Hello, I was wondering if anybody could offer some advice. I will be shooting a corporate event inside a hotel ballroom. My equipment is a Canon 40D, the lense I will be using will be the Canon EF 25-138mm, with a 580EXII. My questions are with regards to getting the best shots in this situation.
1) I beleive the best camera setting would be Manual. If this is the case how do i go about calculating the correct f stop, shutter speed, and iso? The sync speed is 250. However, I've heard that several photographers like to use shutter speeds of 60 or 30 (does this matter?) What are the best f stops? How do i get the correct shutter speed for the chosen f stop? I heard that iso of 100 or 400 are best. What is the best iso? By the way, how good are the pre-programmed settings on the 40D, would the pre-programmed Portrait setting be best for this setting?
2) What is the best angle to position the flash head for shooting people? For shooting a wide angle overview of the ballroom? What is the best setting for the flash?
3) I have a plastic cap diffuser, should I use this on my Speedlight? If I do, should I angle the head differently than it would be if I didn't use the diffuser cap?
4) I also have a homemade foam reflecor diffuser. Will this provide better shots than the plastic cap diffuser? If I use the foam reflector, at what angle should I point the flash head? The foam diffuser also allows for the top part to be bend forward (in order to provide a hood or umbrella type shape) or it can be positioned so that is stays upright, allowing more reflection towards the ceiling? Which position would be best?
5) One final question. Will the end result of the pictures differ if I were to use the flash with the foam reflector or the flash with the plastic diffuser and the foam reflector? Which combination would provide the best lighting for the pictures.
Sorry for all the questions. If anybody can help me out with any of these I would strongly appreciate it. Thanks for your time.

