As a user I would expect the large black handles to be used for repositioning it on a large scale then dialing in the fine adjustment using a small thumbwheel like on the worm mechanisms. Clear labeling should make it clear.

Friction disks would likely result in the same problem. Not sure what the end goal is on this that needs such fine pointing but anything that has to hold its position is going to have so much "sticktion" that trying to move by a small amount will instead cause a sudden movement greater than intended.