Lighting The difference between relative and real spectral power

[L0wbob2017]

Hello folks,

it passed some time since i was active in this forum, but this doesnt mean that i didnt learn anything new.

Something i've come along is the difference between the relative spectral power distribution for LED's / COB's that you can find in their Datasheets and the real spectral power distribution given at a certain power.

At first when i saw comparisions between the relative and the real spectral power distribution i said this cant be true. So i said to myself, i need to learn this stuff and check if it is correct.

The final moment of truth after double-checking 4-5 times came and i am pretty sure i got it correct. ( If not pls correct me )

My personal conclusion of this was, that comparing different color-spectra from LED's / COB's with the given spectrum from the datasheet is the wrong way in terms of light for plants. Dont get me wrong, the relative spectral power distribution charts have their meaning and right to exist, but not in terms of comparing color spectra for plants.

To show you the difference i've made a comparison-chart. I compared the Bridgelux Vero29-C Versions ( 69,4V ) only.
The versions i compared where the following:
BXRC-27G10K0-C-7X
BXRC-30E10K0-C-73
BXRC-40E10K0-C-7X
BXRC-56G10K0-C-74
BXRC-65C10K1-C-7x

and here is the chart:

The dashed lines are the relatives from the datasheet and the normal lines are the real spectral power distribution ( calculated by myself ) at a power of 56,6W.

As you can see, calculating the real spectral power distribution gives a much better overview and is the only way to compare different LED's / COB's in terms of light for plants.

For comparing it for plants, there are some more steps to go, but for all steps you need the real spectral power distribution.

 

[L0wbob2017]

To go more into detail for all COB's here are some values i calculated:

BXRC-27G10K0-C-7X CRI90
56,6 W | 8610 lm | 152,12 lm/W | lightpower 32,08W | efficiency 56,69% | PAR PPF 148,87 µmol/s , 2,63 µmol/J , 17,29 PAR/klx | radiation angle 120° distance 50cm ~ 10900 lx | calc. max PPFD centerpoint 189,55 µmol/m²s

BXRC-30E10K0-C-73 CRI80
56,6 W | 10763 lm | 190,16 lm/W | lightpower 32,32W | efficiency 57,09% | PAR PPF 151,65 µmol/s , 2,68 µmol/J , 14,09 PAR/klx| radiation angle 120° distance 50cm ~ 13700 lx | calc. max PPFD centerpoint 193,08 µmol/m²s

BXRC-40E10K0-C-7X CRI80
56,6 W | 11179 lm | 197,51 lm/W | lightpower 33,73W | efficiency 59,59% | PAR PPF 155,15 µmol/s , 2,74 µmol/J , 13,88 PAR/klx| radiation angle 120° distance 50cm ~ 14200 lx | calc. max PPFD centerpoint 197,54 µmol/m²s

BXRC-56G10K0-C-74 CRI90
56,6 W | 10277 lm | 181,57 lm/W | lightpower 36,98W | efficiency 65,34% | PAR PPF 164,61 µmol/s , 2,91 µmol/J , 16,02 PAR/klx| radiation angle 120° distance 50cm ~ 13000 lx | calc. max PPFD centerpoint 209,58 µmol/m²s

BXRC-65C10K1-C-7x CRI70
56,6 W | 12082 lm | 213,46 lm/W | lightpower 36,06W | efficiency 63,70% | PAR PPF 159,94 µmol/s , 2,82 µmol/J , 13,24 PAR/klx| radiation angle 120° distance 50cm ~ 15300 lx | calc. max PPFD centerpoint 203,65 µmol/m²s

 

[L0wbob2017]

The final step would be to calculate the so called "phyto-lumen" with the unit syn. ( i've done that but i dont think someone cares about the values because the factor used, came from a friend who teached me this and is only used to get nicer values. If someone is interested just pm me).

The problem with this step is, that you need to have an action spectrum for the plant you want to grow.
Also something very important to keep in mind is, that plants use light not only for photosynthesis and optimizing a Lampspectrum for the "action-spectrum" could slow down other processes.

 

[L0wbob2017]

Finally gonna add some ppl i remember in hope of getting some nice input about this

@BigSm0 @pop22 @Mr. Sparkle @iampepe @Baxterwolfe @The Elvis @wwwillie @Dr.Bubbles @KonopCh @archie gemmill @TheMongol

 

[bad dragon bzzz]

heya L0wbob hope you keeping well
big loses for some,small loses for others.i wasnt really expecting that,why you think so ?

 

[L0wbob2017]

heya L0wbob hope you keeping well
big loses for some,small loses for others.i wasnt really expecting that,why you think so ?

Well it depends on how you see it. Personally I would say that they gain when rising the color temperature. The 2700K for example has an almost non visible gain in comparison to the real power at 56,6 watts.

The point is, that for example take the 6500K COB looks pretty normal in the relative color spectrum but if you calculate the real data you can see that the spectral power for the color "greenish" is almost as high as the spectral power of the 3000K COB in the red color.

 

[Dr.Bubbles]

Thanks for the call out. I'm not a lighting scientist...lol...but, I know for a fact I love me some KAAAHBS. Long story short, my buddy had to shut down shop yesterday. Shit got hot, his 6th sense warned him, and today he got a "Sprinkler Inspection". It just so happens to have a sprinkler in the closet, along with a 4x4 tent. He was up till about 3:00 in the morning last night tearing down all his hard work. But the closet looks like it should. Sucks. So...he had some plants going. 4 of them. A DP Auto Euforia, DP Blue Mazaar, and a pair of good old fashioned Phisto Sour Stompers. The Sour Stompers are typical killer Mephisto. Proper LST, but picked a week and a half early. The Blue Mazaar was pretty robust looking. All this weed looks incredible. It's ALL here. So...the show stopper. The Auto Euforia...holy shit fellas. This girl went about 112 days...and she still had a week to go sadly. I've never seen buds this big. I wish I could convey how insane these things are. Pictures.....that helps.

1: Euforia from last week alive
2: One of the 10 tops Euforia
3: Sour Stomper Baby
4: Blue Mazaar or Blazaar lol
5: Stomper I believe
6: Euforia close up. Calyxes!!
7: My 4x4... Beehive Colas
8: That's all four hanging.

There has to be 13+oz here on this Eufo. Back on track...we are not lighting scientists....just a couple guys with some DIY skills that can read the internet. Hell, I didn't even know COBs were a thing 12 months ago. I was a tried and true HPS guy. But I can appreciate technology...and LEDs are certainly the future. So we do a little digging and find out about KAAHBS. Citizen has some killer lights. 3500k was the number we kept hearing, as well as high CRI. So we get some 90CRI Gen6 CLU048 1818s 50v @ 3500k. He couldn't get them at that point so he did 6 total. Three 3000ks and Three 4000ks. All at 52w a piece or so. He likes experimenting so he got some 36v 5700k and 6500k 1212s for starting and some monster CLU058 1825s 3500k for the hell of it. He has 3 of those. One monster that can go to 180w and a pair fixed at 75w each. The monster Euforia grew under the 1825s, not sure which ones. Like I said....KAAAHBS bro. That's about all you need to know...lol. I do know they are super efficient, last forever, have really high PAR values, they look awesome, and grow some monster tight buds.

PS:. Gotta give a shout to this. He was doing this experiment he called Bud Bending [emoji769], where you bend the colas open to allow another cola to pop out...see pic [HASHTAG]#2[/HASHTAG] and you can see what I mean. Sad day for an awesome grower. So there is my 3 cents worth of lighting info. KAAAAHBS For LIFE!!

There called KAAHBS Joe

 

[TheMongol]

Haha, you did it again

Looks like you're bored, haven't you been at university?

 

[L0wbob2017]

So we get some 90CRI Gen6 CLU048 1818s 50v @ 3500k. He couldn't get them at that point so he did 6 total. Three 3000ks and Three 4000ks. All at 52w a piece or so. He likes experimenting so he got some 36v 5700k and 6500k 1212s for starting and some monster CLU058 1825s 3500k for the hell of it. He has 3 of those. One monster that can go to 180w and a pair fixed at 75w each.

I got some time later, gonna make u some graphs about the used COB's to see their true spectral power distribution by the way, there are some tests that indicate that high CRI is the better solutions because of chromaticity. Since the number of reports that say plants grow better under full spectrum are rising, the question came up if high CRI ( or 8 testcolors CRI Ra ) has any impact. Of cause it is true that high CRI COB's put out a bit less power in total compared to low CRI but you get something much better.

For example the difference between CRI 70 and CRI 90 is a much better tuning of the color spectrum. Since blue and yellow is green you could create the "color" green for your eye but an object that reflects a special wavelength (f.e. green ) wont look like it would under the normal sun. The problem is, that the wavelength green is not radiated but combined between 2 colors. So the object would still look green but not in its real green.
A normal LED / COB is mostly made of blue and a combination of green/yellow/orange/red LED's and a LES thats covered in a special phosphor-mix ( mix between special elements for filtering the color spectrum ).
The difference between low and high CRI is that for high CRI certain wavelengths get added/optimized so the color is radiated rather than "created by mixing light colors" and this is the reason for better color representation.

Haha, you did it again
View attachment 877314
Looks like you're bored, haven't you been at university?

haha ofc, i am there at the moment. but math is pretty easy on this early stage ^^

 

[L0wbob2017]

So if i got that right, i am gonna do the graphs for
CLU048 Gen6
- 1818s CRI90 3000K | 4000K |
- 1812s CRI90 5700K | 6500K |

CLU058 Gen6
- 1825s CRI90 3500K

By the way, i got a monster myself, you've seen it alrdy (single COB 205W max passive cooled all the way )