Dang, who is this Zak guy? Seems like a huge nerd.

(spoiler: he's the admin of /r/flashlight, an expert on lighting, a widely respected reviewer, maintainer of the community's quarterly "arbitrary list of popular flashlights", author of "ceilingbounce" for measuring torch brightness over time, and someone who calls himself a "huge nerd" ... so yeah, he knows a thing or two)