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Invisiblecoda


Registered: 04/20/08
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The "Do Lumens Add?" debate
    #344012 - 01/09/10 01:37 PM (4 years, 3 months ago)

So lately I've been confusing myself on lumen output.  Originally I had believed that if had two lights producing 50 lumens, total lumen output would be 100 lumens.  Then someone told me I was wrong and that total lumen output would NOT increase if adding in lights with the same intensity.  Instead of having more lumens you would have more coverage.  So, using my previous example, the total lumen output would only be 50 lmn.

This morning I had posted a reply to a thread in which someone had stated they were running 30K lmn in their box through the addition of lot of CFL bulbs.  I replied that lumen output really didn't work that way and that if you had 10 lights producing 2700 lmn a piece, total lmn output would be 2700.  However, I just didn't feel right about it.  I really felt like I was just recanting more information without any solid evidence.  This really bothered me so I decided to get down to the bottom of this.  Doing research on the web only produced the same confusing results, you have camp A who believes that adding lights WILL increase while camp B believes they WON'T increase.  Frustrated I decided to ask someone who I could trust. 

My sister studied photography, and then biomedical photography.  She is now employed with a company that produces medical equipment which takes photos of the inner workings of your eyes.  I figured someone who has over 15 years experience working with light equipment and the associated sciences behind it would know the answer.

Here is my question:

Quote:

So, PhotoNerd, I have a light question for you. I'm trying to settle a debate on light intensity. I figured you'd probably be able to help me on this one.

If a lumen is a measure of light intensity from a source, adding another light with the same intensity (lumen output) will NOT increase total lumen output, right? So if i had a light that put out 50 lumens, added in another light which put out 50 lumens, my total lumen output would still be 50 and not 100 right?




Here is her response:

Quote:

Nope. Lumens add linearly. if you have 2 50 lumen LEDs in a reflector, it will produce 100lm of light at the source. If you have 2 50lm lights in individual reflectors, pointed in the exact same direction, you still have about the same lumen output.

What startes to get confusing is that lm are relatively useless, because there are so many other variables involved - distance, reflective surfaces, where the light is pointed.

Your real concern is the candlepower of the lights over the surface you're interested. Using those above variables, I can light an object for photography, and make it look identical to the same object photographed in open sunlight, but you couldn't possibly tell me that my little tungsten Tensor lights have the same lumen output as the sun.

Basically, you end up needing to be concerned with the lux at your worksurface more than the initial photon emission of your light. I mean, if you have a 100lm bulb and half of it is pointing into a light-absorbing surface, you're only producing 50lm of usable light.

That's what I've got before coffee on a Saturday...




To which i replied:

Quote:

mm, but does your answer only apply to flash photography? Consider a constant light source such as a CFL light bulb. Removing all other variables such as light absorption and reflective surfaces, concentrating only only total lmn output of a bulb, lms will add with each addition of a bulb. So, using my previous example, two 50 lmn bulbs produce a total of 100 lmn and the number will rise with each addition of another bulb?

The reason I'm asking is because right now there are two camps of people. Camp A believes lmn output increases with each additional bulb, Camp B believes FOOTPRINT is increased but NOT total lmn (in which case the only the increase in out put would be the margins of areas where the light bulbs overlap). The question is dealing with light saturation in an enclosed area to increase plant growth and production. In which the first camp believes more bulbs = more light = faster growth and the second believes using less, higher powered bulbs is better because lmn output is not cumulative.

I have honestly not been able to find a definitive answer on this, it seems like these two camps exist in every thread I find on the subject and no one has any science or proof to back it up. If I had my goddamn light meter I could prove it myself, but I think it's back east with my SLR.




I am waiting on a response from her, I'll see if I can goad her into running a few tests with her 80 bajillion dollar light meter she owns (ok, its only 50 bajillion, but I like to exaggerate).  If there is anyone's opinion on the matter I trust, it would be hers.  She's unbiased in terms of using lights to grow cannabis (which is why I asked if her response was directed towards flash photography).  I'm also doing some research on the subject and am trying to find information that doesn't come from some random forum post.  My next person to bug would be my old calculus tutor who is a complete physics geek.  He would be the guy to break down this into a formula, while my sister would be the one to back it up with physical evidence in terms of a meter reading.

Hopefully we can settle this damn thing because I know it's bugging the shit out of me :smile:


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OfflineKine

Registered: 11/25/08
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Re: The "Do Lumens Add?" debate [Re: coda]
    #344025 - 01/09/10 02:08 PM (4 years, 3 months ago)

Lol...

Physics is what it is; not photography.  Ask your sister how photons work in relation to physics.  Thats what people dont understand.  This isnt "Light Theory 101".  Photons follow the laws of physics.  Here is my thread about this; and in that thread are several links to yet more proof on physics.

http://www.growery.org/forums/showflat.php/Number/339216

Seriously.  How can you think that two photons traveling at the same light speed; can double up and increase the speed?  If a simple example like the cars on a highway dont allow you to understand... i dont think you'll ever understand lighting...

Im not really trying to be a dick... but the answers are right there; and in every physics book on this earth.  Research "Light waves" "Photons" "Photon traveling speed" and read read read.  Learn how a light emits light; learn how the light then travels; and learn that two lights of equal intensity will never double...


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InvisibleHarry_Ba11sachM
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Re: The "Do Lumens Add?" debate [Re: Kine]
    #344026 - 01/09/10 02:13 PM (4 years, 3 months ago)

dude nobody is saying that increasing lumens increases the speed of light, where the hell are you getting that from?

also, your argument in that thread is a fallacy. nobody is stacking two lights on the exact same area when growing weed. sure, for stage lighting, adding two 600W lights won't equal the intensity of a 1200W light, but with growing you'll see FAR better yields with two 600W side by side rather than a 1200W trying to cover the same area.


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OfflineKine

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Re: The "Do Lumens Add?" debate [Re: Harry_Ba11sach]
    #344028 - 01/09/10 02:21 PM (4 years, 3 months ago)

Lol.. ok i give up you guys win.  Lights dont have wave lenghts; lights dont emit photons; and lights dont have to follow the laws of physics.

Im the ONLY one with any proof... yet im the one wrong?  You guys sit there and keep thinking lights add; i already understand how it works.


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Invisiblecoda


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Re: The "Do Lumens Add?" debate [Re: Kine]
    #344030 - 01/09/10 02:28 PM (4 years, 3 months ago)

Dude the link you posted in that thread is WORTHLESS, they delve into the SAME exact debate that im talking about.  Taken directly from the thread you posted.

Quote:

You need to study what you apparently do for a living. Please read this thread: http://www.rollitup.org/grow-room-design-setup/74888-1550-watts-cfl-s-13.html#post968704

There is plenty of math there for you, along with an experiment that proves conclusively that yes, lumens do add.




Quote:

Yeah. I'm sorry, but I'm tired of seeing that lumens don't add when basic physics says they do. I'm also tired of being called stupid for saying so, when it's clear from both the results on this forum and some basic math that they do ... I think if there is a place for this discussion, it's in a thread with the phrase "lumens, they don't add up".





^^ so this guy is saying physics say the DO add, so who's right?
http://www.rollitup.org/indoor-growing/83128-lumens-lux-adding-all-up.html#post968899

A link from the same thread, and even though the pictures are showing total lux output (which seems to actually be more important then lmn output), he gives you a way to convert by a forumla.

So yah, you thread proves nothing but making my point stronger.  In that EVERY thread you read on this subject you have camp A and camp B.  Even with him giving pictures and forumlas to back up his words, people still split on the subject.  THAT is exactly why I started this thread.

The car example proves nothing.


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OfflineKine

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Re: The "Do Lumens Add?" debate [Re: Harry_Ba11sach]
    #344032 - 01/09/10 02:38 PM (4 years, 3 months ago)

:malamute:  ok sure.  You guys win.  I concede. Ill leave it alone after this... Ballsach keeps referencing lux; not lumens.  And all you quoted was some guy saying he believes the opposite with no source for his info. (in my examples the guy says "This is physicis; heres the physicis and how it applies" a lot more credible then your quote)

Obv this is something thats never going to die; an no one will ever agree on.  To me, its common freaking sense!  How can two lights of the SAME intensity; double up?  It cant.  Its like taking two crayola's of the same color and coloring a square... YOUR GOING TO GET THE SAME COLOR... not a "More intense" colour...

But sure.  Lumens add and 100 CFL's is the exact same as a HID... good job; now go spread all that wrong info to everyone else to spew out.  Elementary logic and ya fucked it up... *round of applause*


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Invisiblecoda


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Re: The "Do Lumens Add?" debate [Re: coda]
    #344033 - 01/09/10 02:39 PM (4 years, 3 months ago)

The response from my sister to my last question:

Quote:

No. Total lumens increase. That's how those little LED flashlights work - it's a circle of relatively low output bulbs that create a high lumen light because they're all pointing in the same direction.

The trouble with that scenario is over distance. Output at source is higher, but falls off faster - you'll have fewer lux at the same distance as a single point source of higher initial lumen.




I think what this really boils down to is WHAT is the more important MEASURE of light.  Much like wattage doesn't mean more more light (a 200 watt cfl will not produce as much output as a 200 watt HPS), total lumen output might be relatively worthless if it's total lux which is the important factor.


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InvisibleHarry_Ba11sachM
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Re: The "Do Lumens Add?" debate [Re: Kine]
    #344035 - 01/09/10 02:42 PM (4 years, 3 months ago)

Quote:

Kine said:
Lol.. ok i give up you guys win.  Lights dont have wave lenghts; lights dont emit photons; and lights dont have to follow the laws of physics.

Im the ONLY one with any proof... yet im the one wrong?  You guys sit there and keep thinking lights add; i already understand how it works.





so let me get this right; because we don't blindly accept your word as the gospel truth we're all tards? why don't you just take the time to prove what you're saying? I'm not an idiot, I have two bachelor degrees and I'm about a year from a masters degree, all in scientific fields. I promise you I will be able to understand what you're saying to me no matter how complicated you phrase it. so lay it on, provide equations, charts whatever you need to prove your point, and if you're legitimately correct then your science will back you up and I'll believe it. and don't just link me to a thread and say "here read that," I want YOU to explain it to me since YOU are the one who's apparently so brilliant.

when people disagree with you doesn't mean that they're dumb, it means you haven't done a good enough job of explaining yourself.


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Invisiblecoda


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Re: The "Do Lumens Add?" debate [Re: coda] * 1
    #344036 - 01/09/10 02:43 PM (4 years, 3 months ago)

lastly dude this is a discussion and, honestly, you're acting like a complete fucking dickwad. 

Quote:

Its like taking two crayola's of the same color and coloring a square... YOUR GOING TO GET THE SAME COLOR... not a "More intense" colour...




Does not apply, color is not the same as light.  And actually, coloring over the same square with the same color WILL produce a more "intense" color.  Take a crayon, scribble, scribble over it, it gets darker does it not?  The more layers of color you add the darker the color it gets.  Will it change color, no, but it does saturate to the point where it becomes visibly different.


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InvisibleHarry_Ba11sachM
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Re: The "Do Lumens Add?" debate [Re: Kine]
    #344037 - 01/09/10 02:44 PM (4 years, 3 months ago)

Quote:

Kine said:
Its like taking two crayola's of the same color and coloring a square... YOUR GOING TO GET THE SAME COLOR... not a "More intense" colour...






this example is a logical fallacy because the intensity of the light source is the same. since color is merely the reflection of light then increasing pigment will obviously never increase the intensity. this example doesn't even apply to this debate because we're discussing emitted light, not reflected


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InvisibleHarry_Ba11sachM
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Re: The "Do Lumens Add?" debate [Re: Harry_Ba11sach]
    #344039 - 01/09/10 02:50 PM (4 years, 3 months ago)

so he just got mad and signed off? :lol:

interesting debate skills


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Invisiblecoda


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Re: The "Do Lumens Add?" debate [Re: Harry_Ba11sach]
    #344041 - 01/09/10 02:54 PM (4 years, 3 months ago)

Quote:

And all you quoted was some guy saying he believes the opposite with no source for his info. (in my examples the guy says "This is physicis; heres the physicis and how it applies" a lot more credible then your quote)





which is bullshit because I linked you to two threads in which he posted his experiment in.  Both with photos to a light meter, both with a formula to prove his work.  How that is not having a source for info is beyond me.

Quote:

so he just got mad and signed off?




He ran out of forum posts to quote from, which was exactly what i was trying to avoid.  Going to some random cannabis forum and pulling out posts to prove points.  Which is exactly why I asked my sister who deals with using light and specifically using different intensities of light to produce photographs.  Seeing as it's how she earns a living it would make sense to figure she knows exactly what she's talking about.

Still waiting on a response with her quote about LED flashlights.


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Offlinechucklehead
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Re: The "Do Lumens Add?" debate [Re: Harry_Ba11sach]
    #344067 - 01/09/10 03:48 PM (4 years, 3 months ago)

:bobafett:



I found this on Wikipedia.
http://en.wikipedia.org/wiki/Lux
Quote:

The lux (symbol: lx) is the SI unit of illuminance and luminous emittance. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watts per square metre, but with the power at each wavelength weighted according to the luminosity function, a standardized model of human vision brightness perception. In English, "lux" is used in both singular and plural.[1]

Lux is a derived unit based on lumen, and lumen is a derived unit based on candela.

One lux is equal to one lumen per square metre, where 4π lumens is the total luminous flux of a light source of one candela of luminous intensity:

[edit] Lux versus lumen
The difference between the lux and the lumen is that the lux takes into account the area over which the luminous flux is spread. A flux of 1,000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1,000 lux. However, the same 1,000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux.

Achieving an illuminance of 500 lux might be possible in a home kitchen with a single fluorescent light fixture with an output of 12,000 lumens. To light a factory floor with dozens of times the area of the kitchen would require dozens of such fixtures. Thus, lighting a larger area to the same level of lux requires a greater number of lumens.

[edit] Lux versus footcandle
One footcandle ≈ 10.764 lux. The footcandle (or lumen per square foot) is a non-SI unit of illuminance. Like the BTU, it is mainly only in common use in the United States, particularly in construction-related engineering and in building codes. Because lux and footcandles are different units of the same quantity, it is perfectly valid to convert footcandles to lux and vice versa.

The name "footcandle" conveys "the illuminance cast on a surface by a one-candela source one foot away." As natural as this sounds, this style of name is now frowned upon, because the dimensional formula for the unit is not foot · candela, but lumen/sq ft. Some sources do however note that the "lux" can be thought of as a "metre-candle" (i.e. the illuminance cast on a surface by a one-candela source one metre away). A source that is farther away provides less illumination than one that is close, so one lux is less illuminance than one footcandle. Since illuminance follows the inverse-square law, and since one foot = 0.3048 m, one lux = 0.30482 footcandle ≈ 1/10.764 footcandle.

In practical applications, as when measuring room illumination, it is very difficult to measure illuminance more accurately than ±10%, and for many purposes it is quite sufficient to think of one footcandle as about ten lux.

[edit] Relationship between illuminance and irradiance
Like all photometric units, the lux has a corresponding "radiometric" unit. The difference between any photometric unit and its corresponding radiometric unit is that radiometric units are based on physical power, with all wavelengths being weighted equally, while photometric units take into account the fact that the human eye's visual system is more sensitive to some wavelengths than others, and accordingly every wavelength is given a different weight. The weighting factor is known as the luminosity function.

The lux is one lumen/metre2, and the corresponding radiometric unit, which measures irradiance, is the watt/metre2. There is no single conversion factor between lux and watt/metre2; there is a different conversion factor for every wavelength, and it is not possible to make a conversion unless one knows the spectral composition of the light.

The peak of the luminosity function is at 555 nm (green); the eye's visual system is more sensitive to light of this wavelength than any other. For monochromatic light of this wavelength, the irradiance needed to make one lux is minimum, at 1.464 mW/m2. That is, one obtains 683.002 lux per W/m2 (or lumens per watt) at this wavelength. Other wavelengths of visible light produce fewer lumens per watt. The luminosity function falls to zero for wavelengths outside the visible spectrum.

For a light source with mixed wavelengths, the number of lumens per watt can be calculated by means of the luminosity function. In order to appear reasonably "white," a light source cannot consist solely of the green light to which the eye's visual photoreceptors are most sensitive, but must include a generous mixture of red and blue wavelengths to which they are much less sensitive.

This means that white (or whitish) light sources produce far fewer lumens per watt than the theoretical maximum of 683 lumens per watt. The ratio between the actual number of lumens per watt and the theoretical maximum is expressed as a percentage known as the luminous efficiency. For example, a typical incandescent light bulb has a luminous efficiency of only about 2%.

In reality, individual eyes vary slightly in their luminosity functions. However, photometric units are precisely defined and precisely measurable. They are based on an agreed-upon standard luminosity function which is based on measurements of the spectral characteristics of visual photoreception in many individual human eyes.</ref>






That led me to illuminance.
http://en.wikipedia.org/wiki/Illuminance
Quote:

In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of the intensity of the incident light, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as luminous exitance.

In SI derived units, these are both measured in lux (lx) or lumens per square metre (cd·sr·m−2). In the CGS system, the unit of illuminance is the phot. One phot is equal to 10,000 lux. The foot-candle is a non-metric unit of illuminance that is used in photography.

Illuminance was formerly often called brightness, but this leads to confusion with other uses of the word. "Brightness" should never be used for quantitative description, but only for nonquantitative references to physiological sensations and perceptions of light.

The human eye is capable of seeing somewhat more than a 2 trillion-fold range: The presence of white objects is somewhat discernible under starlight, at 5×10−5 lux, while at the bright end, it is possible to read large text at 108 lux, or about 1,000 times that of direct sunlight, although this can be very uncomfortable and cause long-lasting afterimages.[citation needed]





One more
Quote:

http://en.wikipedia.org/wiki/Luminous_flux
Luminous flux

In photometry, luminous flux or luminous power is the measure of the perceived power of light. It differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light.

[edit] Units
The SI unit of luminous flux is the lumen (lm). One lumen is defined as the luminous flux of light produced by a light source that emits one candela of luminous intensity over a solid angle of one steradian. In other systems of units, luminous flux may have units of power.

[edit] Weighting
The luminous flux accounts for the sensitivity of the eye by weighting the power at each wavelength with the luminosity function, which represents the eye's response to different wavelengths. The luminous flux is a weighted sum of the power at all wavelengths in the visible band. Light outside the visible band does not contribute. The ratio of the total luminous flux to the radiant flux is called the luminous efficacy.

[edit] Contexts
Luminous flux is often used as an objective measure of the useful power emitted by a light source, and is typically reported on the packaging for light bulbs, although it is not always prominent. Energy conscious consumers commonly compare the luminous flux of different light bulbs since it provides an estimate of the apparent amount of light the bulb will produce, and is useful when comparing the luminous efficacy of incandescent and compact fluorescent bulbs.

Luminous flux is not used to compare brightness, as this is a subjective perception which varies according to the distance from the light source.






Hopefully I understood all the terms correctly.  So here goes.

Given lumens add linearly.  Given that illuminance is measured in lux.  Given that lux is defined as lm/m2. 

Given the scenario of two identical light sources relatively close to one another such that the luminus flux from both sources strikes the same uniform fixed ammount of surface area.  Will illuminance be greater on that surface?

Sure looks like it would be.  To illustrate my thought if I have a 50 lumen light and a surface area of 1 meter square then I have 50lm/1m2 right?  So 50lux.  If I have two 50 lumen lights for a total of 100 lumens then I have 100lm/1m2.  So 100 lux.  So more illumination right?

This is complicated and I realize there are other factors like light frequency and distance to consider but if we exclude them from the argument I think my extremely simplified example works.  Oh well I'll keep reading. 

This is a good topic.


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OfflineKine

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Re: The "Do Lumens Add?" debate [Re: Harry_Ba11sach]
    #344072 - 01/09/10 04:03 PM (4 years, 3 months ago)

Quote:

Harry_Ba11sach said:
so he just got mad and signed off? :lol:

interesting debate skills




No, i dont sign on or off or periods of time.  I tab bookmark it and visit when i want.  I have enough of a life not to sit my ass here all day and chat.  I just visit when im bored... And my ubar 1337 debate skillz arent just running away.  Its knowing when to back down.  Its not i want you blindly following my statements; its how can you argue with physics and the way stuff works.  I've figured this out and talked it over with many many people with engineers degrees; electrical degrees; people taking physics class... my job allows me access to a wide variety of sources to pool and discuss with.  I've beat this horse to death; my last thread (Lux vs Lumens) brought a new term to my vocab; lux.  I now know it deals with lumens per sq meter.  Thats how it translates to "Lumens adding".

The problem is simply people assume taking 2 lights of the same lumens and putting them side by side you effectivly double your lumen output.  And thats incorrect.  Cause as soon as you go 1mm away from that bulb... you no longer have max lumen output (if you even had that at bulb ignition).  The further to you; the less you get.  When you put two bulbs together you simply decrease how much less you get as you step further away from the bulb.

Example.  You have one bulb - it produces 100 lumens.  at one inch away your output is now 50 lumens.  two inches now its 25 lumens.  Well; putting another bulb in proximity of the other bulb and of the same lumen and wattage (100 lumens) now at an inch away from the bulb your getting 75 lumens (which is actually your LUX) but this will only apply for where light over laps.  Then at two inches you get say 50.

Thats why in my other thread i was like "If lux is an measure of lumens; and lumens dont add; why can lux go up?"

Lux clearly adds.  No doubt about it... theres meters people have and you can buy for $25 to prove it.  but Lumens cant add.  Its physically impossible.  Light moves in wavelengths at different speeds.  Putting two lightbulbs of the same lumen, kelvin, watt does nothing to change the wavelength so your not getting any increase other then the light deminishes less over space.  Just like a reflector helps do the same as putting another light there.  It takes the photons shooting upwards (bulbs have 360 degrees of lighting) and points them downwards.  Thus using the light that would normally be wasted and using it as a second bulb would act...

P.S. Pulling quotes from other forums is citing that im not just pulling this out of my ass.  Its backed by other people that understand how light works in relation with physics.  Is running and asking someone else for the answer not finding sources online?  Peer to peer information transfer?  Or you want me to be like in elementary school and only cite books from the library with proper bibliography?  MLA Format?  Cause i mean; not like this is a fourm to be discussed with other people.. just like... what you dont want it to be?


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Invisiblecoda


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Re: The "Do Lumens Add?" debate [Re: Kine]
    #344082 - 01/09/10 04:23 PM (4 years, 3 months ago)

Quote:

Lux clearly adds.  No doubt about it... theres meters people have and you can buy for $25 to prove it.  but Lumens cant add.  Its physically impossible.  Light moves in wavelengths at different speeds.  Putting two lightbulbs of the same lumen, kelvin, watt does nothing to change the wavelength so your not getting any increase other then the light deminishes less over space.  Just like a reflector helps do the same as putting another light there.  It takes the photons shooting upwards (bulbs have 360 degrees of lighting) and points them downwards.  Thus using the light that would normally be wasted and using it as a second bulb would act...




And here's where you're wrong.

Quote:

Lumens don't measure photons. It's measuring perception and intensity, in relation to the human eye. It's not a matter of arguing the physics of light, it's matter of quantifying the way we can percieve it.




So you're trying to compare apples to oranges here.  You're saying this isn't true because of the way photons work, but if lumens aren't measured by photon output then your argument is invalid.  Since lumens are a measure of how we perceive light it is entirely plausible that they add up with more bulbs added.  Are you going to tell me that a room is going to be as bright with one bulb as it is with 20?  If I go in my veg cab right now and flip off one of my T-5 banks the grow area is visibly darker.  If a lumen is a measure of light intensity, well, then my light just got less intense.  If I flip it back on it becomes brighter, well, then my light just got more intense.

In the end we shouldn't be concerned with the energy released (which is what lumens measured) rather the illuminance which is how much light makes it to said object.

Quote:

The problem is simply people assume taking 2 lights of the same lumens and putting them side by side you effectivly double your lumen output.  And thats incorrect.  Cause as soon as you go 1mm away from that bulb... you no longer have max lumen output (if you even had that at bulb ignition).  The further to you; the less you get.  When you put two bulbs together you simply decrease how much less you get as you step further away from the bulb.




Well that would hold true if for even one bulb.  At the point closest to the source you would have a higher output then that of a point farther away.  Adding in more bulbs doesn't make this any more or any less true.  The lumen output would rise or fall according to distance (which is something that has already been pointed out).



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Invisiblecoda


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Re: The "Do Lumens Add?" debate [Re: coda]
    #344083 - 01/09/10 04:28 PM (4 years, 3 months ago)

Quote:

P.S. Pulling quotes from other forums is citing that im not just pulling this out of my ass.  Its backed by other people that understand how light works in relation with physics.  Is running and asking someone else for the answer not finding sources online?  Peer to peer information transfer?  Or you want me to be like in elementary school and only cite books from the library with proper bibliography?  MLA Format?  Cause i mean; not like this is a fourm to be discussed with other people.. just like... what you dont want it to be?




No, you misunderstood me.  In the very same thread you're using as a "source" there's conflicting information which invalidates the source you're using.  It's like finding a post that says "Apples are orange!" and saying it proves your point when in that very same thread there's a post that says "No, they're red" and then backs it up.  The links I posted from the thread you're using as a source provide a.)Empirical evidence of the answer and b.) provide a formula to back up the evidence.  The only thing you linked to was some guy talking about something which does not matter in the measurement of lumens or if they are cumulative or not.


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OfflineTrueHerbCrystal
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Re: The [Re: coda]
    #358603 - 02/06/10 09:12 PM (4 years, 2 months ago)

I don't much about the physics of light, but I think that both parties or "camps" are right to an extent.

It seems that both the total lumenes output would add up, but not as perfect as "50 + 50 = 100" but more like , might be 50 lumes + 50 lumes ~ near 100. This is because the lights have to be positioned next to eachother and not directly in the same spot, emitting from the exact same point source (which, according to the laws of space-time, 2 solid objects cannot occupy the same space and the same time. Also, its limited to practical issues like excessive heat, and not just space-time).

So, the total lumens amount would be less than just adding the lumens of the bulbs because of the spread of the light, since its not coming from one concentrated area, but several areas near each other.

And this makes the second party partially right, according to my logic, because since the lights are spread-out over a given area, they increase the "Footprint" or "Spread" of light over an area, so more area is lit-up with multiple bulbs than just one. I'm sure Geometry and maybe even trigonometry comes into play here, but I don't know much about that kind of math, anyone here know about the geometry of light?

I hope that makes sense. If not, feel free to argue againist it.

Addition: Just found this definition from my WordWeb program on the definition of "lumens" that seems to relate to my argument...

"lumen - a unit of luminous flux equal to the amount of light given out through a solid angle of 1 steradian by a point source of 1 candela intensity radiating uniformly in all directions" - from WordWeb computer .exe, www.wordnetweb.com

And here's the def. of "steradian", but it really doesn't say much, but it helps a little.

"steradian - The unit of solid angle adopted under the Système International d'Unités" - again, from WordWeb computer .exe.


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~ TrueHerbCrystaL ~


Edited by TrueHerbCrystal (02/06/10 09:34 PM)


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Offlinepha3r0
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Re: The [Re: TrueHerbCrystal]
    #359062 - 02/07/10 11:34 AM (4 years, 2 months ago)

Quote:

So you're trying to compare apples to oranges here.  You're saying this isn't true because of the way photons work, but if lumens aren't measured by photon output then your argument is invalid.  Since lumens are a measure of how we perceive light it is entirely plausible that they add up with more bulbs added.  Are you going to tell me that a room is going to be as bright with one bulb as it is with 20?  If I go in my veg cab right now and flip off one of my T-5 banks the grow area is visibly darker.  If a lumen is a measure of light intensity, well, then my light just got less intense.  If I flip it back on it becomes brighter, well, then my light just got more intense.





My limited understanding of the physics of light and the meaning of Lumens supports the observation you site here. Lumens are a measure of percieved light. If you move a lumen meter around your grow space you will get different readings. each bulb might be 5900 lumen but at any given point you may read more or less(assuming you have more then one bulb) this is because there is less light hitting that spot the same is true if you turn off one light and measure the same spot, unless that spot is right next to another light.

The hard thing for people to understand is that if you have 20k lumens comming from a filament the size of a golf pencil you can hit all the leaves under it with huge amounts of light(real or perceived that light has to go somewhere) if you have to use 5 CFL's spread the area that HPS is in you might have 20k total lumens and you will perceive a difference when each one is turned off or on but the plants under that are each only getting a piece of the pie. Just think the sweet spot for CFL's is what 5-10 inches? half of all the light it produces goes to the inside of the bulb first and then half of it goes up instead of down. They make a lot of light but it is not all as useable as an HID.

I know that doesn't answer the question scientifically but I think at the root of the lumen question is the CFL/HID debate. If lumens add 1+1 then the CFL fanboi's will scream victory from the roof tops. My money is on "it doesn't matter if you set up correctly and enjoy what your doing"


--------------------
"The proverb warns that, "You should not bite the hand that feeds you." But maybe you should, if it prevents you from feeding yourself."
- Thomas Szasz

"if you arent good with electricity dont go touching it...ive electrocuted myself twice...its no fun"
- mhbound


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OfflineDungenessDank
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Re: The [Re: pha3r0]
    #359065 - 02/07/10 11:43 AM (4 years, 2 months ago)

What really is important is what is the plant itself using to produce its energy. I think spectrum and coverage matters much more for marijuana than the overall light a bulb produces. How much of that light is going to waste vs how much light is the plant using.

Not to change the debate, but this MJ cultivation :rasta:


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Offlinedutc2006
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Re: The [Re: DungenessDank]
    #359069 - 02/07/10 11:57 AM (4 years, 2 months ago)

When it comes to artificial lighting, I think you could put ten 1000W HPS lights in a small closet, and you still aren't going to get results that you could from good sunlight.  So to suggest that you could have too many lights and waste light on cannabis I think is misleading.


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