When I shoot my speedlight into an umbrella, I always pop up the wide angle diffusion panel built into my flash, thinking that this will more evenly fill the umbrella. Is this needed, or am I just wasting flash power? I'm guessing most people just zoom the head out to it's widest position and leave it at that. Another thing I over-obsess about is the distance I place my umbrella from the flash head. Again, I'm trying to fill it, but not spill light past the edges. With a monolight, I can easily adjust it with the modeling light, but I just kinda guess with speedlights. Any suggestions?