Sorry, I don't have the 5D Mk IV but I expect the 5D Mk III should be similar. Not all AF confirmation chips are created equal. There are 1st gen, 2nd gen, 3rd Gen, and 4th Gen. I think only the 4th generation "EMF" versions work with some of the latest cameras from Canon. My SL1 seems to be an exception as it does work with early generation Non-EMF AF ...


If you programmed the chip to return the correct maximum aperture of f/6.3, Autofocus on an EOS 6D is disabled, and therefore also AF-Confirm does not work. The AF-Sensors on this camera need at least a maximum Aperture of f/5.6 to work. You can look at this question and it's answer for more detailed information.

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