Lumens

In the world of tactical flashlights, nothing seems to be more frequently cited yet so commonly misunderstood than Lumens. A Lumen is the internationally accepted unit for measuring “luminous flux”, the amount of light produced. This is very different from “brightness” or luminous intensity which is measured by the Candela.

Statements such as “900 lumens is too bright” are often heard although such a statement is a nonsensical categorical error much like saying “900 amps is too much voltage”. A quantity of light, say 900 lumens (the amount of light produced by an Elzetta High Output Charlie-Model Modular Flashlight), may be concentrated into a tight beam or it may be spread out in a very wide diffuse pattern. In the case of the tight beam, the light will be intense (bright). In the case of a wider pattern, however, the beam will be spread out to cover a larger area and thus the intensity (brightness) will be reduced.

This concept may be easily understood using a fire hose or even a common garden hose with an adjustable nozzle. Turning the nozzle changes the water discharge pattern from a focused stream to a wide spray. The flow rate of water (measured in gallons per minute) is the same regardless of the discharge pattern yet the intensity varies greatly. The preferred pattern depends on the application. If projecting water a long distance or blasting mud off a dirty wheel is the goal, a concentrated stream works best. If rapidly wetting an entire car or watering a garden is the objective, a wider softer spray is vastly superior.

The same is true for tactical flashlights. A given amount of lumens may be discharged in a concentrated beam or a wide diffuse beam. The lumen output (flow rate) is the same regardless of the beam pattern yet the intensity (brightness) varies greatly. The best pattern depends on the application. If illuminating objects far away or overwhelming an assailant with ultra-bright light is the goal, a narrow concentrated beam works best. If lighting up a large area or quickly gaining situational awareness is the objective, a wide diffuse beam is superior.

The photographs in the attached illustration may better establish the above exposition and analysis. Just as one would not use a hose with a narrow high-pressure stream to water a flowerbed or use a wide fanned spray to reach the top of a burning building, the wrong beam pattern from a high-lumen tactical flashlight can also be counter-productive. Maximum performance demands that a flashlight’s beam pattern be properly matched to the application. When selecting the appropriate flashlight, first define its intended use. Next determine what type of beam profile will best serve that utility. Then, select a flashlight that produces the desired beam profile. Whatever your mission, always select the right tools for the job.

Water Flow Analogy for Lumens