exposures are doing. If they are too light or too dark, you can tweak the exposures using the exposure compensation feature built into the camera. In this way, you can end up with perfect images.