Parallax Adjust
After many years of doing it the conventional way (ocular first against blank background then parallax against the target) I finally found a quicker and more successful procedure. The best explanation I've seen is from a post on this forum but I've lost track of who posted it so with my apologies to him:
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"The easiest way to adjust for both zero parallax error and sharp target/reticle focus (making no assumptions about the scope's adjustments whatsoever) is as follows:
1. Adjust objective (side focus or AO) for zero parallax error, i.e. no apparent reticle movement on target while moving your eye around behind the eyepiece. (Disregard target image sharpness or focus.) Now the objective is focused on the reticle.
2. Adjust ocular (eyepiece) for sharpest target image focus (and, coincidentally, reticle focus - since they are now in the same plane). This is much easier than focusing on the reticle alone with a bright blank background, but you should still glance at the image for short periods, and trust your eye's first impression, which will also avoid eye fatigue.
Usually, a second iteration of the above two steps pays dividends in fine adjustment, since detecting parallax error (reticle movement on target) is easier once the image is more sharply focused."
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Try it, you will be surprised how well and easily this works to get your scope correctly focused especially if you are using fine cross hairs or fine cross hairs with dot.