What is unfortunately concealed in all test reports, the YN-568EXii for Canon has the error that occurs very strong underexposure by bounce shooting directly on the camera along with E-TTL2 measurement (2-3 EV is in Blogs the speech, in my tests, the images were almost black, as also helps post-exposure of RAW photos no longer), in some cameras (eg. EOS 5D Mark 2) can be the problem by switching to center-weighted metering fix, with other models ( the newer models EOS 5D Mark 3, 6D) does not help also!
See youtube.com "Faulty Yongnuo 568EX II" google "yn-568exii under expose", for example. Blog on [...], under reviews amazon.com.
The problem is reportedly not on specific Ser. limited, but occurs in all devices, thus regardless of which dealer.
Therefore, the Yongnuo support referred to YN-568EXii eg. As incompatible with EOS 5D Mark 3 (at the different dealers compatibility information are very different). Nevertheless, the Chinese product flyers can be found on the manufacturer's product page [...] photos were allegedly taken with EOS 5D Mark 3 (directly flashed).
The old, first version of the flash YN-568EX has this error allegedly not (otherwise differs allegedly only in the fact that no master flash control as in verse. 2 is possible), but is no longer produced (at least for Canon).
Yongnuo unlikely to fully implement the specification for Speedlites Canon, so it is now with newer EOS camera models to incompatibilities with future EOS camera models might be expected further problems.
Together with the YN-622C should the flash function (but made no intensive testing in this combination).
