Originally posted by woolcotm I have had a quick go a re-calibrating my lens and it seems OK against the chart at 2/3 meters (200mm f2.8).
Wasted time on a red herring. Again, there is absolutely no possible way a miscalibration would have produced the results shown. You need to accept that before you can even begin to solve the problem. Right now, believing there is a calibration issue and spending time attempting to "fix" it is just taking time and effort away from actually getting anywhere.
Quote: I was using the center point and AF-S (and yes I know about keeping the shutter button pressed when recomposing.
good. You have to understand, we don't know you and have no idea what you do or don't know.
Right now, my beat guess is what I already stated - you don't realize just how large the AF sensors are (they are much larger than the red dots), and managed to lone up your shot with the red dot where you waned but part of thebackground still within range of the AF sensor, and for whatever reason, the camera thought the background made a better target.
You need to do some experimenting to learn how big your AF sensors are (eg, by trying to focus on a single black dot on a white piece of paper with the dot in various positions near but not directly under the red dot in the viewfinder). Then you will be better able to choose appropriate focus targets.
Quote: In there you will find loads of shots with my 55-300 over 200 mm at f5.6 and no AF issues
In case you needed proof that there is no camera/lens issue, there you go. It's all a matter technique. 100%, guaranteed.