To understand the advertising about lights which claim “80 lumens” or “1,000,000 candlepower,” you need to understand what those things are. To put it simply, lumens are a measurement of how much light a device produces, and candlepower is a measurement of concentration of the beam a device produces. These are not the same thing.
To use an analogy, imagine you have an adjustable water hose that shoots out 80 gallons of water every minute, and that those 80 gallons of water are spread out in a 6-ft. wide cone so that if you sprayed a wall for 1 minute, every square inch of wall would get about 2.5 oz. If that hose were a light, you could think of the 80 gallons as 80 lumens, and the 2.5 oz. of water per square inch as the candlepower. However, let’s say that you adjust your hose so that it shoots the same 80 gallons of water per minute, but that it is concentrated into a very thin jet that hits a 3-inch circle on the wall instead of the 6-foot one. The wall would still be hit by 80 gallons of water in the course of 1 minute, but each square-inch of the wall would get almost 1450 oz. (around 11.3 gallons) from the jet instead of 2.5 oz. Again, we can think of the 80 gallons of water as 80 lumens of light, and the 1450 oz. as the candlepower.
The important point here is: Just because a light produces more candlepower, that doesn’t mean it produces more light. More candlepower isn’t always better, either – would you use a laser-pointer (which has high candlepower for its brightness) to light up a room? In other words, some flashlights produce a very thin, strong beam which travels for great distances, something that is great for spotting objects a good distance away but very poorly suited to lighting up a general area or searching for something up close. In general, lights that have wide beams good for close-range work are poor for long-range work and vice-versa. A light that has an “in the middle” beam is usually the best choice for most people. Thankfully, fewer and fewer flashlight manufacturers are bothering to rate their products with candlepower, and lumens are being listed more often as time continues. A good rule of thumb is, “Lumens are brightness, candlepower is beam shape. Buy the number of lumens you need with the beam shape for the job.”