If you've ever tried to compare flashlights or lighting of any kind, you've probably been confronted with a bunch of confusing terms like lumen and lux that are supposed to describe how powerful a light is. Well here they are explained in a single image.
The above image, posted yesterday by the folks at Urban Velo explains everything you need to know about the common terms lumens lux and candela. They're obviously thinking about these in terms of bike lights (which you should obviously be using if you ride at night), but they're applicable to everything from flashlights to lightbulbs. [Urban Velo]