Effect of Magnifiction on Reticles

[cowboyarcher]

Hey guys,

Does anyone know the affect of magnification on reticles? I am thinking, if part of a reticle measures 2" at 9x at 100yrds, it should cover 6" at 3x at 100yrds.

Does this sound right?

[geargrinder]

That's it, unless your scope is first focal plane. Then, it covers the same amount at any magnification.

[cowboyarcher]

It's not, that's why I was worried bout it! Thanks! Now I can figure hold overs at both power settings.

God bless,

Adam

[memilanuk]

best take the gun to the range and verify those values against a yard stick or tape measure, lest you find that the scope power as marked on the ring isn't exactly what it says it is...

[frank1947]

I hope to learn something here what do you mean by the scope covering 2" at 100 and 9 at 3x , covering what? is there a formula for this ?

[geargrinder]

Most scope we use are second focal plane. That means that the reticle does not change in size when the magnification is changed.

Let's fully discuss coyboyarcher's example.

At 100 yards with a 3-9x scope.

When the magnification is set at 9x the image is at it's largest appearance and the reticle lines are at their smallest- 2" measured.

Here's the math.

Initial line thickness= T1

Second line thickness=T2

Initial Magnification=M1

Second Magnification=M2


T2 = T1 x (M1/M2) = 2" x (9x / 3x)= 6"

Fhewww. My brain hurts.

[frank1947]

2MIL AT 15X=7.2 INCHES, 4 MIL AT 5X= 14.4 ABOUT 100 YARDS, now what does this tell me about poa or bullet hit difference

[frank1947]

ok i got it at 5x i am 1.8 mil vs 3.6 at 15x this scope ranges at max of 15x , forgive me im in alot of pain today and cant think clearly, i just taked to Nightforce the other day if at 22x 1 hash to the other is 2 moa then at 42x itr is just a tab over 1 moa, I called just to vewrify my thought