Found a Tundra Winchester, mounted hunting scope, roaming around at night. I could see a player running with flare (100-150 meters?) when looking through the scope at him I could not see the flare or any light caused by it....leaving the scope view I could see the illumination perfectly...of course this was at night.

***word of note...I also was using a night vision scope with battery (just in my hands, not mounted on any gun) and that WAS able to see the same guy and his flare illumination perfectly