kelvin? lumens?

can anyone explain how this works i found led's that produce 3 lumen @ 9900k and other led's that produce 12 lumen @ 8000k...well all i found all types of convinations...... now i know that kelvin is the way to measure light but what i wanna how do lumens affect color? is more lumens brighter? does more lumens change color?"JaXtEr"

Kelvin is the color temp. Its based on a black body radiator. 9900K would be the color the black body radiates when heated to 9900 degrees kelvin. For reference, 3500k would a yellow-ish (halogen) light. 5500K-6500K would be milk white. Higher color temps look blue-ish (HID) and even higher, 9000+K start to look purple. The lumen is, in simplest terms, the brightness. More lumens, brighter light. They are two independent specs. Not necessarily related to each other. The InGaN wafer determines the brightness and the phosphor coating determines the color temp. There are manufacturing variances so leds are tested and sorted by color temp, brightness and forward voltage. When buying in large quantity you can specify almost any color temp and lumen output (up to 900 lumens) and the manufacturer will sort and bin a reel for you.

LEDs are usually rated in MCD are they not? (Milli-candela) Ive never seen them list lumen output.

bigjohnny wrote: LEDs are usually rated in MCD are they not? (Milli-candela) Ive never seen them list lumen output.

Small leds are rated in MCD. Large leds 350mA - 2.8A are usually rated in Lumens. Its sort of like voltage vs current. One is an intensity (mcd) the other is a quantity (lumen).