Lighting Interested in a light meter to improve yield, testing bulbs

[L0wbob2017]

@L0wbob2017

Great hack for the phone light meter. I might try to calibrate my phone using the app. Or I might keep the meter I bought so I have a dedicated one and a backup. I'm looking to order my first COB light from cobshop, which means I may be needed yet another meter in the tool box.

I see you have done a lot of DIY work with COB lights. Impressive projects. Are you using a PAR meter at all with all that LED light? Or given the pictures I peaked at, I wouldn't be surprised if you had a spectrometer!!!

haha sadly i didnt had the budged to buy a PAR meter, but it is still on my list of thing i always wanted to have and use, so maybe in the future i am going to add that to my toolbox
Just calibrate your phone-sensor with the LUX-meter you got from ebay so you can use your apps/phone to get a LUX reading that is almost legit

 

[wayward1]

 

[wayward1]

Is this correct, that you can't use a lux meter for led's? It's from a creditable source.

 

[Banjacked]

Is this correct, that you can't use a lux meter for led's? It's from a creditable source.

Won't that depend on the sort of LED?

Blurple will not give a "true" reading but surely, say, 3000K warm white would...

Edit: Note the bit that says "LED grow lights", that's hinting at blurple in my book.

Edited again: There may be some truth in what they say, seems LED lux meters are calibrated to a specific wavelength rather than a specific Kelvin colour. More investigation necessary

 

[L0wbob2017]

Hello there,

maybe i can help there a bit.
Normal LUX-Meters have been calibrated with sunlight. This is because the sun is close to something called blackbody-radiaton with a temperature of ~5777 K (kelvin).
Since the earth has a big airlayer around itself, some light doesnt reach the ground because of absorption. ( Depends on the chemical structures in the air ). The spectrum that reaches the ground is called solar radiation spectrum with an airmass (AM) of 1.5. Thats the spectrum the LUX-meters get calibrated with.

Next thing to know is, that the unit of LUX is lm/m² ( lumen per squaremeter ). There is something to keep in mind. Lumen is measured with the luminosity function. So all values measured are only for the human eye and not for plants. The human eye has a maximum intensity recognition at 555nm with a value of 683 lm/W. ( photopic NOT scotopic )

The combination of both gives the solution.

So long story, short answer: Until it is not a special for LED's calibrated LUX-meter it doesnt show correct values.