How is Light Output/lumen/etc. Measured?

salmonetin said:

....you actually "only" talk about "toys"... ....but actually he can "play" with her "toy"...

saludos

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Somehow I can't understand the point you're trying to make.

pardon my mistake... ....bad joke...

...i saw your pov and respet a lot both positions...

...i cant buy these toys...par meter included...

saludos

Greengenes707 said:

The theory of error is correct. But in reality is negligible. If anything, it's on the safe/low side.

With white LEDs Lux is closer to relevant. But why...which Would you publish for others to review for plant lighting purposes(assume spectrometer is out). It's a quantum process...use a quantum meter...to me that is a more solid theory than not using one because of a less than 10% error at worst based on theory.

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Had the quantum meter measured quantum processes accurately it'd have been a great tool. This way it's no better than theory (I'd guess that most of my calculations have far smaller margin of error than 10%).
Cheap lux meter, quantum meter, PAR meter...it's the same thing. Great for checking distribution and basic comparison of similar whites.

salmonetin said:

pardon my mistake... ....bad joke...

saludos

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Perhaps it was a good one. I just didn't understand.

....other dreamed "toy"...

http://www.aibcusa.com/portable-led-light-spectrometer/uprtek-ai-mk350s-spectrometer




saludos

alesh said:

Had the quantum meter measured quantum processes accurately it'd have been a great tool. This way it's no better than theory (I'd guess that most of my calculations have far smaller margin of error than 10%).
Cheap lux meter, quantum meter, PAR meter...it's the same thing. Great for checking distribution and basic comparison of similar whites.

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A couple things there.
Comparison vs growing relevance.
And that it is inaccurate to say they are so inaccurate.
Show of hands how many people here have tested 4 different par meters and 2 spectoradiometer?

If I had never maybe I would be in the it's shady estimate boat. But I have have checked and cross referenced them all and is why I hold the stance I do.

Would most here agree that numbers can be crunched all day long but the real test where the rubber meets the road would be to take the fully assembled finished fixture and do a point by point grid test for intensities?

It would seem to me that it would be better to have a mid level intensity that is spread more evenly over the whole canopy than super intensity in the middle fading quickly as you approach the outer areas of the grow space.

Like with this Kessil H380, I'm not sure what the were trying to accomplish. Seems like it would be better for midnight road hunting than growing anything

OneHitDone said:

Like with this Kessil H380, I'm not sure what the were trying to accomplish. Seems like it would be better for midnight road hunting than growing anything

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And Yet I Have A Friend Who Can Pull 4ozs From His Kessil Grow After Grow. I'm With Ya Brother A Lot Of Time Numbers Look Real Impressive On Paper But Fall Way Short On Practial Use

The Dawg said:

And Yet I Have A Friend Who Can Pull 4ozs From His Kessil Grow After Grow. I'm With Ya Brother A Lot Of Time Numbers Look Real Impressive On Paper But Fall Way Short On Practial Use

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Right, 4oz 'time after time' but no documentation to support the claim.... anecdotal accounts don't have any place in this thread, just want to throw that out there.

Greengenes707 said:

The theory of error is correct. But in reality is negligible. If anything, it's on the safe/low side.

With white LEDs Lux is closer to relevant. But why...which Would you publish for others to review for plant lighting purposes(assume spectrometer is out). It's a quantum process...use a quantum meter...to me that is a more solid theory than not using one because of a less than 10% error at worst based on theory.

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If there was a meter that was several hundred dollars that could get me PAR readings within 5% accuracy I might be OK with that, but this response is another story.


I do agree that it is good that we know the numbers are lower than actual. I also agree that if I were selling a lamp I would not advertise it using measured LUX values. I appreciate that you have had hands-on with many meters including spectros but based on the response of the Apogee above I am amazed that the numbers agreed.

Anyway I am just suggesting that for the average grower, the Apogee data/calculation may not offer several hundred dollars worth of value versus calculated PPFD and a lux meter. But if you already have a real PAR meter, the data is much more useful than lux meter data. I noticed that my lux meter sees warm white better than it can see cool white. I would never use it to make an output comparison between color temps or any absolute measurement of any kind.

SupraSPL said:

If there was a meter that was several hundred dollars that could get me PAR readings within 5% accuracy I might be OK with that, but this response is another story.
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I do agree that it is good that we know the numbers are lower than actual. I also agree that if I were selling a lamp I would not advertise it using measured LUX values. I appreciate that you have had hands-on with many meters including spectros but based on the response of the Apogee above I am amazed that the numbers agreed.

Anyway I am just suggesting that for the average grower, the Apogee data/calculation may not offer several hundred dollars worth of value versus calculated PPFD and a lux meter. But if you already have a real PAR meter, the data is much more useful than lux meter data. I noticed that my lux meter sees warm white better than it can see cool white. I would never use it to make an output comparison between color temps or any absolute measurement of any kind.

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The FACT that apogee themselves wouldn't certify the Osram horti panel validates your point.............It is not accurate in certain PAR regions and they know it.

SupraSPL said:

If there was a meter that was several hundred dollars that could get me PAR readings within 5% accuracy I might be OK with that, but this response is another story.
View attachment 3443926

I do agree that it is good that we know the numbers are lower than actual. I also agree that if I were selling a lamp I would not advertise it using measured LUX values. I appreciate that you have had hands-on with many meters including spectros but based on the response of the Apogee above I am amazed that the numbers agreed.

Anyway I am just suggesting that for the average grower, the Apogee data/calculation may not offer several hundred dollars worth of value versus calculated PPFD and a lux meter. But if you already have a real PAR meter, the data is much more useful than lux meter data. I noticed that my lux meter sees warm white better than it can see cool white. I would never use it to make an output comparison between color temps or any absolute measurement of any kind.

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I am very empirical. I like results to be manifested in my reality. Spec sheets are just a guide...to be used as a reference to then be checked by field testing. I have tested a lot of lights and against spectroradiometers. Even our favorite 3K cxa. And it can be very well below 10%, like 3-5% with whites of any source, with apogee being closer to the spectroradiometer than licore. For a field measurement, it's more than acceptable ime. For what would be put into a data sheet...only spectroradiometers and/or spheres get on that level. Like NIST testing of the final end system.

I agree. For the average/closest grower sure it's not on the top of the needs list. But for a decent size garden or a professional...it's pretty much a must, even to go the cheap apogee route...a field measurement in relation to growth of the facility is how they truly dial it in. Major agg and horticulture have been doing it for decades.

PSUAGRO. said:

The FACT that apogee themselves wouldn't certify the Osram horti panel validates your point.............It is not accurate in certain PAR regions and they know it.

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Bugbee himself uses licore for all his studies at the university and elses where.
We all know apogee are the budget meters....just like we know a51 are the budget alternative to AT. But they get the job done, and very well.