EDUCATE YOURSELF

General FAQs:

Q: What's the difference between "lumens" and "lux"?
A: Lumens measure the total amount of light output from a particular source. Lux measures the intensity of the light hitting a specified area. For example, an ordinary household lightbulb generates about 1000 lumens, but the intensity of its light at a particular point, such as on a book you're reading, will be comfortably low. Almost all flashlights rely on an optical device such as a reflector or lens to squeeze most of their output into a small area, which allows you to illuminate a point of interest with enough intensity, but without requiring a lot of power. To illustrate this concept, try the following: First, look at your room's ceiling light. In all likelihood, you can stare at it without much discomfort. Now, try looking into a weak flashlight like a traditional incandescent Mini-Maglite. You'll notice that it seems very bright. This is lux. Now, remove your Minimag's head to put it into candle mode. Try switching between its output and your ceiling light's output. Since they're now illuminating approximately the same area, the much higher lumen value of the ceiling light will provide much higher lux values at a chosen point. An extreme example of high lux and low lumens is a laser, which doesn't really create that much light, but focuses it into a tiny, brilliant point.

Q: What are "CCT" and "CRI"?
A: CCT stands for "Correlated Color Temperature" and CRI stands for "Color Rendering Index." CCT is expressed in terms of degrees Kelvin, corresponding to the temperature of a black-body radiator (such as the Sun) at that color temperature. For example, a black-body radiator heated to about 8,000 degrees Kelvin would appear slightly bluish, so a light (an MH HID, for example) with a CCT of 8000K would have a bit of a bluish tint to it. CRI is expressed as a number from 1-100 and refers to how well a light source reveals colors regardless of its CCT. For example, a power LED that creates blue light that is filtered through a yellow phosphor to end up with white has no red component, leaving red and yellow objects slightly faded. This will lead to a low CRI rating. Incans, on the other hand, generally have a CRI of around 100, as they emit all spectra of visible light (as well as IR and UV light).


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