Unforunately that is a "feature" of the ArmA 2 engine that Iron Front shares. Trust me when I say many MANY people have complained about it but nothing has officially been done about it because it'd probably involve a rewrite of the post-processing system. There are some third-party mods that disable it in ArmA 2 but none have appeared for Iron Front yet.
"Rock crushes scissors ... but paper covers rock, and scissors cuts paper! Kif, we have a conundrum." - Zapp Brannigan