Trouble with changing FEC on the 580 EX II from a 70D

[Janeames]

I believe that my 70D should change exposure compensation on my 580 exII on my camera using ETTL mode.  Although my camera does fire the flash it does not change the exposure compensation on my flash from my camera.  I KNOW THAT THIS IS LINE OF SIGHT (IR) .  I have the internal camera flash up.  I use the built in flash menu and set appropriate external flash symbol on camera.  On the flash I have  ETTL settings,  Chanel 1 slave A settings.  The flash symbol on the flash is highlighted.  

Note: I do not have an external flash sign on the LCD on the camera,  there is a FEC symbol on the back of the camera, but this only changes the FEC on the built in flash.

CAN ANYONE HELP ME I HAVE TO SHOOT A WEDDING THIS SATURDAY!!!!!!!!!!!!

[Crista]

Hi Janeames!

Thanks for posting in the Canon Forum! The Forum is not intended for immediate help, but a place to allow for the Community to give you assistance and feedback. If this is an urgent support need, please CLICK HERE to reach our friendly Technical Support Team.

Thanks!

[RobertTheFat]

You're talking "Wireless Flash", right? The 580EX II manual does not mention using the camera's internal flash as the master, so I doubt that you can do it.

That said, note also the caution on page 14 that "If flash exposure compensation has been set with both the Speedlite and camera, the Speedlite' flash exposure compensation amount will override the camera's." That's not in relation to wireless flash; but just in case, make sure that the speedlite has no FEC set.

Please tell us you're not a professional wedding photographer.

[MikeSowsun]

Yes, the 70D's built-in flash can act as Master. You should be able to control both the built-in flash and external Slave Flash FEC using the flash menu in the camera. 

I suspect you are not understanding the system well enough.  To help eliminate any problems, make sure the flash and camera FEC are both at "0" FEC before you start using the wireless system. then do all the adjustments only through the wireless flash menu.