5DIII + 580EX II = Under exposed

Started Jun 18, 2012 | Discussions thread
Olgierd Regular Member • Posts: 397
Re: 5DIII + 580EX II = Under exposed

Loggedonnow wrote:

This weekend was the first time I tried the 580ex II on the 5DIII. If I was smart, I should have tried it when I got the camera just so I was sure it was working properly. But, I am not smart.

On the 7D, I had no problems so I assumed it would be the same on the new camera. Not so.

Eventually, I figured out that the flash needs to be set with FEC +1 2/3 or else the images are very underexposed.

The flash was set to ETTL and the camera with the 24-105 in manual mode, 125 6.3. There were no mirrors or reflective surfaces to throw it off. Nothing unusual, subjects 10ft away or so.

I have even read through the flash manual (first time for everthing) just to see if there is something I am missing here. I can't really believe the 580EX II doesn't play well with the camera.

Not sure if it will help here, but check if FEC compensation is set on the camera. There is one catch to it. Lets say you have dialed -1 FEC on the camera (e.g. last time you shot with it and didn't set it back to zero) and set +1 FEC on the flash. Take picture - it will have +1 FEC since flash overrides camera FEC setting. Now, dial FEC on flash back to 0 and take another picture. It will not come with 0 FEC, but -1 FEC since it's still dialed on the camera.

In short, whenever FEC on flash is 0 and something else dialed on the camera, then photo will be taken with whatever FEC is set on the camera.

Second thing I've noticed on my 5D3 is when shooting with difuser or small soft box and when flash head is set directly forward. No matter what scene I shoot it is always heavily underexposed. This applies to not only 580EX2 but also new 600EX-RT. I've found remedy to it by switching FLASH metering mode from Evaluative to Average E-TTL.

Hope it helps.

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Good or bad I'm guy with a big lens.

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Canon EOS 5D Mark III Canon EOS M Canon EOS 7D Mark II Canon EF 16-35mm F2.8L II USM Canon EF 24-70mm f/2.8L USM +10 more
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