flash is a bit like salt, a little can go along way and it's easy to add too much. flash has a relatively short duration and can be very difficult to judge without experience or chimping. have you considered a rechargeable spotlight? they can be diffused easily and the effect is easy to see. they can bounced off white ripstop or punched through for more contrast. many even have 1/4-20 or 3/8 threads for stand mounting and they run the gamut from lightweight to pretty powerful, inexpensive to hundreds of dollars.