Leupold RX II

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Postby Ranger » Tue Oct 07, 2008 12:46 pm

I understand that when shooting at an angle the horizontal distance is less than the line-of-sight distance and therefore if using a non-angle compensating rangefinder one would need to aim a little lower than the distance the rangefinder gives you but my question with regards to the different speed modes on the RX-II is this: If ranging a distance at an angle in the slowest mode and then changing the mode to the fastest setting and ranging the same point does the compensated distance change and if so does it increase or decrease?

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Postby Merv » Tue Oct 07, 2008 1:02 pm

Zaboy, initially I was with you on this one. But did a bit of a web search and came up with this:

http://en.wikipedia.org/wiki/Rifleman's_rule

Without going into detail on the math, have a look at the diagram Fig. 4. If I imagine another set of curves on the figure with a different initial angel of shot, then it implies that the initial angle of a shot will affect the effective range at an incline and the two will not be the same. Therefore bows shooting at different speeds using the same sight setting (therefore different initial angles of shot) will fall at different points on the incline, although they will fall on the same spot on the horizontal. How much different for variations of speed/angle/incline????

If my interpretation is correct, then I have learned something new. Where are the experts??
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Postby GrootWildJagter » Tue Oct 07, 2008 1:07 pm

Zaboy, I agree with you.

Let me try use another example.

If you have a bow(A) shooting at 300ft/sec and a bow(B) shooting at 200ft/sek.

And the distance is 50yards, but with the angle you need to shoot only 40yards

Both of the bows will hit the same spot if you use the 40yard pin. It does not matter if the on arrow drops more than the other arrow. It tells you which is the 'true' distance to the target.

Speed and arrow drop has nothing to do with the ''true ballistics range''.

The only reason for the different setting I can see if it has to do with the resitance on the arrow or bullet
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Postby Ranger » Tue Oct 07, 2008 1:15 pm

Thanks for the article Merv, I'm going to do some reading and calculating when I get a chance.
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Postby Rory » Tue Oct 07, 2008 1:16 pm

The way I see it hyperthetically speaking... :scratch:

If you shoot the same bow but different lbs the flight/trajectory will differ ie; longer path the lower the lbs so the further your rangefinder will compensate if set to that corresponding lb
20yds @ 60lbs = 22yds (read through rangefinder)
20yds @ 70lbs = 20yds (read through rangefinder)

The speed will work in the same way, the quicker the bow the lower the flight path/trajectory of the arrow.
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Postby Ranger » Tue Oct 07, 2008 1:28 pm

Rory wrote:The way I see it hyperthetically speaking... :scratch:

If you shoot the same bow but different lbs the flight/trajectory will differ ie; longer path the lower the lbs so the further your rangefinder will compensate if set to that corresponding lb
20yds @ 60lbs = 22yds (read through rangefinder)
20yds @ 70lbs = 20yds (read through rangefinder)

The speed will work in the same way, the quicker the bow the lower the flight path/trajectory of the arrow.


The only way to settle this is for someone to test the different speed modes.
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Postby robass » Tue Oct 07, 2008 3:31 pm

If you have a bow(A) shooting at 300ft/sec and a bow(B) shooting at 200ft/sek.

And the distance is 50yards, but with the angle you need to shoot only 40yards

Yes GWJ , but the rangefinder will tell you to "aim" at 40 Yards on your 300fps bow , and "aim at 45 or even 50 Yards with your 200fps bow . The rangefinder gives you 3 settings as in the previous posts , whether or not they are accurate is another story , I am going to range up a building for arguments sake and do a couple of tests on the 3 different settings and report back on what they say .
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Postby Ranger » Tue Oct 07, 2008 4:04 pm

Good stuff Robass! That's just the kind of test we need. Let us know how it turns out.
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Postby Eben » Wed Oct 08, 2008 8:25 am

Ek wou ook gister die setting verander het om te kyk hoe die nommers verander maar het te lekker geskiet en toe vergeet op die ou einde van die dag.

Maar wat ek wel kan se vir die ouens wat dink dat die spoed nie n verskil maak nie , is dat dit doen. Kyk maar net op jou eie boog, kom ons se jy het 2 bows, een is op 70 pond in gestel op 20, 30, en 40 yards, en die selfde peniekies op n 55 pond bow. Op die 70 # boog gaan die penniekies naader aan mekaar wees teen oor die 55 #. dit is omdat die 70# boog vinager skiet, en die gravitasie krag n stadiger uitwerking het op die 70 # bow, die 70# sal verder skiet (as die 55#) voor die pyl begin sak.

Op gelyke grond sal die 70# boog Arguments onthalwe 60 meter skiet wa die 55# boog miskien kom ons se 49 meter skiet, maar waneer jy die 2 bows 45 Grad afwaarts skiet gaan die pyl verder gaan want nou kan jy maar se help die grawitasie krag die pyl , hy trek hom so biekie, so hy skiet verder makliker. Spoed is beslis n biae belangrike faktor, maar di akuraatste is om te kyk hoefeel inch jou pyl sak wanner jy met jou 20 yard pennikie op die 40 yard but mik, dan kan jy presies sien in watter katoegoerie jy jou rangefinder moet sit,wel die RX2 inelkgefal.

Elke setting werk basies uit wat die gravitasie efek gan wees op n sekere boog of puil
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Postby Harry Marx » Wed Oct 08, 2008 1:28 pm

GWJ en andere
Ja, GWJ, jou waarneming is reg dat 2 boe met verskillende arrow speed, gaan dieselfde pin gebruik, as daar geen wrywing was nie.
Die trajek van die pyl is nie simetries nie, en stadige pyle word meer deur die swaartekrag beinvloed. Ligter pyle verloor vinniger spoed, en is meer skew.
Daar bestaan nie werklik 'n "formule" om dit mee te bewys nie, aangesien die wrywing van die pyl van spoed afhanklik is, en die spoed van die wrywing.
So 'n mens bou maar 'n model wat die pyl se trajek "voorspel" op grond van waar dit 'n voet, of duim, tevore was.
In teorie word dit meer akkuraat hoe kleiner die aftand, maar die aantal stappe neem dienooreenkomstig toe, so enige vout met elke stap, vergroot met daaropvolgende voute.

Daarom dan die "rule of thumb" om te skiet op die horisontale afstand. Maar dit is nie 100% akkuraat nie.
Rangefinders implementeer maar gewoonlik hierdie reel.
Die fancy RFs probeer bietjie kompenseer vir spoedverlies met hierdie "arrow speed" faktor.

Na my mening is die beste om vir jou self 'n tabelletjie op te stel met hoeveel jy moet komp vir elke afstand en incline. op en af (want op en af verskil ook effens). Dan toets jy paar ekstreme met jou opset, en pas die hele ding aan tot die 100% werk.

Aan die anderkant, as jou RF se X en jy skiet X en die pyl tref X, dan maak jy so.

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Postby Guardian » Wed Oct 08, 2008 5:20 pm

Harry,
Hoe kan 2 pyle met verskillende spoed dieselfde pin gebruik as daar geen weerstand was nie ?
Dis mos die tyd wat gravitasie op die vertikale as inwerk wat saak maak ?
Die een kom gouer by die teiken omdat hy vinniger trek en sak dus minder omdat gravitasie korter op hom inwerk.

Daarom dat ek ook nie kan verstaan hoekom daar 'n prakties meetbare verskil sal wees as jy bv afwaarts skiet met pyle van verskillende spoed en jou boë is ingestel op die horisontale afstand en dis waarvoor jy mik ?
Ons neem aan jy skiet 2 verskillende set-ups waar die boog ingestel is vir die spesifieke pyl trajek.
As die vinnige boog op bv 30m horisontaal ingestel is en jy skiet skuins af en jou horisontale afstand is 30m, sal jy damn naby aan die spot skiet wat jy op mik.
Presies dieselfde vir die boog wat ingestel is vir die stadige pyle.

So hoekom verskillende verstellings vir verskillende spoed boë ?
Gaan die vinnige pyl hoër of laer skiet as hy op die stadige pyl se setting gestel is teen 'n afdraent skoot ?
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Postby Ranger » Wed Oct 08, 2008 5:39 pm

Has no one had the chance to test their angle compensating rangefinder today yet?
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Postby robass » Wed Oct 08, 2008 7:52 pm

Hi Zaboy , would love to but we had a little flash flood in P.E today so I couldnt .
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Postby Rory » Wed Oct 08, 2008 10:22 pm

Guardian
So hoekom verskillende verstellings vir verskillende spoed boë ?
Gaan die vinnige pyl hoër of laer skiet as hy op die stadige pyl se setting gestel is teen 'n afdraent skoot ?
... I am going to try the different arrow settings tomorrow but will only be able to shoot horizontaly.
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Postby Ranger » Wed Oct 08, 2008 10:38 pm

Rory wrote:Guardian
So hoekom verskillende verstellings vir verskillende spoed boë ?
Gaan die vinnige pyl hoër of laer skiet as hy op die stadige pyl se setting gestel is teen 'n afdraent skoot ?
... I am going to try the different arrow settings tomorrow but will only be able to shoot horizontaly.


No need to shoot, just tell us if the distances the rangefinder tells you to an uphill or downhill target are different on each speed setting.
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