25% more yield with a diffused LED ?
- Thread starter Kimes
- Start date
Physical reality is not up to debate or consensus, all the physical laws apply all the time(inverse square etc) the thing is HOW they apply to the system we try to describe.
It seems easy to "forget about it" because it's "debunked", while actually it's just far more complex than just the basic law.
There is no "real" or "true" answer, just what we are prepared to accept as "close enough".
And to be honest, here we're not really there at all, but we are close enough
Cheers
It seems easy to "forget about it" because it's "debunked", while actually it's just far more complex than just the basic law.
There is no "real" or "true" answer, just what we are prepared to accept as "close enough".
And to be honest, here we're not really there at all, but we are close enough
Cheers
goingrey
Well-known member
They are not focused light either. The Samsung chips (both LM301H and B) have a 120 degree beam angle. This is very wide.
In a tent, a lot of light is reflected back from the walls of course. Reflectance of mylar for example should be in the 90s. So it is some kind of focused light tunnel I suppose.
Cerathule
Well-known member
Then try it, I have the feeling you are well-versed in this.Physical reality is not up to debate or consensus, all the physical laws apply all the time(inverse square etc) the thing is HOW they apply to the system we try to describe.
It seems easy to "forget about it" because it's "debunked", while actually it's just far more complex than just the basic law.
There is no "real" or "true" answer, just what we are prepared to accept as "close enough".
And to be honest, here we're not really there at all, but we are close enough
Cheers
We have the raw amount of photons a single LED (like a COB) generates each second.
A beam angle that contains these and a distance that decreases this energy-density, according to a formula.
If the same amount of photons are released into a 90° cone, shouldn't the energy-density be 6 times higher than compared to a sphere? When measured both times from the same distance from the focal point and the same raw amount of photons are released per second.
We need to construct a mathematically true formula derived from an ideal/theoretical model. Then apply corrections or amends to reflect on the complex reality of a growlight fixture.
It should be possible to have a formula incorporating the beam angle spread that will give a true result on both spherical or conical light emitters.
goingrey
Well-known member
It's possible to have a formula but it has many variables. What kind of LEDs, how many, how they are spaced...
A more practical solution may be to just measure?
Ipotato
Active member
the fact that it is in a tent with reflective sides above the plants makes it into a focused reflector doesn't it?
goingrey
Well-known member
But I guess it's only us home growers that use tents. Professionals will be in greenhouses and warehouses.
Exactly.
The math gets too complicated, unless you are a researcher in the field. Otherwise, experiment is king.
There are also simulation software solutions to visually represent these phenomena. Also Excel can work wonders if one uses data from light manufacturers.
I love this type of device:
Integrating sphere - Wikipedia
interesting thread!
i have a homemade 1680-watt fixture i built from 14-watt walmart household-type bulbs.
it has 60 ea of 2700k and 5000k. these bulbs are on approximate 4"centers.
the diffusers have been removed..
there are a total of 1680 individual diodes. all small at .4375 watts each, approx.
more small diodes spread light more evenly than less large diodes if total power level is the same.
i own a par meter and this light will produce 1500 umols at 26". but it will also produce 1000 umols at 36". no larf.
this is at the center of a 50x50" canopy. the edges of the canopy get about 1250 umols. a 250 umol difference. dropping a reflective shield down all around the light fixture nearly evened out these readings. this is without a tent so i imagine a tent would almost do it automatically if the light were built right.
earlier in the thread someone posted about depth of field. and that most of the led manufacturers don't want to talk about it.
it is my opinion that we are being lied to by most of them on this subject.
height above canopy = diffusion because of beam spread. but, you must have additional power to compensate.
more points of less energetic light but equal in power to less points of more energetic light = greater diffusion.
the more points of light you have spread out as evenly as possible over the entire canopy the more shading is eliminated.
this compounds the light energy's effect on the plant
i built this light to experiment with these ideas. leds are so radically different than hids.
as goingrey said, "A more practical solution may be to just measure?".
i'm getting very nice, even growth with this fixture.
i have a homemade 1680-watt fixture i built from 14-watt walmart household-type bulbs.
it has 60 ea of 2700k and 5000k. these bulbs are on approximate 4"centers.
the diffusers have been removed..
there are a total of 1680 individual diodes. all small at .4375 watts each, approx.
more small diodes spread light more evenly than less large diodes if total power level is the same.
i own a par meter and this light will produce 1500 umols at 26". but it will also produce 1000 umols at 36". no larf.
this is at the center of a 50x50" canopy. the edges of the canopy get about 1250 umols. a 250 umol difference. dropping a reflective shield down all around the light fixture nearly evened out these readings. this is without a tent so i imagine a tent would almost do it automatically if the light were built right.
earlier in the thread someone posted about depth of field. and that most of the led manufacturers don't want to talk about it.
it is my opinion that we are being lied to by most of them on this subject.
height above canopy = diffusion because of beam spread. but, you must have additional power to compensate.
more points of less energetic light but equal in power to less points of more energetic light = greater diffusion.
the more points of light you have spread out as evenly as possible over the entire canopy the more shading is eliminated.
this compounds the light energy's effect on the plant
i built this light to experiment with these ideas. leds are so radically different than hids.
as goingrey said, "A more practical solution may be to just measure?".
i'm getting very nice, even growth with this fixture.
Cerathule
Well-known member
My light meters only measures "a stream" coming from a certain direction but neglects any stray light that hits the measuring probes encasing.
This is especially problematic with HID lamps in an open reflector which create a lot of diffuse light.
The higher the diffuse light the less it will register in these meters while they are good to measure directed focused light.
Now if I measure 1000ppfd under a 600w HPS open reflector it should be more light hitting there if said 1000ppfd came from a LED with an 90° lense, or a closed HID reflector.
There's HID vertical reflectors that throw most of their lightrays towards the sides, not below, and below them not much ppfd can be measured. It just spreads way different and one would need to measure many spots to get an idea of the actual situation.
Personally I treat a tent as almost ideal closed case, use the QER with the powerdraw to get an idea of how much light there in is. But that totally neglects light density at a specific point. The plants sometimes adjusts their leaves to make the most of these local fluences.
Ca++
Well-known member
If your light meter probably doesn't ignore it's casing. No matter how big the sensor, the answer it gives is corrected to a 1 meter sensor. Presuming you use metric.
1000 photons from white LED carry more energy than 1000 photons from hps. Other than that, both are 1000 photons.
Hold over from the HID days. With a light mover a gardener can run some very close canopy to light distances. With the light that close if the mover and light both stop concurrently it can scorch the tops directly under the light. Moving the light for a couple of minutes after lights out solves this issue. Funny enough the scorches are usually interpreted as some deficiency,go figure.
Paid a lot of bills with three arm suncircles 2 sodium 1 halide.
Guys..
You are still mainly focused on the LIGHT aspect of led growlights but don’t seem to talking about the HEAT radiance-issue of led light.
The beaming light wouldn’t be such an issue if it was “cold” in temperature but these photons obviously carry the heat radiance with them.
What these diffuser plastics are also, i’d imagine – they would also act as heat shields absorbing some of the heat element involved with the photons coming out of the led chips. = thou you lose 5-7% of the light, how much heat radiance would these plastics absorb?
..so thou my veg lights will lose 7% of the light when i get the diffuser stuff on them, can i get some of the lighting power back if i can keep the lights closer to my plants cause the plastics will absorb some of the heat out of the photons. This is the stuff we should be talking about.
You are still mainly focused on the LIGHT aspect of led growlights but don’t seem to talking about the HEAT radiance-issue of led light.
The beaming light wouldn’t be such an issue if it was “cold” in temperature but these photons obviously carry the heat radiance with them.
What these diffuser plastics are also, i’d imagine – they would also act as heat shields absorbing some of the heat element involved with the photons coming out of the led chips. = thou you lose 5-7% of the light, how much heat radiance would these plastics absorb?
..so thou my veg lights will lose 7% of the light when i get the diffuser stuff on them, can i get some of the lighting power back if i can keep the lights closer to my plants cause the plastics will absorb some of the heat out of the photons. This is the stuff we should be talking about.
"Impact of Directional Response on Photosynthetically Active Radiation (PAR) Measurements Directional response data (Figure 1) suggest Apogee SQ-500 series quantum sensors and MQ500 quantum meters, which include the SQ-500, will measure accurately under radiation sources with nearly any distribution of angles,"
this from:
this paper shows that apogee meters read combined light very well.
this from:
this paper shows that apogee meters read combined light very well.
Cerathule
Well-known member
I'm talking about a sensor that measures from all directions at once, not just 180° or 120°
LED emit almost no heat radiance. Phosphorescent materials can redshift photons but still you loose a fraction of them. Depending on colour this can sometimes even be beneficial due to plant physiological reasons but at that it's better to just pick a 2200k right away than a 4000k for example.
X15
Well-known member
Yeah I understand the lights rays moving around none stop but I have yet to have anything burn. is that a disadvantage over the use of a diffuser? Or is the diffuser a better option for someone with limited space?Light movers would just move the hot light beams around- they would still be there but not warming the same spot as long - so the hot spots (beams) would just move to fry some other spot for awhile.
The problem with light movers is that many of the modern led-bar lights are rather large in size so many home growers don’t have much room to move their lights in their small growing space, many times just a 100cmx100cm tent or even smaller than that – like me.
The diffuser sheets for two my veg lights were around 15 euros including shipping, i wonder how much would two light mover units cost + the electricity to run them?
Something else that I think should be noted i that our plants are not completely still all cycle, at least mine aren’t. I have circulation adjusted in my room I feel gently exercises the plant canopy and flows through the bottom of it. (I sloped my ceiling to aid in a carousel motion. So most of, if not all of the plant is in slight motion at all times.
Maybe then would a diffuser be less or more noticeable?
I’m just trying to wrap my mind around all these factors and what I’ve experienced and it’s got me fucked up man lol.
Would still plants and perfect light diffusion speed up growth or be the perfect sitch? I feel like clouds move and wind blows, but does that lengthen cycles?
X15
Well-known member
Aww gotcha! My inexperience with HIDs there haha thank you for that! That makes perfect sense
I was asking the question mainly to see if red LEDs are more focused than blue LEDs.
If they had different angles of focus, I was wondering if that created a slight red shift in light, for the plants, when the distance to the light source was increased. However I realise now that they will reduce at the same rate, as a focal field would act as a multiplier to the point source energy value rather than a divisor to the reduction in strength. Hence the answer being no.
If they had different angles of focus, I was wondering if that created a slight red shift in light, for the plants, when the distance to the light source was increased. However I realise now that they will reduce at the same rate, as a focal field would act as a multiplier to the point source energy value rather than a divisor to the reduction in strength. Hence the answer being no.
The rate(gradient) changes depending on how focused a light source is.
Any lens will change the way light spreads, so in some areas you will get more photons than in others.
Led color doesn't say nothing about the lens on the led, the same manufacturer can make different series of the same emitter but with different lenses, so it's important to combine them thoughtfully.
The red stripes some have in their QBs and others, as I said previously, can be caused by narrower reds compared to wider whites.
An example
Example of lenses
Cheers
Will it? I accept it will make the same energy output seem brighter at the target spot, but will it affect the intensity percentage at double the distance? Doesn't it merely start the photons out in basically the same direction? That's the same as releasing photons in all directions at a greater intensity. Once they begin their journey, shouldn't they behave in the same way? ie. Following the I.S.L.? Surely it's the walls rather than lenses that prevent recordings matching predictions.
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