Review on YONGNUO YN2 0X III Teleconverter Extender by Chris Horton

Upon arrival I immediately tested the extender on my 5D IV and 5DSR with multiple lenses including the Canon 70-200 ISII. I was very surprised to find that the sharpness was better than I expected and I found the lack of contrast to be manageable. Autofocus was slower than usual, which was acceptable, but with every lens and camera, exposure was anywhere from 3 to 5 stops over exposure. Not at all suitable for sports or wildlife photography with changing lighting. Maybe this is an isolated case, so I'm sending this one back and ordering another one. UPDATE: Two days later I got a second extension with the same results but just a worse overexposure at 70-200. About seven points. The extension may not work with the new 5D IV or 5DSR. I then tested it on an older 7D model and it worked great. I've been a long-time fan of Youngnuo, but as much as I love the coverage, it's making a comeback too, and I suspect they know the extended one isn't compatible with newer Canon models, but chooses not to give it away. Don't try again. The fact that this happened twice on my two new cameras, combined with another test with the same issue on the new 7D2, suggests that Yongnuo needs a new version. I'm sure they know about it, but I'm surprised they don't mention it.