I've been asked to photograph an groundbreaking ceremony. It's going to be early-mid morning (10:00am). The ribbon cutting is going to be held under one of two conditions. First, the four participants will be under a pavillion (three white people and one very dark, but the most important one to get facial detail) and I will be shooting, facing the direction of where the sun is coming from, in the sun or; all of us will be outside of the pavillion and all of the subjects will be backlit by the sun. I have a Canon 20D and will be using either a 35-105mm 3.5 to 4.5 or a 28mm 4.0 lens. I'm not sure if I should leave it on automatic, as I do not own a light meter. Any suggestions would be helpful on how to get the correct exposure. I also have Photoshop to clean up if there is a solvable problem. I did a shoot like this once before, but the faces were so dark I couldn't salvage any of the pictures.