Any metering issues with the 5D3?

...in following scenario (tested with 580/580II/600 on three different 5d3 bodies):

• 5d3 with flash on camera, head straight forward with diffuser or small soft box and ETTL set to evaluative - exposure requires +2 1/2 to +3 F-stops compensation at

practicaly any scene, even plain dark background. A slight tilt of the flash head up or removal of the diffuser/soft box or switching flash ETTL metering average and problem is gone.

My friends and I have tested it with 24-70 f2.8, 100L macro and 70-200 L II (all at f2.8). Don't see as much underexposure at wider focal lengths (like with 16-35 L II).

Could you please test this on your model? If this is common and bugging some more people perhaps we could ask Canon some questions?

Thanks.

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Olgierd

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