Are you adjusting your optical distance by the scale on the scope, or by your experience with the parallax??
The numbers on the knobs/objective ring are very seldom accurate and just for general guideline purposes...I have a couple of mid range (price, but really good glass) optics that are off quite a bit, I've also had double cataract surgery and have mild ARMD, and I have to adjust my objective settings where there is no parallax when I move my head/eye, regardless of what other indicators might be...
