ETTL Flash Power Question

I've found bypassing Canon's wireless system (radio triggering) results in a different output for the same manual power setting. 580EX II camera left, 430EX II camera right. Both set to 1/32 power for both images. First picture was non E-TTL radio triggered, second picture was using free agent wireless (manual power setting set on flash, not by camera menu, but still triggered by camera). Not shown, power set by the in-camera menu (triggered by 7D popup) and the results were the same as free agent wireless.

oldvultureface wrote in post #13898697
I've found bypassing Canon's wireless system (radio triggering) results in a different output for the same manual power setting. 580EX II camera left, 430EX II camera right. Both set to 1/32 power for both images. First picture was non E-TTL radio triggered, second picture was using free agent wireless (manual power setting set on flash, not by camera menu, but still triggered by camera). Not shown, power set by the in-camera menu (triggered by 7D popup) and the results were the same as free agent wireless.

I wonder if the free agent wireless is trying to compensate for the differences in power between flash models before applying the power ratio, i.e. normalize the 580 to the 430 power range, then have the 580 provide twice as much output as the 430.

oldvultureface - what shutter speed was being used?

Poe wrote in post #13900083
I wonder if the free agent wireless is trying to compensate for the differences in power between flash models before applying the power ratio, i.e. normalize the 580 to the 430 power range, then have the 580 provide twice as much output as the 430.

Both at 1/32 power, the 580 should provide almost twice as much light. But there is less difference in the two shadows using free agent than using radio triggering. I would expect to see identical exposures using the manual modes (radio versus manual wireless), but something in the E-TTL system is intervening.

CliveyBoy wrote in post #13900231
oldvultureface - what shutter speed was being used?

f/11 @ 1/250, ISO 100 for both.