I'm shooting a band on Saturday and would like to check with some of the people on here about camera settings. I already know aperture controls flash exposure and shutter controls ambient, but here's what I'm thinking... I want to take a photo where the band is perfectly exposed, but the background be a little bit darker maybe 1/3 - 2/3 stops under-exposed to help them pop a little. Since I'm shooting a group, I know I'm going to have to shoot at an aperture of f/5.6 - f/8 or something like that to get a good depth of field. The problem I'm running into is that I'm using a speedlight which just doesn't have as much power to pull off a good exposure at f/8 or so. My question is, does raising the aperture draw in more light to help me pull this off? I think it does, but I just wanted to make sure. On a side note, do I need a model release for this? Where could I find one for shooting multiple people? Thanks in advance.