Think ive been led astray

cdgmoney250 said:
I think you have a slight misunderstanding of how "Luminaries" perform compared to the individual LED chips that the Luminaire uses. Depending on the number of chips used, what current they are run at, the spacing between the chips, the thermal characteristics of the fixture itself, and if any optics are used i.e. lenses/reflectors; there can be such a wide range of output. Even the angle of the reflector would play a big part in system performance.
Now you could take data sheet info and then guess and extrapolate the rest of the information... Or you could skip the theorized calculation step and go right to measuring and logging real data. There are a whole lot of claims about watts consumed, efficiency, and performance on this forum that I question unless I saw pictures proving otherwise. It's one thing to work something out on paper, and it's another thing to put it into practice and measure the results.
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The thing is no luminarie can be 120% efficient lol. So even if it got 100% of the light onto the target area it still wouldn't be enough light to produce SK claims. Guess what I venture to say that there will never be a luminarie that is 100% efficient in my life time lol. Facts are facts. Do I believe it will produce close to the same as a gavita 1000? Nope. Will it produce what a 600 hps produces? That's a maybe. I'd say it will be about 10% more efficient than 315 lec watt for watt. Time will tell
 
Ideally we look at both calculated and measured output to judge a lamp. Kind of like the grams/W thing, we really need g/W based on dissipation W and g/W based on system W to get the whole picture.

The PPFD calculation is inaccurate when we are not sure exactly what current the LEDs are running at, what bin we are dealing with, where that led falls within the bin range, uncertainty of the junction temp/temp droop and how much loss relating to optics and walls. That said the calculation is very helpful top get a general idea where we stand in terms of intensity and VERY useful to compare the potential of 2 different designs.

PAR meter PPFD measurement is inaccurate due to variations in the sensor sensitivity, shape and angle, low and varying sensitivity in the deep red range, variations in ambient temp/circulation/ventilation, variations in reflectivity of location/angle of walls, was the lamp fully warmed up after temp droop has stabilized. Apogee provides an approximate correction factor for the deep red problem, but this is really just another calculation not a measurement and it introduces several more sources or error. There would have to be a specific correction factor for a lamp like the SK which has a mix of reds deep reds and warm whites. So unless we have a calibrated spectroradiometer, PAR measurement has significant margin or error as well. It is very useful for checking uniformity, temp droop and for verifying the output is near what is expected from the calculated PPFD.

So there is a margin of error in both methods and on top of that we still do not know how much importance to assign to the 700nm+ range, which is higher for warm whites and HIDs but low for deep reds. There is disagreement regarding the PPFD requirements of 2D canopy vs 3D canopy. Uniformity and CRi/SPD can shift the efficacy of PPFD. All that said, an honest, reproducible side by side measuring grams/dissipation W can add another very useful way to compare 2 lights and that can be easily measured with very good precision and accuracy.
 
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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.
PAR Chart 4.png PAR Chart 3.pngPAR Chart 2.pngPAR Chart.png
 
Also remove the bottom glass on the spectrum king. I would not run it in a grow. Maybe I would put it on before foilar spraying but why would I want it there blocking light.
 
Stephenj37826 said:
[ I'd really like to see the reading took at standard data points of most tests. Also running the sensor flat and not angled twords the light at all.
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I can take some "standard" data points next week if you would like. I angled the sensor because plants are going to look towards the highest intensity of light regardless of which direction it is coming from. If they see it why shouldn't the sensor?

Stephenj37826 said:
Where your readings are diffrent is the outside measurements are only a 3x3 really. Just wanting an apples to apples with other lighting tech.
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I was thinking if you can see the trend of the footprint you'd see the light drop off toward the edge of the 4x4. I can measure the extra 6 inches on 8 points of the perimeter if that is the missing piece of the puzzle for you.

Stephenj37826 said:
Also remove the bottom glass on the spectrum king. I would not run it in a grow. Maybe I would put it on before foilar spraying but why would I want it there blocking light.
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Nope. This is a floor model for my store. Not my personal light. And it's a safety hazard to have an open circuit board exposed. Only takes one dummy to want to touch the LED's and then zap.
Why does your light use lenses instead of reflectors?
 
I guess the verdict is still out on which one is better. I'm working on getting the lenses coated with a anti refractive coating. Should put lenses slightly ahead in getting the light to the canopy. I also am not a fan of having the holders and wires exposed. I agree in not taking the glass off on your display but I would like to see the reading difference. 5%? Maybe more.
 
Angling the par sensor towards the source will skew the #s big time.................Lec's spd seems(pics^) more geared towards flowering annuals compared to SK imo.
 
CXBs are the most lumens per dollar available in any current LED. That's what Cree says anyway. The SKs use outdated LEDs and cost more than CXB high-bays. You can get CXB high-bays at ShineRetrofits at 240 watts for under $500, 24000 lumens, and they have much less bulky heatsinks. I would just get two of them rather than a SK, but I already ordered one so too late. You can choose your own options with that company and I wouldn't even get the reflectors. Save about $25 there. With the SK I would take the parabolic reflector off and just put angled sheets of mylar out to the sides of the lamp, far enough so they won't melt or anything. No point using a round reflector in a square space and that reflector clearly concentrates most of the light in the center. I know it's more cost effective to by COBs and DIY but it's a lot of screwing around so I'd rather just get the CXB high-bays if I do ever need more lights.
 
BobCajun said:
CXBs are the most lumens per dollar available in any current LED. That's what Cree says anyway. The SKs use outdated LEDs and cost more than CXB high-bays. You can get CXB high-bays at ShineRetrofits at 240 watts for under $500, 24000 lumens, and they have much less bulky heatsinks. I would just get two of them rather than a SK, but I already ordered one so too late. You can choose your own options with that company and I wouldn't even get the reflectors. Save about $25 there. With the SK I would take the parabolic reflector off and just put angled sheets of mylar out to the sides of the lamp, far enough so they won't melt or anything. No point using a round reflector in a square space and that reflector clearly concentrates most of the light in the center. I know it's more cost effective to by COBs and DIY but it's a lot of screwing around so I'd rather just get the CXB high-bays if I do ever need more lights.
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Has anyone bought the COB high bays and grown with them?
 
cdgmoney250 said:
I can take some "standard" data points next week if you would like. I angled the sensor because plants are going to look towards the highest intensity of light regardless of which direction it is coming from. If they see it why shouldn't the sensor?
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sensor should be straight up so we can compare to other lights. The idea is to get as many measurement points on a graph as possible and to be able to do it repeatedly consistenttly.. what I like to see is a footprint that doesn't favor a particular grow setup. All of my grows have multiple sources of overlapping light so its really hard to pick an angle that isn't biased one way or another.

cdgmoney250 said:
I was thinking if you can see the trend of the footprint you'd see the light drop off toward the edge of the 4x4. I can measure the extra 6 inches on 8 points of the perimeter if that is the missing piece of the puzzle for you.
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more points of data would give a better picture. but you won't see the trend very well until you get rid of the reflective sides.
 
PurpleBuz said:
sensor should be straight up so we can compare to other lights. The idea is to get as many measurement points on a graph as possible and to be able to do it repeatedly consistenttly.. what I like to see is a footprint that doesn't favor a particular grow setup. All of my grows have multiple sources of overlapping light so its really hard to pick an angle that isn't biased one way or another.



more points of data would give a better picture. but you won't see the trend very well until you get rid of the reflective sides.
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I will take readings like the Hortilux chart next week and keep the sensor pointed sky high, if that makes everybody happy. I will also wrap the inside of the tent with the black side of the black and white poly to reduce any reflectivity, but that has to be the spot where I'm taking the measurements.
 
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