Rahz' notes and observations

CobKits

Well-Known Member
So then what is the conversion for "LED" and where is it listed? I have not seen this for "LED" only Metal Halide, HPS, Fluorescent, etc. I'm not trying to troll here asking a legitimate question.
there is no one LED spectrum
 

alesh

Well-Known Member
I had heard something in another lighting group circle that raised an eyebrow...
Is it possible for there to be two light sources with an equal lumen, lux, par, "output" but yet being at different "frequency".
Yes, it's possible. Two different sources can have equal luminous flux, equal radiant power and even equal photon flux and yet different SPD. Generally it's not the case, though.

So then what is the conversion for "LED" and where is it listed? I have not seen this for "LED" only Metal Halide, HPS, Fluorescent, etc. I'm not trying to troll here asking a legitimate question.
Different SPD means different "conversion factor". You have to use a different one for every LED. And this applies to any light source. There's no universal conversion for all HPS, MH, fluorescents.
 

Evil-Mobo

Well-Known Member
Yes, it's possible. Two different sources can have equal luminous flux, equal radiant power and even equal photon flux and yet different SPD. Generally it's not the case, though.


Different SPD means different "conversion factor". You have to use a different one for every LED. And this applies to any light source. There's no universal conversion for all HPS, MH, fluorescents.
Oh ok this makes more sense to me. See I thought the HPS,MH, etc values were all standard. Thanks for the clarification
 

OneHitDone

Well-Known Member
Yes, it's possible. Two different sources can have equal luminous flux, equal radiant power and even equal photon flux and yet different SPD. Generally it's not the case, though.


Different SPD means different "conversion factor". You have to use a different one for every LED. And this applies to any light source. There's no universal conversion for all HPS, MH, fluorescents.
I believe what @Evil-Mobo is referring to is this

https://www.apogeeinstruments.com/conversion-ppfd-to-lux/
 

alesh

Well-Known Member
Oh ok this makes more sense to me. See I thought the HPS,MH, etc values were all standard. Thanks for the clarification
They're...kind of standard. For example, HPS's of the same technology from various manufacturers usually have quite similar SPD so single conversion factor can be used. Margin of error is as big as is the difference in SPD.
 

lukio

Well-Known Member
someone once told me for 3000k leds, i can divide lux by 69 for a rough guide. so 55,000 lux would be 55,000/69 = 797 ppf. is this this right- ish?

should i just buy a par meter? they're bloomin expensive
 
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