Depends how high you are, 5ft no 50 ft yes. It effectivly is increasing the distance the arrow has to travel to the target.
Please be a little more specific. Is the target you are shooting at straight out, or at a large angle? Like if you're in a treestand shooting to the ground? In the first case, no, if you're shooting at a target that's nearly in the same plane, then no it will not affect it. If you're high up in a tree shooting a target just a few feet away, it will some. If you're high up in a tree shooting a target 30 yards out, then no. A lot the rangefinders now have the capability to calculate the angle. Basically, it's the horizontal distance between yourself and the target. I have one, and I will tell you that I hunt 15 feet up in a tree, at the top of a hill. A 31 yard shot, I need to shoot at 30 yards. So the further out, the less impact. Let us know if that helps.
