Our newest riflescope has an external rangefinder.
What is parallax?
The mechanics of parallax are complicated but identifying and dealing with it is not. Parallax is the shift of the reticle to your eye or apparent reticle movement. It happens because of improper alignment of the scope with the eye or too much distance between your eye and the ocular lens. If you simply slide your head back and forth you should find a place where there is no black around the edges of the scope view. You are then parallax free.
Why are the scope adjustments always called windage and elevation?
It is true that the adjustments are truly horizontal and vertical but the use of the terms elevation and windage are very old and harken back to the history of distance shooting with artillery pieces. The terms have been in use for so long that it’s become the standard. In modern use, these terms are true for scopes that adjust by turrets where you compensate for wind by adjusting the reticle left or right and elevate your bore in relation to the optical sight by adjusting the elevation knob.