... Do this at the end of the day, when your eyes are tired
otherwise they will accommodate instead of focus.
This is exactly the same as adjusting a microscope's eyepiece.
You focus the the reticle while looking at a distant object because our eyes relax at distance,
and are stressed when seeing close. Which is why your high school teacher yelled at you for
looking out the window instead of your lesson in front of you. But I digress.
When you use the focuser, work quickly. If you labor, your eye will 'pull the image' into focus,
and you will wonder why it isn't sharp ! This is the biggest problem have with reticle focusers.
If your prints aren't sharp, you haven't adjusted the eyepiece properly.
...