ORIGINAL: Greg / MO
From my understanding, bow range is supposed to be horizontal distance, so do rangefinders adjust for stand altitude or is it just a point-to-point measurement?
You're correct in the assertion about horizontal distance, and it's what causes a lot of bowhunters to shoot high. Although there are a few rangefinders starting to hit the market that claim to be able to adjust for this, I haven't heard too many great things about them at this point.
You could shoot a few known objects while you were still on the ground, but I find it much simpler to just pick out a tree I want to range and follow its trunk up to the level of my treestand, which is usually 20 feet or so. I then range that tree at that horizontal distance, much as you suggested. That gives me the real distance I should shoot for.
(not directed at Greg, just general)
What causes hunters to shoot high is bad form, dropping the bow arm instead of bending at the waist. The difference in ranges from the ground compared to the tree is less than 2 yards and usually less than one at shorter distances. Worst case scenerio, range the deer and shoot for one less yard, most bows don't know the difference in an inch of point of impact.