The binning of LEDs is a practice used by LED manufacturers to manage the variation of LED performance that is inherent in the mass production. LEDs of similar appearance to the human eye are put in different boxes, or bins. LEDs from the ‘best’ bins are more expensive. Additionally LED manufacturers often operate slightly different binning policies from each other.
Ceramic metal halide (CMH) lamps combine high output with great colour rendering and good efficiency. They produce light by passing an electric arc through a mixture of gases. In a metal halide lamp, the compact arc tube contains a high-pressure mixture of argon, mercury, and a variety of metal halides.
Light emitting diode lamps are flavour of the month, and deliver big energy savings, good colour rendering, dimmability and a long life. The best ones are difficult to distinguish from incandescent lamps. But they come with a hefty price tag – of up to £30 a lamp. And many Chinese versions are, well, rubbish.