I chose first for the Yongnuo YN 565 EX II (the smaller brother). Who does not work on my EOS 400D. (Ging therefore back) Now I have the YN 568 EX II. Am very satisfied. So he also works on the EOS 400D. There are many features included and available settings. However, the on-screen menu is a bit strange. It is essential to study the manual carefully and to the importance of the individual menu items to remember. But if you get it's time it's no longer a problem. All in all a super flash for the price. (Not to mention when compared to equivalent Original Speedlights).