Most scopes are set parallax free @ 100 yards, Leupold at 150, and some shotgun scopes at 50.

The easy way to get rid of parallax, is just turn down the power of your scope.

AO objectives do the same, but are seldom worth fiddling with in the hunting field - - - it becomes no particular focus issue until you get past 7- 8X.

No parallax is present on Aimpoint / Red Dot 1X scopes, as there is no magnification.