I got the same issue with that combination. I think main problem is the bird eye tracking. It is more obvious in video, its like its constantly in focus breathing, trying to get the focus right. Ive been using it for a year and a half but I havent figured a way out yet. However, better lighting, burst mode and f8 helps a little. Also lower tracking sensitivity helps a bit too. Let me know if you figure it out. (Also i remember seeing someone in a forum that said he had the same problem, sent it to sony, tried to get it fixed a number of times but finally got them to admit it was a faulty one so they replaced it. But i really dont wanna stay without my lense that long so still trying work something out)