Hi AMR. I know that when shooting in those modes the flash is typically only fill flashing. So, depending on the scene and metering, that is how the camera interprets how much flash to throw. When you bounce, it is exposing as if there is no flash(at least not fill), and adjusts accordingly. That is why I mostly shoot flash in manual only, unless I do hi-speed or rear-sync. Scott Kelby explains in one of his books(?), to adjust your exposure in manual, with flash off. Get your settings, then turn the flash on, with your f-stop and shutter value the same, then compose and shoot. Seems to work in most instances. I don't have the technical know how to explain it better...I apologize. I, too, use a Sto-fen almost 100% of the time, and actually prefer using it with the flash head at a 45* angle therefore getting somewhat direct, but also bounce at the same time. Hope this sorta helps??