Speedlites

[digital]

FEC at - 2 will cause issues. Remember that the flash overrides in camera meui controls. If you set the FEC using the flash itself you cannot make changes using camera menus. The flash has to be at 0.           

[SternSteve121]

I too have had the same problem with the 580Ex, except mine was more like 1.5 to 2 stops under. I have been doing quite a bit of research on this, and it appears to be an inherent problem with it. Also alot of expermintation, and have found the only I can do is set the FEC +1 3/4 to 2 stops.

[RobertTheFat]

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@SternSteve121 wrote:

I too have had the same problem with the 580Ex, except mine was more like 1.5 to 2 stops under. I have been doing quite a bit of research on this, and it appears to be an inherent problem with it. Also alot of expermintation, and have found the only I can do is set the FEC +1 3/4 to 2 stops.

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The ETTL protocol is highly averse to blown highlights and therefore effectively treats all flash as fill flash. This can make it difficult to get anything but the highlights properly exposed, especially outdoors at night. Indoors, using bounce flash helps a lot, as does exposing for the background. But if all else fails, you may have to use the flash in manual mode.

The good side of it is that when fill flash is appropriate, ETTL works very well. And you don't get blown highlights!