Lenses/ Reflectors worth it for COB?

Trippyness

Trippyness

Well-Known Member
Greetings,

Been speaking to a few people and seen a few threads and some tests.

So are reflectors worth the 10% loss instead of running bear?

Would love to hear a side by side.

As I have a bunch of Vero29 and reflectors, but it may seem that the reflectors may be useless.

I want penatration, but would running bear LED closer not get me penetration without Reflectors?
Mainly talking about Ledil reflectors.

Trippy
 
welight

welight

Well-Known Member
you need to balance optical efficiency losses against beam angle/PPFD, sure you lose some efficiency but you cant get the same High PPFD at 120 degrees or what ever the base COB angle is vs 90 Degree Angelina or alternate reflector
Cheers
Mark
 
Trippyness

Trippyness

Well-Known Member
welight said:
you need to balance optical efficiency losses against beam angle/PPFD, sure you lose some efficiency but you cant get the same High PPFD at 120 degrees or what ever the base COB angle is vs 90 Degree Angelina or alternate reflector
Cheers
Mark
Click to expand...
Thank you mark. Thats what I thought before I saw this:
https://www.rollitup.org/t/testing-timbers-prototype-4000k-660nm-and-my-finger-on-the-flower-trigger.903999/page-10
Would love your take on this. Starts at post #192.

My thoughts are you will get a much more focused beam and better penetration with a 90 Ledil vs 120 bare. Seems like 120 is wasted light.
 
CobKits

CobKits

Well-Known Member
i dont use them. if at all i would use them on the edges of a tent maybe. much more even coverage with an array of 120 deg emitters imo. less hot spots

but i use bjbs which are basically mini-reflectors just to catch that last little bit over 110 deg. going sideways
 
welight

welight

Well-Known Member
Trippyness said:
Thank you mark. Thats what I thought before I saw this:
https://www.rollitup.org/t/testing-timbers-prototype-4000k-660nm-and-my-finger-on-the-flower-trigger.903999/page-10
Would love your take on this. Starts at post #192.

My thoughts are you will get a much more focused beam and better penetration with a 90 Ledil vs 120 bare. Seems like 120 is wasted light.
Click to expand...
I read this, My take is that yes your reflectors take 8.2 or 10% but I could not work out if they tested the COBS with and without reflectors, I have tested 3590 with and without Angelinas absolutely no doubt you get more CBP(centre beam photons) and as many PAR maps here have shown they will diminish as the beam spreads out. You can offset COBS to cross the beams as it were to account for this. It comes down to no reflectors providing less PPFD but a more even PAR map vs collimating the beams, which may suit if your at a COB a plant ratio, I guess the other difference is with no reflectors you need to spend more time controlling the led height from plant. Either will work just depends on your goals
Cheers
Mark
 
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Trippyness

Trippyness

Well-Known Member
CobKits said:
i dont use them. if at all i would use them on the edges of a tent maybe. much more even coverage with an array of 120 deg emitters imo. less hot spots

but i use bjbs which are basically mini-reflectors just to catch that last little bit over 110 deg. going sideways
Click to expand...
Im running a 3 x 3 with 6 Cobs at 2.1A 16" apart.
Would you reccomend reflectors on all COBS as technically they are all on the sides.
Was send wrong drivers unfortunatly so have to work with 2.1A. Still over 900 PPFD but would have prefered 1 cob a sq/f.

Not well versed on optics as of yet. Alot of contradicting things about them.

I'm using these
http://ca.mouser.com/ProductDetail/Ledil/F13381_ANGELA-W
 
sixstring2112

sixstring2112

Well-Known Member
Trippyness said:
Im running a 3 x 3 with 6 Cobs at 2.1A 16" apart.
Would you reccomend reflectors on all COBS as technically they are all on the sides.
Was send wrong drivers unfortunatly so have to work with 2.1A. Still over 900 PPFD but would have prefered 1 cob a sq/f.

Not well versed on optics as of yet. Alot of contradicting things about them.

I'm using these
http://ca.mouser.com/ProductDetail/Ledil/F13381_ANGELA-W
Click to expand...
am i reading this right,45 deg angle on those reflectors? if so thats tight as hell.
 
sixstring2112

sixstring2112

Well-Known Member
also i wanted to add idk if those reflectors will still have 8% loses because its a dif design and dif material being aluminum/metal.im pretty sure the reflectors tested were the standard white plastic 90 deg angelinas most of us use.so maybe your choice is better ?
 
CobKits

CobKits

Well-Known Member
im sure they lose less. look how much light shines right thru an angelina, not even considering what gets absorbed by the plastic
 
Rahz

Rahz

Well-Known Member
The usefulness of reflectors depends on the cob count and area. For instance, when running a single cob in a 2x2 reflective area the spread will be more even with a reflector raised up by about 20% over the non-reflector height and total output will be similar with the reflector having lower center reading and higher corner readings... believe it or not.

The measurements I've taken under a single cob in those conditions don't indicate a loss of light when the reflector is used at optimal height.
 
wietefras

wietefras

Well-Known Member
Reflectors lose light.

The only time they make sense is if you want to hang the lights much higher above the canopy .

Although already then you start with 8% loss on the reflectors , so it's doubtful if it matters much .

In Malocan's test there was higher PPFD where there was no wall to reflect the light back (open tent door) , but only a few cm inside the tent, the PPFD was already better with the reflectors off.

Reflectors pretty much project a circle on the floor measuring from a single reflector is bound to cause measuring anomalies . Just inside or outside gives a big difference for only a small displacement if the sensor.
 
Rahz

Rahz

Well-Known Member
Single emitter, 3 spot measurements representing a 3x3 grid of 8"x8" squares in a 2x2 reflective area, with and without reflectors.

1x center square reading
4x side square readings
4x corner square readings
Average

Reflectortest.jpg

Note the 11" reflector readings -vs- 9" bare readings. Similar center and similar corner readings. Reflector is doing better in the side squares. Across the board the reflector is providing +500 average while bare is providing -500 averages.
 
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Rahz

Rahz

Well-Known Member
It makes sense if you think about it. Running bare will only provide more light if the walls are more reflective than the reflectors.

Things change if you're in enough space that running the center cobs bare will cause less reflectance.
 
CobKits

CobKits

Well-Known Member
Rahz said:
Single emitter, 3 spot measurements representing a 3x3 grid of 8"x8" squares in a 2x2 reflective area, with and without reflectors.

1x center square reading
4x side square readings
4x corner square readings
Average

View attachment 3816268

Note the 11" reflector readings -vs- 9" bare readings. Similar center and similar corner readings. Reflector is doing better in the side squares. Across the board the reflector is providing +500 average while bare is providing -500 averages.
Click to expand...
i like the 10" bare

best uniformity
 
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