Think ive been led astray

cdgmoney250

cdgmoney250

Well-Known Member
SupraSPL said:
Thank you for taking the time to do this testing. It is interesting that as the lamp is raised the average PPFD drops off, I assume this is due to scatter/absorption in the walls. Looks like 24" is ideal?

One thing I have been curious about the SK is the temp droop. Was the lamp fully warmed up before the test (30-60 minutes maybe)

As far as angling the senor, I noticed that the Apogee sensor handles the high angle incident light better than my lux meter but I agree the numbers go up quite a bit when you point it at the light, even with the Apogee sensor. I guess that would be especially true when the light is closest to the canopy and there is a large proportion of high angle incident light.
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It was my pleasure. I've been a geek about light since before I started growing.

It seems like 22" would be the ideal coverage and intensity before the light starts to drop off on the perimeter of the 4x4. I will do some more testing tomorrow when I get the time in the "traditional" method of data points and sensor non-angling. I will include a 22" measurement.

The lamp was fully warmed up when the readings were taken. The light was on display all day and then I played with it while we were slow until we closed. It actually puts off more ambient heat from the reflector and heat sinks than I expected. They are pretty warm to the touch.
 
BobCajun

BobCajun

Well-Known Member
cdgmoney250 said:
It was my pleasure. I've been a geek about light since before I started growing.

It seems like 22" would be the ideal coverage and intensity before the light starts to drop off on the perimeter of the 4x4. I will do some more testing tomorrow when I get the time in the "traditional" method of data points and sensor non-angling. I will include a 22" measurement.

The lamp was fully warmed up when the readings were taken. The light was on display all day and then I played with it while we were slow until we closed. It actually puts off more ambient heat from the reflector and heat sinks than I expected. They are pretty warm to the touch.
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What would the point be of taking a reading with the sensor pointing up? Ain't nothing straight up other than right under the light, unless it's in a tent reflecting off the sides. I suppose it's worth doing though just to see the difference.

Something I'd be interested in seeing is the par levels in the beam of a 100w Cree cob with a lens. The beam looks fairly even. I wonder how even it actually is and how intense it is. Also, what the difference is with and without the lens on. I guess you probably don't have access to cobs though.
 
alesh

alesh

Well-Known Member
BobCajun said:
What would the point be of taking a reading with the sensor pointing up? Ain't nothing straight up other than right under the light, unless it's in a tent reflecting off the sides. I suppose it's worth doing though just to see the difference.

Something I'd be interested in seeing is the par levels in the beam of a 100w Cree cob with a lens. The beam looks fairly even. I wonder how even it actually is and how intense it is. Also, what the difference is with and without the lens on. I guess you probably don't have access to cobs though.
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The point is that it measures actual PPFD and that it's the standardized way (meaning that - limited by the accuracy of the sensor - you can compare the results with other lights). You would be measuring something else when you angle the sensor.
 
AquariusPanta

AquariusPanta

Well-Known Member
A week from today I tested the PAR values of a single Bridgelux Vero 29 COB w/reflector in a 5'x5' space. Besides the in-notebook recordings, I haven't formalized it. If that's something you guys would like to see, let me know and I'll upload the results later today when I find the time.
 
BobCajun

BobCajun

Well-Known Member
alesh said:
The point is that it measures actual PPFD and that it's the standardized way (meaning that - limited by the accuracy of the sensor - you can compare the results with other lights). You would be measuring something else when you angle the sensor.
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Okay, but if you measure one lamp that has cobs spread out evenly over a square area and another than has the LEDs all bunched in the middle then obviously it's not going to be a fair game, because with the cobs you would be pretty much directly under at least one of them no matter where you measured from. Anyway, I guess the ones with the sensor pointed at the lamp were already done.
 
Yodaweed

Yodaweed

Well-Known Member
leds420 said:
Hi there

has anyone else had the misfortune to fall for spectrum king light like me?

I bought one of these lights after been told they would outperform my gavita no problem, the videos looked legit to me on the website where they show them having more light than gavita.

But after 3 months of growing the results were to say the least extremely poor.

Then my buddy tells me that these are just cheap warehouse lights from china and thats what the problem is that they dont have enough light for plants or in the right spectrum.

Please help me, should I try and get a refund or try the grow again, I really dont want to lose 60% of my next crop like I have this time and I gave my gavita away to a buddy when I got my led.
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Sorry to hear you bought a spectrum king. Try for the refund if possible.
 
alesh

alesh

Well-Known Member
BobCajun said:
Okay, but if you measure one lamp that has cobs spread out evenly over a square area and another than has the LEDs all bunched in the middle then obviously it's not going to be a fair game, because with the cobs you would be pretty much directly under at least one of them no matter where you measured from. Anyway, I guess the ones with the sensor pointed at the lamp were already done.
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Why wouldn't that be a fair game? :O
 
AquariusPanta

AquariusPanta

Well-Known Member
If we had two fixtures all bearing the same parts and components, with the exception of light mobility/placement, then you'd be comparing two different outcomes. A fixture with dimensions 24"x12" is going to have less spread/coverage potential than a fixture with the dimensions of 36"x16". The question that should be asked is whether or not there's enough light output to spread outwards with the available light output. In other words, if you have enough or too much in the middle, then it's only right to push as much outwards as possible in attempt to cover more ground.

I'll upload a CAD drawing here shortly, which will hopefully make mores sense of this.
 
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PurpleBuz

Well-Known Member
BobCajun said:
Okay, but if you measure one lamp that has cobs spread out evenly over a square area and another than has the LEDs all bunched in the middle then obviously it's not going to be a fair game, because with the cobs you would be pretty much directly under at least one of them no matter where you measured from. Anyway, I guess the ones with the sensor pointed at the lamp were already done.
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BUT that's one of the main points of measuring with the sensor straight up. NO Bias to lights that are highly center focused versus those that spread the light evenly across the canopy. As a grower I want light evenly across the top of the canopy AND evenly into the canopy with light supplied from side angles for deeper penetration.

Its very fair to show the weakness of the light isn't it ?
 
SupraSPL

SupraSPL

Well-Known Member
BobCajun said:
Why would you NOT aim the meter at the light? The plants are going to turn their tops and leaves to face the light so logically you should do the same with the sensor. The readings should also be taken at the corners of the squares, not the middles (not directing these comments to you personally, SupraSPL, but whoever is doing the readings). We need to know what the intensity is at the outside edges of various sized grow spaces. Grow tents don't come in 2.5 and 3.5 foot sizes. Well they probably do but most people get the even foot sized ones I would think.
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It is a good point you make. But if we do angle the sensor, we lose the ability to directly compare with traditional maps. I guess I will just do both each time.
 
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BobCajun

BobCajun

Well-Known Member
AquariusPanta said:
View attachment 3507164

The Vero 29 had a 90 degree angled reflector attached during this test.
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Very interesting. Was there a lens on it or just the bare cob? I guess it must have been bare or it wouldn't have spread over that large an area. Those readings are remarkably low. See how close it has to be to get above 400, which is the lowest practical level for plant growth. I guess plants can still grow with less but it drops off drastically. So this looks like my theory of requiring at least two cob beams overlapping may be correct. The 8 cob unit on page 13 does look like a good intensity at 24" though. Better than the SK. Dunno why he put a 9th one in the middle.
 
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PurpleBuz

Well-Known Member
SupraSPL said:
It is a good point you make. If the traditional method is NOT to point the senor at the light, which is understandable, this actually penalizes a light that does have good spread.
.
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I don't follow you , sounds backwards, please explain?

does have or doesn't have a good spread?
 
SupraSPL

SupraSPL

Well-Known Member
Sry I am just confusing the issue, fixed. The reflective wall problem plays in also and probably affects the measurements even more. That would make a huge difference when comparing bare COBs to lens/reflector COBs and the important changes depending on the distance to canopy.
 
cdgmoney250

cdgmoney250

Well-Known Member
BobCajun said:
What would the point be of taking a reading with the sensor pointing up?

Something I'd be interested in seeing is the par levels in the beam of a 100w Cree cob with a lens. The beam looks fairly even. I wonder how even it actually is and how intense it is. Also, what the difference is with and without the lens on. I guess you probably don't have access to cobs though.
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alesh said:
The point is that it measures actual PPFD and that it's the standardized way (meaning that - limited by the accuracy of the sensor - you can compare the results with other lights). You would be measuring something else when you angle the sensor.
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Sorry Bob. I only have access to what I have. I know @robinccn has been doing some research on optic performance of lens/reflectors compared to bare COB. I know during my research, the amount of usable PAR increased substantially when reflectors were used. I'm not sure about lenses as I haven't done any testing. I would assume you pay an efficiency penalty with a lens vs a reflector, but I'm not positive.
 
alesh

alesh

Well-Known Member
cdgmoney250 said:
Sorry Bob. I only have access to what I have. I know @robinccn has been doing some research on optic performance of lens/reflectors compared to bare COB. I know during my research, the amount of usable PAR increased substantially when reflectors were used. I'm not sure about lenses as I haven't done any testing. I would assume you pay an efficiency penalty with a lens vs a reflector, but I'm not positive.
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That's ok. Both lens and reflector will decrease total amount of photons but they may help to get them where you want them. The most efficient lens and reflector has a very similar efficiency - about 93%.
The use of either totally depends on the whole setup - height, open space/tent and many more.
 
OneHitDone

OneHitDone

Well-Known Member
cdgmoney250 said:
So after some data logging, the results are in... I will let you guy's come to your own conclusions. I'm doing this because I have access to both the lamp and the tools.

I have taken data points at 17 different locations in a 4'x4' area with a PAR meter at varying distances from the bottom of the reflector. All points were taken in the center of each square foot and one reading in the center point of the 4'x4'.

*****DISCLAIMER*****
Yes, these readings were taken in a tent. I'm really sorry if that's a problem. The ceiling at my store is an acoustic tile drop ceiling so options for hanging the light were limited. The tent just so happens to be a 4x4 (56"x56") and has cross bars to make hanging simple. The reflectivity from the tent wasn't even a factor at 24" and closer. I tried my best to hang the fixture as level as I could using Sun Grip hangers and a tent to hang it from. Any unevenness is probably reflected in the data to a negligible amount. I aimed the PAR sensor towards the light and took the highest reading that spiked for each quadrant. These readings are what I logged.
View attachment 3503754 View attachment 3503755View attachment 3503756View attachment 3503757
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I am just a by stander in all of this trying to build a knowledge base of which techs and lights on the market are legit and worth taking a look at.

Are you calling bullshit on the par #'s shown in this video?

 
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PurpleBuz

Well-Known Member
OneHitDone said:
I am just a by stander in all of this trying to build a knowledge base of which techs and lights on the market are legit and worth taking a look at.

Are you calling bullshit on the par #'s shown in this video?

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in that video they are only measuring the center point. look at how high (around 3 feet) they are actually hanging to get a sufficient spread over the whole canopy.
 
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