Originally Posted by ntg
...So my question is say I've got a x14 power scope without that adjustment. How much will parallax effect my shotting at say 700 yards? It's implied that the scope also has to have decent clarity at max power which some do not in the price range I'm looking at.
Thanks in advance.
The exact answer is difficult to calculate. It depends on how far away your eye is from the center of the exit pupil. If the objective is large and you're looking at objects in bright sunlight, the eye can be off center quite a bit.
For a 40 mm objective, however, the exit pupil at 14X is 2.9 mm wide. In bright daylight your eye pupil will be about 2 mm, so you can't move your eye more than about +/- 0.5 mm without noticing a change on the sight picture. That means you will have a natural tendency to center your eye, which minimizes parallax error. I calculate that for a 14X magnification, a 100 yd scope focus, and a 0.5 mm eye offset, the parallax error is 1.7 inches at 700 yds.
In general, if you train yourself to always center your eye so that the sight picture is centered, you will not have problems with parallax error on a 40 mm objective scope.