So with lumens being the total light output, does Lux roughly equate to candle power/ intensity of the light?
I get lumens, but the Lux/Candella that I don't fully 'get' just yet.
Thanks
Lux is a measure of how bright the target looks to you. Its the lumens per square meter....so the more lumens you send into a square meter of target, the brighter the target looks to you.
The equivalent Lux at one meter is the candela (cd) rating for the light. This is a way of standardizing the specs.
So if a light puts 10k lux on a target one meter away, it's rated at 10k cd.
Examples:
If the beam angle is the same, for a given range, if I double the lumens it will double the lux (Because I am sending twice the lumens per square meter).
If I want to keep the lux the same at that range, I can make the beam angle wider, to spread the added lumens out over twice the area (So I end up with the same number of lumens per square meter).
The lux will decrease with range, so more distant targets are progressively dimmer.
The targets will look one quarter as bright at double the distance. (4X DIMMER at 2X distance)
That means that the 10k cd light in the above example, with 10,000 lux at one meter, would have 2,500 lux at 2 meters, and 625 lux at 4 meters, 6.25 lux on a target at 40 meters, and 1 lux at 100 meters, and, finally, 0.25 lux at 200 meters, and so forth.
The ANSI standard uses a 0.25 lux limit as defining a light's maximum range...so, if a light is advertised with a 200 meter range, that means it's rated at 10k cd, and so forth.