Is there an inexpensive light intensity or par meter?

[Vividled]

Just how linear the curve was and parallel to the par map is extraordinary I never expected them to be that close. Certainly with white led. Shame he hasn't tried with several phones yet. But very promising results from the s8 certainly.

[unkle_psycho]

You can get the relational info to balance things, but probably not the real intensity figures.

[The_Mouse_Police]

Just how linear the curve was and parallel to the par map is extraordinary I never expected them to be that close. Certainly with white led. Shame he hasn't tried with several phones yet. But very promising results from the s8 certainly.

My Nexus 5X, XZ1C, and now-long-gone Nook (don't have model handy) all got within a few percent of each other. With a fixed spectrum, that'll do the job very well, to even out the spread. If you get to adding wavelengths that aren't green, like 660nm, 730nm, 420nm, etc., the relative additions in PPFD from those, compared to the baseline white, will not match the increase in lux, though - that's where cheap just doesn't cut it. If you can get decent readings with only a supplemental light channel on, though, you should be able to get those in good positions on their own, and end up close enough.

[Vividled]

Just how linear the curve was and parallel to the par map is extraordinary I never expected them to be that close. Certainly with white led. Shame he hasn't tried with several phones yet. But very promising results from the s8 certainly.

My Nexus 5X, XZ1C, and now-long-gone Nook (don't have model handy) all got within a few percent of each other. With a fixed spectrum, that'll do the job very well, to even out the spread. If you get to adding wavelengths that aren't green, like 660nm, 730nm, 420nm, etc., the relative additions in PPFD from those, compared to the baseline white, will not match the increase in lux, though - that's where cheap just doesn't cut it. If you can get decent readings with only a supplemental light channel on, though, you should be able to get those in good positions on their own, and end up close enough.

Does additional green map more accurately even with basic sensors?

[The_Mouse_Police]

Green is what we, and common lux sensors, are most sensitive to. Many cheap ones more or less ignore deep blues. More broad spectrum green will give a ton more lux, but not much more PAR. Meanwhile, deep blue or red might read at 1/50th of what the green does, so you could double the PAR, but only see another several percent of lux.

[TEKNIK]

You need a spectrometer to measure it properly, regardless of what brand you end up with the internal spectrometer is usually made in Japan and expensive. I'm working on making a cheaper product but it's not that easy.
If you are using white LEDs then you can get away with a lux meter to get an approximation. As soon as you add red or blue monos into the mix then things change really fast

[GreenGrow]

Here's two links for anyone using a LUX meter, or interested in doing so.
https://www.apogeeinstruments.com/conve ... fd-to-lux/
https://horticulturelightinggroup.com/b ... ux-to-ppfd

And as TEKNIK said, the quantum sensors are expensive. The meter/display seems to be quite cheap in comparison. I've seen LEDGardener use sensor + multimeter in some video, and I'm guessing Migro is using some kind of homebuilt equivalent (?) as well.

Anyway, I think those two LUX to PPFD links are quite good. Just wanted to share and contribute
I've also stumbled upon this picture sometime in the past. Not sure when or where, but I saved it. Might be interesting to someone.