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Setting CrossBow Scope Questions

fairchaser

fairchaser

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Joined
Sep 13, 2011
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Location
TN, USA
I have an Excalibur Crossbow that shoots 330 FPS and have the scope adjusted so that from the ground, it shoots accurately for the multi-lines at 10-50 yards. My question is could the speed adjustment on the scope be adjusted to accurately compensate for a tree stand angle? The X bow should shoot high using the yardage measured from an elevated position, so I was thinking I could adjust the speed on the scope a little faster to compensate for this. Anyone have any experience here?
 
It will shoot the same as long as you go by the horizontal distance rather than the line of sight. Meaning, rather than estimating how far the deer is from your eyeball (line of sight) estimate his distance from the bottom of your stand.

That being said, the effect that the height of your stand has on the arrow is negligible. I know alot of rangefinder companies have made a ton off of ARC (angle range compensation or something similar) but it's really not worth it.

Say you are shooting on a 45 degree angle (i.e. You're 15 ft up a tree and the deer is 15 ft from the base of your tree). From your eyeball to the deer is ~21 ft. Not sure about your crossbow but mine is deadnuts with the first mark out to 25 yards, therefore you're gonna use the first crosshair from 0-25 yards. The 6ft difference isn't worth worrying about.

Moving out a little farther and say the deer is at 20 yards and you are still 15 ft up the tree. From your eyeball to the deer is 20.6 yrds, so you're still using your first crosshair.

Jump way on out to 50 yrds. with you still 15 ft up the tree. Line of sight distance is 50.25 yrds, so you're still using your 50 yrd crosshair.

Worrying about the difference your height makes isn't really worth your time. If you have it dialed in from the ground you won't have anything to worry about come opening morning when he steps out within ~50yrds.
 
Thanks Rubberduck. Do you have the formula for the calculation? I am a bit surprised that the difference is so slight once you get out farther but I was never that good with geometry.
 
fairchaser said:
Do you have the formula for the calculation? I am a bit surprised that the difference is so slight once you get out farther but I was never that good with geometry.
Click to expand...

It's actually trigonometry rather than geometry.

You use the Pythagorean Theorem. Its the Standard formula for calculating the third side of a right triangle. Where A=Stand Height, B=Horizontal Distance to Target and C=Line of Sight Distance, C=sqrt(A*A + B*B). Or you can use this calculator and find the value of C http://ncalculators.com/number-conversi ... eorem.htm/.
 
Rubberduck270 said:
fairchaser said:
Do you have the formula for the calculation? I am a bit surprised that the difference is so slight once you get out farther but I was never that good with geometry.
Click to expand...

It's actually trigonometry rather than geometry.

You use the Pythagorean Theorem. Its the Standard formula for calculating the third side of a right triangle. Where A=Stand Height, B=Horizontal Distance to Target and C=Line of Sight Distance, C=sqrt(A*A + B*B). Or you can use this calculator and find the value of C http://ncalculators.com/number-conversi ... eorem.htm/.
Click to expand...


Thanks, that is probably more math than I want to tackle. You ever see a monkey solve a math problem? I will take your word for it RubberDuck. :D
 
Its more gravity affecting the arrow drop than the actual distance, shooting at downward angles has less gravitational effect on the arrow than shooting horizonally. Thats why there's a difference when shooting high out a treestand as opposed to shooting at ground level.
 
Rubberduck270 said:
Gravity affects the arrow the same. No matter if you are shooting horizontally or vertically. The affect of gravity is the same.
Click to expand...

Hey Rubberduck:
If you drop an arrow at the same height at the same time that you shoot an arrow will they hit the ground at the same time just like a bullet?
 
holstonangler said:
Its more gravity affecting the arrow drop than the actual distance, shooting at downward angles has less gravitational effect on the arrow than shooting horizonally. Thats why there's a difference when shooting high out a treestand as opposed to shooting at ground level.
Click to expand...

I think it is because it is a shorter distance than the other leg of the triangle.
 
fairchaser said:
Hey Rubberduck:
If you drop an arrow at the same height at the same time that you shoot an arrow will they hit the ground at the same time just like a bullet?
Click to expand...

Yes, provided the arrow is shot horizontally.

fairchaser said:
holstonangler said:
Its more gravity affecting the arrow drop than the actual distance, shooting at downward angles has less gravitational effect on the arrow than shooting horizonally. Thats why there's a difference when shooting high out a treestand as opposed to shooting at ground level.
Click to expand...

I think it is because it is a shorter distance than the other leg of the triangle.
Click to expand...

I don't understand what he's saying 100% but I think I know what he's referring to. By shooting at a downward angle gravity is helping your arrow accelerate towards your target, thus affecting the speed of your arrow rather than it's flight path. So, if you were shooting straight down, gravity would have no affect on where your arrow would hit (i.e. no affect on it's flight path) but rather just help speed it along. So in a sense he is correct, at steeper angles gravity's effects on the arrows flight path is lessened. Fairchaiser, you are also correct in saying that it is because of the shorter horizontal distance because the steeper the angle you are shooting downward, the shorter the horizontal distance your target is from you.
 
Rubberduck, now if you could just solve the nation's oil problems we would appreciate it. Great answer! Learned something myself too.
 
Don�t even consider the effect of gravity on a shaft, the calculations are mind-boggling. Best to test sight in your multi reticle. Use a good range finder to set distances from your stand and trust the reticle graduations. I �0� mine at 20, move back to 30 drop one graduation, step back to 40 drop to two below �0� etc out to 50, any further then that is a �crap� shoot unless conditions at perfect. If there is an odd yardage �say� 35 just split the difference and send it. The optic engineers are good at setting up scopes, all manufactures spend $$$$$$$$ getting these correct. I tried a friend�s multi red dot. Don�t bother with one of that design, I�ll take line graduations anytime
 

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