rayuki
Well-Known Member
they started life in a 4x4 tent, ditched the tent about 20 days in and just had them in the room which is 10x10 they were up on a table i made for them under the lights.
Bridgelux EB-series on a 2' x 4' SCROG
- Thread starter graying.geek
- Start date
Michiganjesse
Well-Known Member
Can I steal your quote have too pee on the fenceNow that's what I'm talking about! That is a serious blanket of photons raining down now...and it comes at a good time. You can finish the run strong with plenty of photons.
And I would definitely suggest getting some UV grow glasses. I have a very similar setup, and my eyes hurt if I do not wear them everytime I am near those lights.
And if that is just your second grow...well...it reminds me of a Will Rodgers quote:
“There are three kinds of men. The ones that learn by readin’. The few who learn by observation. The rest of them have to pee on the electric fence for themselves.”
You must be one of the few!
BuddyColas
Well-Known Member
Credit Will Rodgers for that awesome insight into human nature. Feel free to copy...and stay away from that fence!
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Hello.... What driver did you use ? How wired series ?
GrowLightResearch
Well-Known Member
It will not fall off as quickly as the inverse square law (ISL). You are measuring as if you were dealing with a single light source. If I recall correctly you are using 48" strips. The ISL will only work with the LED directly above the light meter's sensor. All others are at an angle. To get an accurate estimate, without a cosine sensor and an aperture, you would need to measure each and every individual point light source.
What is happening is when you lower the fixture 4" (16% for 24-20") only the distance between the sensor and the "one LED" directly above the sensor. All the other LEDs had the distance to the sensor reduced less than 16%.
From 24" to 20" represents a 16% reduction in distance.
If the sensor is positioned in the middle of a 48" x 48" fixture the distance from the sensor to the furthest LED would be 24" x 1.4 or (1.4 ≈ square root of the sum of squares) to the corner of the fixture. The sensor is 24" below the fixture.
To measure the distance between the sensor and the LED we need to calculate the angle which is needed to calculate the distance. Both calculations require a little right angle trigonometry.
The distance from the center point to the corner, we can look at that area as a 24" square and calculate the distance from corner to corner. https://www.mathopenref.com/squarediagonals.html
sq. root of 24² + 24² = 33.9411" which is the horizontal distance. The vertical distance is 24".
The angle is the arctangent of 33.9411" ÷ 24" ≈ 36°
https://www.mathopenref.com/arctan.html
We need the angle of the top angle which is 90° minus 31° = 59°
https://www.mathopenref.com/arctan.html
The distance is the height (adjacent side of angle) ÷ cosine(angle) = 40.9"
At 20" height the distance is 38.7"
You can check my work here: https://www.mathopenref.com/cosine.html
Make two triangles, 33.9" wide and 24" and 20" high.
When you dropped the height from 24" to 20" the distance to the corner LED changed from 40.9 to 38.7 = 2.2"
Therefore in the ISL formula you use a D1 = 40.9 and D2 = 38.7.
The ISL changes the irradiance of the one LED by 44% but reduces the corner LED by only 11%.
Check that with an ISL calculator, where D1 =24" D2=20" and for the other use 40.9" and 38.7"
http://www.radprocalculator.com/InverseSquare.aspx
You cannot use the same irradiance for the one LED and the corner LED. You must take into consideration the spacial radiation distribution (i.e. view angle).
So in the LM561 data sheet find the relative flux at 59°.
Which is about 43%
So we must multiply the irradiance of the one LED by 0.43 to get the equivalent irradiation at 59°
So the irradiance from the corner LED is 43% of the one LED and its irradiation reduced only 11% due to the ISL. The total change in irradiance for the corner LED is only 4.73% when compared to the expected change due to ISL.
It also depends on the error rate of your light meter. An inexpensive $150 lux meter is going to have an error of over 20% .
At less than 3000 lux this $1,200 quality lux meter has an error (if you follow all the detailed use instructions) of 6% and plus or minus the least significant digit. Error spec on page 45:
http://cdn.tmi.yokogawa.com/510_illuminance_IM51011_S01_EN_010_AA.pdf
http://cdn.tmi.yokogawa.com/510_illuminance_IM51011_S01_EN_010_AA.pdf
A $25 lux meter will not be in the ball park. That alone could account for your measurements being off. I confirmed my calculations with a $3,000 Stellarnet Blue Wave spectrometer. When I measure irradiance between 24" and 20" it follows the ISL fairly closely. I am always moving the sensor significant height to find the correct range. It is much easier to change the distance between the sensor and fixture than change the integration time to get the signal in the correct range. I will easily see a 200x difference between the bottom and top of the tent.
I mounted my sensor in a 4" cube of wood and use various stacked lengths 4" PVC to adjust the height of the sensor.
Bottom line ISL works. All the reasons given were done likely done so in good faith. But they made my eyes roll.
The 301Bs are now being released to distribution. 218 lm/W is not going to make a difference when compared to the LM561. Your strips will work as well as they did in Oct for many years to come.
http://www.radprocalculator.com/InverseSquare.aspx
wietefras
Well-Known Member
No it doesn't and that's correct. If inverse square would actually apply to fixture heights in grow tents, then the floor would be dark if you hang the light at the top. Going from 4" to 80" is a reduction of 99.75% according to inverse square law (from 440 tot 1.1 : 440 / (80/4)^2 = 440 / 400 = 1.1)
No he's not. He's measuring ambient light from all angles. As it should be, because plants do the same. They don't sit peering up through a straw to only see the light single led exactly above them. They receive light from pretty much ALL light sources above them.
Yes exactly, you have to completely force things (ie screw them up) to measure only a single spot of light source to see ISL. That doesn't happen in real life because in real life you have reflection and overlap. So that's why there is no inverse square for the height of a whole fixture. That's not a bug, that's how reality works.
And demonstrated that there was no inverse square relation between the distance of the fixture (even a strip) and light intensity.
You started at 440 at 4". If inverse square actually applied to fixture height you would have seen 110 at 8", 27.5 at 16" and all the way down to 1.1 at 80" (so the floor would be pretty much completely dark). Doesn't happen now does it?
"ISL" works yes, but that does not mean it applies to distance between fixture and plants. It doesn't because light reflects back and multiple light sources overlap.
You can keep pretending that only light dispersing from a single light source matters since that does follow ISL and you are desparate to see "ISL" somewhere so you can pretend you were right all along. However, that would only be applicable if you light your whole grow area with a single dot of light. No one does that.
GrowLightResearch
Well-Known Member
Your whole post is just rambling gibberish. You just do not understand this stuff at all. I cannot respond to gibberish. All I can do is roll my eyes, shake my head, and shrug my shoulder as I read your ramblings.
wietefras
Well-Known Member
I'm sure you can't understand it. Which is why you shouldn't be posting on this subject to begin with.
GrowLightResearch
Well-Known Member
Opps, my bad. Or is it?
I am still waiting on the citations for reflection and overlap.
What about your equations to make those grey on blue background objects.
What happens to the reflection and overlap when the height is changed? When does reflection and overlap cancel out ISL? When height increases? Or decreases?
Please clarify "real life". Are you sure you know which it is?
force things? screw them up? Huh? To damn technical for my little pea brain. Could you dumb it down for me please.
Actually there are CMOS and CCD sensors that can filter out those pesky other angles. There are also linear photodiode arrays, CMOS linear arrays, and linear CCD arrays.
Let's look and see how Inverse Square Law does not work.
I said
You are measuring as if you were dealing with a single light source.
Would a single light source have multiple angles? Do you have an ISL formula that has parameters for multiple angles? Would it make sense if ISL worked with multiple angles?
Will the distance between the sensor and LED be the same for each angle?
With multiple angles, and therefore multiple distances, which distance do you use in the ISL?
What about the 5 times rule? I mentioned this to you previously. Forget? For Inverse Square to work well, the distance must be 5x the largest dimension of the source.
Because each LED has a longer distance to the sensor than the center LED and as the center distance decreases 20% (24/20) all the other LEDs decrease less than 20%. That is why there is a 5x rule. When the sensor is 5x away from the source, the change in distance of the other LEDs becomes negligible.
You can also, as I showed you previously make a correction for the various angles by applying the cosine.
Let's see how much error the ISL had from 24 to 20 inches. 24" is pushing the 5x rule, but there is plenty of slack. At 5x the error is negligible. At 1x or 0.5x not too bad. Less than 10%.
20" 39900
24" 30200
(24/20)² x 30200 = 43,488
Measured: 39900
Calculated: 43,488
1 - ( 39,900 / 43,488 ) = .082 = 8.2% error.
Why does the error increase as the height decreases? Must be those damn pesky angles.
What happens to the distance for the LED in the corner or the fixture?
Newer mind. I'll save you the time: WRONG, because I said so. I am the great and powerful wietefras
I have no evidence to prove you are wrong, you are wrong because I say so. Anything I do not know, it does not exist in my Universe (aka real life). Get away from that curtain!
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wietefras
Well-Known Member
Well pretty much that is what it seems to come down to yes. You are so stuck in theories which you don't actually understand that you keep making complete bullshit statements.
The error between measurement is increasing over distance because reflection kicks in.
There is no "citation" that overlap and reflection end inverse square. That's just common sense. If you understand physics that is.
I'll explain again. Please read it really slowly this time:
1) Overlap: Doubling the distance means the light will have spread to over a surface 4 times as big for each light source. That doesn't mean the light is gone, just that it spread out further. Which means that the lights from surrounding light sources also spread and all that fills up to the same amount of light again.
2) Reflection: If you could have 100% reflective walls then you could extend the distance infinitely and still have the same light intensity. Which is how glass fiber works to transmit light over vast distances.
GrowLightResearch
Well-Known Member
Why does a laser beam not spread out in ambient air?
Laser does not apply to ISL because the laser beam is a beam not a wave, and not applicable to wave optics. When light is collimated it becomes a beam and ISL is no longer applicable. A CoB with an 80° lens will decrease ISL results.
There is a little more to light waves bouncing around reflective walls than the reflective index of the walls. Example Fresnel’s law and reflective, refractive, phase shift loss and conservation of energy.
You have been saying reflection and overlap cancel ISL. That ISL is not applicable to a grow fixture.
The question was how does moving a fixture from 24" to 20" alter the reflection so much that the reflection decreases the light that reaches the sensor? And vise versa. When the fixture is raised from 20" to 24" how does the reflection alter the light waves reaching the sensor.
You claim to have written an app that calculates in the reflective effect with those grey blobs on blue background. This should be a rather simple question to answer seeing you have written this app.
That sounds very similar to the ISL. As if the ISL cancels out the ISL.
Let's not forget about the canopy. It spreads out pretty much only until it reaches the canopy and slightly beyond for a much less significant number of photons. A fair amount of those photons are converted to electrons when they are absorbed by a leaf. After reaching the canopy, percentage wise, how many photons remain photons and how many become electrons? I assume this also is a major factor in your app.
So the light spreads out reaches the canopy then reflects around to the sensor and cancels the effect of ISL how?
If you don't mind could you briefly explain it in terms of physics rather than your "common sense"? Your common sense has no worked well, for me, at explaining anything so far. So let's test my understanding of physics. I have this overwhelming tendancey to go with science more so than someone's opinion and common sense. You may be correct and I may be wrong. You have never answered my questions. Just saying I'm wrong with no science to back it up is getting a bit tired.
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wietefras
Well-Known Member
That's called an outlier. Probably a typo or otherwise a measuring error. It should be something like 38200 instead of 30200 to fit with the rest of the numbers.
Anyway, if it was an inverse square relation, then at 24" it's 6 times the distance so it should be 1/36th of the 51000 measured at 4". So that would be 1417. It's not even remotely close to that.
I have explained several times. You are not listening and instead keep grasping at straws to pretend that everybody is wrong and you are right.
If you actually want to understand then start with that inverse square law does not make light disappear. Inverse square law just states that light spreads over a surface four times the size when doubling the distance. In a grow tent that cannot happen (too far) because light bounces back off the reflective walls. That's the end of "ISL" right there. It's beyond me what citations and "science" you would need to understand this.
With overlap, the light from each source spreads out according to inverse square, but that also means that light from more and more neighboring light sources will overlap at the same rate. If you have 4 light sources that each produce a quarter of the light intensity at some point, you still have the same intensity in total.
Overlap does pretty much the same thing as reflection. Reflection basically causes the light to overlap with itself.
Either way, the only light you lose in a grow tent is the light that hits the walls and is not reflected back. Wall losses increase by the ratio of the amount of wall exposed to light and reflectivity of the material. That's is not an inverse square relation
GrowLightResearch
Well-Known Member
I have been saying the closer you get to the canopy the error from a lux meter is going to increase exponentially. I explained the math in detail as to why that is happening between 4" and 8". You are having difficulties with that so let's keep it simple.
You say reflection will nullify ISL. ISL does not work at all in a grow chamber (tent).
I have also been saying the reflection will not skew Inverse Square Law (ISL) to any great extent. Certainly not enough nullify ISL.
Then you brought "overlap" and likely coined this new meaning. Your definition to this new phenomena you invented sound like the reason as to why ISL works.
Your definition of "OVERLAP"
The inverse-square law, in physics, is any physical law stating that a specified physical quantity or intensity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cause for this can be understood as geometric dilution corresponding to point-source radiation into three-dimensional space (see diagram).
I am referring ONLY to the height from 24" to 20". Forget 4"-20" exists for now. One thing at a time. The 20" to 24" is the easiest issue here. Let's start with that one. Then bring in the ones you are having a more difficult time explaining.
So for now I would like you to explain why ISL works from 24" to 20" with only 8% error. That is not a typo or mistake. Maybe @graying.geek is again enough to begin graying but a geek at any age is going to know how to read a meter and type the numbers. You never mentioned typos previously when you were explaining you thoughts on his ISL issue back in October. The numbers did not look like a typo until you needed them to look likea typo. Coincidence. I don't think so. More like your SOP. When you couldn't explain reflection you invented "overlap" .
You claimed to have an app to calculate the relationship between ISL and reflection. You even explained how the app found my tent surfaces had 50% reflection. Now where are the formula or even just a brief explanation how those formulas work?
This does not explain anything It's just you saying this happens. Your app did the math.
I am saying the fixture should be close to the canopy no more than 10" away. Later we can get into dropping from 8" to 4" or less. There reflection will not be in the equation.
Even GG's numbers show what you are saying is not true. Even though there are problems the measurements the irradiation at the canopy increased significantly. You are saying there will be no difference. Not only that but the numbers between 24" and 20" follow the ISL probably has less less then the lux meter specification, unless got a better meter than the $25 meter. Certainly very good measurements considering they violate the 5X rule. The 5X rule says your measurements will be less than ISL. That would account for GG's measurements to be lower than ISL.
The question again and only this specific question. Why are the measurements between 24" and 20" ignoring your reflection and "overlap" as the measurements are so close to ISL especially in lieu of the 5X rule that explains the measurements will be lower if 5x rule is violated as shown in GG's measurements. I'm not buying typo.
I've been saying the growers listening to you are throwing away money to the electric utility Co.
graying.geek
Well-Known Member
@GrowLightResearch and @wietefras : Christ, you 2. Way to fuck up an otherwise collegial and useful thread. You both know your stuff and have a ton of knowledge. Please consider stepping back from the animosity and dick measuring. This is useless bullshit.
wietefras
Well-Known Member
@graying.geek Yeah sorry. It's clearly pointless trying to explain anything to him anyway. Maybe if he ever actually creates a grow light and uses it, will he understand how all this works. I'm out.
eyderbuddy
Well-Known Member
klx
Well-Known Member
They ended up keeping the same spear shape but they yielded a little less than usual so I guess those extra watts at the start of flower do count! Nice tight nuggs though and easy to trim.
eyderbuddy
Well-Known Member
klx
Well-Known Member
The strips are 4000k 80cri and the cobs are 3000k 90cri. I am guessing that is what changed the shape of the buds and the lack of wattage is what affected the yield. Just assumptions.