Light Output Versus Beam Distance Part 2 of 3



Light Output Versus Beam Distance Part 2 of 3

Why is this possible?  Because Light Output is simply a raw measure of the rate at which a light source generates light – i.e., how many photons, how much “luminous flux,” the source generates per second.  It tells nothing about how well or poorly that light is gathered and directed.  Beam Distance, on the other hand, is a measure of the maximum distance from which an optimally focused flashlight will cast a useful amount of light on a target.  The ANSI Standard effectively defines a “useful level of light” by prescribing that the Beam Distance is the maximum distance at which the flashlight will produce ¼ lux of light.  A quarter of a lux can roughly be described as the light level provided by a full moon in an open field on a clear night.  That’s not as bright as day, but it is bright enough to see by – a good, standard, working definition of a “useful level of light.”
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