If you need to get rid of light halos, use a combination of bezier masking and the levels filter. You may or may not need to click the little triangle on the bottom left corner of the eventFX window (pre/post toggle).
Thanks! I don't have a problem with halos, it's more some scenes where the person on stage has too much light on their face. I've printed off the tutorial - I'll read through it tonight.
Ack, I thought that you were talking about another situation (where the lights are shining into the lens and raising blacks in the whole image).
In any case, the tutorial does mention how you can rescue some highlight detail. But if that doesn't work then the highlight detail is kind of clipped to begin with.