Have a target of some sort to lok at - a brick wall is good, so you are looking DOWN it at an angle. The bricks become graph paper for you! Pace out the 40 yards you want and drop your hat or something next to the wall (hedge?) Then turn the objective until the hedge/wall is sharp at the range you want - or a tree / fence post at the desired range and just bring it into focus at the highest magnification. Higher the magnification, the more precise the focus. Then do the lock ring up. It will probably only need two turns or even less.
Thank you, but turn it in or out?
I would guess turn it