hi chalib,
then again, if you ask someone verbally, by chance level you will get equal amount of encouragements and discouragements. the forum won't serve as a filter for [only good comments].
btw, it would help if you can tell us how you normally shoot the events,
perhaps what settings you use, eg
iso
manual mode or semi-automatic modes like Av or Tv.
where you point your flash
what synchonisation method you used with your flash
there are many ways to skin a cat. results differ slightly also depending which method you use.
to shoot without blur, i guess i would use manual mode, shutter @ 1/60 at least, aperture at f4 at least (for group shots), f2.8 for (single persons). wide aperture allows for shallow DOF.
but you see, i use D70s. while it's a decent camera, those with mid end or high end wouldn't have as much concern for noise at high ISO.
yah, i agree with chanxj, say if you flash at iso400 and iso800, iso800 would show a brighter background. lower iso used with flash might cancel out ambient lighting, esp if it's direct flash.
so if you're flashing, esp if it's ballroom, and if ceiling is high, you need to dial up your flash to be more powerful? to create more bounced light off the ceiling.
if you have a bounce card, attach one to your flash. dun expose too much of it. so some light get reflected forward and light up your subjects.
if not, i like using lightsphere for ballrooms as it's keeps my background well lit, while using diffused light on the subjects. i find bounce card hard to control and create a lot of undesired shadows at neck, nose, eyebags etc.
to use what setting, you need to test and know your preference. do you mind noise? i quite dislike noise, so i rather flash more, use ISO low. IF possible, that is.
once you shoot more, you probably will start paying attention to the white balance and stuff. so you will probably be able to correct yourself by then.
if unsure, shoot in RAW! ha.
as you can see, i'm no pro also, but i've came by your problems also, and kept learning how to shoot better in events also. ha.
when you're better at it, try bouncing flash at different walls. that is, create directional lighting. it adds a whole different dimension to the output of your shots! gambatte!