Not so much the composition, more technical aspect. I have a Canon 30D with 550Ex speedlite, probably be using the 50mm most of the time as I am shooting for a friend (there will be a pro there for the group shots), I am only there for the wedding/candids.
The question is, using the flash, I have a diffuser, now what settings should I use ? Lets assume it's indoors with light bulbs.
Do I?
1) Av mode with flash sync at 1/250 ? Is that with 550ex pointing at the subject with diffuser?
2) P with the same flash set up?
3) P, bounce everything off the ceiling
4) point the flash up with the little reflector thing sticking out 90 degrees.
Thanks. 




