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Tech. Question on MOA Calcs. 
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sscoyote
Optics Journeyman Joined: October/05/2004 Status: Offline Points: 327 
Thks. Dale.

Steve

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sscoyote
Optics Journeyman Joined: October/05/2004 Status: Offline Points: 327 
The reason that i ask this question is that rangefinding is not linear, since angular measurements are nonlinear. It's supposed to be a trigonometric function. A mildot reticle subtends 3.6" @ 100 yds., and 7.2" @ 200 yds., but does it also subtend exactly 5.4" @ 150 yds.? I don't think it does. If u use that mildot for rangefinding, and the object ranges @ 100 yds, then it will gap .5 of that subtension @ 200 yds., but if it gaps .75 that subtension it is not exactly 150 yds. away, it is more like 130 yds.
If my assumption is correct then if a particular ballistic reticle's stadia is set up to have one zero @ say 100 yds. and the next stadia is 200 yds. then 150 yds. is a little closer to the 2nd stadia than 2.5. It would be something like 2.6, or maybe .7.
This effect may be negated by the parabolic nature of trajectories, since the "50" yd. mark (in the example above) would then conversely be closer than the .5 mark.
This is just theoretical stuff that i was wondering about, and didn't know where else to pose these questions. 
Steve

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Dale Clifford
Optics Jedi Knight Joined: July/04/2004 Location: United States Status: Offline Points: 5087 
The reason that i ask this question is that rangefinding is not linear, since angular measurements are nonlinear. ,
angular measurement are linear, there are no higher order terms in the expression to give them any more degrees of freedom than linear, trig. fun, and polar coordinates are just another way to express cartesian coordinates. the mill does subtend 5.4 by definition.
its not theoretical its just "math" stuff
trajectories follow a natural decay curve (ln against some set of distance pts. say (x))compensating systems don't work in the same way as mil dot. the "progressive" scale used becomes calibrated to the some point in space that matches the points in 2 dimensions of the actual path. the weakness in the arguement comes from the statistical nature of the trajectory, which depends on data from that shot, but if the discussion is started with an exact set of numbers for this then the stadia marks on the cross hair will coincide with the bullet path.
if the first stadia wire is set for 100 yds and the second by definition at 200, the 150 "marker" would be closer to the first stadia wire, but proably less than a thickness of stadia wire. as it follows the data determined by traj
"This effect may be negated by the parabolic nature of trajectories, since the "50" yd. mark (in the example above) would then conversely be closer than the .5 mark." this does occur in mildotting. and why the dial in would be x+some constant and also the advantage of a compensating devicetheoretically 
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sscoyote
Optics Journeyman Joined: October/05/2004 Status: Offline Points: 327 
Thks. DaleI understood most of it.

Steve

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