UPDATE: Just answered many Q's in the comments. -DH
It's simple math. If you are shooting outside in the sun and limited to 1/250th of a second sync (or worse) you are are going to be shooting through a tiny hole as your aperture. Even if you crank your ISO down as low as it will go, you'd better like that background. Because you are going to see it in pretty sharp focus.
Or maybe not. In addition to high-speed sync, there are a few ways to bleed some aperture from your exposure settings in full sun.
Three blurry choices, inside. Read more »