Anyone Thinking of Dumping LEDS and going back to Halides

oreo57 said:
that is just wrong...
blueLED.jpg


White LED's are nothing but phosphor doped blue led's........and this is cheap.
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Not exactly accurate . . .



White light

There are two primary ways of producing white light-emitting diodes (WLEDs), LEDs that generate high-intensity white light. One is to use individual LEDs that emit three primary colors—red, green, and blue—and then mix all the colors to form white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works.

There are three main methods of mixing colors to produce white light from an LED:

blue LED + green LED + red LED (color mixing; can be used as backlighting for displays)
near-UV or UV LED + RGB phosphor (an LED producing light with a wavelength shorter than blue's is used to excite an RGB phosphor)
blue LED + yellow phosphor (two complementary colors combine to form white light; more efficient than first two methods and more commonly used)[90]

Because of metamerism, it is possible to have quite different spectra that appear white. However, the appearance of objects illuminated by that light may vary as the spectrum varies
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JPMagyar said:
Not exactly accurate . . .
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You are splitting hairs. When people counter your argument about LEDs not having a spectrum and discuss white LEDs, it's clearly phosphor-converted (pc) blues they are discussing. And they do have "spectrum" and yes, it's achieved with a coating not unlike fluorescent bulbs. But the net result is light with "spectrum". And yes, there are other ways to make "white" from LEDs (e.g., ocean coral white or RB + pc amber) that won't provide as "full" a spectrum.
 
JPMagyar said:
If you have a friend in a physics department who has access to the right equipment ask him or her to plot the photon flux of individual wavelengths for one single LED, not one CREE LED but one individual P/N junction.
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I'm not sure the point of this argument. It's the output that matters, not the components prior to being run through a phosphor coating. Your suggestion is akin to saying we should look at T5 bulbs with the coatings removed and use that to determine whether T5 bulbs are adequate for lighting.

You've said many times that LEDs don't have "spectrum". They do. Yes, it comes from a coating, but why does that matter to the output?

I don't need expensive equipment to tell me that corals grow better under today's metal halide and T5 fixtures.
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I agree with you 100%. As I said before, I'm not pro-LED and I'm switching my tank from T5/LED to MH/T5. And your tank is amazing and makes mine look like my 2-year old set it up. But LEDs do have "spectrum"...
 
175mhlamp.jpg


not very natural, but probably reproducible, within limits, w/ current LED tech. WHY someone would want something so un-natural though.. ;)

As was said "photons are photons" regardless if they come from phosphor emissions, Mercury bands, or whatever..

There is no "magic" light.. just combinations..

electrospectruminwater.jpg


Metal halide is the exact same "collection of narrow emission spikes" as is any large collection of monochromatic LED. White LED's can be looked at as combining MH like technology (but one spike instead of 1/2 dozen or so) w/ T5 "phosphors"..Photosynthesis uses a "broad band" approach to bandwidth use..
 
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Was the Radium bulb an accident? What I mean is, was the intent to create a bluer 20K bulb and the result just happened to work as well as it does? It looks extremely white to me with blue overtones, certainly not 20K.
 
markalot said:
Was the Radium bulb an accident? What I mean is, was the intent to create a bluer 20K bulb and the result just happened to work as well as it does? It looks extremely white to me with blue overtones, certainly not 20K.
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I would agree. Especially run at the wattage they are intended.
 
markalot said:
Was the Radium bulb an accident? What I mean is, was the intent to create a bluer 20K bulb and the result just happened to work as well as it does? It looks extremely white to me with blue overtones, certainly not 20K.
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It is my understanding it was created as a blue (ish) bulb to light exterior walls of buildings, and it so happens to be a great aquarium bulb as well.
 
for lazy readers...
rad.jpg

For some odd reason my browser doesn't always show certain images. If this chart is seen twice.. My apologies.
Wasn't in my first look at the orig. post..
 
JPMagyar said:
Not exactly accurate . . .
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It appears that some folks may have missed your point... So I will rehash.

White that is derived from mixing RGB has nothing to do with real white light. You ca get "white" from 3 spectral peaks that have zero ability to drive photosynthesis... It is not WHITE your brain just interprets it that way...

There is so much bad information in this thread that I would not even begin to know how to correct it.

Somebody said that a pile of LEDs are pretty much the same as a MH bulb... Just a bit different with regard to peaks...um no, not even close. A MH bulb emits light from a plasma arc, it by definition is continuous spectrum. It may have peaks, but there are no gaps in wavelengths. A pile of LEDs emits a very narrow pile of peaks with gaps in between.

Phoshpors? T5 and LED... Again worlds apart. The fluorscent bulb uses a mercury arc to create UV light. The UV drives the phosphor stokes shift. The same phosphors can not be used for LEDs because of the input wavelength difference. Decades of research went into FL phosphors. White light was a priority, as there is no way to create a reasonable RGB FL bulb to produce white light. In the LED world things are different. Read on....

I will say it again, almost everything we use in this hobby is a direct purchase from industrial stock. While white led phosphors are getting better, there is little drive for better white rendering when it is easier to build an RBG emitter that can be tuned to emit whatever pleasing color is wanted. The RGB emitter combo does solves the color rendering issue for humans, but is (again) devoid of much the spectral content required for photosynthesis. Not sure why so many folks are having trouble swallowing the reality... Until there is an industrial demand for LEDs with broad spectrum phosphors... There will be no LEDs with broad spectrum phosphors. Agricultural applications got their uv and deep reds, they don't really need whites, as they are looking for growth, not aesthetics and growth. Nobody in industry cares about my or your aquarium :)
 
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It's so smooth because they aren't showing the gaps. Compare it to sunlight, you'll notice that the colors are in completely different places. The entire right third of the LED plot is red with a little bit of orange. The same colors take up 1/10th of the plot on sunlight. Most colors other than RBG are mostly or totally absent on that LED plot, they just put the colors together in such a way as to make it look smooth.

In short, yes, they lied.

The second link also seems to only show RBG LEDs, unless I'm missing something.
 
BeanAnimal said:
It appears that some folks may have missed your point... So I will rehash.

White that is derived from mixing RGB has nothing to do with real white light. You ca get "white" from 3 spectral peaks that have zero ability to drive photosynthesis... It is not WHITE your brain just interprets it that way...

There is so much bad information in this thread that I would not even begin to know how to correct it.

Somebody said that a pile of LEDs are pretty much the same as a MH bulb... Just a bit different with regard to peaks...um no, not even close. A MH bulb emits light from a plasma arc, it by definition is continuous spectrum. It may have peaks, but there are no gaps in wavelengths. A pile of LEDs emits a very narrow pile of peaks with gaps in between.

Phoshpors? T5 and LED... Again worlds apart. The fluorscent bulb uses a mercury arc to create UV light. The UV drives the phosphor stokes shift. The same phosphors can not be used for LEDs because of the input wavelength difference. Decades of research went into FL phosphors. White light was a priority, as there is no way to create a reasonable RGB FL bulb to produce white light. In the LED world things are different. Read on....

I will say it again, almost everything we use in this hobby is a direct purchase from industrial stock. While white led phosphors are getting better, there is little drive for better white rendering when it is easier to build an RBG emitter that can be tuned to emit whatever pleasing color is wanted. The RGB emitter combo does solves the color rendering issue for humans, but is (again) devoid of much the spectral content required for photosynthesis. Not sure why so many folks are having trouble swallowing the reality... Until there is an industrial demand for LEDs with broad spectrum phosphors... There will be no LEDs with broad spectrum phosphors. Agricultural applications got their uv and deep reds, they don't really need whites, as they are looking for growth, not aesthetics and growth. Nobody in industry cares about my or your aquarium :)
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There was nothing wrong w/ my statements, just your interpretaTION..

and nobody would use rgb Led's as a white LED substitute (correction for clarity RGB produces white but is really relegated to novelty lighting, oh and TV rct. HOPEFULLY you get my drift)........ Not even part of this conversation really..

Many industries ie display companies, marketing, photograpy "need" high CRI broad spectrum LED's
Your not paying attention..........
http://www.yujiintl.com/high-cri-led-lighting
 
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GroktheCube said:
It's so smooth because they aren't showing the gaps. Compare it to sunlight, you'll notice that the colors are in completely different places. The entire right third of the LED plot is red with a little bit of orange. The same colors take up 1/10th of the plot on sunlight. Most colors other than RBG are mostly or totally absent on that LED plot, they just put the colors together in such a way as to make it look smooth.

In short, yes, they lied.

The second link also seems to only show RBG LEDs, unless I'm missing something.
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Independent verification of what you believe is impossible.. ;)

mag3aa1.gif

This web page will be for nothing but spectra of high-powered white LEDs.

Ocean Optics USB2000 Spectrometer donated by P.L.
As of 10-10-07, I've been using a PC2000-ISA Spectrometer from Ocean Optics that I received several years ago, but that I didn't have a home for until now.
As of 03-08-08, I once again have the USB2000 spectrometer, enabling color spectra again.
As of 09-19-09, I no longer have the PC2000-ISA; it was sold to prevent an eviction
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http://ledmuseum.candlepower.us/specx02.htm

In case you are wondering I'm sure some "smoothing" is applied but NOT what you seem to believe. Surely a real white (blue plus phosphor) spectrum exists to prove your point.. or is
it a global conspiracy??

http://www.digikey.com/en/articles/...-considerations-for-white-led-color-rendering


TZL111_Spectral_Design_Fig_10ab.jpg

Everyone recovering form 420 or what..???
 
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I was talking specifically about that one post. Phosphor coated LEDs can absolutely produce a broad spectrum. Just need someone to tinker up the right mix of phosphors to match the popular T5 tubes, and you're in good shape, at least in terms of spectrum.

The post I was responding to linked to a page using RGB LEDs and trying to pass them off as broad spectrum.
 
GroktheCube said:
I was talking specifically about that one post. Phosphor coated LEDs can absolutely produce a broad spectrum. Just need someone to tinker up the right mix of phosphors to match the popular T5 tubes, and you're in good shape, at least in terms of spectrum.

The post I was responding to linked to a page using RGB LEDs and trying to pass them off as broad spectrum.
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Nah, that's just a hobbiest page testing different lamps, including a reveal lamp and exposing the fact they are not broad spectrum.
 
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