When I bought my Sigma 150-600 I bought the USB dock to go with it.
Yesterday I decided to calibrate/micro adjust the focus. It's done using the bundled software and lets you micro adjust for 16 different places
150mm at 6m - 12m - 15m & infinity
Then you do the same for 300mm etc
The 1st 3 are easy, I put a tape measure out, marked the ground then put out a home made focus calculator at the set distances.
My question is (this is going to sound stupid) how the hell would I do that for infinity?
Calibration wise, does this have a set distance as to which it becomes 'infinity'?
I focused on an object about 40m away and I had some serious back focusing.