ETTL & flash exposure compensation

Started Feb 11, 2013 | Discussions thread
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Izabelle OP New Member • Posts: 17
Re: ETTL & flash exposure compensation

Thanks everyone, still not understanding!

Philip Kendall wrote:

Izabelle wrote:

Another question is, the pre-flash is meant to determine and automatically set the output of the flash. But i don't see this happening, because like i've said i always adjust the flash output myself.

I'm not sure you're correctly understanding what FEC is: FEC means that it takes the output power for the flash that was calculated from the pre-flash and then modifies that by whatever FEC you have set. That obviously can't work at all without the pre-flash to set the default output power of the flash.

If you were setting your flash power fully manually (ie you were setting 1/32 power or whatever), then that's a completely different question and then you wouldn't see a pre-flash.

I use my camera in full manual mode. My flash settings for the 600ex are as follows: ETTL, manual zoom, and the output is 1/1.

Can someone please explain the difference in turning down the output in the M mode on the 600ex compared to turning down the output in ETTL mode?

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