GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Optics, Range estimation & related subjects => Topic started by: truck on December 25, 2018, 12:18:40 PM
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I have this scope https://airgunopticsplus.com/collections/scopes/products/discovery-optics-vt-2-4-5-18x44-sfir-side-focus-illumination-mil-dot-reticle-rifle-scope-with-sun-shade
How do I do the math to use those mil dots?
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Barry,
I use gun-chair to get my hold-over/under.
see discovery website for better detail of the Mil-dot on the scope.
http://www.discovery-optics.com/index.php?m=Product&a=show&id=147 (http://www.discovery-optics.com/index.php?m=Product&a=show&id=147)
Discovery also says the true Mil-dots are set to 10X on the scope.
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You will need to know the velocity of the pellet to know exact holdovers. Before I had a crono, I used info on the gun I was shooting from youtube reviews and reports from shooters here.
What gun are you sighting in ? Im sure we can get you shooting long range in no time ;)
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According to the Ad you linked, the MilDots are accurate at 10X.... That scope is only 4.5 - 18X, and it's a SFP scope, so the distance between the Dots will change as you zoom the scope.... One MilDot is 3.6" at 100 yards (3600 inches) because a true MilDot is an angle equal to 1/1000, ie 1" at 1000", 1 ft. @ 1000 ft. etc.etc….
If you set your maginification to 10X, then the MilDots should be accurate.... At 4.5 X the distance between them at 100 yards will be (10 / 4.5) x 3.6" = 8".... and at 18 X at 100 yards they will be (10 / 18) x 3.6 = 2" apart.... How that relates to your trajectory depends on the pellet, velocity, scope height and the range you are sighted in....
Hope that helps....
Bob
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Here is a video on using mildots.
https://youtu.be/9X3SLslalJE
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Now I have a better understanding of how to use mil dots. Thanks.
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This is exactly why I have switched to FFP scopes . No math required .
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This is exactly why I have switched to FFP scopes . No math required .
The same math is required for SFP or FFP.
The only difference is that you will not need to factor in the magnification when zooming on a FFP scope. I'm mostly using FFP scopes now.
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This is exactly why I have switched to FFP scopes . No math required .
I actually really love the math. It's the only thing I actually like applying math for. As Bob details above reticle subtension is inversely proportional to magnification in 2FP optics, and the "mil-ranging formula" defines rangefinding with any angular system from mil-dots to plex reticles to archery sight pins (if one wishes), and also defines downrange zeroing as well. Some pretty amazing things can be accomplished by applying math in the field sometimes.