Exercise: Focus with set aperture

For a number of trial runs I found it very diffucult to focus correctly, many where blurred. I wondered if the problem was with my variable focus glasses. Eventualy friends pointed out that my camera had a dioptric knob to adjust for my lenses. It worked and makes a big diffrence, I should have paid more attention to the manual. Still lots to find out about the camera.
I need to practice more to get the focus where I want it to be. Also need to practice on some bigger things.