7D over exposing with external flash

[Lensjockey]

I have a 7D MK II that I am using with Elinchrom BRX 500 kit. When I use the wireless TX or the cable direct to the flash all the shots are totally blown out by several stops. If I use the Canon 580EXII on the camera to trigger the strobes everthing looks great. I have used new cables, new Elinchrom wireless and the old ones. The only other way to get the shots right is all manual settings. I am using the Custom Settings. 

[Waddizzle]

Manual mode and a compatible light meter seem to be the proper way to go with what you described.  If this is the correct model, then it does not have TTL compatibility, just manual control. This is a clip from B&H.

[MikeSowsun]

Your f/2.8 and ISO 640 settings are all wrong for a powerful strobe like the Elinchrom BRX 500.

f/2.8 and ISO 640 is more of an "available light" exposure.

When using your 580EX II to trigger the optical slave on the Elinchrom BRX 500, I suspect you are using ETTL mode which fires a preflash and does not properly sync with the Elinchrom BRX 500. With the "everything looks great" exposures, you are probably just seeing residual light from the main flash which has occurred too early. 

A wireless TX or the cable direct to the Elinchrom BRX 500 provides proper sync and you see the full effect of the flash. To get the correct exposure, just turn down the power, stop down the aperture, or lower the ISO.  Start with f/5.6 and ISO 100 and adjust the power for the shooting distance. 

You can use the 580EX II to properly sync with your Elinchrom BRX 500, but you must use manual mode on the 580EX II so that there is no ETTL preflash.

[Lensjockey]

Thanks for the info, I will give it a try

[Lensjockey]

Thank you for the reply, any idea if updating the Elinchrom firmware thats due out this year will help? or the lack of TLL is hardware?

[ebiggs1]

"...all the shots are totally blown out by several stops."

It is just simple exposure adjustment.  Go back to your basic photography training.

[Lensjockey]

In manual it all works fine, however this problem was not happening before, especially when the camera and lights were wired together. Even adjusting the flash compensatory doesn't make a difference since I upgraded the firmware...that was my first mistake. Thanks for your help, I appreciate you taking the time to read and answer my post.

[MikeSowsun]

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@Lensjockey wrote:
In manual it all works fine, however this problem was not happening before, especially when the camera and lights were wired together. Even adjusting the flash compensatory doesn't make a difference since I upgraded the firmware...that was my first mistake. Thanks for your help, I appreciate you taking the time to read and answer my post.

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Upgrading firmware has nothing to do with it. 

The Elinchrom BRX 500 is a MANUAL strobe. If you somehow managed to get acceptable results using ETTL or some Auto mode, it was just blind luck. 

[Waddizzle]

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@Lensjockey wrote:
In manual it all works fine, however this problem was not happening before, especially when the camera and lights were wired together. Even adjusting the flash compensatory doesn't make a difference since I upgraded the firmware...that was my first mistake. Thanks for your help, I appreciate you taking the time to read and answer my post.

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Manual is your only choice with your current setup.  Your gear lacks the parts and smarts to do eTTL flash control with a Canon body.  But, there are other options available that allow you to vary the output power.