the side focus will take out parralax at given ranges, that will improve your long range accuracy and close up high magnification work. the numbers are in yards. if you have good eyes you can use the side focus as a rangefinder. simply focus the scope on the target and see what range your at on the dial. focus adjustments are just there for high magnification when your depth of field (acceptable focus) is more touchy. if you in the heat of the moment, you likely wont be in the high end of your scopes magnification and thus you will have no need to touch the focus dial. hope this helps