Parallax
OK went and read the article, and I'm starting to think the confusion, has to do more with the TERMs used, and the understanding of those terms, and the number of different terms for the same thing.
So for the sake of my understanding, and if I'm correct maybe someone elses.
I'm going to try and explain my understanding of Parallax with using as few terms as possible.
Parallax = 0 , when there is 0 difference, between distance to target plane, and distance to reticle plane. Turning the Adjustable Objective lens back and forth,
is running the focused RETICLE image plane out and back. Between target and objective lens.
It would have been easier, if instead of Parallax, they called it Retical Plane Distance. So I'm gonna just call it that RPD.
An example I think, would be like sitting in your Living room , with a Mini maglight. You have 3 walls all at different distances, what the distance is doesn't matter as long as they are different. When you shine the light on each wall, in order to have a crisp clear edge circle of light, you have to rotate the front end of the light, focusing the light. In each, case matching the distance to the wall( target) with the distance to the sharpest circle of light(RPD). The plane where the circle of light is sharpest is a variable adjusted by the end of the maglight.
I'm saying the crisp circle of light, is roughly equivalent to a crisp,sharp reticle image.
The adjustable bell on the maglight, is like the AO adj. on the scope,
turning either runs the crisp circle of light or the crisp reticle image out and back as an optimum adjustment. Matching with the wall or target plane.
And if thats right, I want to change my answer on optimum scope mounting height.
Optimum scope mounting height is where it centers optical axis with the height the eye is off comb with solid repeatable stock/cheek weld. We can get rid of one variable right there. Proper paralax adjustment should make the centering of optical axis a little less critical.
I apologize if it's an over simplification, simpler was my goal.
If I still don't have it,, I cordially invite all and sundry to jump on it as I am determined to understand this.