hi all what aperture do you use when have your external flash on?? e.g day time and night time. i am using d80 and sb600. i find that when i use maximum aperture e.g f2.8 with my external flash.. all i get if overblown photos.. but when i changed to f8. it turns out quite nicely. i want to learn a bit more abt aperture with flash but cant seem to find much. is there a good book or some more experience photogs here can help ?? how do you know what aperture is best with flash (TTL) on>?? thanks for help in advance.