Light Penetration - misunderstood

[Frosty Buds]

Weezard, I think what love? is referring to is that certain wavelengths penetrate deeper into the canopy due to them being absorbed less than other wavelengths.

IIRC red penetrates further than blue and that is why more red light causes stretching whereas more blue light keeps plants compact, this being due to the plants receiving more red light thinking (?) they are surrounded by other plants and stretching to get above them and get more light.

Red being a longer wavelength doesn't come into contact with the atoms/molecules as often because there is more space between the waves.
Blue being a shorter wavelength comes in contact with the atoms/molecules more because there is less space between the waves.
A simplified explanation because I don't know all the proper scientific terms.

So using that information I would say that to design an LED light you want to make sure you have enough red light and blue light (plus the rest of the spectrum from 300nm to 700nm) to ensure they flower as well as you want them to and then add more blue light to reduce stretch and keep them as compact as you want them to be.

 

[Weezard]

It all makes perfect sense, in pounds, dollars, and pence.

It all makes perfect sense, in pounds, dollars, and pence.

This exactly what I've been trying get across to LEDGirl, but she stubbornly reuses to admit this. She advertises that her light are the world's most advanced LED systems, when in fact they are not!

I have also built DIY'd 5 watt emitter component based LED light with the same results.

And now we all know why, Hempyguy.

Don't waste time on closed minds brah.

In her defense, she's probably heavily invested.

That forces ridgidity, an' that's a hard place to be with nascent technology
Her lights will kick a UFOs ass.
But are bound to fail, ignoring facts.


Still, the proof is in the budding, yah?


Research is continuing on the dot, unfettered, and un-edited by vested interests.

Every now and again I make a "pearl run" here and drop a few seeds to see if they get "edited" for whatever pretense.

Thanks for the validation, and please post your results and reasoning.

Aloha nui
Weezard

 

[TugWheezy]

I'm familiar with audio waves, extensively, and I've been kind of using that reference to understand some of this material. Lower frequencies carry for longer distances and I'm wondering if a "lower" light frequency would penetrate farther through a canopy as a 50Hz tone would in comparison to a 15k tone.
I'm wondering... the ISL will disperse the audio (light) equally over space however at what point does the wavelength effect its penetration through a canopy. I wanna say it's negligible, do you think that's safe to say?
Pardon me if this is a stupid comment

 

[Weezard]

Safe to say? Hmmm, prolly

Safe to say? Hmmm, prolly

I'm familiar with audio waves, extensively, and I've been kind of using that reference to understand some of this material. Lower frequencies carry for longer distances and I'm wondering if a "lower" light frequency would penetrate farther through a canopy as a 50Hz tone would in comparison to a 15k tone.
I'm wondering... the ISL will disperse the audio (light) equally over space however at what point does the wavelength effect its penetration through a canopy. I wanna say it's negligible, do you think that's safe to say?
Pardon me if this is a stupid comment

Not stupid at all.
ISL is not the only loss factor.

You make a good point about shadowing and scattering.
And it would be quite valid at audio frequencies.

The effect on sound will be profound.
While R.F. microwaves slip through,
above a gigahertz or two.

(Yeah, I know it's a bit higher, so call it poetic license).

Considering the wavelength involved, measured in angstroms, vs. the size of the obstructions, measured in inches, it would be very difficult to detect/measure any difference in penetration at visual wavelengths cause by scattering.

So I would concur in your conclusion.
It's prolly quite safe to say.

With the exception of actual obstruction, reflection and absorbtion are, of course, affected by the color of the surfaces involved.

A bit off from my original point of relationship between distance from the light to the crown's effect on penetration.

And I must admit that I'm winging it here.
So please, don't quote me as any kine authority.
With luck, someone with a real education will be along anytime now to cite real references.

Aloha Y'all

Weezard

 

[ericcalif]

I'm familiar with audio waves, extensively, and I've been kind of using that reference to understand some of this material. Lower frequencies carry for longer distances and I'm wondering if a "lower" light frequency would penetrate farther through a canopy as a 50Hz tone would in comparison to a 15k tone.
I'm wondering... the ISL will disperse the audio (light) equally over space however at what point does the wavelength effect its penetration through a canopy. I wanna say it's negligible, do you think that's safe to say?
Pardon me if this is a stupid comment

The only problem is comparing sound waves with light waves. Sound is an expression of pressure moving though a material (solid, liquid, gas) but light is a particle of electromagnetic radiation.
http://www.eoearth.org/article/Electromagnetic_radiation
This thread is good, got me to refresh my old memory.
Towards the bottom is a summary of inverse square law. I looked around at a couple of pages, no where is frequency added into the equation.
Obviously there are variables when it comes to 'penetration' (our ozone layer blocks UV for example) but all things being equal, measuring light strength for our growing application, I don't see anything that justifies the myth that HPS 'penetrates' farther than any other artificial light source we use to grow our girls.

In my grows, vegetation density affects penetration way more than anything else. I'm experimenting with bottom lighting for just that reason.

 

[foaf]

In my grows, vegetation density affects penetration way more than anything else. I'm experimenting with bottom lighting for just that reason.

I think you are right that the main factor is the density of your plant. My answer to penetration is to put the light on the top, on the bottom, and on the inside. Ill let you know how the "bottom canopy" turns out. Ive got 680 watts clf below the plant this time, 1360 cfl inside the plant, and 1000 HPS overhead. That should penetrate pretty well.

 

[bipotato]

Light intensity & penetration is directly related and relevant to each other IMO, and the easiest way I can illustrate my point is to ask you to look at your plant. Look at the density / quality / maturity of the flowers at the top vs. the bottom. Much more apparent visually with purple strains especially late, you can really tell where the intense light is hitting.

Here's a plant pulled from the edge of a "4x4" lit by a 1000w HPS.



Empty spot where she used to be:

 

[ericcalif]

I think you are right that the main factor is the density of your plant. My answer to penetration is to put the light on the top, on the bottom, and on the inside. Ill let you know how the "bottom canopy" turns out. Ive got 680 watts clf below the plant this time, 1360 cfl inside the plant, and 1000 HPS overhead. That should penetrate pretty well.

Now THATs penetration! Awesome job there. I just don't want to work that hard but I definately admire your design work.

 

[ericcalif]

Look at the density / quality / maturity of the flowers at the top vs. the bottom. Much more apparent visually with purple strains especially late, you can really tell where the intense light is hitting.

Very true. Here's a cola from my last round... you can tell the difference from the top to only a few inches down.

 

[Tony Aroma]

I always thought "penetration" had to do with the size of the bulb. An HID bulb is closer to a point source than a fluorescent bulb. A tube spreads out the light more than a bulb. The light from a tube is less concentrated.

If you take two bulbs that put out the same amount of light, one HID and the other fluorescent, the HID bulb will penetrate further. It's the inverse square law in action. At any given point, you will measure more light from the HID bulb because all of its energy is concentrated into a smaller area. Fluorescents on the other hand may not penetrate as far (less light at a particular distance), but they spread their light over a larger area. Concentrated = stronger, spread out = weaker (at any given point). Total amount of light is still the same.

Depends what you want. Do you want maximum light energy at a greater distance or do you want less distance but more area covered?

 

[bipotato]

Size / wattage of bulb, amount of reflection & angle, and type of canopy would all play a role in penetration I guess.

 

[foaf]

Its complicated. In almost any grow, we set it up so that all photons fall on plant. Our lights have reflectors that widen the light very much compared to a point source. If it hits the walls, we have 90+% reflective stuff, and we usually have plants up to the walls. So the idea of lost light, mostly doesn't apply to fancy modern indoor growing.

What percentage of light hits where, how it distributes between the canopy and the deeper plant, and how different the light is at one part of the canopy vs another are the issues.