What is Parallax?
When the shooter is looking through their optic, they will notice the crosshairs are perfectly centered and aligned with the target. Once the shooter starts to move their head around, they notice the crosshairs appear to move a little in relation to the target. The shooter will notice the optic lens and target are not perfectly aligned which is known as parallax. Parallax happens when the shooters eye is not centered on the eyepiece.