Hey guys I have a question about lumens. Iam currently running a 400 w hps and I also have cerventes grow bible And it states a 400 w hps 1 foot away its apox. 50000 lumens but I usually keep my girls about 3 in away so how many lumens would that be ????
So, with the given charts, at 4 inches, 143,239FC (foot-candles), which is 1,541,251.64Lux. Now, to reevaluate your lumen output: lumens=1,541,251.64*<your square footage>/10.76
Well, you're not completely done yet.. Lumens is an extraordinarily inaccurate way of measuring light output for such applications as growing. Lumens only refers to the intensity of light energy in the spectrum visible to the average human eye. You still have to deduct what would fall outside of this curve. This measurement is more geared toward home lighting.
Ohhhhh even more information I will defiantly have to take this under consideration, I have heard they have light meters than can measure all the different type of stuff ! But I have not really looked into it yet this question came to me when I was reading that book high..... And well you know how that goes