Lens and Reflector Optics for COB

robincnn said:

Ledil F13838 Reflector and Kingbrite's KB-D82-90RF Reflector
Tested on cxb3590 cd 3500k 1.39amps with 50-2303CR holder and 50-2300AN reflector adapter

View attachment 3576238 View attachment 3576239 View attachment 3576241 View attachment 3576242View attachment 3576240

View attachment 3576244

Left: Kingbrite's KB-D82-90RF $0.80
Right: Ledil F13838 Reflector $4-$10

LEDIL reflector is thinner plastic, more flexible so locks easily. KB-D82-90RF is slightly more thick and takes just a little longer to fit.
The outer size is the same for both reflectors. The ledil has rings/steps that are missing on KB-D82-90RF. The width of base(as highlighted in red) is more in KB-D82-90RF, which means reflector walls angle is more, which means more center focused.

View attachment 3576237
Measurements taken with an average of 2 samples of KB and Ledil
The readings outside the 1x1 were almost the same.
inside the 1x1, the KB-D82-90RF has slightly more light in center, Ledil F13838 has a more evenly distributed light.
Reflectivity looks about the same. Hard to test if reflectivity will degrade faster for any of the two.

Ledil seems better due to more even light distribution.
But the light distribution differences are small and the price difference is huge. KB-D82-90RF looks like a great cheep option. You can always swap them out with original Ledil reflectors if you do not like KB

Click to expand...

Wow, ask and ye shall receive huh? Did you just do that? This makes me want to start a "best of" resources thread.

robincnn said:

Ledil F13838 Reflector and Kingbrite's KB-D82-90RF Reflector
Tested on cxb3590 cd 3500k 1.39amps with 50-2303CR holder and 50-2300AN reflector adapter

View attachment 3576238 View attachment 3576239 View attachment 3576241 View attachment 3576242View attachment 3576240

View attachment 3576244

Left: Kingbrite's KB-D82-90RF $0.80
Right: Ledil F13838 Reflector $4-$10

LEDIL reflector is thinner plastic, more flexible so locks easily. KB-D82-90RF is slightly more thick and takes just a little longer to fit.
The outer size is the same for both reflectors. The ledil has rings/steps that are missing on KB-D82-90RF. The width of base(as highlighted in red) is more in KB-D82-90RF, which means reflector walls angle is more, which means more center focused.

View attachment 3576237
Measurements taken with an average of 2 samples of KB and Ledil
The readings outside the 1x1 were almost the same.
inside the 1x1, the KB-D82-90RF has slightly more light in center, Ledil F13838 has a more evenly distributed light.
Reflectivity looks about the same. Hard to test if reflectivity will degrade faster for any of the two.

Ledil seems better due to more even light distribution.
But the light distribution differences are small and the price difference is huge. KB-D82-90RF looks like a great cheep option. You can always swap them out with original Ledil reflectors if you do not like KB

Click to expand...

I tried to locate the part online with no luck. Do you have a link?
KB-D82-90RF

DarthBlazeAnthony said:

I tried to locate the part online with no luck. Do you have a link?
KB-D82-90RF

Click to expand...

They may not have listed the reflector on their website as it is a new product. Plenty of threads and info about KingBrite.
You can reach Jerry Meng Email: [email protected]
Shenzhen KingBrite Electronics Co., Ltd

@augusto1
See the chart on page 1 to see results for glass lens. KB 80 and KB 120
The test setup for data on page 1 was not the same. So do not compare reflector chart on page 2 with a chart on page 1.

What do you think of the Ledil "F13702_BARBARA-WW-PF" for vero 18? In this datasheet it looks like it spreads the light very evenly. And what do the red and blue lines mean in the graphs?

It seems the real advantage to lenses and reflectors, even with a loss in total light, is better canopy penetration. Wouldn't this become more important the softer you drive the LEDs, CXB3590 driven @ 700ma only put out 4000 lumens. Maybe in instances where the LEDs are driven higher, 1.4mA+ for CXB w/ multiple COBs the penetration isn't as much of an issue.

My

mduke said:

It seems the real advantage to lenses and reflectors, even with a loss in total light, is better canopy penetration. Wouldn't this become more important the softer you drive the LEDs, CXB3590 driven @ 700ma only put out 4000 lumens. Maybe in instances where the LEDs are driven higher, 1.4mA+ for CXB w/ multiple COBs the penetration isn't as much of an issue.

Click to expand...

My guess is that that only really applies with single lights, The intuition that brighter lights have more penetration.

Since you have twice as many point sources of lights and Studies seem to show diffuse lighting and penetration is increased and very helpful, you may very well have better penetration running at 700ma.

For sure, the heat and light should be distributed more evenly throughout the canopy. Throw in the benefit of more diffuse light and my best guess is you improve penetration, and yield.

good day to all
wanted to ask when you look at the chart robin showed of the spread from the reflector at 1 foot.. if you had lets say 12 cobs set at at 1 foot apart would you see the #s go from 240 to 480 on the corners? and the sides from 345 to 690 from the cross over?
thanks

Bonjour
I guess if you put a cob over each square foot of your box you will have the same amount of light everywhere...
It is the best use of spread we could have with cob...something you could only diy...or buy individual cob panel but I do not know any cie who sell low amp individual panel!
16 cob over each sq/ft of a 4x4...30w each...would I need lens or reflector or even both with Ledil...?
I know I can put them really close...but I do not know how deep they go @1050mA?...
And I don't know anyone who got this configuration atm...there's some who have 16 cxb3590 in a 4x4! But not OVER each sq/ft they are all on big hs (hps style!)...if nobody do it before I will be the first to have a fixture almost the size of my tent...lol (110x110...44x44!)
If you put 1ft between 30w cob you can put 1.5ft between 50w cob !
CU

cfnorg said:

What do you think of the Ledil "F13702_BARBARA-WW-PF" for vero 18? In this datasheet it looks like it spreads the light very evenly. And what do the red and blue lines mean in the graphs?

Click to expand...

Looks like a nice reflector. Beam of 60 looks a little narrow but should be fine since smaller COB and if several of them spaced evenly. Light spread looks very even.


I would not worry about the red and blue since they almost overlap.

Red is the C0-C180 plane. Blue is C90 to C270 plane. If you are looking at light area from the lamp position, left to right is one plane, the other plane is top to bottom. This article covers it well..
http://www.olino.org/us/articles/2009/10/29/background-measurement-data-lamp-measurement-articles

It also talks about how to calculate 'PAR number for the light of a lamp'. Some COB values here

mduke said:

It seems the real advantage to lenses and reflectors, even with a loss in total light, is better canopy penetration. Wouldn't this become more important the softer you drive the LEDs, CXB3590 driven @ 700ma only put out 4000 lumens. Maybe in instances where the LEDs are driven higher, 1.4mA+ for CXB w/ multiple COBs the penetration isn't as much of an issue.

Click to expand...

Penetration seems to be one of the main advantages of the lens and reflectors. I agree at softer drive currents the COB output is not as intense and would benefit more from optics.

The light from COB has a wide angle. Reflector or lens tightens the beam a little so you get more penetration.

I think that even if you run at 1.4mA, 2.1 or higher watts, you could still benefit from optics.
The reflector or lens may have its losses but may actually help efficiently deliver more photons towards the plants.



Consider this chart from from page 1. Assuming you have 1.4amps cobs spaced apart. The red represents light towards 1 sqft. The blue and red together represent light going at 4sqft.
Any photos going out of 4sqft box are at going too much side ways and are not going to be efficiently delivered towards grow space. For these sideways photons
a) if reflective sides then reflective losses, some photos will be reflected away from plants.
b) If large area of plants then those side photons hit somewhere on top of canopy. So you have high numbers on top of canopy but not as much light penetration.

That 4sqft area would be an angle of 90 degrees. Round to 100 degrees. 50 each side. anything outside +/- 50 on each side highlighted in yellow


For taller plants and during flowering.When those photons in yellow area focused a little, it should give better penetration and better overall light utilization.
Which is essentially what a good optics can do. For example the Angelina Reflector as below.

iceman3000 said:

good day to all
wanted to ask when you look at the chart robin showed of the spread from the reflector at 1 foot.. if you had lets say 12 cobs set at at 1 foot apart would you see the #s go from 240 to 480 on the corners? and the sides from 345 to 690 from the cross over?
thanks

Click to expand...

Yes for multiple cobs designs for estimate i add the values. Like you said 12 inches or 1 ft COB separation. for 2 cobs spaced you can estimate the chart like this.

So 240 to 480 and 345 to 690 seems correct.
For 4 cobs spaced 12 in apart in square would get complicated. even harder to predict for 12 cobs spaced equally for 12 sqft. You will need a PAR meter if you want exact numbers.


You should get a nice even coverage as long as they are spaced apart equally.

robincnn said:

Yes for multiple cobs designs for estimate i add the values. Like you said 12 inches or 1 ft COB separation. for 2 cobs spaced you can estimate the chart like this.
View attachment 3577689
So 240 to 480 and 345 to 690 seems correct.
For 4 cobs spaced 12 in apart in square would get complicated. even harder to predict for 12 cobs spaced equally for 12 sqft. You will need a PAR meter if you want exact numbers.
View attachment 3577691

You should get a nice even coverage as long as they are spaced apart equally.

Click to expand...

Thank you for taking the time to reply

iceman3000 said:

Thank you for taking the time to reply

Click to expand...

...and not just a quick yes or no, but in depth. I just learned something, too!

robincnn said:

The light from COB has a wide angle. Reflector or lens tightens the beam a little so you get more penetration.

Click to expand...

Reflectors won't increase the average light intensity of the grow room as a whole. So the light penetration would remain the same also.

A lens or reflector tightens the beam, but the available amount of light is still the same. So the increase in PPFD under the COB is caused by taking away light from other parts of the grow area. In the end the average PPFD over the whole grow area is still the same.

The average PPFD figures only depend on the total PPF from all the COBs combined over the grow area and the size of the grow area. Average PPFD=PPF/m2

note: I left the reflection losses out of the equation to simplify the example.

I think there are a lot of parameters that go into "penetration". In theory it's not possible to increase PPFD using optics... except in the instance that optics increases the amount of light actually reaching the plants. Optics aren't perfect and a reflective surface doesn't direct 100% of the light at the reflective angle. They aren't much different in that regard to a reflective tent wall. I think the pertinent point is that the measurements favor optics.

I have a theory on this which I've brought up before. The sensor relies on the light source approaching directly from above. Light bouncing off a reflector will be much more direct than light bouncing off a tent wall. The plants don't care where the light is coming from but the sensor does. At 45 degrees the effective surface area of the sensor is half. For this reason I don't think a light sensor can accurately quantify the difference between a cone reflector and a tent wall reflector.

If we penalize the tent wall to 70% and assume 20% of the light hits the walls that's still 14% for a total of 94% reaching the canopy. If we take the readings at face value we would have to assume a reflective wall reflects almost no light at all.

wietefras said:

Reflectors won't increase the average light intensity of the grow room as a whole. So the light penetration would remain the same also.
A lens or reflector tightens the beam, but the available amount of light is still the same. So the increase in PPFD under the COB is caused by taking away light from other parts of the grow area. In the end the average PPFD over the whole grow area is still the same.
The average PPFD figures only depend on the total PPF from all the COBs combined over the grow area and the size of the grow area. Average PPFD=PPF/m2
note: I left the reflection losses out of the equation to simplify the example.

Click to expand...

I have been waiting for you.

wietefras said:

Reflectors won't increase the average light intensity of the grow room as a whole. So the light penetration would remain the same also.

A lens or reflector tightens the beam, but the available amount of light is still the same. So the increase in PPFD under the COB is caused by taking away light from other parts of the grow area. In the end the average PPFD over the whole grow area is still the same.

The average PPFD figures only depend on the total PPF from all the COBs combined over the grow area and the size of the grow area. Average PPFD=PPF/m2

note: I left the reflection losses out of the equation to simplify the example.

Click to expand...

you have made a circular argument here, and you don't seem to realize it. Your assumption (which is different from everyone else) is PPFD if measured in the whole grow the room, the entire footprint, but everyone here is taking about PPFD ONLY for the canopy.

'So the increase in PPFD under the COB is caused by taking away light from other parts of the grow area. In the end the average PPFD over the whole grow area is still the same.'

here's your mistake. The PPFD over the whole grow area is the same because the size doesn't change, but when you take that spread and redirect it down, your by definition get more PPFDENSITY because the same amount of photons are now directed towards the canopy and not the entire grow room. And because you now have more photons in a smaller area, by definition your penetration will also increase. This is clearly demonstrated in the charts Robin has posted. Am i missing something here? Regardless of all this theory, real world results show an increase in yield with the use of optics, so tell me what happening here other than more photons being delivered in a more useful way to the plants.

other than that, I really like your arduino thread, great stuff and your ahead of the ball compared to most growers on that.

Here is some more depth


Try to imagine them as 3 dimensional and forget the 2 dimensional PAR plots.
The red represents the typical COB spread.
Blue represents and wide angle optic like KB 80/120 lens or 90 degree reflector F13838_ANGELINA-XW
Green represents a very narrow focused light from FN14074_STELLA-HB
Consider these as different 'Gears' and which one is most efficient in your grow space depends on many factors:
Beam angle of optics, COB separation, Individual COB intensity, height of COB,
Depth of plant canopy, Plants distance from reflective walls, reflectivity of walls, Plants distance from each other and other aspects of growing style. May be different for each type of plant.

For a very dense canopy but not as deep and for veg no optics may be better. With no optics the cobs can get a little closer to plants.
With taller plants your mid/lower foliage/buds may be better off with extra penetration of KB 80/120 lens or 90 degree reflector F13838_ANGELINA-XW.
**If you have wide reflector for full cycle grow. You may lose less in veg with optics and gain more by using optics during flowering. So overall a wide angle reflector may help.

Narrow beam angle lens like Stella lens may be good if your plants are extremely tall and not as dense... But may not be efficient with smaller plants or a full cycle grow.

Removable optics like F13838_ANGELINA-XW reflector are great for testing.
Jerry's 80 cents reflector makes it even cheaper to try optics . 4 reflectors and 4 adapters with China mail should be around $15 or less

Here is something i have been trying in my reflective tent. Identify a few random points in your canopy. Some top, some near mid, some under shadows of upper foliage. Try measuring light with PAR meter or a lux meter at these points with and without optics.
This test is limited by 'field of view' of your PAR sensor so choose random points as per leaf orientation and not just point straight towards the COB. Then identify at what height would the benefits of the 'optics' outweigh 'no optics'.

Or you can try to grow with both optics on and no optics and compare results. May be even no optics until canopy thickness in under 10 inches and then optics.
If you plan to put optics in half you space, then the plants in the middle might give biased results as they will benefit from Strong COB penetration with optics and the wide spread of adjacent cobs without optics.

Keep calm and grow weed and please let us know how reflectors perform for you.
Optics is not new. Diy-cob-reflector is an another thread
If you have tested any optics please do not forget to vote on this thread.

robincnn said:

Or you can try to grow with both optics on and no optics and compare results.

Click to expand...

The most valid test IMO.

I do appreciate all the work you have done on this. I don't expect many people to pack 14 cobs in an 8 square foot area and despite my insistence that there are good reasons to leave them off I think some types of optics are a good idea in most grow situations.