exposure problems with highlights

I know this forum is about equipment more than technique, but here goes:

I was taking pics at a fashion show indoors, it was dark but spot lights occasionally hightlighted the runway. I left the 10D in P mode and let my 420EX flash determine the amount of light and ISO 400. It set exposure at 1/60 and f4.0. Most of the pics came out exposing the foreground fine but the parts of the face was washed out due to the spot lights shining on the face. I made sure the active (AF) focus point was on the face, but the face was overexposed. It did not appear that my flash was a factor in the problem. it was the spot light hitting the model's face.

Should I go manual settings. What lighting or expose techniques should I have used? is there some resource for teaching lighting techniques?

What i always do is review the image with historgram. It shows you if there are highlights that are 'blown out'. If it does, i change the exposure compensation (the big dial on the back) with 1/2 stops till the highlights are gone.

My tip: learn to use the histogram.

Rob

The answer to your question depends on a number of different factors: 1. Were you shooting with the flash on or off camera on a bracket? 2. Was the main source of light for the face the flash or the spotlights with the flash as fill? 3. Was the flash pointing directly at the models or bounced?
Shooting in any situation with a wide variance in light levels is difficult, such as the one you describe with spots. Flash makes it even more difficult. If the spots are bright enough to light the subject and you are trying to reduce shadows you might dial in anywhere from -0.7 to -2 flash compensation. Galen Rowell's magic number is -1.7 for flash fill. Pick a number to dial in and bracket your exposures. You can do this in P, A, T , and M modes. You could also set the camera on manual and set the exposure based on a hand held spot meter reading off the model's face. Or if you are able, take an incident reading from the model's position under the lights. If the flash is the main source of light for your subject then aperture and shutter speed will mostly control background exposure. Try different levels of flash exposure compensation till you get a decent histogram or LCD image. I find a decent LCD image is usually good enough to be worked on in Photoshop Elements 2.0.
If your flash is mounted on the camera you might try using a "Canon Off Camera Shoe Cord 2", and putting your flash on a bracket higher and to the side of the camera or holding it off to the side with your hand. This will reduce the harsh lighting. Also bouncing the flash or using a diffuser could help.
I suggest, "Mastering Flash Photography" by Susan McCartney.
I hope you found that useful.