i think whats happening is the same as what happened to the tamron ,new and inexperienced users looking for more than is possible ,and not realising theres a learning curve .the comments " i got it yesterday did a quick MFA set up and then went out to use it " fill me with dread ,if it aint broke don't fix it ,one guy had the sense to comment it could be atmospherics over long distance causing a problem ,one which i now know full well IS most definitely a problem ,and or also camera shake as these shots are probably hand held at nearly 1000mm focal taking crop into the equation .i'm still learning with mine even after a month or more with it .but would i sell it the answer is no its a versatile all rounder thats worth taking time with