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Total darkness, an odd topic.

Badchoice 43 Replies 4,818 Views
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Page 2 of 3 · Replies 21–40 of 44
#21
gorillaglueaaron said:
I just checked and it said 600 ppfd from 8 inches and 30,000 lux (front camera)
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I think what that app is doing is using a math calculation to get ppfd from lux. But its using the conversion factor for intense sunlight something like x .02. Our lights are closer to .0175. It will get you a very close measurement but not exact. For our uses it works great though 👍
 
#22
Milson said:
Smart phone light meters have been, in my experience, not very reliable. One reason is they typically cap at a pretty low measurement (sub 50k for sure) and are really meant for much lower indoor light situations, especially the front camera meter. Further, any measurement of "par" is almost certainly just a conversion from lux for some standard light spectrum. I would not trust it for much if you are outside of a "standard" spectrum.

Oh you don't know what "Standard Spectrum" means? Yeah me either lol. Hence why I don't put much faith in them.

If you care, you can chase down papers from this on the subject: https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator I think. Maybe it was a black dog whitepaper. Whatever, it's find-able.

If you want a good primer on cannabis and light, then I recommend Bruce Bugbee on YouTube.

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Bruce Bugby is my hero 😻
 
#23
Grownsince95 said:
I think what that app is doing is using a math calculation to get ppfd from lux. But its using the conversion factor for intense sunlight something like x .02. Our lights are closer to .0175. It will get you a very close measurement but not exact. For our uses it works great though 👍
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There are a bunch of different modes (sun, cmh, cfl, led blue red, led full spectrum...)
Do you think the difference between each of them is a different conversion factor?
 
#27

This is a legit explanation I believe. So it looks like it's just taking an integral from a light spectrum curve between two points on the spectrum (the parts we think are usable by plants) and multiplying it by a scaling factor.

Thanks for nudging me towards figuring that out! I had just been blackboxing the multiplier in my head until now.

Oh, the day is off to a good start now! :-D
 
#29
Milson said:

This is a legit explanation I believe. So it looks like it's just taking an integral from a light spectrum curve between two points on the spectrum (the parts we think are usable by plants) and multiplying it by a scaling factor.

Thanks for nudging me towards figuring that out! I had just been blackboxing the multiplier in my head until now.

Oh, the day is off to a good start now! :-D
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You kill me with this stuff @Milson ❤🌱❤
 
#30
gorillaglueaaron said:
Oh so it's a bit more complicated than just a simple linear equation.
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Yes. So basically, there is a different amount of power (in terms of number of photons, which is what the plant cares about because it captures those photons for photosynthesis) for each portion of the spectrum. The integral solves for that by outputting the area under the spectral curve fluidly. If you are trying to approximate with a bunch of linear equations, it will be just that.

I can write something more up about it later if I can figure out how to not talk totally out of my ass past this point lol.
 
#31
Milson said:
Yes. So basically, there is a different amount of power (in terms of number of photons, which is what the plant cares about because it captures those photons for photosynthesis) for each portion of the spectrum. The integral solves for that by outputting the area under the spectral curve fluidly. If you are trying to approximate with a bunch of linear equations, it will be just that.

I can write something more up about it later if I can figure out how to not talk totally out of my ass past this point lol.
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No no thanks but it's ok. This is about as far as my brain will understand.
 
#34
I was curious so I took some data from the app and I got this:
ppfd:...........lux:
1 ...................81
4.................. 220
5...................240
7...................390
14.................760
36................1900
455.............24600
751.............41000
Not sure what to do with this though🤣
 
#36
gorillaglueaaron said:
I was curious so I took some data from the app and I got this:
ppfd:...........lux:
1 ...................81
4.................. 220
5...................240
7...................390
14.................760
36................1900
455.............24600
751.............41000
Not sure what to do with this though🤣
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It's tough to figure because the instrumentation is imprecise, but it sure does look to be moving pretty much in line to me. Like 7-14 is roughly double for both. 14-36 is twice and half again for both...like roughly.
 
#37
Milson said:
It's tough to figure because the instrumentation is imprecise, but it sure does look to be moving pretty much in line to me. Like 7-14 is roughly double for both. 14-36 is twice and half again for both...like roughly.
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The point of all of this is there is no need for par unless you are comparing between spectra because it moves the same as lux. So, since you are likely functionally making relative adjustments within a spectrum, as you learn to read your plants re: lux, it will be just as good as par until you switch lights.
 
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#38
Aight small change of topic but close different dark cycles. Is 12 the best? What would happen by doing 10-14 or 11-13 or heck 13-11.
 
#39
Badchoice said:
Aight small change of topic but close different dark cycles. Is 12 the best? What would happen by doing 10-14 or 11-13 or heck 13-11.
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I tried 11-13 and my plant grew nanners but not sure if thats what caused it.
 
#40
gorillaglueaaron said:
I tried 11-13 and my plant grew nanners but not sure if thats what caused it.
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man kindof afraid mine might do the same during the transition and first week of bloom I using a black out curtain to cover the door and I’m sure light was leaking in since I’m on week 7 and no signs of buds
 
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