I recently joined a post on the Gear Review forum about a member looking at the Leupold RXII rangefinder which supposedly has a ballistic compensator that compensates for the shot angle and give you the actual distance to the targetrather than the "line of sight" distance. I'm in the market for a new rangefinder as well and would like somebody to help me with what I might be missing here because I just can't get the numbers to work out. Now I'm no mathematician so in advance I admit I may be completely calculating things wrong, that's why I'm asking for help.
I'm trying to determine the difference between actual distance vs. line of sight distance from a treestand. My own calculations are that you should be able to use the Pythagorean theorum we all learned at one point or another in Geometry class which states a2 x b2 = c2. You should be able to calculate the distance of any of the three sides of the triangle created (height of rangefinder above ground, distance from base of tree to target, line of sight distance from hunter to target) by applying that formula.
In applying the formula Ifigure that if you're 21 feet up a tree on level ground (7 yards) and your rangefinder reads 30.0 yards the actual distance to the target is 29.2 yards. That's 30 squared minus 7 squared equals the distance squared or 900-49=851 the square root of which is approx 29.2 yards.
A more extreme example, say you are40 feet up a tree. Now that's high! And that's a pretty steep shot angle. You range the animal at 30.0 yards. The actual horizontal distance calculated to26.9 yards.
Ok so lets look at the advertisements in the catalog. The manufacturer shows that a hunter ranging a target at 40 yards would get a true range of 34 yards. That'sa difference of 6 yards or almost 20% of the actual distance, definitely significant. Using the formula however,I would calculate that hunter to be 21 yards above the target level or 63 feet up a tree. Wow, now that's nosebleed! Considering most hunters don't go much above 20 feet that seems unlikely.
Myconclusions seem to be supported by another member who tried the rangefinder in the field and reported in that same thread that he tried ranging bow ranges as steep as he would ever take a shot and didn't get more than a yard or two difference.
So I'm hoping that somebody out there with a lot better understanding of math and ballistics can help explain this to me and anybody else out there who might be interested. Thanks.