The penetration of COBs, strips and boards

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1212ham

Well-Known Member
Some say cobs penetrate better, but I've never seen a good explanation of how they can do so. What is the science that explains how cobs can penetrate better? I'm not looking to start a fight, but looking for a better understanding of the penetration topic.
 
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1212ham said:
Some say cobs penetrate better, but I've never seen a good explanation of how they can do so. What is the science that explains how cobs can penetrate better? I'm not looking to start a fight, but looking for a better understanding of the penetration topic.
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I love my cobs, and believe that they do make for some large nuggets. That said, i am on my first grow with some qb's so the jury is still out
 
The inverse square law would apply to this, although not in a straightforward way exactly. A brighter single light source will depreciate over a longer distance compared to a lower intensity single source. COBs although technically are a bunch of diodes, act more like a single source than a typical QB does. Of course it gets complicated due to LED light output overlap and such, and I'm not a physicist so can't really explain it.

Here's a link to inverse square law, which is the basic principle that the theory of COBs having better penetration rally around: https://en.wikipedia.org/wiki/Inverse-square_law
 
PJ Diaz said:
The inverse square law would apply to this, although not in a straightforward way exactly. A brighter single light source will depreciate over a longer distance compared to a lower intensity single source. COBs although technically are a bunch of diodes, act more like a single source than a typical QB does. Of course it gets complicated due to LED light output overlap and such, and I'm not a physicist so can't really explain it.

Here's a link to inverse square law, which is the basic principle that the theory of COBs having better penetration rally around: https://en.wikipedia.org/wiki/Inverse-square_law
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Nice. So it's not really an argument, it's a Law, lol.
 
PJ Diaz said:
You can have both with the right fixtures, but you also need to have enough overhead between the light and the canopy for the more intense light sources.
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You mean like 1200+ watt water cooled monster LED's? cause at that point, might as well just hang DE's
 
i got some bro-science for ya. cobs/pucks are the perfect balance. enough light sources spread over the canopy to increase penetration without sacrificing intensity per light source the way you do when you spread your power over 1000+ diodes.
 
Snob said:
You mean like 1200+ watt water cooled monster LED's? cause at that point, might as well just hang DE's
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No, I mean by using higher powered diodes than the typical lm301b's. Using higher powered diodes like a 5050 series LED, so that you're putting 3x the current through each diode with less diodes on each board for a small board foot print. That part gets you the penetration, then you spread a few of those boards around the canopy, and because they have 120degree angles, they get good photon distribution from multiple angles. This sort of system is also typically less expensive because it requires less total diodes. The trade off is lower efficiency, but still at 2.4 umoles/joule it's not bad at all.
 
my view, a light ray loose energy when its reflected, expansion of the universe and gravitation shouldnt matter in our scale.
the better you spread your lightsources the more direct light hits your plants and in the end this is the "penetration".
comparing CXB cobs to panels or strips i would need to hang my cobs way higher to have a similar distribution, more reflections needed,means less energy, less penetration.
can only speak for tent configurations.
 
Think theres alot more variables than just the light source. After dropping the cobs and moved on to qbs and strips, my energy consumption went down, and yield stayed the same. That's because I work with strains I'm familiar with and scrog with heavy training. My nugs usually come out the same size with very little b size nugs.
Not hating on the Cobs, I definitely think they penetrate better, but that doesn't matter with other variables like training, genetics, vod, substrate/feed/ etc etc.
 
Before everybody starts arguing about which has better penetration is there even any agreement of what is definition of penetration? And what is it good for?
I know some say penetration is basicly how far down on the plant do you still get decent size and density nuggs.
Other say high light intensity deep down in the cannopy is a sign of penetration.

Is there any other way of defining penetration? Cause personally i dont think the light source have very much to do with either of those definitions, i think what we conceive of as penetration is somewhat of a myth, at least in terms of light source, but i think you can make a valid point of some spectrum penetrating deeper in the cannopy.
Any thoughts? And thank you @1212ham for the thread, ive been dying to bring this up, but im also quite prepared for this turning into a flamewar.
 
PJ Diaz said:
The inverse square law would apply to this, although not in a straightforward way exactly. A brighter single light source will depreciate over a longer distance compared to a lower intensity single source. COBs although technically are a bunch of diodes, act more like a single source than a typical QB does. Of course it gets complicated due to LED light output overlap and such, and I'm not a physicist so can't really explain it.

Here's a link to inverse square law, which is the basic principle that the theory of COBs having better penetration rally around: https://en.wikipedia.org/wiki/Inverse-square_law
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intensity has nothing to do with it. beam angle determines penetration. a narrow beam angle will penetrate deeper but the footprint of the light will grow more slowly
 
mauricem00 said:
intensity has nothing to do with it. beam angle determines penetration. a narrow beam angle will penetrate deeper but the footprint of the light will grow more slowly
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What if you are comparing two LEDs with the same beam angles but different intensities? Then does intensity make a difference? I would argue that yes it does.

Also I feel like you are contradicting yourself. Wouldn't the fact that it has a more narrow beam angle (assuming the same wattage) also make the light more intense?
 
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PSUAGRO. said:
A single light source in a reflector turns into multiple light sources imo....... So inverse square law becomes skewed or non applicable.

Then their is the whole diffuse light /intra canopy argument. Can debate for ages, most LED packages deliver now so pick your poison.
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It may be skewed a bit, depending on where your first measured point falls, but having measured HPS reflector fixtures in the past at various points myself, I can absolutely assure you that it's quite applicable.
 
Throwing in my $.02, having measured PAR and spread at multiple heights using COBs, mid power diode strips and boards, it is very evident that PAR remains relatively evenly spread with strips when adjusting height above canopy however PAR readings remain even from a ratio perspective , overall point measurements are lower as you get further away.

Boards, depending on shape and size act similay to strips but with more concentrated light in the center as the spread of the diodes over the prescribed coverage area is slightly less even than with strips due to the physical placement of the diodes with respect to the intended coverage area.

COBs, as @PSUAGRO. pointed out act almost like a projector beam with high photon flux output from a small area of densely packed diodes. These perform better at higher operating heights which allow the light to be more evenly spread over the intended coverage area. This is why COBs are generally used in high bay warehouse lighting as a replacement for HID/HPS/CMH style lights.

Penetration is a subjective measurement however absent of defoliation practices COBs arguably penetrate to lower branches better than mid power diodes. Similar to a garden hose with multiple settings, the ‘jet’ setting provides more strength to the water output than the ‘shower’ setting which spreads the water out more with less overall velocity and strength per sq mm.✌
 
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