I think its pretty much like this...when your sittin high in a tree your mind and your eyes adjust and set up thinking the shot is farther than it really is. You might choose the 30 yard pin when its really 20-25 yards or something and then you shoot high. Practice practice practice and you will be fine. Some people are good at judging distance others are not. Practice and a rangefinder and that should work. mistakes are part of learning. just don't miss the big buck! ha