I'm new to using an umbrella, or I will try to use and umbrella soon, and I'm interested in knowing which umbrellas are good for what.
I kind of have the general idea for all three of them, I think. The silver reflector umbrella allows more contrast, the gold reflector does the same except that it's much more warmer, and the shoot-thru is like a soft box.
But in a situation for outdoor portraits at night what would you shoot? or in the afternoon... in San Francisco.
I did check out this guy by the name of Dustin Diaz on flickr, and looking at those images he took inspired me to try it out.
Could I please get a Strobist/Umbrella use 101, please? Just the general idea of why more than one flases are used, where to put each umbrella, which one is better for which par of the day. 
is just what you're looking for.
