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Reticle Calc - Is My Math Correct?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/03/2009 at 17:01
Risasi View Drop Down
Optics GrassHopper
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...or should I take off my shoes and count again using fingers AND toes?

MOA @ 2x

MOA @4x

MOA @ 6x


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Basically what I did was took the reticle numbers from Vortex's website on their D-Back/Viper 2-7x scopes. Multiplied each number by 7, to get me to 1X magnification. Since I figure most of the time I'll have the scope set at 2x power, 4x power for open field hunting, and 6x power for possibly p-dog hunting at 300-400 yards. I took my 1x power numbers and divided by 2, 4 and 6 respectively.
Does this look right? I'm thinking if I keep with the rifles, or memorize these calculations I can use them for holdovers and rough range estimation at whatever power level I'm using. Since I only plan on the three I listed this should work, right?











Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/03/2009 at 23:43
0311GRUNT View Drop Down
Optics Apprentice
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get an optic with ffp and mildot and you will have much less math my friend....easy to use...in fact it is "Grunt Proof"
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2009 at 01:49
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Optics Jedi Knight
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Another way of checking your maths is:
 
Set up a target with with a 1 inch grid (several available on a Google search) at 100yds
Place your rifle on a solid rest and bag it so it will not move.
Set your scope on the 2X and observe through the scope how many inches you get covered at the various points such as in your diagrams.
Dial to 4X and make the same observation.
Dial to 6X and repeat.
This simple excercise will give you the absolute movement for your scope and build confidence.
I think that the magnification as given by the manufacturer is also approx and may not work in a straight maths calculation.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2009 at 01:55
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I think your numbers are off at 6x.   Double of 2 is 4 but double of 4 is 8 so 800 yds  then 600 is back half way between.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2009 at 07:23
RONK View Drop Down
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Originally posted by Urimaginaryfrnd Urimaginaryfrnd wrote:

I think your numbers are off at 6x.   Double of 2 is 4 but double of 4 is 8 so 800 yds  then 600 is back half way between.
 
Huh?
 I checked his math and it all worked out for me, and I think his method is sound.
 The fly in the ointment though, is whether the manufacturer actually makes the reticle to spec, and whether the magnification ring is marked to the true magnifications, and whether the glass is set up to magnify exactly as spec'd on the advertising literature. Many scopes are not true to the magnification specs. A scope advertised as a '2-7x32" may in reality magnify, say, 2.3-6.8X (Just pulling random numbers out of the air to illustrate my point.) 
 Wouter is right, a grid at carefully measured distance will reveal the difference between theory and reality.
 
Edited to spell "carefully" without the "W"!


Edited by RONK - December/04/2009 at 07:26
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2009 at 07:26
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Optics Jedi Knight
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What 8's said. The power numbers are a guide and not the true level of magnification. A 3-9 scope could actually be a 2.7-8.6 even though advertised as a 3-9. If you are going to use the plex reticles in this manner you should set up a scale and measure your specific scopes properties. Only then will your math will work properly.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/04/2009 at 07:56
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Optics GrassHopper
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Grunt,

Copy that. I just haven't found any FFP scopes I like for a general "do-everything" scope, that also won't force me to sell a major organ in my body.  
I'm taking fast on target, low-light, etc. into the equation. I'm not sure mil-dot will do that for me. I'm thinking plex or some sort of BDC in a low power scope, I think plex would be the best KISS variable scope out there, but I'm being tempted by some of the BDC scopes for hunting small vermin in the 300-400 yard range.
Anyway, I also intend to purchase a fixed 10x or 12x with mil-dot for more precise longer range rodent and paper killing.

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RONK and 3_tens,

Right, I did know about the magnification not necessarily being correct. I've run into some of the Leupold scopes having some seriously "fudged" numbers.


8,

I also know about this other method of measurement you're talking about. But since I don't own the scope I'm just looking for something to get me on paper before I purchase. Trying to make sure I buy what I want, then I'll likely use a more precise method to verify reticle dimensions.

---

A true 1-4x is probably what I really want. But if I can stuff some shorter range verminating into a low power variable I'll do it. That's why I'm leaning toward a 2-7x or 1.5-6x 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/05/2009 at 08:39
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Optics GrassHopper
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Vortex got back to me. They said the magnification levels are "very, very close". Which is good enough to give me a general idea of reticle dimensions. If I do get these scopes I'll still use the more precise paper method to verify my dimensions.

I'm still trying to decide which scope, and still shopping around. I started shopping FFP scopes, so far I haven't found any in a lower power level, that don't cost upward of $800 each. And since I need two and would like a third hot spare, that is getting expensive.

Paul at Vortex also told me they will have a 1-4x Viper coming out which will have an illuminated reticle. I might hold off for the time being and see how it turns out.

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