LED and BUD QUALITY

[delta9nxs]

photons are like potatoes. one potato, two potatoes, 3 potatoes, 4.

you count them individually.

the sun is a stronger source than a diode, everybody knows that.

but we are illuminating a target. so source strength does not matter as long as the same amount of light is hitting the target.

the par meter is saying that 200 umols is 200 umols, regardless of the source.

in horticulture measurement at the source is a luminaire comparison tool, not a measurement of what the plant is getting.

you can put a 400 watt hps on a plant at close range and get the same reading with a 1000 watt hps further away.

the par sensor measures the flow of photons at a particular point.

i can get a reading of 2000 umols outdoors on a bright day and i can get a reading of 2000 umols with that humongous light i showed above.

which 2000 umols is stronger?

neither

we could take 3 different light sources at different power levels and measure them all at a specific range.

say 1 foot. yes indeed, we get 3 different readings.

but if you light a plant with them, adjusting them individually, some close, some farther, you can get the same reading on a spot on the plant.

 

[delta9nxs]

up to this point, all i've been trying to do here is get you to agree on known scientific definitions of light and how to measure it in regard to plants.

we can't really get any further without that.

intensity is measured at a point on the plant, yes or no?

 

[delta9nxs]

instructions on how to use a par meter - Google Search

the meter they are using is crap but it does show how a meter is used.

notice that he is not measuring the light at the fixture.

 

[Corpselover Fat]

Different intensity/pressure. A firehose will knock you down, but the same volume from 1000 sprinklers won’t.

Eh? That has much more to do with how large of an area the water lands on. Doesn't matter if you have 1000 small water streams or one big one if the area they land on is the same.

 

[[Maschinenhaus]]

Although in German, but it is worth reading there with translator.

Photosynthese

In English and also well explained by a manufacturer.

Plant lighting explained in numbers | PAR, PPF, DLI etc.

Anyone planning and comparing plant lighting needs accurate data. In the field of plant lamps, these are the measured variables PAR, PPF, PPFD, DLI and others.

cre.science

This master thesis deals with the effects of light emitting diodes (LEDs) on the growth, nitrate content, relative photosynthetic performance and carbon the carbon content of selected plants cultivated on hydroponics.

The basis of the work is several experimental approaches with different light intensities, light spectra and plant species. It was found that the limits of the EU - Regulation 1258/2011 for the nitrate content in vegetable plants, of plants grown under artificial plants grown under artificial lighting on hydroponics.

In addition, it could be verified that portions in the green spectral range cause a reduction of the nitrate content in certain plant species. Furthermore, it was shown that prolonged high light intensities induce stress responses expressed by the C13 value in the plants.

The last research question reviewed the suitability of using light emitting diodes in plant tissue culture compared to conventional fluorescent lamps. It was found that they are an energy-saving alternative, with the same effect on the plants. The results of the master thesis show potentials for new developments in the field of urban crop production with artificial lighting.

 

[snakedope]

photons are like potatoes. one potato, two potatoes, 3 potatoes, 4.

you count them individually.

the sun is a stronger source than a diode, everybody knows that.

but we are illuminating a target. so source strength does not matter as long as the same amount of light is hitting the target.

Wrong, source strength is what defines intensity, not how much light lends on a target.

the par meter is saying that 200 umols is 200 umols, regardless of the source.

If you count at source it does matter, it says if your source is high intensity or low, there are ratings to high intensity and for low.
HIDs called HIDs because no one is making a 1w hps bulb, it will be LIDs.

in horticulture measurement at the source is a luminaire comparison tool, not a measurement of what the plant is getting.

We are talking about the source and it's strength, don't mix stuff around

you can put a 400 watt hps on a plant at close range and get the same reading with a 1000 watt hps further away.

You are right, it only works when you measure lower watts, you can achieve the same with higher watts, basic logic, but can you do it vise versa ? No.
If I put 2 250 hps lamps and out your meter under both of them you think I will get more then the rated source ? Yes or no ? Haha

the par sensor measures the flow of photons at a particular point.

i can get a reading of 2000 umols outdoors on a bright day and i can get a reading of 2000 umols with that humongous light i showed above.

which 2000 umols is stronger?

neither

Lol at the target ( canopy) both of them are same but they are not from the same source, you had to put 3840 sources to match this 1 source strength, if all of your sources were in the same place (source) which is impossible of course, maybe you had some merit in your saying... But that's not the case.

we could take 3 different light sources at different power levels and measure them all at a specific range.

say 1 foot. yes indeed, we get 3 different readings.

but if you light a plant with them, adjusting them individually, some close, some farther, you can get the same reading on a spot on the plant.

Won't change the source rating,
You talk a lot about measuring light in space which is fine by me but has nothing to do with intensity of the source.

up to this point, all i've been trying to do here is get you to agree on known scientific definitions of light and how to measure it in regard to plants.

we can't really get any further without that.

intensity is measured at a point on the plant, yes or no?

No, sorry.
Intensity is rate of production at source not at target.

Eh? That has much more to do with how large of an area the water lands on. Doesn't matter if you have 1000 small water streams or one big one if the area they land on is the same.

It does, because the rate of production is the important factor, not how much light lends on each spot.
You can take a COB and point it to a certain place and this point has the most light in it but the diodes that make this light is using numbers to accomplish the task, instead of brute force of a single source.

 

[[Maschinenhaus]]

To consider the photon flux density alone would be wrong, because the beam angle or the scattering of the light and thus the distribution of the photons over a certain area also plays a decisive role. For uniform and large-area scattering of light, interconnected horticulture LED lighting systems in strip form are commonly used.

Square lighting systems, on the other hand, tend to achieve a greater depth effect, making them more suitable for tall-growing plants and smaller areas. Information on photon flux density and light scattering is usually provided by the PPFD plots included in the data sheet.

Even if the PPFD parameter says nothing about the actual light spectrum and the associated grow application, it still provides an additional point to objectively evaluate and compare different light sources. The disadvantage, however, is that not all manufacturers disclose their PPF values and these are hardly self-measurable.

Light saturation point

Plants cannot absorb an unlimited amount of light. Every plant has a light saturation point (LSP). Beyond this point, a plant's photosynthetic output can no longer be increased by increasing light intensity. If the light intensity is increased beyond the LSP, the photosynthetic apparatus can be damaged, thus reducing the photosynthetic output or causing the plant to die.

Basically, plants can be divided into 3 categories: Shade plants (low LSP), Sun plants (high LSP) and C4 plants (very high LSP). For example, an average exposure of 300-400 μmol/m²s would be desirable for most flowering and fruiting plants.

Reference in German

Cannabis needs to be reclassified, I count Cannabis Indica as a C4 plant. There is just more and more evidence that this is the case.

Compendium: Earth-Water-Light-Microorganisms-Ion-Exchange-Nutrients

Chapter 8 Indoor cannabis cultivation - Many problems? Many problems can be prevented in advance, good gardeners know it, less is more! Interactions between nutrients - causes of malnutrition. Causes of nutrient deficiencies are inharmonious nutrient ratios in the soil, in addition to...

www.icmag.com

and here

Compendium: Earth-Water-Light-Microorganisms-Ion-Exchange-Nutrients

Chapter 8 Indoor cannabis cultivation - Many problems? Many problems can be prevented in advance, good gardeners know it, less is more! Interactions between nutrients - causes of malnutrition. Causes of nutrient deficiencies are inharmonious nutrient ratios in the soil, in addition to...

www.icmag.com

The articles are still being refined and supplemented!

 

[snakedope]

You will have the light of 3840 diodes present in your readings, but all of them are same rate of production diodes ! So while you can count and add the light hitting a source value, you cannot add the rate of it being produced at the source by adding the same strength source next to it !
And if you don't understand that I'm done explaining it to you.

 

[Corpselover Fat]

And if you don't understand that I'm done explaining it to you.

I wish that was true.

 

[delta9nxs]

this man is a professor of crop physiology at Utah State University.

he has done a lot of work with cannabis.

 

[delta9nxs]

in the above video, he compares cannabinoid and terpenoid production under some different light sources. very revealing.

he's not getting significant differences in production.

 

[zachrockbadenof]

we were using hid for years, till we downsized to a tent and 1000watters were toooo much for a small tent - then we moved to 315cmh's, 2 of em in a 4x3.5ft tent, and felt not enough light - now moved up to a 5x5ft tent with a mars fce800 and will see results in some months.... but to say i am confused... would be an understatement...

 

[[Maschinenhaus]]

but to say i am confused... would be an understatement...

What exactly do you mean by confused?

 

[exploziv]

Probably by the diferences in growing under hids versus leds or vice-versa. They are usually more evident than one expects them to be..

 

[zachrockbadenof]

Probably by the diferences in growing under hids versus leds or vice-versa. They are usually more evident than one expects them to be..

just reading the various posts.... led's are great..... no led's suck.... hid's are great.... no they suck..... the sun is great.... u get the idea

i am about a month into veg with the mars fce8000 - so far all good ... except the temps.... hard to get the tent over 75F... plants look fine, my only observation is the nodes appear to be much tighter then under cmh's...

 

[Corpselover Fat]

plants look fine, my only observation is the nodes appear to be much tighter then under cmh's...

Probably due to more light overall, and partly due to less IR and more blue.

 

[Sipina]

my only observation is the nodes appear to be much tighter then under cmh's...

Probably due to more light overall, and partly due to less IR and more blue.

I think the LED spectrum in general having less blue-light is the main cause for a bit more stretched plants.

 

[[Maschinenhaus]]

Probably due to more light overall, and partly due to less IR and more blue.

I think the LED spectrum in general having less blue-light is the main cause for a bit more stretched plants.

In a direct comparison between MH/CDM and LED, the spectral band for blue is very narrow, plus the gap at about 480nm. This in combination with the strong light emitted by LEDs leads to the observations on the plants. Also the ratio red to deep red is often wrongly implemented by the manufacturers! Better is a certain ratio 660nm to 730nm, it would also be better if the spectral band would go up to 800nm.

It is also speculated in expert circles, whether the many strong light sources of the COB and SMD panels lead to stress-like reactions? With COB-LED somewhat weaker than with boards with hundreds or thousands of SMD.

For a few COB LEDs with glass lenses that are strongly energized, the effect is demonstrably less than for strips or boards.

Another issue is temperatures, the plant gets a lot of light under LED but usually little heat.

For lamps for scaperaquariums, I bundle the LED into a strong light source that has a wide spectral band (full spectrum). I get 100% positive feedback.

For cannabis, here's what I'm trying at the moment:

Few, heavily populated COB with few small SMD based PCBs, raising the range around 380nm to about 500nm and tuning red and deep red.

Lamp module length 100 cm - total 350 watts, dimmable and initially without optics with 120° radiation.

Nothing is set in stone yet, it's just a "trial and error".

 

[delta9nxs]

dr bugbee again

at 21:20 he talks about the differences between energy in the light field and photons.

from here to the end he discusses the effects of far-red on various plant species.

he does not recommend adding a lot of far-red for cannabis as it is a high light shade-avoiding plant.

 

[JKD]