All of us have, at some point or another, complained about the use of lumens as a metric – for a variety of reasons. First, lumens are not very accurate as a proxy for perceived brightness. Second, there is a temptation to increase lumens by ‘cheating’, for instance on the chromaticity of a lamp – ponder this next time you are subjected to a depressingly greenish fluorescent lamp! Third, the lumen race pushes the industry to compromise on competing aspects, especially color rendition. If two LEDs emit the same number of optical watts, but one generates more long-wavelength photons to properly render deep-red tones, it is by definition penalized in terms of lumens.