If you are talking about the group with the torch being 50' into the forest, then I would still make it fairly easy - so long as the people outside weren't too far a way. If they are right outside the forest (say up to 50') then the torch should still grant them a bonus to see the group (+15 to + 30, maybe more). This is assuming it is all occurring at night. During the day, the torch probably wouldn't make any difference at all. Of course, none of this is taking into consideration the lay of the land, hilly, flat (though very few areas are truly flat), mountainous, etc. More modifiers.