Example of improvement using this bit of kit
Calibrated
Uncalabrated
Both pictures exactly the same settings and distance. Check the scale and you will see the difference. This is my Sigma 120-400mm at the 120mm . There is absolutely no editing at all. The pictures are straight from the camera, just resized as required for posting on here
Still not EXACTLY right as the camera fine focus was at its maximum after calibration
Azz would you please leave as a new thread
Bazza