LEDgardener

I’d like to be able to move panels,boards,straps around so that coverage is uniform and to avoid hot spots.
I’d like to know if I use dimmer how much is being delivered in par at the chosen height.
I’m wanting to keep lights at fixed distance and use dimmer if needed.

Can someone suggest a brand and/or model of par meter?

I think there is a recent thread on the matter in another section. If your spectrum is not too complex you can probably find the ratios and measure it with a LUX meter. Teknik knows his measuring gear thats for sure, but he might be more focused on pro solutions.

If under about 700 uMol, most any phone or tablet with a light sensor will work (50klx), with any app that offers a max and/or hold. For higher PPFDs, a 200klx light meter should be fine. Just make sure it has a hold or max function. The ratio of light A's lux to PPFD in uMol/sm^2 may be 65, and light B's may be 72. But if you read 40klx in spot X, and 30klx in spot Y, spot Y's PPFD or YPFD will be 25% lower than spot X's, for the same light. That's not good enough to do a proper PAR map, but plenty good enough to get even coverage, and even check that with plants inside.

Really a cell phone app might possibly work?
I was googling and there’s a DIY meter that uses an apogee sensor and a cheap volt meter on YouTube and the person compares it with his 3-400 dollar unit and claims it’s just as good.

I’ll try the phone app and see what happens.
The DIY I may look into.

I am working on a cheap par meter, samples were no good so it's going to take a while for it to be resolved, trying to keep the price between $160-$200

Indiled wrote: ↑

Wed Oct 02, 2019 5:40 pm

Really a cell phone app might possibly work?
I was googling and there’s a DIY meter that uses an apogee sensor and a cheap volt meter on YouTube and the person compares it with his 3-400 dollar unit and claims it’s just as good.

I’ll try the phone app and see what happens.
The DIY I may look into.

I saw the apogee + volt meter too. I might get something like that next year when budget allows

Currently I use a $20 ali lux meter using 9v battery. For me that's enough actually. I would never use a smartphone because I don't believe in that shit. How can 1 app get the same measurements from thousands of phones which are all different? Anyway, I do lux*0.0150 and that works out. When I need to set my lights, I just measure until I see a number I like.

You can use conversion factors. There are a few on the internet.
https://www.waveformlighting.com/hortic ... calculator
Dont know how good.

edit: as teknik said, only for white lights!

These threads and similar ones contain some gold information about this subject: https://www.rollitup.org/t/cree-cxa-300 ... is.832666/
https://www.rollitup.org/t/estimating-l ... mp.902597/

Dont know where to dig... these guys have already done a lot of the work. Unfortunately the threads can be huge.

If you are trying to measure simple white LEDs a lux meter does the job, if you have alot of red and blues that's where it fails, I can tell you the conversion rate for most white spectrums if you have a lux meter. Phone apps don't work too good for lux readings

TEKNIK wrote: ↑

Thu Oct 03, 2019 8:03 pm

I can tell you the conversion rate for most white spectrums if you have a lux meter.

That would be sticky worthy mate. I see a lot of people doing themselves a disservice by hanging a light at wrong heights. Lights too close might be the biggest problem people have with leds

A lux meter will tell you how spread is working regardless of intensity. If you tell me your strip color such as 3000K CRI80 I can give the conversion rate pretty quickly. The conversion rate won't be 100% accurate as a cri80 3000k spectrum can have quite a few variances and it get more complex going into cri90 and even more so in cri95 but it will give a good approximate indication

Not sure if you have taken a look at this one, sharing anyway


Also i cant remember where i read it, but someone else can confirm or deny this maby,
That you can use your actual lux reading an divide by 67.3, and that would give approx PPFD reading, under 3500k lights that is.
Not sure how accurate it is, but might give some ballpark idea.