Second Focal Plane (SFP)

With SFP riflescopes (Second Focal Plane), the reticle always remains the same size.
 The holdovers are only correct at a certain zoom level, but the reticle always remains clearly visible.

FFP (First Focal Plane), on the other hand, increases or decreases the reticle size when zooming in. The reticle sometimes becomes very small, but the lines for the aiming point remain correct at every zoom level.