PPFD Meter Phone App - Crowd Sourcing Lux Readings

Hi Growers -

I'm hoping you can help me and your fellow growers out.

I built an android app that uses the light meter in your smartphone to convert the LUX reading to PPFD.

The app will be completely free once it's ready for the app store.




The conversion factor used to go from LUX to PPFD depends on the selected light source.

I was able to get these conversion factors from a few manufacturers, but the accuracy of the light meter in the various smart phones is something I'm hoping this community can help me figure out and account for in the app.

Here's the problem...A Samsung S7 will likely have a different Lux reading than a Pixel 3 XL. Without knowing the exact Lux reading of a particular light, at a specific distance, and for the users exact brand and model of smart phone, the readings won't be as accurate as they would be otherwise.

If you're willing to help a brotha out, please install a lux light meter on your smart phone and answer the questions below...

1. Phone brand and model?
2. Light source? - please be specific
3. Total Watts it's pulling from the wall?
4. Lux reading at exactly 12 inches
5. Lux reading at exactly 18 inches

Some lux meters in the app store:

https://play.google.com/store/apps/details?id=com.doggoapps.luxlight&hl=en_US
https://play.google.com/store/apps/details?id=crunchybytebox.lightmeter&hl=en_US
https://play.google.com/store/apps/details?id=kr.sira.luxmeter&hl=en_US

Thanks and happy growing!

I wasn't aware phones can do that, I know they have sensors for knowing when to dim the screen but as far as acting as a meter, cool. I'll have to download and try it out on my Galaxy S6.

1) you can estimate your lux to ppfd conversion factor from the colour temperature or spectrum. There's at least two threads here detailing how to do so.

2) you don't have to worry about the cameras response, see https://www.researchgate.net/publication/317596937_Smartphones_as_a_Light_Measurement_Tool_Case_of_Study

3) maybe add a hold button to your app. This was the big problem with other apps (you have to put your finger over the sensor move it into position then remove your finger to take a reading then put it back over the sensor to take it out of the tent.

TrippleDip said:

3) maybe add a hold button to your app. This was the big problem with other apps (you have to put your finger over the sensor move it into position then remove your finger to take a reading then put it back over the sensor to take it out of the tent.

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Great point. Yep, I've had the same issue.

newbie2323 said:

View attachment 4396767

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Looking pretty slick. Did you find the threads on converting lux to ppfd from spectrum graphs? What's your thought, to create a database or dropdown of lights to choose from or something?

Edit: nvm see the dropdown.

what happened to the PPFD app? My friend said to get a PPFD meter instead of my Lux one. I was wondering if your app is ready?

Their is a app already.
“Korona”
I got it and tested it against MFG PPFD claims and it’s pretty accurate

Bookush34 said:

Their is a app already.
“Korona”
I got it and tested it against MFG PPFD claims and it’s pretty accurate

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That's currently an iPhone only app. OP is building this for Android as there is yet no such app.

SYNN3R said:

That's currently an iPhone only app. OP is building this for Android as there is yet no such app.

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I did not know that.

Light lux meter... app was fairly consistent when tested with a £2000 lux/umol meter.
The quality of the light sensor gets a mention.