LUX Meter- What Can I Do With It?

Moflow

Moflow

Well-Known Member
I tested this app for Android devices today. Keuwlsoft

Using the big light in the sky as a reference point.
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Keuwlsoft light meter full sun, cannot compute overload!
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Apogee PAR meter reads
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Using lux to par conversion from waveform lighting sunlight setting we get
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1725 umols/s/m2 v 2400 on the apogee meter.

Then i tested under 5 x 2ft strips with added 660nm 730nm. Centre of fixture. 260 watts
Keuwlsoft app
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Apogee meter
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1160 umols/s/m2 v 661 on the Apogee.
Probably about as much use as an ashtray on a motorbike.

But.... at 17 inches away I know that 61,000 lux on the Keuwlsoft App is approximately 661 umols at 260 watts! under my strips :bigjoint:
That's bound to help someone lol
 

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hillbill

hillbill

Well-Known Member
Downloaded and upgraded, numbers as well as K ratings seem remarkably close to known specs when source settings are correct. The “diffuser” is a total game changer fo4 using Korona. iPhone 7.
 
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Rocket Soul

Rocket Soul

Well-Known Member
10WeekFlushBro said:
Someone on this forum tested a lux meter against a PAR sensor and the lux meter was about 30% off, both sunlight and white leds. It's a useful tool for white leds if you know how wrong your meter is. Otherwise I would advise against trusting the readings completely.

edit: Since you are planning to compare two very similar (I assume) light sources the actual accuracy of the measurement is not important
Click to expand...
Note that many lux meters come with settings for electric or sun light. And you allways need to resd the plants.
 
GBAUTO

GBAUTO

Well-Known Member
I use the same meter in my grows.
I think that Migro did a video on Utube comparing that meter to an Apogee.
I think that he found using led's ranging from 3000k to 5000k, each 10000 lux reading equaled 250 ppfd spot reading.
I try to maintain 30000 to 40000 lux(750-1000 ppfd) during flower.
 
wietefras

wietefras

Well-Known Member
Horselover fat said:
Why would you pay $5 for a lux meter instead of using the free apps?
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Lux meters in phones are pretty much useless though. They are very direction dependent. If the light comes under an angle the intensity is measured much lower than it should be. Lux meters with these white diffusion caps are much less sensitive to incident angles.

Plus the phone sensors are not well calibrated. They only need to detect sort of how much light is measured to adjust the display intensity. It's not designed to be an accurate sensor.
 
Horselover fat

Horselover fat

Well-Known Member
wietefras said:
Plus the phone sensors are not well calibrated. They only need to detect sort of how much light is measured to adjust the display intensity. It's not designed to be an accurate sensor.
Click to expand...
$5 for an app isn't going to make the metering any better, but I thought these apps would use the camera for measurements. If they use some other light sensor that would explain why my old phone only measured to 10k lux.
 
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wietefras

wietefras

Well-Known Member
Horselover fat said:
$5 for an app isn't going to make the metering any better, but I thought these apps would use the camera for measurements. That would explain why my old phone only measured to 10k lux.
Click to expand...
I have never seen them use a camera for that.

Still the point is that when you use a phone to measure light uniformity, you will see large difference over the surface. I also used a phone and noticed that the light uniformity did not match at all with what I calculated. So I ordered a cheap lux meter. When using a "real" lux sensor with diffusion over the sensor the light was perfectly uniform as I had calculated it would be.

The readings can really be 50% off with a phone light sensor. At least with mine it was. Depending on where I held the sensor under the light sources.

Which is another issue since they are all so different. Again, the phone sensors are designed as cheap simple light sensors. Not as accurate lux meters. So you can expect that they are not accurate.
 
HydroKid239

HydroKid239

Well-Known Member
Horselover fat said:
$5 for an app isn't going to make the metering any better, but I thought these apps would use the camera for measurements. That would explain why my old phone only measured to 10k lux.
Click to expand...
The Korona lux meter app is free 99.. the $5 is an in app purchase for the ability to read PAR for the white LED's/whatever light you have is $5 each.
 
HydroKid239

HydroKid239

Well-Known Member
wietefras said:
I have never seen them use a camera for that.

Still the point is that when you use a phone to measure light uniformity, you will see large difference over the surface. I also used a phone and noticed that the light uniformity did not match at all with what I calculated. So I ordered a cheap lux meter. When using a "real" lux sensor with diffusion over the sensor the light was perfectly uniform as I had calculated it would be.

The readings can really be 50% off with a phone light sensor. At least with mine it was. Depending on where I held the sensor under the light sources.

Which is another issue since they are all so different. Again, the phone sensors are designed as cheap simple light sensors. Not as accurate lux meters. So you can expect that they are not accurate.
Click to expand...
I heard white copy paper over the lens = diffuser but haven't tried it.
 
Horselover fat

Horselover fat

Well-Known Member
wietefras said:
I have never seen them use a camera for that.

Still the point is that when you use a phone to measure light uniformity, you will see large difference over the surface. I also used a phone and noticed that the light uniformity did not match at all with what I calculated. So I ordered a cheap lux meter. When using a "real" lux sensor with diffusion over the sensor the light was perfectly uniform as I had calculated it would be.

The readings can really be 50% off with a phone light sensor. At least with mine it was. Depending on where I held the sensor under the light sources.

Which is another issue since they are all so different. Again, the phone sensors are designed as cheap simple light sensors. Not as accurate lux meters. So you can expect that they are not accurate.
Click to expand...
Sure, I'm just saying there's no need to pay for an app to use your phone as a meter. I didn't Look at how they measure. I just assumed they would use the camera... I only tried measuring once with my new phone. Didn't get large variation across my area, but yeah, the glass probably reflects a lot of the light that comes at an angle.

Edit and I did buy a lux meter, but it gave strange readings so I returned it.
 
hillbill

hillbill

Well-Known Member
HydroKid239 said:
The Korona lux meter app is free 99.. the $5 is an in app purchase for the ability to read PAR for the white LED's/whatever light you have is $5 each.
Click to expand...
The paper defuser makes everything work, and $5 for a month includes all light sources as well as an apparently very accurate K value sensor which comes very close to known specs.
 
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