5DII speedlight underexposure

It shouldnt matter the ISO as ETTL should adjust for that up to the point where the speedlight is unable to output enough or too much flash power. Id imagine that it is related to the metering. Did you try switching the average and evaluative settings on the flashhead?

Here is a new one for everyone. At F1.4 and ISO 400, this target should be blown out to smithereens. Im at +2 stops of FEC and still no go. It about a full stop under still. Im bouncing off the cieling about 5 feet behind me. Well withing the power capability of the flash. Just for giggles, I tried it again at full flash power (manual) and it was about 3 full and a half over exposed.

Anyone have any suggestions?

EDIT: Tried this again with the flash set to the opposite flash metering mode. I cant remember which I switched it to but now it works great with the target. I guess the evaluative vs average is more important than I thought.

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