dotsep calculation

If you have a first-focal plane (FFP) reticle, your dot separation remains constant and you use the same calculations throughout your magnification range. If your reticle is on the second focal plane (SFP), it will only be 'true' at one magnification (usually max).

An easy way to tell is just to look through the scope while changing the magnification. If the reticle changes size when you change magnification, it's FFP. If it doesn't it's SFP.

GsT