Bob H in NH

Its really a multi-part answer, the "science" of it is that you are closer to the target than the range finder will say, so you will hit higher. Gravity only effects on the horizontal plane and the range finder works on line of sight. Use the pythagoream theorem to figure out the "real" distance.

So if you are 20 feet up, the range finder says 20 yds to the target (line of sight), to figure out the horizontal difference its: 20 feet squared + horiz dist squared = 60 feet squared (30 yds converted to feet).

this comes out to a horizontal distance of: 56.57 feet or 19.5 yards.

Be honest, can you tell the difference in impact of 1/2 yard.

So for "normal" heights, at "normal" distances the real distance is a wash, hold dead on and shoot. As the line of sight gets longer, the horizontal gets closer to it. Only really becomes a factor on CLOSE shots from up HIGH, then you have to deal with paralax.

Now that's the "theory". reality is that theory only works if your form is dead on. Most don't maintain solid form when shooting down, they lower the bow arm to point down rather than bend at the waist, I know I do when hunting. So this changes the anchor point slightly, which makes you "miss" high or low, usually high, but you really have to go out and try it and see what happens to you.

--Bob