Choosing an LED Light

Hello RIU,

Lighting is arguably one of the more important, and expensive parts of your grow operation. We designed this guide to help you compare not only Timber Grow Lights, but any LED light. There are many factors to consider - hopefully this helps to answer some of the more frequent questions. If you have any questions, or would like additional information, always feel free to contact one of our knowledgeable lighting experts or post a reply in this thread.

Have a safe and Happy Thanksgiving holiday.

Best Regards,
Your friends at Timber Grow Lights

Happy Holidays to you and yours

nice info graphic.

can you explain how you measured and quantified "penetration" and determined that cobs have more?

why I ask is that on average a 100W strip light will produce more photon flux than a 100W COB so I am confused on how a COB penetrates better due to its Photon Flux but strips do not despite having more PF per watt.

I always thought a COB was one bigass LED chip, encased under a "fisheye" lens which casts the light. Time to crack more books. Great post!!

MidnightSun72 said:

nice info graphic.

can you explain how you measured and quantified "penetration" and determined that cobs have more?

why I ask is that on average a 100W strip light will produce more photon flux than a 100W COB so I am confused on how a COB penetrates better due to its Photon Flux but strips do not despite having more PF per watt.

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That is a very good question and one that we get asked a lot. Penetration is a subjective term - and is typically used in reference to photon density/flux.

Flux is the flow of energy through a surface and is a vector measurement (has speed and direction). The surface area of a COB is roughly 1.5" in diameter and emits more photons per mm² than an SMD (be it a 2835, 3030 or 561 style chipset). While photons do spread, it's tantamount to water coming from a hose. Higher pressure will emit a stronger stream that travels further than free flowing water with the same volume output.

I hope this helps - and thank you for highlighting this very important concept.

PopAndSonGrows said:

I always thought a COB was one bigass LED chip, encased under a "fisheye" lens which casts the light. Time to crack more books. Great post!!

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Thanks for the kind words. A COB (chip on board) is an array of densely packed diodes (LEDs) arranged on a substrate. The orange center is a phosphor overlay that gives the COB it's color temperature characteristics.

COBs were developed as a general lighting replacement for SSL style lights in high bay applications, such as MH and HPS. They can be found in high-bay lighting, street lights, and high-output track lights and downlight installations.

They are not without their drawbacks as compared to SMD style LEDs. COBs require heatsinks that must be capable of dissipating the heat generated by a large amount of wattage present in a small area. The use of specialized heatsinks, such as pin and splayed pin style, help to transfer the heat from the COB to the heatsink. We use Arctic Silver 5 in addition to splayed pin heatsinks in order to assist with the heat transference. The high-density filling of micronized silver and enhanced thermally conductive ceramic particles present in this product works in conjunction with the ceramic underside of the COB and the aluminum surface of the heatsink in order to ensure optimal and efficient thermal dissipation.

It is vitally important that heat dissipation is maximized in LED applications as the removal of heat aids in not only increased efficiency but also longevity of the LED.

RainDan said:

That is a very good question and one that we get asked a lot. Penetration is a subjective term - and is typically used in reference to photon density/flux.

Flux is the flow of energy through a surface and is a vector measurement (has speed and direction). The surface area of a COB is roughly 1.5" in diameter and emits more photons per mm² than an SMD (be it a 2835, 3030 or 561 style chipset). While photons do spread, it's tantamount to water coming from a hose. Higher pressure will emit a stronger stream that travels further than free flowing water with the same volume output.

I hope this helps - and thank you for highlighting this very important concept.

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I am not sure i understand the analogy. In the case of the hose, the water is higher pressure= higher velocity once the water reaches atmospheric pressure and converts the potential energy in the water to kinetic. as per this manipulation of Bernoulli's equation.

we can see in this equation as pressure P increases so will velocity V.

Light on the other hand is already at max speed and does not have the capacity to hold any "potential" since it is just energy it is the potential.

I'd love to see PPFD measurements taken through a canopy for both types of lamp.

Would be a great way to verify how deeply the photons penetrate the canopy.

MidnightSun72 said:

I am not sure i understand the analogy. In the case of the hose, the water is higher pressure= higher velocity once the water reaches atmospheric pressure and converts the potential energy in the water to kinetic. as per this manipulation of Bernoulli's equation.
View attachment 5033881
we can see in this equation as pressure P increases so will velocity V.

Light on the other hand is already at max speed and does not have the capacity to hold any "potential" since it is just energy it is the potential.

I'd love to see PPFD measurements taken through a canopy for both types of lamp.

Would be a great way to verify how deeply the photons penetrate the canopy.

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I completely agree about PPFD measurements on top of a canopy vs intra-canopy. Unfortunately, there are many subjective variables such as defoliation, intensity of the foliage and leaf size.

My analogy was simply to illustrate that the size of the aperture and the volume of photons exiting is similar to that of water emitting from a hose. This is similar to why PPF measurements are stronger underneath a reflector than an open LED. It's the aggregate energy of the photons per volume since C (speed of light) is a constant.

I appreciate your opinion - penetration is always a subject of intense discussion, and rightfully so. At the end of the day, distance from canopy along with each grower's opinion and preference(s) are the final say.

LEDS last 10years?

RainDan said:

Hello RIU,

Lighting is arguably one of the more important, and expensive parts of your grow operation. We designed this guide to help you compare not only Timber Grow Lights, but any LED light. There are many factors to consider - hopefully this helps to answer some of the more frequent questions. If you have any questions, or would like additional information, always feel free to contact one of our knowledgeable lighting experts or post a reply in this thread.

Have a safe and Happy Thanksgiving holiday.

Best Regards,
Your friends at Timber Grow Lights



View attachment 5033855View attachment 5033856View attachment 5033857View attachment 5033858

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LEDS last 10 year, is a bit of a strech. They start degrading the moment you light them, all be it at a very slow rate. I've seen estimates for typical grow cycles lossing 20% after 5 years. The diode might last for 10 years but the light output will be down the drain.

MidnightSun72 said:

nice info graphic.

can you explain how you measured and quantified "penetration" and determined that cobs have more?

why I ask is that on average a 100W strip light will produce more photon flux than a 100W COB so I am confused on how a COB penetrates better due to its Photon Flux but strips do not despite having more PF per watt.

Click to expand...

Mate, it's all about the angles.

Penetration is a function of light passing through gaps (direct or reflected). Light at different angles can pass under a leaf easier than light shining directly on top of it.

The Inverse Square Law turns to shit as soon as you divide the light into multiple sources and shine it from different directions at the same object.

Diffused light penetrates better than direct light. That's why photographers use diffusers to eliminate shadows.

Prawn Connery said:

Diffused light penetrates better than direct light. That's why photographers use diffusers to eliminate shadows.

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Interesting analogy. I quite like it. The reason a diffuser eliminates shadows is because it makes the light source bigger in relation to the subject. If you move the diffuser further you get more shadows, because you're making the light source smaller. If you placed smaller light sources further away in an array matching the apparent size of the duffuser, you would get similar reduction in shadows. Since you are now further away from the subject you need to increase power because on the inverse square law. What also happens is that the relative distance between the nearest and farthest points of the subject decreases in relation to the light source.

Tl;dr: for a scrog a light source near the tops will light all the buds just fine, but doing the same on trees would not light the lowers. For trees you want the light source further away, but for a scrog the required increase in power would be wasted.

Horselover fat said:

Interesting analogy. I quite like it. The reason a diffuser eliminates shadows is because it makes the light source bigger in relation to the subject. If you move the diffuser further you get more shadows, because you're making the light source smaller. If you placed smaller light sources further away in an array matching the apparent size of the duffuser, you would get similar reduction in shadows. Since you are now further away from the subject you need to increase power because on the inverse square law. What also happens is that the relative distance between the nearest and farthest points of the subject decreases in relation to the light source.

Tl;dr: for a scrog a light source near the tops will light all the buds just fine, but doing the same on trees would not light the lowers. For trees you want the light source further away, but for a scrog the required increase in power would be wasted.

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Diffusers break up the light and deflect it at different angles. Shadows are eliminated not just by making the light source "bigger" but by bouncing it off walls, the roof and other objects in the room. That is the secret to penetration: creating multiple angles of light that can shine or bounce under the foliage to penetrate the lower canopy.

In your example, if we took that same light over the "tree", split it into four lights 1/4 the strength each and shone those lights from each corner of the grow area, more light would penetrate, as there would be more photons passing through the canopy at different angles increasing their chances of passing through the gaps.

If I am holding an umbrella and you drop a bucket of water on me from directly above, I wont get wet. But if I walk outside where it is raining and the wind is pushing the rain sideways as it falls, some of that rain will be pushed under the umbrella and wet me.

The Inverse Square Law turns to shit when you multiply the light sources instead of applying it to a single light source, because multiple light sources can overlap each other.

The plant in the middle gets the least penetration because its canopy shadows the undergrowth. The plants on either end get the most penetration, because the light passes under the top canopy into the lower foliage. Now imagine having one light over each plant: they would all get good penetration due to the different angles from mulyiple light sources passing under the top canopy into the foliage below.

Does that make sense now?

Prawn Connery said:

Diffusers break up the light and deflect it at different angles. Shadows are eliminated not just by making the light source "bigger" but by bouncing it off walls, the roof and other objects in the room. That is the secret to penetration: creating multiple angles of light that can shine or bounce under the foliage to penetrate the lower canopy.

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That makes the apparent light source bigger. I have a flash and by putting it in a reflector I make the light source bigger, because the light source is the reflector now.

Prawn Connery said:

The Inverse Square Law turns to shit when you multiply the light sources instead of applying it to a single light source, because multiple light sources can overlap each other.

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Nah. You just need to figure out the relative size of the light source. It becomes larger with the added light sources. Treat them as a single large source. If the light hits a wall and reflects it adds to the size of the light source.

Prawn Connery said:

The plant in the middle gets the least penetration because its canopy shadows the undergrowth. The plants on either end get the most penetration, because the light passes under the top canopy into the lower foliage. Now imagine having one light over each plant: they would all get good penetration due to the different angles from mulyiple light sources passing under the top canopy into the foliage below.

Does that make sense now?
View attachment 5036129

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That is what I was saying. You add point light sources in there and you get a bigger more diffuse light source lighting your subject. Look at it from the perspective of the subject. The actual size of the light source is irrelevant, as far as diffusion goes, as long as the relative size of the light source stays the same.

If I put a soft box right next to a person I will have strong diffuse light on the side of the soft box and the other side will recieve much less light. If I use a larger soft box further away (keeping the same relative size) I will need much more power, but i will have more uniform light on the subject because the distance between the sides of their face is now smaller relative to the light source.

Sorry I'm not explaining my view very clearly. I don't think our ideas differ much. I could probably do a bit better job if I wrote in finnish, but uhm. Yeah... This is something I've spent quite a few hours trying to figure out. I think I have a fairly good grasp of how things go, but it is all rather confusing.

I guess my main point is there are at least two different things people mean when they talk about penetration (besides what you are thinking, you perv ) :

1) light reaching all parts of the plant by coming from many angles

2) uniform lighting from top to bottom of plants

For #1 you need a big light source or multiple sources. For the plant it's all the same as long as photons come from all directions.

For #2 you need distance between the light source and the plant. For short plants a short distance is sufficent, but tall plants need more distance.

I use a small tent and I have a big source near my short plants. It just makes more sense to me in my space. If I had an infinite warehouse I'd grow trees with lights up high.

cobshopgrow said:

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Sun is small compared to the diffusion panel right next to the plant and the diffusion panel is the light source as far as the plant is concerned. Relative size rules.

youre right
i may get something wrong (non native english either), but sun is never small on planet earth as there is diffusion due to dust particles in the atmosphere and further diffusion due to clouds (if theyre there).

This is a pretty good illustration of the other kind of penetration. It's impossible to light all models evenly if the light source is near. A stop is how photographwrs measure light. One stop more is twice the light.

cobshopgrow said:

youre right
i may get something wrong (non native english either), but sun is never small on planet earth as there is diffusion due to dust particles in the atmosphere and further diffusion due to clouds (if theyre there).

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Yes, when it's cloudy there are very little shadows because the whole sky is the light source. The blue sky does scatter light, which is why we see it, but the light from it is much less than what comes straight from the sun. Sun makes hard shadows because it is a small source, relatively. The shadows are not completely black because of the scattered light from the blue sky. If you take a photo or look closely you can see how the shadow areas are actually quite blue on a bright day.

nothing youve posted is wrong.

am aware of how the color temparature change over the day and where it comes from, also am aware of the working principle of a softbox and how light travels.

my example is refering to diffusion foils used in greenhouses, so its working with the sun as the light source.
in this case the foil becomes the light source and the sun is small compared to.
you where refering with the "diffusion panel " to the diffusion foil, got it.
your ilustration is much better, just missing a plant to show the effect.

even without extra diffusion the sun outdoor is always quite big, soft, even distrubuted, compared to pointy led lights in our indoor tents.
there is never a change of a few hundred ppfd when you raise or lower your meter .outdoor a 30cm f.e.

cobshopgrow said:

nothing youve posted is wrong.

am aware of how the color temparature change over the day and where it comes from, also am aware of the working principle of a softbox and how light travels.

my example is refering to diffusion foils used in greenhouses, so its working with the sun as the light source.
in this case the foil becomes the light source and the sun is small compared to.
you where refering with the "diffusion panel " to the diffusion foil, got it.
your ilustration is much better, just missing a plant to show the effect.

even without extra diffusion the sun outdoor is always quite big, soft, even distrubuted, compared to pointy led lights in our indoor tents.
there is never a change of a few hundred ppfd when you raise or lower your meter .outdoor a 30cm f.e.

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I didn't mean to rail on you. I'm sorry if I came over rude. It wasn't my intention, but i know i can get carried away. The reason the ppf doesn't change with how high you meter is is because of the enormous distance to sun. The meter is not really any closer to sun even if you took it on top of mount everest.