Cob drive amperage & effective penetration

KarmaPaymentPlan

Well-Known Member
yes i understand that..and to be fair ...nothing penetrates a leaf..it penetrates where their are openings

as far as i can understand ppfd is ppf over a whole area averaged out

but i would prefer not to act like i know what i am talking about ..because my post was a question..because i don't know for sure..and i am not sure you know the answer [either]
we are all trying to learn
im curious too
i thought ppfd was a spot measurement which is subject to angle of the par meter


think about how the light emitted is denser and not stronger, how can that penetrate better?
 

OLD MOTHER SATIVA

Well-Known Member
150w is stronger...and will have a higher ppf reading further down than the 50w

ok i took a reading[parmeter] of acree @50w and abnichia ar 34 w..the cree had higher
reading of ppf further down than the nichia..and yes i know they are not the same cobs..
but its all i have
 

OLD MOTHER SATIVA

Well-Known Member
my friend ...wtf is " dense"?
i think you are more confused than i am
but then again wtf do i know..?[not alot]..or i would nay have asked the question in the first place
dude..we both need a guru right now
 

OLD MOTHER SATIVA

Well-Known Member
ok thanks!... but what does that have to do with penetration..my par meter says ppf when i use it..
and isn't ppfd ppf readings taken over the area one wants to cover?
[original question]
 

KarmaPaymentPlan

Well-Known Member
ok thanks!... but what does that have to do with penetration..my par meter says ppf when i use it..
and isn't ppfd ppf readings taken over the area one wants to cover?
[original question]
your PAR meter works from a spot measurement thats why everyone is hot about sphere testing, again is a spot measurement your determining the density at that point of measurement

how does a photon differ from its wattage of origin? will 1 photon from 150w cob be stronger then 1 photon from 50w, or is it just simply more from coming from 150w at one time?...
 

OLD MOTHER SATIVA

Well-Known Member
and a spot measurement shows the penetration...the reading of the 150 will have the same reading as the 50w cob..except way further in..[penetration]
 

PhotonFUD

Well-Known Member
Penetration in the context of light usually refers to high energy focused forms such as laser. Light for photosynthesis is either absorbed, reflected or even refracted when it hits plant material. If the light we were using to grow plants had high penetration that would be akin to making grilled greens on the barbq. Actually, that is the principle of how infrared grills work.

Instead of penetration, effective range/draw/throw of a light source may be more correct and is simple to figure out with a PAR meter. Take light source, measure a distance away and take a PPFD reading. Go a bit further away and take another measurement. The difference in length is the 'throw distance' and the difference in PPFD is the photon count 'range' that your leaves will receive.

Another quirk in the efficiency equation is the wavelengths produced by the light source. Depending on the wavelength photons may carry different amounts energy. Longer wavelengths, eg. red, have less energy than lower wavelengths such as those in the blue regions. That is photon to photon. Plants are photon counters needing ~8 photons to power a reaction.

Generally speaking, higher wavelengths are better for organisms that haven't specifically adapted to higher energy (shorter) wavelengths. The problem comes with managing the free energy when the photon gets absorbed; shorter wavelength high energy photons require more effort from the organism. Some wavelengths in the UV range are highly destructive. Photosynthesis has a wonderful way of managing the excess energy by retransmitting it through chlorophyll fluorescence allowing other parts of the plant to use the photons. Unfortunately it isn't very efficient and most of the light energy absorbed by plants is wasted as heat.

And here is where I shamelessly plug my opinion of ~400 umols consisting of 10% warm white + 90% 600-730nm being optimal for photosynthesis.

:)
 

a mongo frog

Well-Known Member
Penetration in the context of light usually refers to high energy focused forms such as laser. Light for photosynthesis is either absorbed, reflected or even refracted when it hits plant material. If the light we were using to grow plants had high penetration that would be akin to making grilled greens on the barbq. Actually, that is the principle of how infrared grills work.

Instead of penetration, effective range/draw/throw of a light source may be more correct and is simple to figure out with a PAR meter. Take light source, measure a distance away and take a PPFD reading. Go a bit further away and take another measurement. The difference in length is the 'throw distance' and the difference in PPFD is the photon count 'range' that your leaves will receive.

Another quirk in the efficiency equation is the wavelengths produced by the light source. Depending on the wavelength photons may carry different amounts energy. Longer wavelengths, eg. red, have less energy than lower wavelengths such as those in the blue regions. That is photon to photon. Plants are photon counters needing ~8 photons to power a reaction.

Generally speaking, higher wavelengths are better for organisms that haven't specifically adapted to higher energy (shorter) wavelengths. The problem comes with managing the free energy when the photon gets absorbed; shorter wavelength high energy photons require more effort from the organism. Some wavelengths in the UV range are highly destructive. Photosynthesis has a wonderful way of managing the excess energy by retransmitting it through chlorophyll
fluorescence allowing other parts of the plant to use the photons. Unfortunately it isn't very efficient and most of the light energy absorbed by plants is wasted as heat.

And here is where I shamelessly plug my opinion of ~400 umols consisting of 10% warm white + 90% 600-730nm being optimal for photosynthesis.

:)
So you believe in light penetration? Would of thought you would talked about how that all lays on the gardener and his/her garden. Not the light source. Well lets just say from any type of horticulture lighting worth a shit.
 

wietefras

Well-Known Member
The point is that in the end you will have a mostly uniform PPFD at the canopy of somewhere between 400 and 1000umol/s/m2. The penetration (based on light intensity) of that will be similar regardless of whether it came from a 150W COB, 50W COBs or an 1000W HPS .

The other part if penetration, diffusion, will be better for light sources more spread out and closer to the canopy.

I noticed much more light penetration when I replaced my HPS by a COB fixture (which produces roughly the same amount if light)

The light from the COBs slips under the leaves much easier than the more direct light that you get from a single stronger light source further away.
 

OLD MOTHER SATIVA

Well-Known Member
And here is where I shamelessly plug my opinion of ~400 umols consisting of 10% warm white + 90% 600-730nm being optimal for photosynthesis.
according to my par meter[sourced from the this forum]..~400 umols will grow

pretty good and is efficient as far as not having to use a pile of cob watts per area

as for the 10% warm white + 90% 600-730nm ratio..wonder if there is a side by side test with just warm white..did you do one?
 

ya bongo

Well-Known Member
And here is where I shamelessly plug my opinion of ~400 umols consisting of 10% warm white + 90% 600-730nm being optimal for photosynthesis.
optimal for photosynthesis?10-90.JPG

simulated data:
10% warmwhite 3000K 80cri
30% 625nm
40% 670nm
10% 730nm

There are three types of FUD:
the first and more genuine is (#1) the intentional spreading of falsehood, mostly to gain some marketing advantage over a competing product. While I despise this practice, I understand it.
Then there is (#2) FUD spread by ignorance, when the originators are so blindly enraged by their hatred for a product that they don't care about getting the facts straight.
And finally, there is a third kind, not less dangerous, which is (#3) the spreading of FUD with good intentions, when the authors believe that they have the facts straight and they want to help.
 

MeGaKiLlErMaN

Well-Known Member
PPFD dictated how much light is hitting your area, we have that established correct?

So if you have 25% (just giving a stable rate of fall off through leaves/spaces) of what ever value coming through to the next level that then the higher amount of useable light pushed out will come through accordingly. So in this case you would use a par meter to check you canopy levels, and move 6"down to see what your readings are.
Do this at least I every square foot of your growing space and then you have your penetration (I would think 100-200ppf is the cut off point)

Test this in HPS, de HPS, and cobs and you have an answer if they are all the same percentage or something different if it's something more.

I think it's directly related to the par throughout the canopy.

Has anyone ran this test? If not I may once my lights kick on.
 
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