light Foliage provides concealement, not cover.

Tree trunks though are cover.
50' of foliage would suggest you cannot even see the target, thus, total concealement, which is a -5 attack penalty.
ie, you couldn't even see a man through 50' of light brush/tall grass and plants unless you
a) spotted him (Perception check)
b) he was wearing bright coloured/shiny metal
and it was brightly lit, and the light playing directly on him.
c) he was not trying to remain hidden or the foliage wasn't very high.
Long time ago, me, my pals and local friends (grown men, lol) were playing tag in local woods, re-living our childhood (we're still big kids, hehe).
One fella stood right by me without even seeing me, crouched at the bottom of a tree, until I grabbed his ankles...he screamed, lol
