flash is powered by quantum battery do switch flashes before flash gets overheated same thing occurs with just batteries however exposure inconsistent usually under exposed but can be over exp am allowing time for recycling have sent flash to canon same poroblem exists are there any flashes compatible with the 5d that will give good consistent results know anything about the quantum T5d-r desperate for help i shoot events so need to shoot fairly quickly thanks
mary

flash is powered by quantum battery do switch flashes before flash gets overheated same thing occurs with just batteries however exposure inconsistent usually under exposed but can be over exp am allowing time for recycling have sent flash to canon same poroblem exists are there any flashes compatible with the 5d that will give good consistent results know anything about the quantum T5d-r desperate for help i shoot events so need to shoot fairly quickly thanks
mary
Post examples, good and bad with EXIF info so people can see whats going on, it helps to make a better judgement as to whats going on.
That said, if your shooting sequences, the 580EX does fine for me when used in fill flash mode and flash is set manually to whatever works flash amount wise. Using full power will cause inconsistant flash output as it can't recycle as fast as the camera can fire off frames.

JS

That was a pain to read...
It may be the quantum. Did you try AAs? I am sure Canon sent it back,because they tried with those and found nothing wrong.

I use the 5D with 430EX and have no problems - I always use AA Alkaline Duracell and it works fine but will not keep up with the 5D shooting rate if the batteries are low on power.

I normally don't shoot flat out for long normally bursts of 3-6 shots.

Camera set in manual flash in auto mode.

Roger