Originally Posted by
Burton
Sensitivity aside - light intensity is still inversely proportional to the square of the distance. So effectively - if you want twice the reach of a 500 lumen light - you need four of them ( or one 2,000 lumen light. And if you want three times the reach - you need nine of them - or one 4,500 lumen light.
Or one that's focused to a tighter beam. It still will go as the one over the square of the distance, but if it has 1/2 the angular spread, it will be the same intensity at twice the distance.