sixstring2112
Well-Known Member
I can tell you for sure my blurple mars panel grows some seriously dank weed,its just a design flaw they have with thermal management and trying to cut corners.but you wont see a fuller spectrum with ir built in.
CRI test and Mcree weighted results
- Thread starter Rahz
- Start date
Johnnycannaseed1
Well-Known Member
You missed my point but I realized I had mistaken (remembered incorrectly) chlorophhyll A/B work was done by Anderson and Evans....But my comment still stands McCrees data is flawed
Agreed, almost wondering if were pretty much splitting hairs when it comes down to CRI and spectrums of light.
In the vein, Id like to see a test setup to see the relationship for wattage/yield vs spectrum/yield.
Johnnycannaseed1
Well-Known Member
But Red and blue solely can be used to greater effect than white light depending upon what you are growing...seems you have missed the points in my post.
Incorrect see reply above... as Satived has correctly pointed out people are cherry picking Mc Cree data, but Mc Cree data was also cherry picking and is incomplete... That is not very scientific!
So because it is held up as some type of standard that makes it right is that what you are saying lol? Plenty of things have been held up as standards in the past only to crumble over time.
So by your logic because everyone else is doing it guess you are saying I should be a follower lol....Your comment here clearly shows you do not understand what I have previously said...I have explained in another thread the issues and the solution, wonder how many different crops under different spectra you have tested?
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Johnnycannaseed1
Well-Known Member
Good post.
Additionally the results of a single leaf still gives a very incomplete picture of the results on a plant with more than one leaf layer. The MCCree curve is cherrypicked over more complete info but ironically it only shows what a poor choice 3500k is.
Notice the ~450 an ~660 in the blue graph (and the ~625, matching very well with cri 90).
Blurple led manufacturers didn't make up any wavelengths. They, like the naysayers now, cherrypicked a few graphs they thought they understood and used those to convince themselves and others.
If anything, what both show is that 3500k (as a color temp, not perse individual cob....) is a poor choice. Red should be highest, rest only enough. It's that last part where plant species differ most, and what we don't know exactly. There's no reason to choose so much blue and green, it's far less efficient for the plant. 2700k cri 90 is a good alternative to a more expensive WR led light (the ideal for now).
The blue YPF curve above still does not account for the effect blue has on the accumulation of different accessory pigments and vice versa, and does not account for the effect of for example FR on photosynthesis throughout the crop rather than measuring a single leaf. In reality that blue light become less efficient much faster than red (ironically making red even more efficient relatively...).
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Funny how the value of a "few" % more or less light fluctuates so fast around here to suit one's preconceived notions. Compare those "few" % beyond 700 of the orange curve to the ppf difference in % between cri80 3000k and the cri90 2700k... in Malocan's post.
Obviously the difference in light output is so small already either way. Obviously your posts reek of bias towards 3500k. Obviously the 3500k lights people have above their plants and the ones you sell are not more efficient or higher in output than what's possible with 90cri. That is far more a matter of cob brand/bin/version/amount/driver. Letting that dictated the spectrum for plants for a grow light that should last for more than a few years is just... unwise.
That's just where you connect the dot to, to blurple, appareantly the only thing where the line attached to in your limited reference frame. Doesn't mean it has anything to do with blurple, just means you have a few gaps in your knowledge and playing the one-eyed king parroting riu nonsense at the dutch forums has "grown to your head"... Citizen isn't the only one who suggested something very similar and has nothing whatsoever to do with burple.
Equally good post to which I could not agree more...you are right people are misinterpreting what they are reading or worse still they are making incorrect assumptions - Then others follow - and before you know it a trend has developed which in turn becomes "the standard"... what happened to real world testing and creating your own standards based upon observation aka "real" science lol!
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Johnnycannaseed1
Well-Known Member
A Hps lamp works, are plants underneath it following Mc Cree data?..Or the lovely swoosh of the Mc Cree curve?.
What about crops that are grown under alternating light regimes how do they fit into Mc Cree data?
Or what about the effects of monochromatic sources under white light?
Let alone photo-period manipulation and how all of the above affects different plants in different ways...
Mc Cree data is one dimensional at best, not to mention it tells me absolutely nothing about the effects of light on post harvest yields and quality,
There is no way I would use it as a reference point, just because of the fact of what that experiment fails to take into consideration.
What about crops that are grown under alternating light regimes how do they fit into Mc Cree data?
Or what about the effects of monochromatic sources under white light?
Let alone photo-period manipulation and how all of the above affects different plants in different ways...
Mc Cree data is one dimensional at best, not to mention it tells me absolutely nothing about the effects of light on post harvest yields and quality,
There is no way I would use it as a reference point, just because of the fact of what that experiment fails to take into consideration.
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Does an HPS light not fall within the curve or something? What are you getting at?
I dont think it was developed with any of that even in mind. I wouldnt knock it for not being able to answer things it was never intended to answer.
Rahz
Well-Known Member
Each 5nm span of a spectrum has it's percentage of output determined. When the Mcree factor is applied to each as a number from 0 to 1 it changes the output of each 5nm span to the percentage of it that causes photosynthesis in the Mcree study. My digitized plant response climbs quickly to .5 and stays in the .500s up to around 550-560 at which point there is a steady climb to 625 then a slight pause and an uptick to 665-670 and after which a steep decline. This is the logical plot if we take out the two high samples on the left and the two low samples on the right.
Thanks for the offer on the li-cor. Let's wait and see how things look when I normalize the test readings. If Apogee's response chart is accurate then the result should be as well.
Rahz
Well-Known Member
Did you even look at the results? How can that possibly be biased towards 3500K? It didn't win pre or post conversion. I have an interest in getting to the bottom of the issue same as you. I was rooting for high CRI and was suprised 3000K 70CRI came in first even after the Mcree conversion. It's the exact opposite of what you preach so I suspect you will have issues with it, but it's not my bias that's providing the results. I'm just providing some controlled test results and a spectrum weighing system that favors low K and high CRI profiles. So again, how am I reeking of bias? You must either agree with the test results, or suspect that I somehow plotted to make 3500K look good... by inflating the 3000K spot reading results.
If I were sure of the results I would immediately start selling 3000K 70CRI lamps.
But I'm not reading too much into it yet. Once the sensor deficiency has been accounted for the 3000K 70CRI result will be reduced, but it was first by a pretty good margin so at worst it will be somewhere near the top performers. If we can read anything into the results at this point, it's that "any cob will do".
Well, warm white at least. It's logical that higher K samples would suffer most when weighed against the Mcree data, and with SPDs to compare with we can infer 4000K wouldn't place too far behind while 5000+ begins to looks sketchy.
Your assertion that the 700+ range will sway the results is unfounded. Do the math, you will see it is only a few percent of the total (be sure to subtract the 700-730 low CRI total from the result while you're at it), and we're not talking about a few percent that magically transforms into highly usable light, we're talking about a few percent that provides a meager return in photosynthesis. It's not possible to figure into the test, but if it was I suspect the difference would be minimal at best and an ill spent resource at worst.
Rahz
Well-Known Member
Because HPS contains relatively little blue and lots of orange, it will score quite high against the Mcree curve potentially better than some or all of the cob samples. I haven't digitized any bulb spectrums but I'm sure that according to Mcree HPS should work well despite not having a swoosh. It's more a matter of where that light is falling in the Mcree shoosh.
ttystikk
Well-Known Member
I thank you for going to the effort of testing these and creating some data.
I find it interesting that HPS does so well even while its spectrum distribution is so poor. I get better quality results from Philips 860W CDM Allstart lamps, even though I may be giving up a smidgen of yield.
I'm pulling personal best numbers from my COB LED rack, which was designed to pull the same watts as the HID rack it superceded, and quality is even better still. I am sure that once I've dialed my technique in to make the most of them, the COB LED runs will blow away the results I've come to expect from HID lamps of any type.
EDIT: Every chip in the rack is a Cree CXB3590 3500K 72V CD BIN, driven at 54W each and actively chilled to 55F.
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JorgeGonzales
Well-Known Member
"A widely used estimate of the effect of light quality on photosynthesis comes from the Yield Photon Flux (YPF) curve, which indicates that orange and red photons between 600 to 630 nm can result in 20 to 30% more photosynthesis than blue or cyan photons between 400 and 540 nm (Figure 3)[3], [4]. When light quality is analyzed based on the YPF curve, HPS lamps are equal to or better than the best LED fixtures because they have a high photon output near 600 nm and a low output of blue, cyan, and green light [5]."
But...
"The YPF curve, however, was developed from short-term measurements made on single leaves in low light. Over the past 30 years, numerous longer-term studies with whole plants in higher light indicate that light quality has a much smaller effect on plant growth rate than lightquantity[6], [7]. Light quality, especially the fraction of blue light, has been shown to alter cell expansion rate, leaf expansion rate[8], plant height and plant shape in several species [9]–[11], but it has only a small direct effect on photosynthesis."
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099010
In other words, forget trying to be photosynthetically efficient, worry more about how the plant reacts photomorphogenically. And fuck blurple, it's psychologically painful if nothing else.
sixstring2112
Well-Known Member
That's a wrap, going back to hps now 
ttystikk
Well-Known Member
That's a wrap, going back to hps now
Lol have fun with that
wietefras
Well-Known Member
The Chlorophyl chart is in their datasheet ..... so ... ehm .... yeah I connected that "dot".
If only something would actually go to your head. Ah well, it's good to see you finally made the step from COB bashing to trying it for yourself. Now if you have some actual experience under your belt, perhaps you'll understand that spectrum means very little and photons are king.
McCree obviously also shows that blue and red are most readily used by the plants since chlorophyl is responsible for the bulk of the photosynthesis, so indeed it makes sense in a greenhouse to supplement with that. Moving a much lower red peak by a few Nm to the longer end of the spectrum is not going to overcome a huge deficit in quantum yield from CRI90.
weed-whacker
Well-Known Member
@Rahz
thanks for the tests
ive read over your posts here and although I do believe(no reason) the high CRI should achieve better scores i think it does fall into the same basket as white vs blurple.
it is my simplified understanding that white cobs can produce more of the blue and reds per watt than blue or red monos, plus you get bonus colours for free
lol
so it seems we have gone full circle now, lumens are for humans sure....but also plants like them
hence the 70 CRI getting better scores, i suspect that a low CRI high kelvin would absolutely destroy the rest
i look forward to more info and sincerely appreciate all that you contribute to this forum.
thanks for the tests
ive read over your posts here and although I do believe(no reason) the high CRI should achieve better scores i think it does fall into the same basket as white vs blurple.
it is my simplified understanding that white cobs can produce more of the blue and reds per watt than blue or red monos, plus you get bonus colours for free
lol
so it seems we have gone full circle now, lumens are for humans sure....but also plants like them
hence the 70 CRI getting better scores, i suspect that a low CRI high kelvin would absolutely destroy the rest
i look forward to more info and sincerely appreciate all that you contribute to this forum.
CobKits
Well-Known Member
a coincidence
JorgeGonzales
Well-Known Member
3000K80CRI 905
3000K90CRI 856
That's the only 80 vs 90 comparison @Rahz made, and I wouldn't consider ~6% "huge", or the peak shift from 600 to 630nm insignificant.
And your high Kelvin low CRI light recommendation is almost 75% green and blue, not to mention peaking at ~565nm, so you must really believe a photon is a photon:
PhotonFUD
Well-Known Member
Totally over complicating something that is simple. Until we can saturate an entire plant with photons using artificial light we have a long way to go.
Plants are photon counters. 8 photons are needed to create the fundamental building blocks of sugars. Plants use sugars as a transportable energy source to build what it needs to grow. More photons, along with base elements, will produce more sugars which results in the potential for more growth.
Here is a link from a university that has some great information related to the topic:
http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/ligabs.html
(edit) and this one from wikipedia:
https://en.wikipedia.org/wiki/Photosynthetic_efficiency
What all of you have been looking for is the most efficient way to create light energy useable by plants (photons) from electrical energy. It takes more energy to generate a photon at a lower wavelength than that of a higher wavelength. Therefore, if you are only looking for photons then you should be going for higher wavelengths corresponding with high electrical energy to light energy conversion. With today's LED technology that is basically a distribution highly weighted towards much red wavelength at the highest efficiency possible.
Some might ask 'well it takes more energy to produce lower wavelengths so they must have more energy' and yeah, that is correct, the photons carry more energy. That is also why they are more harmful - that extra energy is wasted as heat. It is 8 photons required for photosynthesis regardless of wavelength.
A better way to think of it is to make as many photons available to the plant as possible. As far as science knows, it has been assumed that all plants are quite efficient and able to use any photons with wavelengths in the PAR spectrum. However there haven't been very many studies involving wavelength responses in specific plant species and that could provide another element for consideration in the light discussion.
Wanted: 300w 620-700nm @ ~390lm/w (wrap your head around that one and figure out the micromoles for fun)
Plants are photon counters. 8 photons are needed to create the fundamental building blocks of sugars. Plants use sugars as a transportable energy source to build what it needs to grow. More photons, along with base elements, will produce more sugars which results in the potential for more growth.
Here is a link from a university that has some great information related to the topic:
http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/ligabs.html
(edit) and this one from wikipedia:
https://en.wikipedia.org/wiki/Photosynthetic_efficiency
What all of you have been looking for is the most efficient way to create light energy useable by plants (photons) from electrical energy. It takes more energy to generate a photon at a lower wavelength than that of a higher wavelength. Therefore, if you are only looking for photons then you should be going for higher wavelengths corresponding with high electrical energy to light energy conversion. With today's LED technology that is basically a distribution highly weighted towards much red wavelength at the highest efficiency possible.
Some might ask 'well it takes more energy to produce lower wavelengths so they must have more energy' and yeah, that is correct, the photons carry more energy. That is also why they are more harmful - that extra energy is wasted as heat. It is 8 photons required for photosynthesis regardless of wavelength.
A better way to think of it is to make as many photons available to the plant as possible. As far as science knows, it has been assumed that all plants are quite efficient and able to use any photons with wavelengths in the PAR spectrum. However there haven't been very many studies involving wavelength responses in specific plant species and that could provide another element for consideration in the light discussion.
Wanted: 300w 620-700nm @ ~390lm/w (wrap your head around that one and figure out the micromoles for fun)
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