Par/Lux Meter hack

ok people. a few here know Ive been big on the Lux/Par conversion, and if its correct.

Here is a HydroFarm PAR meter and my Hacked Lux meter, with a simple hole and tape over it to diffuse the light and used to calibrate it.

Ive matched it with my COB Rig, and its right on the money, and Ive used it with my Perfect Sun mini blurple light. For simplistic, I took pics with the blurple because its easier to get distance and flat surface measurables.

Take my word for it with the COBs, its on the money with the HydroFarm. I can take a pic if demanded, lol.. Those Hydrofarms are NOT worth the $130..

Ive been saying, they BOTH read INTENSITY, NOT SPECTRUM. Both measure 400-700. This is definite proof, and used a lux conversion of 65 for my meter calibration.

the last one was hard to get the camera and angle with out distortion, the hacked is 1334 and the hydro is 1329

InTheValley said:

Ive been saying, they BOTH read INTENSITY, NOT SPECTRUM.

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You say that like it's something wrong, but measuring intensity is EXACTLY what they should both be doing.

Indeed in the 400-700nm range for PAR. A lux measurement can be simply corrected for spectrum by a simple correction factor. Which you did with that tape on top.

You will get horrible directional issues with that cap on the sensor though. With the cap on, you will only measure light from straight above and not the light coming in at shallower angles. That's not a good way to measure light intensity for leaves.

What are you trying to prove here. 2 cheap meters can put out the same numbers?

Neither is accurate.

wietefras said:

You say that like it's something wrong, but measuring intensity is EXACTLY what they should both be doing.

Indeed in the 400-700nm range for PAR. A lux measurement can be simply corrected for spectrum by a simple correction factor. Which you did with that tape on top.

You will get horrible directional issues with that cap on the sensor though. With the cap on, you will only measure light from straight above and not the light coming in at shallower angles. That's not a good way to measure light intensity for leaves.

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its still the same as the hydrofarm, *shruggs

just trying to help people, and im getting hammered for it,lol.

Did you "calibrate" the lux meter for the purple light or for the "COB light". Or both separately?

wietefras said:

Did you "calibrate" the lux meter for the purple light or for the "COB light". Or both separately?

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didnt need to, the 65 conversion seems to be perfect for both,

So your using 65 as the division factor? X ÷ 65 = par?

InTheValley said:

didnt need to, the 65 conversion seems to be perfect for both,

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If im reading 47,000 at 12-14 inches is 723 correct

grilledcheese101 said:

If im reading 47,000 at 12-14 inches is 723 correct

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yes, but then add 10% of that, so your at about 795 PAR, ive seen to add 10% on the final factor by what the comparisons say of the Apoggie 500 meter. BUT, more red or lower K factor, the percentages get lower.
5000K+ 16%
4500K+ 13%
4000K+ 10%
3500K+ 7%
3000K+4%
2500K+1%

So, a 4000K lux reading is 50,000---divided by 65 + 10% = 846PAR

3000K lux reading is 50,000---divided by 65 + 4%= 799 PAR

5000K lux reading is 50,000---divided by 65 + 16% = 892 PAR

InTheValley said:

yes, but then add 10% of that, so your at about 795 PAR, ive seen to add 10% on the final factor by what the comparisons say of the Apoggie 500 meter. BUT, more red or lower K factor, the percentages get lower.
5000K+ 16%
4500K+ 13%
4000K+ 10%
3500K+ 7%
3000K+4%
2500K+1%

So, a 4000K lux reading is 50,000---divided by 65 + 10% = 846PAR

3000K lux reading is 50,000---divided by 65 + 4%= 799 PAR

5000K lux reading is 50,000---divided by 65 + 16% = 892 PAR

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Im about 50/50 5000k/3500k

The measurment was centered under 1 panel, in a 2x4x6 tent. Im using 15 9w led bulbs from the dollar store. 135w per panel. Is like 840 par good for 1 panel? Like i said i have 2 and then in the middle is a 150 hps. Its fuckin blinding when it all comes on, thats all i know. I get 27,000 lux at 4.5 feet from the lights in the dead center.

I also have a keg fridge in similar style but its a 12x 9w and it makes about 30,000 at the floor, like 22 inches

InTheValley said:

its still the same as the hydrofarm, *shruggs

just trying to help people, and im getting hammered for it,lol.

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Welcome to riu bud lol. There is a lot of put down and hate on this forum. Just keep your experiment to yourself brother you’re better off.

i use LiCors (because im in the photometrics biz) but those hydrofarms are a fantastic value for growers

CobKits said:

i use LiCors (because im in the photometrics biz) but those hydrofarms are a fantastic value for growers

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I'm glad you say that because most of what you read online regarding the hydrofarm strongly suggests its crap.
For conversation sake, how large do you think the margin of accuracy is between the hydrofarm and the LiCor/apogee meters? You'd think the difference is huge from all the hate.
Yes, LiCor sensors are proven accurate pieces of equipment.
BUT, the hydrofarm is by no means a cheap tool. You would think a $100+ sensor would provide at least above average repeatable measurements.
Iv been wanting to get one for a while.

CobKits said:

i use LiCors (because im in the photometrics biz) but those hydrofarms are a fantastic value for growers

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I look at my HF meter as a guide. It lets me get repeatable light intensity when I have to make adjustments.
Ultimately, I let my plants tell me what they want.

GBAUTO said:

I look at my HF meter as a guide. It lets me get repeatable light intensity when I have to make adjustments.
Ultimately, I let my plants tell me what they want.

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Does your HF meter give you repeatable measurements of the same luminarie at the same height each time?

InTheValley said:

ok people. a few here know Ive been big on the Lux/Par conversion, and if its correct.

Here is a HydroFarm PAR meter and my Hacked Lux meter, with a simple hole and tape over it to diffuse the light and used to calibrate it.

Click to expand...

Once calibrated with correct opacity of tape, does it give accurate readings for DIFFERENT light types? For example, once you calibrated for 3000K, does it then do correct readings for blurple or does it need to be calibrated per light type?

HydroFood said:

Does your HF meter give you repeatable measurements of the same luminarie at the same height each time?

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Yes, it does. That's what I use it for-getting repeatable intensities when I have to reposition the fixtures.

caretak3r said:

Once calibrated with correct opacity of tape, does it give accurate readings for DIFFERENT light types? For example, once you calibrated for 3000K, does it then do correct readings for blurple or does it need to be calibrated per light type?

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I got the same readings for both light rigs, COB and Blurple, with the 65 conversion calibration. At the end of the day, its about measuring intensity to get a general idea of what your plants might be getting. Is it exact? No, probably not, but neither is the hydrofarm. All this hack does is show intensity measurement percisly (lol, spell check didnt even know) that is = to the Hydrofarm

if you move either meter, or actually ALL the meters, you get different readings, inch this way, inch that way, inch up or down, it all adjusts. We are just looking for intensity with these, and this hack is a great way to get that information, while saving $hundred bucks that can be used for something else.