All's I can tell you is my parrlex adjustable scope is a pain in the a***! Nightmare when stalking about.
having to adjust for each distance for each shot,even 5yards out and it's out focus,Unless i leave it blurred and out of focus for each shot at different distance ,dose not effect the aim point just clears up the picture to sharpe perfect image.
However I can set it to fixed ,still isn't half as clear as my non adjustable parrelx scope though.