Question about Sigma USB Dock for Canon EF bayonet

It is not difficult in itself, but it is relatively time-consuming. You have to try to measure/estimate the corrections for different focal lengths and then check them again etc. With my 18-35, there was also the fact that it plays a role whether the lens focuses from infinity or from close-up.
If your camera can correct internally, then the dock is probably not absolutely necessary.

My 50mm 1.4/ART on the Canon 5DsR, I could only calibrate correctly with the dock! The adjustment via cam gave unsatisfactory results depending on the distance. The advantage of the dock is that four distances can be fixed individually. I can only recommend it! As the previous speaker mentioned, it IS labour-intensive, but personal requirements also count here.