Math behind

NoFucks2Give said:

IF it's so fuckin' easy, show me the math on how to get the PPFD from the LED datasheet.
I'm still waiting for you to show me the math used in Alesh's spreadsheet. If it's so fuckin' easy WTF is your problem in producing the math?

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The math is already there. What would I even need to produce?

The point is that you obviously have too much trouble to understand "the math", so why bother when you don't need to? Besides you are really poor at math. You keep making mistakes when you need to perform a few calculations in a row.

Like I said, why not simply measure the PPFD and the lux values using that spectrometer and calculate the factor by dividing lux by PPFD? THAT is what's easy.

wietefras said:

No, the SI symbol for Mole is mol.

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Do you even fuckin' read??????????????

NoFucks2Give said:

Mole is an SI unit of measure. mol is the unit symbol or abbreviation

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Are you saying a Mole is not a mol? Is one Mole not equal to 1 mol? You really need to pull that stick out of your ass.

NoFucks2Give said:

The metrics have their place. It's me that does not find them useful in selecting LEDs or grow light fixtures.

How do you feel about the charlatan grow light vendors that publish the PPFD with a spectrometer or PAR meter when they did the measurements at six inches. Or are you on the same boat as @wietefras where the distance does not matter.

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CONTEXT matters!

We mentioned very specific situations where distance doesn't matter
1) When you want to convert from lux to PPFD, the distance doesn't matter.
2) Or as CobKits said, when measuring PPF in a sphere, then distance doesn't matter.
3) alesh and I explained that there is no "standardized" distance for measuring PPFD

The notion that you can use a PPFD spot measurement to get PPF is nonsensical. The only way to do that is to measure a huge matrix of PPFD values over the whole lit area. That would be a flat plane integration.

NoFucks2Give said:

Do you even fuckin' read??????????????



Are you saying a Mole is not a mol? Is one Mole not equal to 1 mol? You really need to pull that stick out of your ass.

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I'm saying the symbol to use is mol and not Mole or Moles. You keep using "Mole" as the symbol. That's retarded.

BTW, way to go with the deflecting again. The point is that your use of terminology, units and symbols is a mess. Be more precise in the symbols used and things will be a lot more clear. Or at the very least your mistakes will be more obvious.

NoFucks2Give said:

The metrics have their place. It's me that does not find them useful in selecting LEDs or grow light fixtures.

How do you feel about the charlatan grow light vendors that publish the PPFD with a spectrometer or PAR meter when they did the measurements at six inches. Or are you on the same boat as @wietefras where the distance does not matter.

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The distance to me is more about inconvenience in moving your lights on a daily basis to service the plants and also adjust for vertical growth. The last thing I want is a fixture so close to my plants that if I don't make it to adjust the light every day they may grow into the light and burn.

My ideal mounting heights are 18"-24" in a tent and 30"+ in an open room/commercial facility.

wietefras said:

Like I said, why not simply measure the PPFD and the lux values using that spectrometer and calculate the factor by dividing lux by PPFD? THAT is what's easy.

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I do that and it works well. What does not work well is the numbers from the spreadsheet.

wietefras said:

The math is already there. What would I even need to produce?

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Please explain why in column E, B2 over photon energy is used, and then in cell F4 column E is divided by column B?
Does that or does that not negate the digitized SPD numbers?

I don't understand the math???? I have a post there going through the spreadsheet step by step. Point out the errors. If it's so goddamn simple for you to convert lumens to PPFD show me my errors. Explain where I may have misinterpreted how to go from photon count, to photon energy, and on to luminous flux. Show me the math how to convert one µMole at 660nm to lumens. I showed you you how I do it. Where did I make a mistake? Newsflash, I did NOT make a mistake. I verified my calculation with measurements. Really I dare you. Show me how you convert µMoles to Luminance.

Stephenj37826 said:

The last thing I want is a fixture so close to my plants that if I don't make it to adjust the light every day they may grow into the light and burn.

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That's not the issue.. I'm taking about the specification for a grow fixture.

For example your spec on one of your fixtures is PPFD 887 umol/sec/m2 in a 4X4 area
I guess you ARE on the same boat. You do not specify the distance. Is the 887µmol measured with the fixture at a specific height?

Do your fixtures magically put out the same PPFD at 24" as they do at 18"???

Whereas Heliospectra specifies a height of 18" in their PPFD spec.

Fluence says:

wietefras said:

The notion that you can use a PPFD spot measurement to get PPF is nonsensical.

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Jesus Fuckin' Christ!!
I told you yesterday that you cannot convert between irradiance and radiance and now you are going to flip flop and tell me the same thing? I also have said over and over PPF is useless, irradiance will not give me the radiance at the leaf. I DO NOT want PPF. I want nothing to do with PPF. Irradiance is shit.

wietefras said:

I'm saying the symbol to use is mol and not Mole or Moles.

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You did not answer my question. Is one Mole equal to 1 mol? Is one µMole equal to 1 µmol?
That stick up your ass must be really big to bitch about mol vs. Mole. There is NO DIFFERENCE between the two, one is a symbol for the other. Do you mean I have to use the symbol λ and cannot use the word wavelength? Fuck off!

NoFucks2Give said:

Jesus Fuckin' Christ!!
I told you yesterday that you cannot convert between irradiance and radiance and now you are going to flip flop and tell me the same thing? I also have said over and over PPF is useless, irradiance will not give me the radiance at the leaf. I DO NOT want PPF. I want nothing to do with PPF. Irradiance is shit.

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No the problem is that you don't (want to) understand what you are doing wrong. So you insist everybody is saying incredibly stupid things, but it really is you who is making the mistakes.

Again, CONTEXT matters.

You said that QER doesn't exist. I said it did. In turn you translated that into "So you're saying irradiance and radiance is the same". I was not saying that at all. It's your own lack of understanding which is throwing you off. Just read properly and understand before you start screaming.

You did not answer my question. Is one Mole equal to 1 mol? Is one µMole equal to 1 µmol?

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The problem is that you keep making a complete mess of your calculations. You are mixing up units and symbols all over the place. Just learn to consistently use the correct terms, units and symbols and you will hopefully be less error prone.

NoFucks2Give said:

That's not the issue.. I'm taking about the specification for a grow fixture.

For example your spec on one of your fixtures is PPFD 887 umol/sec/m2 in a 4X4 area
I guess you ARE on the same boat. You do not specify the distance. Is the 887µmol measured with the fixture at a specific height?

Do your fixtures magically put out the same PPFD at 24" as they do at 18"???

Whereas Heliospectra specifies a height of 18" in their PPFD spec.

Fluence says:

If you want to find out the true light intensity of a lamp over a designated growing area (e.g. 4’ x 4’), it is important that the average of several PPFD measurements at a defined height are taken. Lighting companies that only publish the PPFD at the center point of a coverage area grossly overestimate the true light intensity of a fixture. A single measurement does not tell you much, since horticulture lights are generally brightest in the center, with light levels decreasing as measurements are taken towards the edges of the coverage area. (Caveat Emptor: Lighting manufacturers can easily manipulate PPFD data. To ensure you are getting actual PPFD values over a defined growing area, the following needs to be published by the manufacturer: measurement distance from light source (vertical and horizontal), number of measurements included in the average, and the min/max ratio). Fluence always publishes the average PPFD over a defined growing area at a recommended mounting height for all of our lighting systems.​

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That is the average of the fixture. PPFD is the average ppf per m2. Total Photon count is very relevant especially once you are in a confined reflective area such as a tent. For instance bare cobs would be preferable in a tent but not so much in an open area. As stated earlier goal #1 is to create as much light as possible in a given spectrum per watt. Once you have that you then worked on light distribution. How you want the light to spread is dependent on each growing situation. So to say there is a one size fits all approach is not optimal.

A good example is Nextlight here

http://getnextlight.com/nextlight/index.php?route=information/information&information_id=19

NoFucks2Give said:

Please explain why in column E, B2 over photon energy is used, and then in cell F4 column E is divided by column B?
Does that or does that not negate the digitized SPD numbers?

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If you want to understand the math, everything is explained in the first few posts of this thread.

You are completely misunderstanding the point of "the math". It's goal is to get the QER and LER from the SPD. Which can be used to calculate the conversion factor (LER/QER)

Just insert the relative SPD data you measured, into column B and you will get the QER and LER.

You cannot convert one Mole at 660Nm to lumens. That's a nonsensical question. The units don't match.

You could however create an SPD with only 660Nm and then you would get:
LER = 41.663122lm/W
QER = 5.517169159µmol/J

luminous to PAR conversion factor would then be 7.551539711. So a light source producing a PPF of 1µmol/s from only 660nm would be producing 7.551539711lm.

wietefras said:

When you want to convert from lux to PPFD, the distance doesn't matter.

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wietefras said:

The notion that you can use a PPFD spot measurement to get PPF is nonsensical.

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Do you understand you are contradicting yourself???

How is converting lux to PPFD different than converting PPFD to PPF???

Just like "the notion that you can use a PPFD spot measurement to get PPF is nonsensical." So is converting lux to PPFD. Why in the fuck would anyone care about PPF?? Or Lux? I use the word Lux and I use it improperly because I like the word and no one understands I am using it improperly. Otherwise you and the stick up your ass would have called me out on it.

wietefras said:

Or as CobKits said, when measuring PPF in a sphere, then distance doesn't matter.

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What is the radius or diameter of a integrating sphere? Any standardization there? They all kinda look to be the diameter. Is there some reason for that? And the little ones, is there anything different about the measurements from the little spheres?

BTW I also don't give a fuck about sphere measurements. That's for light bulbs not LEDs. I do not give a shit how the light scatters. It's a bullshit measurement for manufacturers to exaggerate their specs. All I want to know is how many photons reach the leaf. WTF do you not understand about that???

What they give me:


What I want.

wietefras said:

If you want to understand the math, everything is explained in the first few posts of this thread

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No everything is not explained. Some formulas pasted from Wikipedia does not tell me why in the fuck B2 is in the E column formula then again in the F4 cell. That part is not in the "explained in the first few posts of this thread". Or if I'm wrong point out to me where in the first few posts (or why) the SPD gets cancel out in F4.

I don't think you understand any of the conversion formulas but you have no problem telling me I do not understand them but you do not do so with anything substantial except your big fuckin' mouth.

I'd agree with you, but then we'd both be wrong so could ya just fuckin' try to not be ignorant all your sorry-ass life, making your ass jealous of the shit that comes out of your mouth, and acting like your arrogance is a virtue. You must have delusions of adequacy.

QQ a little more.

I'm with @The Dawg on this one...

NoFucks2Give said:

Do you understand you are contradicting yourself???

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I'm not contradicting myself. Not there at least.

How is converting lux to PPFD different than converting PPFD to PPF???

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lux and PPFD are both irradiance measurements. So no problem converting between the two. PPFD and PPF are irradiance and radiance respectively. So those cannot be converted.

Also PPF and lumen are both radiance, so these can be converted. With the same conversion factor as used for converting between lux and PPFD.

This is exactly why I keep harping on about the need to consistently use the correct units and symbols. It's the basis of everything. If you get that wrong, nothing will make sense. Not to you and honestly not to us either. We constantly have to keep guessing what you actually measured or meant to say.

You said you measured 3000 lumens. You did not. You use a spot measuring device, so you are measuring irradiance which would be expressed in lux (which is lm/m2).
You said you measured 65 µMoles. Which really makes no sense at all. You probably meant 65 µmol/s/m2 and that's comparable to that measurement in lux.

NoFucks2Give said:

No everything is not explained.

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Yes, it really is.

I don't think you understand any of the conversion formulas

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I understand them perfectly fine. Which is why I had no trouble applying your poorly formed question after turning it into something that actually can be answered.

Just post your SPD data in column B and get the QER and LER results from the sheet. Why on earth must you insist on understanding something which you clearly are not able to understand? What's the point? How does it make everyone else idiots if you cannot understand what it says?

I've been dealing with your shit for over a week now, so yeah after a few days of your abuse I started getting irritated and I treat you back the way you treat me.

If you can't understand it, just let it go and work with what you actually can deal with. Stop this madness already.

wietefras said:

You cannot convert one Mole at 660Nm to lumens. That's a nonsensical question. The units don't match.

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I can, it's you that cannot. You do not even understand that is is NOT nonsensical.

Fuck!, you are a hoot. "The units don't match". Of course they don't match that why they need to be converted.
Are you brushing up on your ignorance? If you keep talking do you think someday you may say something intelligent?

So you do not understand the math. The spreadsheet has to do the conversion you call nonsensical. Notice how each row of the spreadsheet represents a specific λ? How does the spreadsheet get from the digitized SPD number to lumens in cell F2? What is the unit of measure for the SPD number in column B?

100 lumens @ 660nm = 2.400 watts    
100 lumens @ 660nm = 13.243 µMoles

1 µMole @ 660nm = 0.181 W   
1 µMole @ 660nm = 7.55 lm 

One Mole at 660nm = 4546 Sextillion lumens, plus or minus a few

NoFucks2Give said:

1 µMole @ 660nm = 7.55 lm

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No, that makes no sense. One is an absolute amount of photons and the other is a function of time.

Learn to USE THE CORRECT SYMBOLS AND UNITS!

What I said was 1µmol/s @ 660nm = 7.55 lm and that is correct.

You're welcome.