Use camera's flash exposure compensation instead of external strobe to save battery?

[DazedAndConfuzed]

Lwang - I checked this on my camera as I am interested in saving camera battery but mine does not work like this. If I adjust my internal flash output then the TTL to the external flashes is likewise reduced giving an underexposed image. I spoke to a mate of mine who uses Nikon and he has reduced flash output settings that puts out the TTL codes for a normal exposure. My Olympus does not put out TTL on reduced manual output which means the SnS110a and the Inon Z240 need to be set manually, not a great problem but I am having a little love affair with my Z240/110a and TTL. Still regardless of the battery drain it still lasts above 300 exposures which gets me through a day even if it didn't, changing batteries between dives is not the end of the world.

I know it is not possible with my YS-01 since it only has exposure decrease in TTL, but if any strobe had exposure increase in TTL, then your 'reduced flash output setting' on your camera could be offset by 'increased flash output setting' on the external strobe.