Guys, keep in mind that gravity affects an arrow VERY differently when it is shot on an incline or decline, and it is very easy to overshoot your target when shooting from an elevated position. It is for this very reason that my final sight-in before hunting is done from a 20' elevated position shooting down.
If you guys have your bows zero'd at close to level, I guarentee you will be shooting high from a treestand.
For example: My 20 yard crosshair is useless on anything closer than 30 when shooting down from the treestand....for a 20 yard shot I have to use the 10 yard marker and still aim low......my best advice is for you guys to take a bag target out to your stands one day and take a couple of shots, you will be amazed at the difference in POI from your stand.
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Rangefinders
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IAMCANADIAN
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I find this last post interesting. I have just decided to hunt from a tree stand again after 11 years. I purchased a new climber with all the goodies, and safety equipment.
I used the Pythagoreum Theorum, and found that at 15-20' up, there is basically only a yard difference from ground level to that height(with around 10 yds the exception, there it is closer to 3 yds). I have also lasered trees at ground level and again at level height to my position in the tree. Those results favor the math, about a yard difference.
Now I understand gavity only affects the level arrow flight, about 1 yd less than lasered. One yard doesn't make that much difference in POI.
Am I missing something here? For impact to be greatly diffent, there must be another reason. I know shooting up/down with a vertical bow, unless bending at the waist, there is a "form" break. This changes the triangulation of the sights as seen, thus changing the POI. With a scoped crossbow, I don't see this event. Can someone, more intelligent than I, explain scientifically why those experiencing this have this result, ie hitting high? I would really like a definitive answer on this issue once and for all.
I used the Pythagoreum Theorum, and found that at 15-20' up, there is basically only a yard difference from ground level to that height(with around 10 yds the exception, there it is closer to 3 yds). I have also lasered trees at ground level and again at level height to my position in the tree. Those results favor the math, about a yard difference.
Now I understand gavity only affects the level arrow flight, about 1 yd less than lasered. One yard doesn't make that much difference in POI.
Am I missing something here? For impact to be greatly diffent, there must be another reason. I know shooting up/down with a vertical bow, unless bending at the waist, there is a "form" break. This changes the triangulation of the sights as seen, thus changing the POI. With a scoped crossbow, I don't see this event. Can someone, more intelligent than I, explain scientifically why those experiencing this have this result, ie hitting high? I would really like a definitive answer on this issue once and for all.
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IAMCANADIAN
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Well....it's pretty much as I laid it out, but I'll give it another shot 
You are focusing on distance, but in truth it's not the distance that makes a bow shoot differently on a sharp angle, it's the change in how gravity affects your projectile while on an incline that you need to compensate for.
When you sight your bow in on a level course, you are more-or-less playing with a constant gravitational pull on your arrow, and that's what you compensate for with your scope calibration. As you know, an arrow fired on the level drops a BUNCH every ten yards, hence the need to constantly aim higher the farther out you move.
Now: When you are shooting up or down with your bow, gravity plays very little into the equation, as the gravity isn't acting on a constant like it is with a level arrow, and therefore the calibration you used on level ground no longer applies, and you won't get near the drop that you do when the bow is level.
Look at it this way: If you shoot your bow dead level, the arrow is IMMEDIATELY affected by gravity, and will hit the dirt very quickly...now, point your bow up at 45 degrees and shoot again.....the arrow will go MUCH further before impacting, as gravity doesn't really begin to affect the arrow until it has reached the apex (top) of the arc.....the same principal applies if you are shooting down: Gravity has a much smaller effect on the arrows path, and therefore it wont drop nearly as quickly.
The easiest way to prove or dis-prove this for yourself is to set up your target in the yard and ensure it is shooting dead-on at 30, and then go up on the roof and shoot the same target/distance.....you are going to shoot high, I guarentee it.
Clear as mud?
You are focusing on distance, but in truth it's not the distance that makes a bow shoot differently on a sharp angle, it's the change in how gravity affects your projectile while on an incline that you need to compensate for.When you sight your bow in on a level course, you are more-or-less playing with a constant gravitational pull on your arrow, and that's what you compensate for with your scope calibration. As you know, an arrow fired on the level drops a BUNCH every ten yards, hence the need to constantly aim higher the farther out you move.
Now: When you are shooting up or down with your bow, gravity plays very little into the equation, as the gravity isn't acting on a constant like it is with a level arrow, and therefore the calibration you used on level ground no longer applies, and you won't get near the drop that you do when the bow is level.
Look at it this way: If you shoot your bow dead level, the arrow is IMMEDIATELY affected by gravity, and will hit the dirt very quickly...now, point your bow up at 45 degrees and shoot again.....the arrow will go MUCH further before impacting, as gravity doesn't really begin to affect the arrow until it has reached the apex (top) of the arc.....the same principal applies if you are shooting down: Gravity has a much smaller effect on the arrows path, and therefore it wont drop nearly as quickly.
The easiest way to prove or dis-prove this for yourself is to set up your target in the yard and ensure it is shooting dead-on at 30, and then go up on the roof and shoot the same target/distance.....you are going to shoot high, I guarentee it.
Clear as mud?
If you can't set a good example, at least serve as a horrible warning.
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Yup, clear as mud. Gravity affects the level shot arrow the same as one dropped at the same time, from the same height. The shot arrow just goes further from the point of firing. Elevating the shot arrow causes it travel farther, but it still hits the ground at the same time as the one shot level, or just dropped. Time of flight will be just a little longer due to aerodynamics though, helping to hold the shot arrows up a bit longer.
Now having shot some 3D and some field with bows and crossbows, I don't find that high hitting to be that much of an issue. If you shoot the shot for the level distance, POI is correct. Now let me clarify.
Shooting from a stand 21' high, at a lasered distance of 50 yds to target below. Using math, the actual distance becomes 49.5 yds. To verify, I have lasered that same tree at my height (21'), and the distance is 49 yds. Gravity now acts on the level distance of 49 yds. The trajectory of bow shooting 300 fps will be high 1.25" high using a 50 yd sight. This is not enough elevation difference to cause a miss on deer sized game. It might keep me out of the X ring, but will still score a 10.
I feel there is something else out there causing these high impacts. Any scientific data? Again, am I missing something?
Now having shot some 3D and some field with bows and crossbows, I don't find that high hitting to be that much of an issue. If you shoot the shot for the level distance, POI is correct. Now let me clarify.
Shooting from a stand 21' high, at a lasered distance of 50 yds to target below. Using math, the actual distance becomes 49.5 yds. To verify, I have lasered that same tree at my height (21'), and the distance is 49 yds. Gravity now acts on the level distance of 49 yds. The trajectory of bow shooting 300 fps will be high 1.25" high using a 50 yd sight. This is not enough elevation difference to cause a miss on deer sized game. It might keep me out of the X ring, but will still score a 10.
I feel there is something else out there causing these high impacts. Any scientific data? Again, am I missing something?
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IAMCANADIAN
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Again, everone is focusing on the distance.....distance from the tree, lazered distances, etc. etc.......distance has very little to do with the discussion....in fact, for the purpose of this discussion and in attempt to keep things exactly clear, lets speak of only one distance: 30 yards.
A target shot at 30 yards, on level ground, using the 30 yard pin will put the shot in the bull. This is because the sights have been calibrated to compensate for the effect of constant gravity on the arrow at a (close to level) initial launch and flight path.
Now, that same target placed at 30 yards, but being shot at a downward angle of...lets say....45 degrees....if you use the same 30 yard pin that you did on level ground, your shot will be very high, likely over the target.
The reason? Gravity has a far lesser effect on an arrow travelling on an incline (either up or down), and therefore won't "pull" your arrow down as much as if the launch had been horizontal.
It is my belief that this is where 75% of "deer jumping the string" reports come from....the deer didn't crouch, but the hunter sitting 20' up in the tree used his 30 yard pin (which was calibrated on level ground) and shot over the deer.
Trust me on this....or go grab your bow and try for yourself....the science is sound.
One more thing. You said :
The fact is that an arrow shot level will hit the ground a whole lot sooner than one launched at an upward angle....and will hit the ground a whole lot later than one fired at a downward angle....you don't need a physics degree to figure that one out
Speaking of which, if anybody more enthusiastic about algebra than I am wants to calculate exact holdovers for their bows, here is the sieara method (there are actually three methods for figuring out incline/decline effects on trajectory, but this method is far more accurate when discussing low velocities like our X-bows....and I'm pretty sure this is the formula that A.R.C. technology in the new rangfinders in based on)
1. Measure the inclination angle of the target.
2.Measure the slant range distance to the target.
3.From the level trajectory at a horizontal distance equal to the slant range distance, take both the Drop and Arrow Path.
4.Change the algebraic sign on the Drop number (because Drop is always negative in Infinity change it to a positive number). Then, multiply this positive number by the quantity [1.0 - cosine (inclination angle)].
Algebraically add the result of step (4) to the Arrow Path (remembering that Arrow Path can be either a positive or negative number in Infinity) to obtain an adjusted Arrow Path. Then use this result to adjust the aim of the bow at the inclined target.
*or*...you could just do what I do drag your bag targets out to your stand for some pre-season target practice...it makes my head hurt less than the above
A target shot at 30 yards, on level ground, using the 30 yard pin will put the shot in the bull. This is because the sights have been calibrated to compensate for the effect of constant gravity on the arrow at a (close to level) initial launch and flight path.
Now, that same target placed at 30 yards, but being shot at a downward angle of...lets say....45 degrees....if you use the same 30 yard pin that you did on level ground, your shot will be very high, likely over the target.
The reason? Gravity has a far lesser effect on an arrow travelling on an incline (either up or down), and therefore won't "pull" your arrow down as much as if the launch had been horizontal.
It is my belief that this is where 75% of "deer jumping the string" reports come from....the deer didn't crouch, but the hunter sitting 20' up in the tree used his 30 yard pin (which was calibrated on level ground) and shot over the deer.
Trust me on this....or go grab your bow and try for yourself....the science is sound.
One more thing. You said :
You are correct that an arrow shot perfectly level will hit the ground as one dropped from the same height, but your above statement contradicts itself. The arrows time of flight can't be "a little longer", yet still hit the ground at the same time.Elevating the shot arrow causes it travel farther, but it still hits the ground at the same time as the one shot level, or just dropped. Time of flight will be just a little longer due to aerodynamics though, helping to hold the shot arrows up a bit longer.
The fact is that an arrow shot level will hit the ground a whole lot sooner than one launched at an upward angle....and will hit the ground a whole lot later than one fired at a downward angle....you don't need a physics degree to figure that one out
Speaking of which, if anybody more enthusiastic about algebra than I am wants to calculate exact holdovers for their bows, here is the sieara method (there are actually three methods for figuring out incline/decline effects on trajectory, but this method is far more accurate when discussing low velocities like our X-bows....and I'm pretty sure this is the formula that A.R.C. technology in the new rangfinders in based on)
1. Measure the inclination angle of the target.
2.Measure the slant range distance to the target.
3.From the level trajectory at a horizontal distance equal to the slant range distance, take both the Drop and Arrow Path.
4.Change the algebraic sign on the Drop number (because Drop is always negative in Infinity change it to a positive number). Then, multiply this positive number by the quantity [1.0 - cosine (inclination angle)].
Algebraically add the result of step (4) to the Arrow Path (remembering that Arrow Path can be either a positive or negative number in Infinity) to obtain an adjusted Arrow Path. Then use this result to adjust the aim of the bow at the inclined target.
*or*...you could just do what I do drag your bag targets out to your stand for some pre-season target practice...it makes my head hurt less than the above
If you can't set a good example, at least serve as a horrible warning.
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2008 Equinox, Lumizone, FFF String
2007 Ten Point CLS and 2004 Titan : sold!
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Chuck Gravel
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IAMCANADIAN
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Chuck Gravel wrote:when im in the stand at 30 yards with my rangefinder on the angle mode i just use the 20 yard pin and it hits dead on.
That's pretty much what Ive found as well.
10 yards, aim low
20 yards: 10 yard pin, aim slightly low
30 yards: use 20 yard pin
40 yards: use 30 yard pin, but aim like 35 yards
50 yards: aim like 45
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theoldarcher
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^^^^That method is commonly called "The rifleman's rule", and is a quick and dirty way to get a range estimate that has been used by rifle shooters shooting up/down hill. Not 100% accurate as it doesn't take the trajectory into account though, and with 300FPS arrows, trajectory plays a huge part. Rangefinders with ARC technology take both angle, distance, and trajectory into account, and a computer does the math I outlined in the above, so we don't have to worry about the math The distance is simple geometry, it's once you start in with the trig/algebra that it makes it really nice to have one of these gizmos...gotta love technology!
So....anybody try shooting from their roof yesterday?
The distance is simple geometry, it's once you start in with the trig/algebra that it makes it really nice to have one of these gizmos...gotta love technology!So....anybody try shooting from their roof yesterday?
If you can't set a good example, at least serve as a horrible warning.
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2009 Equinox, Lumizone, FFF String
2008 Equinox, Lumizone, FFF String
2007 Ten Point CLS and 2004 Titan : sold!
_______________________________________
2009 Equinox, Lumizone, FFF String
2008 Equinox, Lumizone, FFF String
2007 Ten Point CLS and 2004 Titan : sold!
quote
"You are correct that an arrow shot perfectly level will hit the ground as one dropped from the same height, but your above statement contradicts itself. The arrows time of flight can't be "a little longer", yet still hit the ground at the same time."
I know it's not going to hit at exactly the same time, there will be a slightly longer time due to aerodyanamics, but still very close, I think.
I'm starting to get your mud cleared up now. I talked to a physics teacher today. This can be fiqured out using trig. ugh. His explaination is that due to the velocity, gravity has less time to exert its effect on the arrow. Now that I can understand.
He is going to try and get a formula to me that I will be able to use to calculate this impact. I'll see.
What I still have a hard time understanding, is why you have to shoot for 10 yds closerin most cases. This is roughly 15 MOA, or at 30 yds, about 4.5". THis added to the difference of trajectory equals 6" higher. This much seems like way too much for the distances involved.
I will, when the opportunity presents, shoot from the elevated position at the lasered distances to determine for myself. I hope it can be soon however, as I don't want to miss the big one out of ignorance.
I realy appreciate the dialogue.
"You are correct that an arrow shot perfectly level will hit the ground as one dropped from the same height, but your above statement contradicts itself. The arrows time of flight can't be "a little longer", yet still hit the ground at the same time."
I know it's not going to hit at exactly the same time, there will be a slightly longer time due to aerodyanamics, but still very close, I think.
I'm starting to get your mud cleared up now. I talked to a physics teacher today. This can be fiqured out using trig. ugh. His explaination is that due to the velocity, gravity has less time to exert its effect on the arrow. Now that I can understand.
He is going to try and get a formula to me that I will be able to use to calculate this impact. I'll see.
What I still have a hard time understanding, is why you have to shoot for 10 yds closerin most cases. This is roughly 15 MOA, or at 30 yds, about 4.5". THis added to the difference of trajectory equals 6" higher. This much seems like way too much for the distances involved.
I will, when the opportunity presents, shoot from the elevated position at the lasered distances to determine for myself. I hope it can be soon however, as I don't want to miss the big one out of ignorance.
I realy appreciate the dialogue.
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Re: Rangefinders
hey crispy l've just brought a basic Leupold rx-1 its great no frills & not at all complicated thats all you need mate & it works awesome ah. best regards frankCrispy wrote:Kinda in the market for a rangefinder,I never used one. How inportant is the angle feature on some? Does anybody use one? Not looking to break the bank but dont want a junker either. Is the bushnell(Chuck Adams edition) any good? Nikon(Archers Choice)? Any suggestions? Thanks for any info, Crispy
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IAMCANADIAN
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Isn't trig fun? Better than finite though......vaguru wrote:quote
"You are correct that an arrow shot perfectly level will hit the ground as one dropped from the same height, but your above statement contradicts itself. The arrows time of flight can't be "a little longer", yet still hit the ground at the same time."
I know it's not going to hit at exactly the same time, there will be a slightly longer time due to aerodyanamics, but still very close, I think.
I'm starting to get your mud cleared up now. I talked to a physics teacher today. This can be fiqured out using trig. ugh. His explaination is that due to the velocity, gravity has less time to exert its effect on the arrow. Now that I can understand.
He is going to try and get a formula to me that I will be able to use to calculate this impact. I'll see.
What I still have a hard time understanding, is why you have to shoot for 10 yds closerin most cases. This is roughly 15 MOA, or at 30 yds, about 4.5". THis added to the difference of trajectory equals 6" higher. This much seems like way too much for the distances involved.
I will, when the opportunity presents, shoot from the elevated position at the lasered distances to determine for myself. I hope it can be soon however, as I don't want to miss the big one out of ignorance.
I realy appreciate the dialogue.
Anyway, the easiest formula to use is the one I posted earlier....the only thing you need to know in addition is the arc of your arrow (easy enough to determine...shoot the center of the bull with the 20 yard pin at 10-20-30-40-50 and measure the drop of your arrow), and then use the following:
Where it gets REALLY interesting is if you start to look at the parrabelum if arc due to the arrow slowing down and including that in the equation....remember, it may be doing 300 FPS when it leaves the bow, but has slowed considerably by the time it hits 40 yards, and the rate of drop increases exponetially...MPBR on an arrow is like 25 yards, so it is important to include these figures.1. Measure the inclination angle of the target.
2.Measure the slant range distance to the target.
3.From the level trajectory at a horizontal distance equal to the slant range distance, take both the Drop and Arrow Path.
4.Change the algebraic sign on the Drop number (because Drop is always negative in Infinity change it to a positive number). Then, multiply this positive number by the quantity [1.0 - cosine (inclination angle)].
Algebraically add the result of step (4) to the Arrow Path (remembering that Arrow Path can be either a positive or negative number in Infinity) to obtain an adjusted Arrow Path. Then use this result to adjust the aim of the bow at the inclined target.
I attempted to write out the equation once.....never again
I'm sure I could source the whole thing if your teacher comes up dry.
IAC
If you can't set a good example, at least serve as a horrible warning.
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2009 Equinox, Lumizone, FFF String
2008 Equinox, Lumizone, FFF String
2007 Ten Point CLS and 2004 Titan : sold!
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2008 Equinox, Lumizone, FFF String
2007 Ten Point CLS and 2004 Titan : sold!
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michiganman
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bushnell
the only thing i wish the yardage pro had was scan.so when you move to check different target you didnt have to reset it each time.
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Philzleads
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Leupold RX600
I bought a Leupold RX600. It doesn't have the angle trajectory fancy stuff but it works fine. It will not work through screens on a blind. And as I had to find out the hard way, niether will a crossbow bolt... 
It will range the target block at 10yds, 20yds, etc., and it will do a continuous range if you keep the button down. The 750 model does the angled trajectory stuff. This 600 allows you to change between 3 reticles. I also rifle hunt and so I needed a dual purpose. I think it was around $230. It's simple and lightweight, which is what I wanted.
It will range the target block at 10yds, 20yds, etc., and it will do a continuous range if you keep the button down. The 750 model does the angled trajectory stuff. This 600 allows you to change between 3 reticles. I also rifle hunt and so I needed a dual purpose. I think it was around $230. It's simple and lightweight, which is what I wanted.