Interested in a light meter to improve yield, testing bulbs

[lunarman]

did a few searches but could not find anything. Figured this DIY board would be the best place to post this question since people here would likely be apt to measure light.

I don't need to measure LED's at this point. Just HPS.

And I want a meter that is:

• Under $50
• Can help me test areas of the canopy so I can find ways to position plants or lights better.
• Be able to tell is HPS bulbs are older and need replacing because output has dropped, so I think this means be able to measure that a bulb is putting out 90,000 Lux or whatever it should be.

I have a lux meter in my amazon shopping cart that I am thinking of buying. Would you buy this for what I want to do?

Dr.Meter LX1330B Digital Illuminance/Light Meter, 0 - 200,000 Lux Luxmeter

 

[wwwillie]

Have you tried any of the phone apps that use the camera? Just curious, but they might be worth fiddling around with.

 

[BigSm0]

Par is the measurement you want. I did see the 50 dollar max and the cheapest par meter is the hydro farm around 130 dollars.the down side is most meters on the cheaper end do not adjust for colors so red and blue will read much higher even though it may be less. The more expensive meters $500-2000 dollars correct this but to expensive to most growers. I'd stick to the phone app or save up for a hydro farm.

 

[lunarman]

Have you tried any of the phone apps that use the camera? Just curious, but they might be worth fiddling around with.

I do have 2 android light meter apps that I played with yesterday. I did order the Dr Meter lux meter from amazon last night and should get it today. Will definitely compare it to the phone apps and I'm hoping it is better and worth the $40.

 

[lunarman]

Par is the measurement you want. I did see the 50 dollar max and the cheapest par meter is the hydro farm around 130 dollars.the down side is most meters on the cheaper end do not adjust for colors so red and blue will read much higher even though it may be less. The more expensive meters $500-2000 dollars correct this but to expensive to most growers. I'd stick to the phone app or save up for a hydro farm.

Hey @BigSm0

I know you're the COB kit guy and I could see myself getting a couple of your lights for a small area of my tent that I can't fit in HPS lights/fixture/exhaust vent tube. I will likely need some an LED based solution with enough to flower 2 auto flowers that I can't fit under my existing HPS. Right now they are seedlings under an 8 tube T5HO fixture.

But I don't follow why I need a PAR meter for what I need to do. I thought a lux meter would help me understand light intensity of HPS bulbs on the canopy. I just need to know what areas of the canopy are getting good light and what are not. I don't need to really know values read from a PAR meter. I just need to know the relative difference of light of different spots on my canopy as I move my light up and down etc. And I want to be able to tell if my HPS bulbs need replacing because their intensity has decreased significantly enough that my yield will be low and I should replace the bulb.

Sure I'd like a good PAR meter, but won't a lux meter help me get by even if it's not the real way to measure light for growing?

 

[BigSm0]

You are right. Within the same light source it will tell you which areas are getting good light and which not as much. I was thinking about adding additional light sources and comparing which would be affected by the meter. Even a par meter which measures par isn't as effective as a spectroradiometer but more valuable than a lux meter for measuring lumens. Good idea. If it's more accurate or helpful for you that's great. If it's similar than the phone app you can always return it.

 

[lunarman]

I have the DR Meter lux meter from Amazon. It works great and much different than the 2 phone apps on Android I have. The 2 apps were consistent at least, measuring room light at 130 lux. But the meter measured value is 400 lux. That is a big difference. I assume the meter is way more accurate than the phone, but not sure how I can be sure of that.

Measured lux values around the the top of the canopy and my 600 watt HPS lights can be anywhere from 60,000 to 110,000. I dialed things in so that the canopy is getting 85,000 lux. I do like having the ability to measure relative data points so I can raise or lower the lights to what i hope is ideal intensity. And it helps to position the plant containers below the lights left and right, closer to the front or back etc.

I am not sure how to test the output of my bulbs and if they are near end of life or still in good shape. Might just have to measure on a regular basis and look for changed.

 

[bad dragon bzzz]

im sure i saw a pic in live stoners the other day of a plant a hand holding a light meter.
@L0wbob2017 got a light meter a while back,is a thread to but cant remember what its called.im sure he would love to compare notes.
keep er lit.

 

[L0wbob2017]

I have the DR Meter lux meter from Amazon. It works great and much different than the 2 phone apps on Android I have. The 2 apps were consistent at least, measuring room light at 130 lux. But the meter measured value is 400 lux. That is a big difference. I assume the meter is way more accurate than the phone, but not sure how I can be sure of that.

Measured lux values around the the top of the canopy and my 600 watt HPS lights can be anywhere from 60,000 to 110,000. I dialed things in so that the canopy is getting 85,000 lux. I do like having the ability to measure relative data points so I can raise or lower the lights to what i hope is ideal intensity. And it helps to position the plant containers below the lights left and right, closer to the front or back etc.

I am not sure how to test the output of my bulbs and if they are near end of life or still in good shape. Might just have to measure on a regular basis and look for changed.

well just for your information, i also tried the Phone-Lux-meter-Apps and i came to this result:

I did some research about the light sensors of smartphones and the thing is that even if you got the same model 2 times, when u install the same app, the chance of getting same results is very low. Thats because the calibration of these sensors is made on big plates with about 100 smartphones on it. Then they add the light fixture and do a mass calibration.
The problem is that the light distribution is not even enough so every phone has slightly different results but all in an "acceptable range of failure".

I got 2 smartphones of the same model ( Samsung galaxy S4 ). I installed on both the same app and compared, They were mostly about 2000 LUX away from each other.
Then i ordered this LUX meter from amazon: Grandbeing Digital Luxmeter for 20 bucks.

So i calibrated the smartphones with the LUXmeter from amazon and the factors i had to use were these:
Smartphone1: factor = 0.71
Smartphone2: factor = 0.89

This means for my own case: The sensors of my 2 smartphones showed way too much LUX compared to the LUX-meter i got from amazon.

A friend of me tried this with his new Samsung Galaxy S7 he bought yesterday and his sensor showed way less LUX than my LUX-meter.
This seems to be random if a light sensor is giving more or less LUX than it is.

So you can see a smartphone light sensor only works when once calibrated with a factorycalibrated LUXmeter. After that it works the same and gives me almost same results ( difference is about 20 LUX, readings on smartphone dont get stable )

 

[lunarman]

@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!!!