I really don't have any clue of why this is happening, but this happens to both me and my husband when we shoot and we aren't sure why, so here's the deal...

We are both shooting with 5d's and 580 ex flashes and Quantum turbo 2x2's. Regardless of what lenses we use, we seem to be able to get one (or several) properly exposed images and then we will get one (or several) severely underexposed images. There is no rhyme or reason, nor is there any consistency to it. Nothing will have changed between the shots for there to be a difference in exposure. I am always shooting in manual when it happens and my husband has played around with different modes and had it happen in manual, aperture priority and program.

We always have fresh batteries in our flashes and the quantums are fully charged - so we can't figure out why this is happening or how to fix it.

Any input would be greatly appreciated! Thanks!

Stacey

Probably the ETTL of the flash finding a different metered point and altering it's flash output significantly. Unless you're shooting on a tripod and there is no chance of things having moved, that is.

The Canon ETTL has its moments, that's for sure

Your probably right. We often shoot off camera (hand held light) and have the same issue. I found that most often when this happens, were not pointed directly at the subject.
This should not happen at all if the flash is set to manual mode.

One way of getting more reliable ETTL and exposure from your flash is to FEL (flash Exposure Lock) as you shoot. Generally, you can center your shot for what you'd like your flash/camera to meter off of. Hit the * button which will fire a pre-flash and lock your exposure for the next shot or two, if you're quick on the trigger. After you've FELed, then you can focus/recompose to what you're desired composition is, aim your flash head more to your subject, and fire away.

Give that a whirl next time out and see if it helps.

C.

Are these underexposed shots taken quickly after the others? The turbo batteries don't recycle as fast as you may think so if you are trying to take shots right after each other that may be the issue. If you're using your flash in manual mode, then power it down a little so it will recycle faster.

Hi all,

my wife started this thread, so I am part of the subject under discussion. :-)

We did a wedding on Saturday, and I positioned myself off to the side for the garter toss. A series of shots were taken in a single burst as the toss took place, and although there were usable shots, most of them were underexposed. Maybe the flash could not recycle fast enough? Batteries not full strength?

But wait, even the first shot was underexposed, and there is another baffling thing. From the same position, with the same equipment, and batteries (flash & Quantum) that must now be more depleted, if even slightly, a burst of images of the bouquet toss were taken. ALL images correctly exposed!

I just don't get it!

Hugh