....but its most precisely done by moving your aiming eye closer or farther from the scope than the distance allowing the full field-of-view. This results in part of the FOV being blacked out, which is due to seeing only through the exit pupil. If you center this smaller FOV, and also the reticle, when aiming, there is no parallax, because your eye is aligned with the center of the scope....
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That would be a stupid thing to do.
