Color Temps, Wavelengths, spectral distribution, oh my! (CFL, PL-L, LED, etc)

[Architechno]

I've been trying to come to a complete understanding of lighting systems and and have discovered an interesting anomaly....
We talk a lot about color temperature in K in the CFL threads, but in LED threads people talk about wavelength in nM. These are of course different ways to talk about the same thing - one more specific than the other.

Now when I look at something like the graph on page 3 of this: http://www.1000bulbs.com/images/PDF/philips-138446-specs.pdf
or page two of this: http://www.1000bulbs.com/images/PDF/ge-cinema-fluorescent-sell.pdf
It looks to me like the temperature of the bulb is an averaging of all the different wavelengths of light it produces. That looks like the graph I want to look at when bulb shopping - so I can mix and match my light peaks to get the exact light that I want!
The problem is... these two PDF's on 1000bulbs are the ONLY place I have EVER seen that graph for any CFL lighting.

So someone, please, either tell me I'm off base here and my thinking is misguided, or point me in the direction where I can find more of these charts

 

[Architechno]

bump

 

[magiccannabus]

Mixing for a wide spectrum is nice, but I would not get too hung up on making the absolutely perfect combo. A Ceramic Metal Halide will outperform any of those fluoros in the wide spectrum department any day.

Anyway, you should notice that "color temperature" is a correlated figure. Not all companies label them the same, nor do the same rated color temperature bulbs always have the same actual output color. Only monochromatic lights such as LEDs or low pressure sodium can be rated accurately with a single number like that.

 

[etinarcadiaego]

Hey man. First off color temp in Kelvin is not the same as light wavelength measured in nM, and no the K temp is not the averaging of the wavelengths . . .

Here's the Wiki on Color Temp, verbatim "The color temperature of a light source is determined by comparing its chromaticity with that of an ideal black-body radiator."

So they heat a black body radiator up until it glows a certain color . . . and they compare that to the light source and when it matches the light source is said to have the color temp measured in K of the black body radiator when the colors match . . .

The reason you're having trouble finding documented details about CFLs in terms of wavelengths is that many companies simply haven't done this kind of testing . . .

Only recently (last 10 - 15 years) have CFLs been used for horticultural reasons, and nowadays as they're gaining popularity companies are marketing this selling point. In time the research will come, but it could be a while. And even then it's been proven that some of the research is questionable, like the wavelengths readings for so-called wide-spectrum HPS bulbs. But there is little documentation of this on the web unless you're good at reading technical bulletins and the like.

In my experience the only TRULY valuable information about a light source (to plants) is it's spectroscopy or what have you, something that expresses a lights output radiation in terms of wavelengths measured in nanometers. But that still leads us to wondering how much is really known about what wavelengths plants needs the most? Is that research complete? Can we depend upon it?

The bottom line, I've seen (ACTUALLY SEEN) grows under targeted light sources that outperformed HID lights, and SEEN that self-same grow fall short . . . leading me to believe there are more important things than lights. You'll experience the best results by trying to cover each angle, light/food/ventilation rather than focusing the bulk of your efforts on a single aspect of your grow.

Hope this helps!

 

[Architechno]

gratzi to both you guys

 

[magiccannabus]

The color temperature in kelvin still has to be correlated. It's not the same measurement system, but a specific color temp does directly correspond to a specific wavelength in nanometers. That is to say, if you heated carbon in a vacuum to a specific temperature, the radiation from it would be at a specific wavelength. Most of the lights we use output spikes in different areas of the visible, infrared, and UV spectrum, and it's the averaging out of these that produces the perception of a specific color. So we have to base the comparison on human eyes mainly, because carbon at 6500K does not put out the same light as a 6500K fluoro, nor do they put out the same light as competing fluoros. There's a lot of wiggle room.

 

[etinarcadiaego]

This guy seems to sum it up pretty well . . .

Nanometric Scale - Visible Light Spectrum

The visible light spectrum is from Violet to Magenta with Green in the middle, measured in nanometers (nm). Purple is not a single colour of visible light, it is 2 colours, blue and red.

Colour Rendering Index - Not for measuring critical light for Plants

As soon as you see the picture above, know that it has nothing to do with plants, unless you are particularly concerned about what humans see, it is the root of all ignorance and "creative salesmanship". This chart is frequently used by those wishing to mislead plant growers into buying "gay & pretty looks" rather than useful radiation.

CRI rating is important when checking your clothes, especially separate tops, trousers or skirts and to ensure that the colours are not influenced by the light source, and the general "made-up" opinion of what good colour is. Anyone who knows their CRI is also well qualified to distinguish the subtle tonal differences found in navy blue blouses and dresses.

To help indicate how colors will appear under different light sources, a system was devised some years ago that mathematically compares how a light source shifts the location of eight specified pastel colors on a version of the C.I.E. color space as compared to the same colors lighted by a reference source of the same Color Temperature. If there is no change in appearance, the source in question is given a CRI of 100 by definition. From 2000K to 5000K, the reference source is the Black Body Radiator and above 5000K, it is an 'agreed upon' form of daylight.

An incandescent lamp, virtually by definition, has a Color Rendering Index (CRI) close to 100. This does not mean that an incandescent lamp is a perfect color rendering light source. It is not. It is very weak in blue, as anyone who has tried to sort out navy blues, royal blues and black under low levels of incandescent lighting could tell you. On the other hand, outdoor north sky daylight at 7500K is weak in red, so it isn't a "perfect" color rendering source either and would just ruin subtle contrasts in your Pinks, that just wont do. Yet, would you believe it, it also has a CRI of 100 by definition.

CRI is useful in specifying color if it is used within its limitations. Originally, CRI was developed to compare continuous spectrum sources whose CRI's were above 90 because below 90 it is possible to have two sources with the same CRI, but which render color very differently. At the same time, the colors lighted by sources whose CRI's differ by 5 points or more may look the same. Colors viewed under sources with line spectra such as mercury, metal halide or high pressure sodium lamps, may actually look better than their CRI would indicate. However, some exotic fluorescent lamp colors may have very high CRI's, while substantially distorting some particular object color.

Technically, CRI's can only be compared for sources that have the same Color Temperatures. However, as a general rule "The Higher The Better"; light sources with high (80-100) CRI's tend to make things look better to humans than light sources with lower CRI's.

Why still use CRI if it has so many drawbacks? It's the only internationally agreed upon color rendering system that provides some guidance. It will be still be used until the scientific community can develop a better system to describe what we really see. It is an indicator of the relative color rendering ability of a source and should only be used as such. Plants, even lady ones, are not concerned with CRI ratings.

Kelvin Scale - Not for measuring critical light for Plants
People talking about black body's and radiators ? What are they talking about? Usually they don't really know, and even more worrying , they never explain it properly.
Based upon the definitions of the Centigrade scale and the experimental evidence that absolute zero is -273.15°C, thus 373.15K is the same as 100°C. The Colour Temperature represents the colour that Carbon is when heated to that temperature. So when carbon is heated to 2000K it looks "red" hot. Carbon does not look green at any temperature, if it did, it's what we would call "white Hot". So remembering that Kelvin is used to measure an 'overall' colour, it's ok as a guide only, to differentiate between PURple and Green, Kelvin is useless.Even the Diamond & Gemstone industry has "seen the light" when it comes to Kelvin....

LUX Meters - Not for measuring critical light for Plants

In 1924, the Commission de l'Eclairage (CIE) created a standard photopic luminosity function or 'standard observer' for photometric measurements. For the human eye, an efficiency of 1 was assigned to the wavelength of 555 nanometers (nm). The logarithm of this function is the 'relative visual brightness'. Nothing to do with plants, all to do with the response of the human eye.

All LUX meters are biased, measuring power and lumens based on the phototropic curve. On the PURple chart below you can see the large phototropic curve (the green line) peaking at around 550nm. So when you put a lux meter under a green light (white & bright looking to humans) you get a massive reading on your LUX meter. The less well informed assume that lots of lumens here are good, and over look the fact that all plants reflect at least 50% of this away, which is why plants look green.

Now if you put the same LUX meter under a blue or red light, which is the same power e.g. 200w, instead of 20,000 Lumens you will measure 10,000 Lumens. The red or blue light will actually look dimmer to you, because you are a human. But in reality, the red and blue light is most useful to plants, so the lumens rating is useless for measuring useful plant light. Micro-Einstein's are a better way to measure useful light but even these measuring instruments suffer from (more linear) biasing [more]. We recommend 300 to 500 microeinsteins/square meter/second (umol/m2/s) for growing plants.

Illuminance: the luminous power incident per unit area of a surface. One lumen per square meter is one lux. One lumen per square foot is one foot-candle.

Lux: an illuminance equal to one lumen per square meter.

Lumen: by definition there are 683 lumens per watt of radiant power at a wavelength of 555 nm (wavelength for green light).

Lumens are for humans to judge and measure the brightness of mainly green light (that looks bright white to humans), which is also the the colour that plants reject the most, that's why chlorophyll is green.

Purple

Green (~550nm) for humans and plants like it blue (~450nm) and red (~660nm), with a bit of yellow to make chlorophyll. Always more than 50% of greenish light is reflected from plants and not useful.
Green Lumens are for humans, PURple is for plants

Yellow=Plant Growth White=Purple Spectrum Green=Human Senstivity

he Photosynthesis Action Spectrum is commonly accepted to be between 350 to 700 nm, thus most fluorescent lights made for domestic use emit near 100% PAR (Photosynthetically Active Radiation). Study of Photosynthetically Useful Radiation (PUR) created an evolution in nurturing light technology, applying absorption theory and combining unique techniques for preparing phosphors, the PURple nlite. PURple is generally accepted by the experienced as “the best" fluorescent plant light. nlites emit most of their light in the wavelengths that are more efficient for photosynthesis, namely the red and blue ends of the visible spectrum. As expected, because we all really like green, these light sources can look dim to the human eye and consequently have poor lumen ratings. Also, their colour temperature (K) and CRI ratings have little, if any, meaning [more]. PURple nlites were not designed to be "seen" by humans, but to efficiently stimulate plants with Photosynthetically Useful Radiation (PUR).

"why the green spike?" - Phosphor/metal prices in China are 3x more for red than blue and cost of production would increase to reduce the green spike. Also, without the green spike, the light would "look" so "dim" to humans they would not want to buy it. So, the green spike is to keep the costs competitive and make it look bright to humans.

Purple
Green (~550nm) for humans and plants like it blue (~450nm) and red (~660nm), with a bit of yellow to make chlorophyll. Always more than 50% of greenish light is reflected from plants and not useful.

Green Lumens are for humans, PURple is for plants

The Photosynthesis Action Spectrum is commonly accepted to be between 350 to 700 nm, thus most fluorescent lights made for domestic use emit near 100% PAR (Photosynthetically Active Radiation). Study of Photosynthetically Useful Radiation (PUR) created an evolution in nurturing light technology, applying A-Wave theory and combining unique techniques for preparing phosphors, the PURple nurturelite. PURple is generally accepted by the experienced as “the best" fluorescent plant light. nurturelites emit most of their light in the wavelengths that are more efficient for photosynthesis, namely the red and blue ends of the visible spectrum. As expected, because we all really like green, these light sources can look dim to the human eye and consequently have poor lumen ratings. Also, their colour temperature (K) and CRI ratings have little, if any, meaning [more]. PURple nuturelites were not designed to be "seen" by humans, but to efficiently stimulate plants with Photosynthetically Useful Radiation (PUR).

When you remove the green from the emission the light appears dimmer, but most importantly, the actual amount of Photosynthetically Useful Radiation is actually a lot higher.

Need to know why the plant growth curve is purple, mainly red and blue


Purple light
The only other lights we found designed on these principles are used by NASA and they are very expensive Light Emitting Diodes (LED) systems.

PURple for flowers in space, red & blue LEDs systems. 670 nm (red) 470 nm (blue).
By combining the absorbencies of both Chlorophyll A and Chlorophyll B and to a lesser extent the Carotenoids, a wave of Absorbency can be identified. This is the theoretical underpinning for designing the target Spectral Distribution of a PURple nurturelite Lamp. Continuous research of 21st century technology and proven practitioner findings are essential for development of products that are truly 'useful', theory alone is not enough, but nonetheless we have plenty of it!

Why is everything going PURple?
Red light is very important to plant reproduction. Photochrome pigments absorb the red and far red portions of the light spectrum and regulate seed germination, root development, tuber and bulb formation, dormancy, flowering and fruit production. Therefore, red light is essential for stimulation of flowering and fruiting.

Blue light stimulates chlorophyll production more than any other colour, encouraging thick leaves, strong stems and compact vegetative growth. excellent for plants cropped before flowering stage, such as lettuce and cress.

Carotenoids, the yellow-orange pigment in plants, absorb blue light and control leaf fall and fruit ripening. Although over 50% of green light can be reflected away by the plant, carotenoids are able make very good use of blue/green light. The Carotenoids and Chlorophyll A molecules transfer their electronic excitation energy to Chlorophyll B molecules, leading to the production of chemical energy. Riboflavin, containing another pigment, absorbs violet light and influences phototropism, consequently directional growth and movement in the foliage of the plant. The plant canopy will be more capable of efficiently positioning itself for the absorbance of photosynthetically useful radiation (PUR). Another benefit is possible, many believe that Near UV light, at the correct wavelength, is highly beneficial for flowering, it can enhance their appearance and fragrance, also producing higher quality fruit."
Basil Growers use PURple for maximum trichomes and maximum resin - essential oils

3-Dimensional Lighting for plants - The nlite Sabre is pioneering the next generation of fluorescent light application. Finally, the place for fluorescent lighting to be most effective for plants can be reached. Now you can safely hang the power of PURple right in amongst your plants and pets. The photoponic effect exceeds all other lighting for plants we have ever tried and we are very excited about our initial results. The unique poly carbonate sabre sheaf distributes the heat for safe operation, surface temperature is below 25C, plants can grow round and up the sabre using it as support.

There ya go!!! Hope this answers some questions and helps with choosing light for new growers or those that are looking to switch but haven't seen good reasons to do so, enjoy.....