The 5d Mark II we have used for 1 1/2 years is all of sudeen under exposing with a flash. Using it side by side with a different 5d II or a 1d Mark IV shows it under exposing over a full stop.
Shooting the other cameras in manual mode at 1250 iso 1/60 af f 5.6 +1/3 flash (ettl not average ) give a proper exposure with the other cameras this camera requires the flash to be +1 and 1600 iso to get the same exposure. I don't know how its connected but this happened after using the camera to do some video sequences that were 20 minutes at a time.
