580EXII User Help

[J-Chan]

You'll need to understand that the flash emits a finite amount of power, and thus a finite range as defined by the inverse square law.. beyond which, even if the flash is maxed out its power, the light would simply not enough for it to register as a proper exposure..

plus, if you are shooting above sync speed in high-speed sync territory, you'll yet again lose more light inorder for the flash to fill the frame properly..

 

[conkeychua]

First question: which mode? The metering works differently, depending on the shooting mode you are in. Easy to check: take a slightly dim room, take out your cam, use Auto or P mode (flip up flash in P) and half-press the button. Note down the values. Switch to Av , dial to the same aperture value as seen in Auto or P and half-press - you will see an obvious difference. The reason is that Auto/P has a different target when metering, compared to Av mode (and also M).
If your subject is still underexposed try a) increasing ISO (not possible in Auto) or b) using FEC to get better illumination.
More about EOS and flash: http://photonotes.org/articles/eos-flash/

I Mainly use M mode. Probably is because of my ISO cause i put it on ISO100. Will try the different setting.
Thanks alot