Light penetration question

Apologize if this is a newbie question but I'm trying to wrap my head around light penetration among various types of lights.. Does it make a difference in how much light the lower buds receive if the light intensity (ppfd) is the same at the top of the canopy?

For example:

Light A: Fluence Spydrx plus produces ~950 ppfd at the top of the canopy with a hanging distance of 6 inches above the canopy.

Light B: Gavita produces ~950 ppfd at the top of the canopy with a hanging distance of 3 feet above the canopy.

Light intensity at the top of the canopy is the same. Will there be a difference in how much light the lower buds receive?

i am not sure what these lights are, but HID's (HPS and MH) will penetrate much much further than LED's and fluros

CMH LEC penatrate 30 inches

led do not penetrate well but they are amazing if you have an even canopy. light penetration is how well the light go's past the canopy to the lower branches.which isnt very necessary if you train your plants.

purplehays1 said:

i am not sure what these lights are, but HID's (HPS and MH) will penetrate much much further than LED's and fluros

Click to expand...

Well one is an LED and one an HID. I was thinking light is light and a given equal light intensity between 2 lights would at some point in the distance be equivalent since the speed that light travels is the same. I've heard that HID gives better penetration just dont really understand why.

Light and other electromagnetic radiation[edit]
The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the energy (in the same time period)

https://en.wikipedia.org/wiki/Inverse-square_law

purplehays1 said:

i am not sure what these lights are, but HID's (HPS and MH) will penetrate much much further than LED's and fluros

Click to expand...

NO you're mistaken.

Pig4buzz said:

CMH LEC penatrate 30 inches

Click to expand...

No you're mistaken.



This is not a simple question and there are many factors that affect "penetration" those blanket generalizations are worthless bullshit.
@kelly1376
In matters of PAR/PPFD stoner bro science is not even worth your consideration..

Read some over here:https://www.rollitup.org/t/light-intensity-led-vs-hid.912964/


*the inverse square law is not operational in a reflective space with multiple light sources.

a pretty good read..

http://www.stouchlighting.com/blog/lighting-comparison-led-versus-hid

testiclees said:

NO you're mistaken.

No you're mistaken.



This is not a simple question and there are many factors that affect "penetration" those blanket generalizations are worthless bullshit.
@kelly1376
In matters of PAR/PPFD stoner bro science is not even worth your consideration..

Read some over here:https://www.rollitup.org/t/light-intensity-led-vs-hid.912964/


*the inverse square law is not operational in a reflective space with multiple light sources.

Click to expand...

Really? I have CMH lec. 30 inches plus is dense buds. My experience

Pig4buzz said:

Really? I have CMH lec. 30 inches plus is dense buds. My experience

Click to expand...

i dont deny it...just as a blanket statement/reference point it's not relevant.

Let's see a 30" stem with a ruler and buds all down the line???? Plz

That want happen with any light get real. A bud 30 inches down the branch will be dense. Doesn't mean a 30 inch branch is one gaint cola. Never said that.

Pig4buzz said:

That want happen with any light get real. A bud 30 inches down the branch will be dense. Doesn't mean a 30 inch branch is one gaint cola. Never said that.

Click to expand...

No i gotcha, i wanna see a 30" branch with a solid, for real nug at the base. I wouldnt expect a 30" cola indoors.

ll measure the braches on my mad berry and Kali Mist. I may have 30" branches with buds on bottom, not sure though i may be overestimating....i'll measure tmwr. These are led cob grown in fabric pots, hi brix soil method.

testiclees said:

NO you're mistaken.

No you're mistaken.



This is not a simple question and there are many factors that affect "penetration" those blanket generalizations are worthless bullshit.
@kelly1376
In matters of PAR/PPFD stoner bro science is not even worth your consideration..

Read some over here:https://www.rollitup.org/t/light-intensity-led-vs-hid.912964/


*the inverse square law is not operational in a reflective space with multiple light sources.

Click to expand...

Thanks man! That's a great thread. Looks like I have some reading to do

Get the tape out.

They look nice dude. Is that your space? It does look like it's possible that he's got nugs 30" down.

The speaker though doesn't seem too knowledgeable. I have rd through :https://www.rollitup.org/t/lec-light-emitting-ceramic.866862/ and ive seen nice CMH grows. It still wouldnt be very helpful to say CMH has 30" of penetration for a couple reasons. #1 "penetration" is not really a thing. Plants arent growing buds 30' down because of photosynthesis 30" down in the canopy
#2 in that space in the vid,lamp overlap is having a multiplier effect on the PAR. So blanket statement cmh penetrates 30" i say no. In a particular setup you might get buds 30" deep but it doesnt mean that you're getting 30" of penetration.

Another issue is the reflector at least 20% of the photons are lost there. There are good growers on RIU getting great results with CMH so no argument on whether it works.

If thats your grow are those plants so leafy because of the light or is it the strain?

Not sure why your saying plants don't grow buds 30 inches down. I have autos that have buds 30 inches down. As for lights the led cob are good lights too. No not my space at all. I think they said the strain was Dublin berry maybe.

testiclees said:

NO you're mistaken.

No you're mistaken.



This is not a simple question and there are many factors that affect "penetration" those blanket generalizations are worthless bullshit.
@kelly1376
In matters of PAR/PPFD stoner bro science is not even worth your consideration..

Read some over here:https://www.rollitup.org/t/light-intensity-led-vs-hid.912964/


*the inverse square law is not operational in a reflective space with multiple light sources.

Click to expand...

No you are mistaken, ill leave some vague explanation of why later.

purplehays1 said:

No you are mistaken, ill leave some vague explanation of why later.

Click to expand...

Are you trying to ask a question?

", but HID's (HPS and MH) will penetrate much much further than LED's and fluros" you have no fucking idea what you're saying. Provide us with the citations you use to talk out your ass.

Do some research pussy, I'm not your dank tutor.

testiclees said:

Are you trying to ask a question?

", but HID's (HPS and MH) will penetrate much much further than LED's and fluros" you have no fucking idea what you're saying. Provide us with the citations you use to talk out your ass.

Do some research pussy, I'm not your dank tutor.

Click to expand...

lol you sound like some angry (just in general) individual who spent thousands on LED lights that produce lower quality bud than my $99 HID (probably made you more angry), and wants to justify their overspending/stupidity. I may be wrong, but i doubt it.