Light output, reported in lumens, is determined by the total amount of light coming out-the-front (OTF) of the flashlight, which is related to the LED’s efficiency and how much power it uses.
Typical output of a ultra-high outputLED flashlight.
Typical output of a high-output LED flashlight.
Typical output of a mid-range LED flashlight.
Typical output of a general purpose LED flashlight.
Peak beam intensity, reported in candela, represents brightness as perceived by the human eye and is related to how the beam is focused by the optical system (typically a reflector, lens, or optic). Our perception of brightness is non-linear, and for a light to appear twice as bright as another, its beam intensity has to be four times that of the other light.
Typical intensity of a tightly focused LED flashlight or spotlight.
Typical intensity of an LED flashlight.
Typical intensity of an LED worklight.
Beam Pattern (Candela/Lumen Ratio)
Beam pattern describes the relationship between light output and beam intensity. Tight beams are great for illuminating distant objects, but a bright hotspot can be blinding when used indoors, so it’s important to pick a flashlight with the right type of beam.
Deep smooth reflectors or total internal reflection (TIR) optics produce spot beams that are optimized for outdoor use.
Shallow smooth reflectors, orange-peel textured reflectors, hybrid smooth/textured reflectors, or TIR optics diffuse light into a larger hotspot.
Shallow reflectors give off a wide area of light, which is typically found on work lights and best suited for indoor use.
Some reflectors or optics can be adjusted for a variable spot to flood focus, but usually introduce artifacts, such as rings or holes, into the beam.