Angle compensation rangefinders

[MountainMan]

Has anyone used the new Bushnell Chuck Adams rangefinder? I pre-range objects when I set up in an area so I need a rangefinder that will read brush, grass etc... Nothing more frustrating than a rangefinder that won't give you a reading off a clump of grass twenty yards away.

Thanks,
MM

[MountainMan]

After doing some more research it doesn't sound like replacing my current rangefinder with one that does angle compensation is worth it. The compensated difference is so small at archery distances it is not even worth measuring. I won't bore you with the math and examples.

[BottomDweller]

even at high-angle near-vertical terrain compensation?  not boring - let us know and if people are bored by it they don't have to read it

[MountainMan]

This is the equation an angle compensation rangefinder does for you (as far as I can tell):
[(Actual distance from you to target)^2 - (distance you are from being on horizontal plane with target, up or down)^2]^1/2 = compensated range
Clear as mud right. Lets say you are standing on a cliff face 5 yards higher than your target, which your normal rangefinder ranges at 30 yards. 30 squared is 900. 5 squared is 25. 900-25=875. Square root of 875 is 29.6. 29.6 is what the angle compensation rangefinder would show.

Lets say you are 10 yards (30 ft) above your target which is 40 yards away. The compensation would still only be 38.7 yards, less than two yards!

An extreme example: If you were 30 yards (60 ft) higher than your target, and you range your target at 60 yards. You'd want to use your 52 yard pin, which is a difference of 8 yards, which would actually be worth compensating for. But those figures put you four times higher than an average tree stand and about twice as far as I like to shoot.

BD, near vertical shots definitely change things. If you are 30 feet up on top of a vertical rock outcropping and an and elk is standing five yard from the base of the rocks your rangefinder might read 15.8. But you know if you use your 15 yard pin you're going to shoot way over it. You'd have to shoot like the elk was five yards from you. I like to think most of those shots can be estimated without an ARC rangefinder.Anyway, kind of interesting.

I'm no math professor, but I think this is right. Take it for what it's worth.

[Forktail]

 My understanding of the subject is that angles affect both arrow and bullet flight, although differently.  All an angle compensating range finder does for you when shooting something with your bow, is tell you the run (carpentry terms here) of the triangle.  If you're 11 yards up in a tree and the target is 40 yards (diagonal (line of sight)) away, the range finder will tell you to aim as if the target is 39.5 yards away.  Not a big deal.  If however the target is directly below you, say 3 linear yards away, when you're 11 yards up, a non angle compensating range finder will tell you the target is 11.5 yards out.  This is assuming you are shooting at extreme tree stand angles.  I'm not saying it doesn't happen in other situations, but we're not hunting in trees, and I still think the 20 yard pin would do the job.
  Bullets act differently.  They will still shoot high, if aiming for the line of site range, but I there is more involved.  Check out this link for the whole story:  http://www.exteriorballistics.com/ebexplained/5th/33.cfm 
  The summery is that, unless you are shooting great distances (400-500 yards), at extreme angles (45+ degrees) you should still hit the vitals. I bought the Leupold VX-II 2 years ago before I new this info.  The VX-II has different settings for different bow speeds and bullet trajectories.  It supposedly calculates all this for the perfect shot.  Would I buy it again? Probably not.  I'd hold a couple of inches low if I found myself in an extreme situation.