Before I got married, I asked my in-laws about the photographer and they assured me that they had it covered. A friend of theirs was a great photographer, and she was going to shoot our wedding. Long story short, the "photographer" had a point-and-shoot, used on-camera flash, and couldn't compose at all. The pictures of my wedding make me weep inside.
Last year, a friend of mine was getting married on a shoe string budget. I had only an XTi and the 50/1.8 and no experience as a wedding photographer. But I knew that if I did not volunteer to photograph the wedding, they may end up with something truly horrible.
I bought a 430EX, practiced with it for a month, and shot the wedding. Ideal? No. Better than my own wedding? Much.
So rather than add to all the advice about cameras and lenses, I would like to encourage you and thank you for volunteering to shoot the wedding.
Be sure to practice a lot. Go to the church and figure out the light. Take a friend to model and figure out what settings you need for natural light and using bounce flash. Add lenses and lighting equipment based on what you need.
Good luck!
XTi, 50/1.8, 430EX, & Love
