Second Focal Plane Reticles
A Second Focal Plane, or SFP, reticle stays the same size regardless of the power setting. The reticle on a SFP scope will subtend, or cover, a set distance at only one power setting and will cover less of the target at the highest ranges. March Rifle Scopes using reticles in the second focal plane have some of the highest usable power settings available on the market today.Dot pattern reticles do not change size as the magnification changes. However, the size of the area covered on the target covered by the dot will change. Each March Scope has a standard magnification where the apparent size of the Dot will match the reticle fitted to your scope.
Standard magnification of a dot reticle in SFP scope is :
48x (48×52, 40-60x52EP zoom), 32x(5-32×52), 40x (10-60×52, 10-60×56, 5-50×56, 8-80×56), 10x (1-10×24), 25x (2.5-25×42)
For example, 1/8MOA dot is 1/8MOA @40 power for 10-60×52. 1/8MOA dot @20 power will be 1/8MOA x (40/20) = 1/4MOA.
The formula is : (Nominal dot in MOA) x (Standard Magnification of Dot in MOA) / (Current Magnification)
Please click HERE for SFP Dot reticle.
This formula can also be used with other reticles that use hash marks or dots to determine target coverage or distance to the target.
You can learn more in our SFP manual. https://marchscopes.com/sfp_man/#target/page_no=33
You can also check the line thickness from HERE.