player.cpp
int player::overmap_sight_range(int light_level) const
{
int sight = sight_range(light_level);
if( sight < SEEX ) {
return 0;
}
if( sight <= SEEX * 4) {
return (sight / (SEEX / 2) );
}
if ((has_amount("binoculars", 1) || has_amount("rifle_scope", 1) ||
-1 != weapon.has_gunmod("rifle_scope") ) && !has_trait("EAGLEEYED")) {
if (has_trait("BIRD_EYE")) {
return 25;
}
return 20;
}
...etc
Download the source and use notepad++ to search with better results.
Also, this is first time I was made aware that rifle scopes can be used as binoculars in the game 