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kelvin, light & color temp

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kelvin, light & color temp
Old 10-05-2012, 07:44 PM   #21
 
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this shows the variable rates of attenuation of the different wavelengths

all visible light wavelengths reach to about 20 feet in saltwater, even if it is the case that is was only half as far in freshwater, for instance, that would mean in two or three feet only an insignifican amount would be lost

Last edited by Quantum; 10-05-2012 at 07:48 PM..
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Old 10-05-2012, 07:55 PM   #22
 
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incandescence is the emission of light due to temp - not limited to household lighting

this is not to be confused with exothermic chemical reations that emit light
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Old 10-05-2012, 07:57 PM   #23
 
and for the sun which it appears that the whole kelvin scale black body radiator is trying to mimick


our cheap house lights don't mimic the hypothesised Kelvin all too well


the kelvin rating for lighting is too theoretical, it's too "it appears right to the human eye" but the real world uses more than just a high green light
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Old 10-05-2012, 08:14 PM   #24
 
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yes, the surface of our sun is about 6000 K, which corresponds to the emission of white light, hotter stars will emit shorter wavelength light, cooler ones will emit longer wavelength light

Kelvin, when applied to fluorescent lighting is not completely useless, just not exact, and often the only info available to determine what light is emitted

edit: just noticed that the x-axes on the above graphs extend beyond visible light, here we are talking about visible light, the spectral curves within the visible portion of the EM spectrum are mostly linear

Last edited by Quantum; 10-05-2012 at 08:20 PM..
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Old 10-05-2012, 08:21 PM   #25
 
Quantum, this would really extend into chemistry, physics & astronomy to really gain an understanding of what is going on.

for floresent lighting it's an electrical arc inside the tube that gives off photons that charge the phosophorous to produce the desired light spectrum output.

it's not as simple as "Kelvin", kelvin over simplifies things and allows marketing to push merchandise and products that do not preform but do comply to the desired "kelvin" you seek

if i remember correctly a High pressure Mercury light has an insane light output that can't be beat or matched, ... of a very specific yellow light spectrum that plants would go blind with, but to our eyes it's insanely bright.

if you want to say Kelvin is an accurate understanding of light spectrum, ... i can also sell you a box of dehydrated water, just add water.

your right the clorophyll absorbtion rate is different from it's photochemical efficiency, ... but it follows the same general curve, high in blue, negligable green, high in red, and a few spikes in there in the blues and red (and a single orange)

but that's not kelvin, kelvin is a mix to appearnces, the same as the old CRT TV's and monitors that can mimic millions of colors based on 3 basic phosophors, how much red, how much green, how much blue, ... low equal amounts and you get a dark grey, high equal amounts and you get bright white, equal red & green and you get yellow, ... but there is no yellow or white phosphor.

just like in the visible part of the electromagnetic spectrum there is no white, yet 5500-6500k appears very white to us.

much like the eye retina, we've got rods and cones (i don't remember what does what, but), one picks up grey scale, shades of light, but no color. the other picks up color by 3 types of cells specializing in red, blue and green pickup, and from that we can see millions of colors, and none of them are "white" but we recognize white very well, just like every other color we see.

if your stuck on wanting to believe kelvin is some absolute understanding of what composes and makes 3500 different from 6500, different from 10,000 or any other supposed hypothetical spectrum we are sold, ... so be it, ... can't change your mind, and clearly asking you to do some research isn't helping your understanding or desire to understand why.
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Old 10-05-2012, 08:43 PM   #26
 
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Quote:
for floresent lighting it's an electrical arc inside the tube that gives off photons that charge the phosophorous to produce the desired light spectrum output
electrical current passing through Argon gas forms a plasma, which causes Mercury also present to emit photons at UV wavelengths, these UV photons are absorbed by phosphors coating the inside of the glass, which then emit photons at longer wavelengths (visible light)- fluorescence

Quote:
if you want to say Kelvin is an accurate understanding of light spectrum
I didn't say this, the opposite in fact, didn't you say it in an earlier post?

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your right the clorophyll absorbtion rate is different from it's photochemical efficiency, ... but it follows the same general curve, high in blue, negligable green, high in red, and a few spikes in there in the blues and red (and a single orange)
that is not my point, photosynthesis is not the only photochemical process governing plant physiology, green light is not wasted, evolution does not work that way

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but that's not kelvin, kelvin is a mix to appearnces, the same as the old CRT TV's and monitors that can mimic millions of colors based on 3 basic phosophors, how much red, how much green, how much blue, ... low equal amounts and you get a dark grey, high equal amounts and you get bright white, equal red & green and you get yellow, ... but there is no yellow or white phosphor
which is why Kelvin numbers can be useful in estimating spectral output, a roughly equal mix of red, green, blue will produce a white light, which approximates a 6000K incandescent source, a higher K rating will indicate relatively less red/more blue

Quote:
if your stuck on wanting to believe kelvin is some absolute understanding of what composes and makes 3500 different from 6500, different from 10,000 or any other supposed hypothetical spectrum we are sold, ... so be it, ... can't change your mind, and clearly asking you to do some research isn't helping your understanding or desire to understand why
again, I never said this, you did
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Old 10-05-2012, 08:51 PM   #27
 
actually, plants appear green because they do not use green, they reflect it.

more specifically it's a yellow orange it reflects almost totaly, a blue green & red it aborbs quite completely, a deeper green/blue & deeper red it reflects again (the spikes on this are not as great but quite significant, then as it trails out from these two spikes it tapers into absorbing more.

but yes there are significan "reflection" and unused parts of the spectrum
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Old 10-05-2012, 08:58 PM   #28
 
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so that I can get it through my thick skull: from the above post I am to understand that green is yellow orange, and not green, and plants reflect green light, but also absorb it quite completely
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Old 10-05-2012, 09:48 PM   #29
 
absobtion


relection


photosynthetic response curve


photosynthesis action


photosynthesis absorbance

LED grow lighting


now if it uses green, wouldn't the LED light shown above kill your plants ??
don't give up, just do more research

like incandescance vs sun and kelvin
kelvin & chemisrty, biology, physics
color spectrum, visible light, & the electromagnetic spectrum
phosphorous types, energy convertions, psychology of color

you've got your phosphorous down, i, personaly, would never trust you on the rest of your knowledge

for the last month i've been looking online most every day about lighting for aquariums, first i found the basic 2watts per gallon rule, and i looked farther and found spectums and looked farther and found tthere are no 2 lights alike, each supposedly same spectrum (based on kelvin) is quite different, but they appear the same, i looked farther and found the whole kelvin & watts-per-gallon rule are archaic and a bad judge, sure they were good 50 years ago (guessing the timeline), everyone kept mentioning there have been advances in aquarium lighting, and there are differences in aquarium lighting, and how each difference is at times just marketing to appear bright, to qualify for a kelvin color rating while the spectrum could be drastically different. still i looked farther
and the human eye is really sensitive in the middle of the spectrum, while plants not so much, there are guesses that this is evolutionary, if we look at insects they see more towards the UV spectrum, and can see things our eyes cannot on plants.

it gets really hard when all you want is to find out "how much light do i want", because i could find out the 2watts-per-gallon rule, then find out this is based on 3500k, T12 lighting, that advances in technology push the 2watts per gallon into archaic history, so then i search as to why, what's the difference. ... instead i find all kinds of information that says we can't trust the 2 watts per gallon rule anymore.

more complex formulas based on Lux & lumens based on the equatorial clear summer day at 120,000 lumens, then compaire the footprint of your tank with watts per gallon, multiply the lumens your light is putting out, ... wait lumens counts for what's visible to the human eye, so more research.

trying to find lighting, how much is enough, how much is too much (yes there is such a thing as too much) and these numbers are not consistant, what is "enough" for one plant will starve another and a third will burn

adding additional heat can improve the intensitiy the light is capable of handling, adding CO2 can improve it as well, and in all areas there is a "too much"

but don't stop there, figure out where this PAR and PUR is from, try to find some measure of how this is measured, ... that's a really good question, because the only people that seem to care about selling PAR are selling LED, floresent is selling Kelvin

LED & PAR don't really look at PUR because that can screw their sales as it relates to what the plant uses instead of just what the plant responds to

Florescent & kelvin try to avoid the actual spectrum, most significantly PAR values because they need sales, ... and it's really hard to sell a light the buyers can't see anything (see above pic)

but don't stop researching, don't ever think you have enough, because clearly you don't, you have kelvin and phosphores, but you don't have spectrum, you don't have photosynthetic action, responce, reflection. you don't seem to display that kelvin (according to the black body radiation) is literally never ever seen in any artificial light, and no creature on earth has a clear equal response right across the board.

how our theoretical Kelvin rating does not list a spectrum
and the color spectrum of our sun, a little yellow star is based on the photon emitions of a half-dozen elements who's individual spectrums are mapped and they are found to be consistant with simular stars in space, ... exactly one of the ways we measure what kind of star we are looking at in space (red-shift aside)

so please somewhere the specifics of what words you used or what words i used, ... i don't really care, from what your saying it just sounds like what you know is very surface without any deeper understanding of what makes up what your talking about.

so please, just do more research, just saying you've got a thick skull kinda is a statement of limitation, your only as limited as you let yourself become.

and yes, this got way off topic.
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Old 10-05-2012, 10:21 PM   #30
 
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are you so damned stupid that you don't realize my sarcasm was to point out the nonsense you had typed in the previous post?

again, you are fixated on chlorophyll and photosynthesis, is that all plants do? and when did I say lack of green light would kill plants?

what is hypothetical or theoretical about Kelvin? A body at a certain temp will emit light of a certain spectral distribution. Tungsten filament bulbs don't 'mimic' Kelvin just as they don't mimic Fahrenheit, they either are or are not a certain temperature and what temp they are will determine what light they emit

at this point, I really don't know what the hell you are trying to say about K, as evidenced by such brilliance as this:
Quote:
Florescent & kelvin try to avoid the actual spectrum
edit: I've said all I will on this thread, continue to bark at the moon if you wish
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