Understanding light.

[BigCube]

Lux today, my latitude, Northern California around 75000 lux, not yet noon, plus sun is still low in the sky. Just for comparison, measured my four cree cob light, my clones are under, 50000 lux at the canopy about 14” below the lights.

Here in BC, 10am overcast its 8300 lux
In my flower tent it's about 65000 lux at 21" from the light.

 

[Dan789]

Here in BC, 10am overcast its 8300 lux
In my flower tent it's about 65000 lux at 21" from the light.

I’ll measure my big light tonight when it comes on, running a night time schedule, we’re already at 80º yesterday, so can’t grow during the summer because of the heat...Don’t want to have to use A/C for any a grow, just extra expense.
Do us a favor, though and send some of that rain south, we could use it...thanks in advance.

 

[BigCube]

For most growers, I wouldn't recommend getting either. You can tell how much light a plant is getting by just looking at it. However if you build your own lights and like experimenting like many do around here, I would get an accurate measure

Well that's where I disagree with you. I do think a lot of new growers (the people this post is for, as evidenced by the very basic level it starts at) dont understand just how much light you need in certain situations.

A FREE downloadable app that can do that, is what I suggest. I then show how it is in fact a valid way of measuring plant lighting and being able to use the measurements to better control your environment.

I admit in the post that par is more accurate, and yet you chime in only to say par is more accurate... I know, I said that in the post.... that you claimed to have read...

 

[Dan789]

Much thanks for the information @BigCube, glad you saw the humor in the “do us a favor, though”...

 

[PipeCarver]

Well that's where I disagree with you. I do think a lot of new growers (the people this post is for, as evidenced by the very basic level it starts at) dont understand just how much light you need in certain situations.

A FREE downloadable app that can do that, is what I suggest. I then show how it is in fact a valid way of measuring plant lighting and being able to use the measurements to better control your environment.

I admit in the post that par is more accurate, and yet you chime in only to say par is more accurate... I know, I said that in the post.... that you claimed to have read...

I use a 1000w hps in a 25sq' room 5x5 = 40 w/sq' any more and I think I'd fry them. I'm using it for veg and flower by moving my vegging plants under it for 9-10 hrs per day then back into veg room for the night. Do you see any problems with me doing that? Plants seem to like it and are growing like weeds now.

 

[BigCube]

Much thanks for the information @BigCube, glad you saw the humor in the “do us a favor, though”...

Hah. You can have all my rain!

I use a 1000w hps in a 25sq' room 5x5 = 40 w/sq' any more and I think I'd fry them. I'm using it for veg and flower by moving my vegging plants under it for 9-10 hrs per day then back into veg room for the night. Do you see any problems with me doing that? Plants seem to like it and are growing like weeds now.

Lol sounds good. A lot of work though. Other than power consumption and heat, that's why I wanted to go with quantum boards. The more even distribution. Maybe 2 600s would be better, you could get more light, spread them apart so you could get better distribution but have your hot spots be not so hot, save crisping the plants.

But if what you're doing is working, and you dont mind the work lol.. I see no problems

 

[PipeCarver]

Hah. You can have all my rain!




Lol sounds good. A lot of work though. Other than power consumption and heat, that's why I wanted to go with quantum boards. The more even distribution. Maybe 2 600s would be better, you could get more light, spread them apart so you could get better distribution but have your hot spots be not so hot, save crisping the plants.

But if what you're doing is working, and you dont mind the work lol.. I see no problems

the rooms are only a few feet apart and although it's a pain I like the intensity of the 1000w and feel I might as well use it while its on if I have the space to do that. My veg room needs an upgrade to t5's from the t8's I have and although they veg OK I rather see them vegging under a more intense highout put light. I have an umbrella type fixture that's open air with the 1000w and I love the heat it puts out, without the heat from it I'd need to heat the space for 10 months of the year, July and August not so much.

 

[BigCube]

the rooms are only a few feet apart and although it's a pain I like the intensity of the 1000w and feel I might as well use it while its on if I have the space to do that. My veg room needs an upgrade to t5's from the t8's I have and although they veg OK I rather see them vegging under a more intense highout put light. I have an umbrella type fixture that's open air with the 1000w and I love the heat it puts out, without the heat from it I'd need to heat the space for 10 months of the year, July and August not so much.

Yeah, I hear that. I used to run a 1000w in a closet that was about 4x5. It was intense... definatly nice in the winter months

 

[Homesteader]

Lux is not the measure people should be using for several reasons and recommending certain levels offers nothing to them other than an overload of information. The only measurement that I personally would use lux meter for is to get an even canopy and even that I wouldn't use an app. A phone doesn't correct cosine so angles of light wont give you anywhere near accurate measures

Disregard the fact that lux is a measure for the human eye and weights yellows and greens because of it and hardly touches reds and blues. What will anyone achieve by using it as a guide? I just don't see any benefit at all to be honest.

Compare one persons light to another without using the same phone at the same angles and what will the difference be?
I bet you if 10 people using their apps on the same light they will get ten substantially different readings because of it.

Don’t ‘Phone It In’: Why Smartphones Are Poor Substitutes for Light Meters - kW Engineering

There are dramatic differences between smartphone light meter apps and standalone light meters when used in the lighting world. As a lighting professional, I’ll show you how and why leaving this unitasker at home can have serious implications.

www.kw-engineering.com

It’s Not All Sparkle. It’s Spectrum and Cosine Correction: Your Guide to Buying a Light Meter - kW Engineering

[…]

www.kw-engineering.com

 

[BigCube]

Lux is not the measure people should be using for several reasons and recommending certain levels offers nothing to them other than an overload of information. The only measurement that I personally would use lux meter for is to get an even canopy and even that I wouldn't use an app. A phone doesn't correct cosine so angles of light wont give you anywhere near accurate measures

Disregard the fact that lux is a measure for the human eye and weights yellows and greens because of it and hardly touches reds and blues. What will anyone achieve by using it as a guide? I just don't see any benefit at all to be honest.

Compare one persons light to another without using the same phone at the same angles and what will the difference be?
I bet you if 10 people using their apps on the same light they will get ten substantially different readings because of it.

Don’t ‘Phone It In’: Why Smartphones Are Poor Substitutes for Light Meters - kW Engineering

There are dramatic differences between smartphone light meter apps and standalone light meters when used in the lighting world. As a lighting professional, I’ll show you how and why leaving this unitasker at home can have serious implications.

www.kw-engineering.com

It’s Not All Sparkle. It’s Spectrum and Cosine Correction: Your Guide to Buying a Light Meter - kW Engineering

[…]

www.kw-engineering.com

I agree, your phone reading lux isnt a good PROFESSIONAL light meter. Never said it was, he even stated the 5% difference that I did. 5% is good enough for me. I've seen hydrofarms quantum meters out more than 20%

Nobody's advocating for professional light meters, even you said you dont. So why even bother pasting articles that compare your phone to professional light meters?

I have already said many times there are more accurate meters. Its like you're not even reading what I type.

 

[Homesteader]

So what will people achieve from going out and reading their lux on their phone again? Do you think the 5% difference in readings was on the same phone? I do but regardless

I'm not advocating buying a lux meter at all. I think ilux is almost worthless for plants even it was accurate. That isn't an insult to you. Its my opinion.

The first article was why phones aren't worth anything because they aren't light meters and don't correct cosine and the second shows that even with accurate equipment, many of the LED colors are not measured.
So why use it?

 

[BigCube]

So what will people achieve from going out and reading their lux on their phone again? Do you think the 5% difference in readings was on the same phone? I do but regardless

I'm not advocating buying a lux meter at all. I think ilux is almost worthless for plants even it was accurate. That isn't an insult to you. Its my opinion.

The first article was why phones aren't worth anything because they aren't light meters and don't correct cosine and the second shows that even with accurate equipment, many of the LED colors are not measured.
So why use it?

They will be able to give their plants a within 5% accuracy of optimal light for their current application. For free, with just a little bit if knowledge......
Isnt that enough?

The article title is IT’S NOT ALL SPARKLE. IT’S SPECTRUM AND COSINE CORRECTION: YOUR GUIDE TO BUYING A LIGHT METER

Who's buying anything? I agree, if you buy a light meter, buy one that is accurate.

The phone apps I have, have calibration settings where you can look up your known manufacturers (LG, sylvania, GE etc..) specs for their bulb, and calibrate your phone. It's just math man. As for degree angle, the hydrofarm appears to be the worst for that. That's just user error. Use an app like the one I have, it show maximum readings on a graph in real time So you can be sure you captured the right angle.

Anyways, dont use one if you dont need one. I dont absolutely need one. But it sure is nice when you're trying to get even distribution from multiple fixtures. And to keep track of my led output as a % when dimming. But many new growers can definitely use this to be sure they are in the correct range of light for the current stage of their plant.

The entire post started off describing what light is and how it works. How the par spectrum and lux spectrum are in fact the same spectrum. Yes with weight in certain places or not. I then go in to show how you can, using math (or even easier, online calculators) using the color temperature of your spectrum as a variable, get a decently accurate par or umol count.

If you dont like anything I said specifically, please quote it and we can talk about it. If I'm wrong I'd live to correct it.

 

[Homesteader]

They will be able to give their plants a within 5% accuracy of optimal light for their current application. For free, with just a little bit if knowledge......
Isnt that enough?

How?

 

[Homesteader]

Nevermind. Good luck!

 

[BigCube]

I mean, you can just read that guys conclusion. Lol

A smartphone does a lot of stuff in the field. It can take pictures, record field notes, and doubles as a reasonably good bubble level. A smartphone is not a light meter.

A lighting professional – be they a designer, consultant, manufacturer rep, installer, or start-up technician – has too much on the line to draw conclusions based on a faulty light meter. A smartphone light meter app has too many levers involving too many unknowns that cannot be reasonably accommodated by either the programmer or via a ‘calibration’ function.

Light meter apps based on my experience and the experience of others fail to correctly measure light when compared to calibrated light meters designed for that purpose. Avoid the guess work and invest in a good light meter and treat it gently.

 

[BigCube]

Lol a lighting professional...

Yeah I agree with everything he said...
What did I say that was wrong? Are you just playing devil's advocate?

 

[Homesteader]

I don't play nor am I going to argue with you. Good luck!

 

[BigCube]

I don't play nor am I going to argue with you. Good luck!

Fair enough. Thanks man, you too

 

[BigCube]

I was like:

 

[Hidd3nGr0w]

Lux today, my latitude, Northern California around 75000 lux, not yet noon, plus sun is still low in the sky. Just for comparison, measured my four cree cob light, my clones are under, 50000 lux at the canopy about 14” below the lights.

Good looking out!