Never had a scope with a adjustable Parallax Adjustment. In this case it is called a side focus parallax adjustment. Conceptually I think I understand Parallax. The factory setting is for 100 yds. But I am trying to understand how to use this. Probably need to go out to a range to play with it more Question 1: I sight in at 200 yds - does that mean I should dial it up to the 200 setting? Or keep it on 100 yds ( Factory setting)? Question 2: If I have it set on 100 yds and go to 200 yrds or 300 yrds - does that affect where the bullet impact is at vs lets say moving the adjustment to 200 or 300 yds. Think I am asking the right question - Does the distance to the target and the associated parallax adjustment affect POI. If adjustment is at 100 yds and I shoot at 200 yards - can I expect the impact to be off lets say 1 MOA more than if it was matched? Question 3: I read somewhere you can estimate distance with the parallax adjustment they still recommend a range finder - But how do you estimate distance? Appreciate any input.