Thread: Parallax adjustment or no parallax adjustment

Please help me out here long-rangers; in your experience do you need a focus adjustment on your scope to knock out parallax for longrange or not ?

To narrow things down a bit; shooting out to 600 metres only (probably close enough to virtual infinity), focus adjustment either on the side or via a threaded objective, either way getting the image and reticle into the same plane for zero parallax. Assumes hunting situations rather than bench where always getting a perfectly consistent cheek weld / eye position is not possible. Maybe include the magnification, or perhaps just the scope type, for example is the S&B 3-12x50 PM II useable or does it need to be a 3-12x50 PM II/P ? Leica in changing from ER to ERi have moved from a side focus on the ER 3.5-14x42 to not having an adjustment on the replacement ERi 3-12x50. Do these two examples indicate 12x as the accepted cut-off point perhaps ?