Looking for neutral colour T8 tubes

Check out the pinned thread at the top of this lighting forum...

The same principles apply to T8.

 

Hi,
The real question is; What is neutral? Every light bulb has a color so if it isn't red or yellow it will be green or blue. The folks that don't like pink/yellow light merely consider the green/blue lights more pleasant and call that "neutral". Furthermore, green plants will cause green reflections so this concept of "neutral" is an illusion.

All bulbs are suitable for the planted tank. Plants don't care about CRI, and they certainly don't care about neutrality, that's for sure.

Cheer,

 

Well, yes I understand perfectly what you're getting but this is also an illusion. Let me explain why I'm being so obstinate.

In the morning the sun rises over the horizon. Think about what color the sky is at dawn....red and yellow. Well, that's the color the plants see and get colored by. As the sun rises higher in the sky the reds and yellows get filtered and the blues dominate. In fact blue is so overwhelmingly dominant during the brightest part of the day that our eyes have to filter out blue. Our brains have very poor blue sensitivity. That's why in a dark room with blue light it seems dim to us and we have difficulty with acuity in this light. Have you ever seen a video taken outdoors by a so-so videocam? Doesn't it look harsh with the colors washed out? Well that's the closest thing you'll see to neutral, and the truth is that it's far from neutral because of the massive levels of blue. Cinematically, when you see a movie, the reason the colors look so "natural" on film is that the photographers add filters to the lenses, or the film is processed remove the blue and to restore the other colors. This is part of the problem with color balance in photography.

Plants love blue because it has very high energy. In fact blue/violet light has about the highest energy levels of any frequency light that we can see. Our eyes also have very poor red sensitivity. Think about how dim a darkroom with red light seems. On the other hand our eyes have extreme green sensitivity so if a light has green in it then it will seem relatively bright to us. That's why most fluorescent light bulbs are very high in green, because it's very effective for us. An incandescent light bulb has mostly reds and yellows so they seem dimmer and less "clean" than a nice "fresh" fluorescent bulb.

When you view your world you are perceiving it through a very specialized filter called the visual cortex. This filter strongly affects your perception of the world. If you are in a room lit with incandescent bulbs the room doesn't seem yellow does it? When you are in a room lit by fluorescent bulbs it doesn't seem green at all. The brain filters these colors out for you so if you look at a white piece of paper it looks white not yellow or green even though it is being lit by those colors. Plants do not share this filter and they absorb/reflect whatever light energy is available. I have kept plants under natural daylight. In the morning they look dim and boring. At high noon the tank looks bright and washed out because of the overwhelming blue. So the idea that somehow one needs a bulb that reproduces natural sunlight is actually quite absurd because first of all no such bulb exists and secondly the spectral quality of sunlight is affected by the time of day in which the combination of atmosphere plus the the sun's position filters the light that reaches the surface of the planet. The best that can be done to simulate daylight in a bulb is to put lots of blue in it and to make sure that it overwhelms whatever yellow red and green light it produces.

Therefore there is no "natural" or "neutral" because not only does the color changes throughout the day, but your eyes deceive you as to what these colors actually looks like anyway.

What seems apparent is that you simply don't like look of the pink bulbs. That's normal, and I agree that if there are too many of them they make the tank look eerie, but this is a much more realistic approach than to concentrate on neutrality, which isn't really appropriate. To cancel out the effect of the overabundance of pink one merely has to use a bulb that has more blue and/or green tones to balance out the "look". Any so-called "daylight" bulb or bulb of high Kelvin rating will do the trick. Also interesting to note is that pink bulbs will do a better job of showing the red in red plants and fish. If there is enough of the other bulb colors this will hide the eeriness but the red component will still be there but will be masked in the overall look.

Here is an example of the a plant lit under "daylight" and blue bulbs alone.


Here is the very same plant with a pink bulb added. Although the overall look did not change dramatically the plant itself seemed to "pop" with better colors. I guess what I am trying to say in a long winded fashion is that trying to achieve neutrality in colors ought not to be the goal. The goal ought to be more about what colors you like to see in the tank. The plants don't care but the viewer will respond emotionally to the colors regardless of neutrality.



Cheers,

 

Well, the Kelvin ratings on bulbs sold are so totally screwed up that they have become meaningless. An electronic camera flash is in the region of 6000K and so this is called "daylight". 3.5 foot is an oddball length and the only color I can see on the Lampspec site is "White 35" which I have no idea what that actually looks like. The only thing I can tell you is that the particular brand of phosphor coating they refer to, Halophosphate is the older style phosphor coating used in the typical office building tubes and is considered harsh and unpleasant because it emits lots of yellow and blue but very little red and green. As a result the CRI (Color Rendering Index) is low but so what? CRI is flattering if you are looking at human flesh which is pink and want to reproduce that. It's completely meaningless if you are looking at something that already has lots of green.

Since I can't see the world through your eyes I can't say "yeah get these, they'll look fantastic" but I guess that they are the opposite of those spooky pink bulbs, so might cancel some of the effects of the pink. They are also super cheap so at least if you're disappointed in them it won't be too much of a loss (except for shipping/insurance of course).


Cheers,

 

Yeah, like I said the entire color temperature game is screwed up so I wouldn't be surprised at whatever color shows up in the post to tell you the truth. :? But remember JamesC's post Cheap HO T5 fluorescent tubes - Update with photos and the ones you show the link to are the Osram 840 which is shown as the second photo from the top. I've very familiar with the 840 because I use them a lot. They have an orange tint so I don't think you want to go there...

Cheers,

 

Well, parameters such as CRI Kelvin temperature and even Lumens are completely worthless statistics for our purposes because they do not address the way in which plants use light energy. What these parameters do is they describe in objective terms how the light correlates to the way the human visual cortex perceives and interprets the world.

Kelvin rating and CRI are also not directly related. The Kelvin temperature of the bulb merely describes the way in which a theoretical "black body" would glow based on the amount of heat being absorbed and reflected by that object. For example imagine a block of steel in a foundry. It's probably easy to imagine that as you heat that block of steel the color at which it glows would change depending on how hot it is. In "black body" radiation lower temperatures radiate reddish and higher temperatures radiate more blueish . Medium temperatures would make the black body radiate yellowish.

This has little to do with, or is only indirectly related to Color Rendering Index which is a parameter that is more concerned with color fidelity. CRI is more useful in photography. In the example I gave in a previous post, lets say a blade of grass is green and that it reflects light at a specific wavelength, say 500 nanometers. If perfectly white light is shone against this grass then 500 nm wavelength is reflected and the grass can be perceived as that color. If reddish light is shone against the grass the reflected color will be a combination of 500nm plus higher wavelengths, say 600nm for arguments sake. Therefore when we look at the image, the composite color that we perceive the grass to be will be corrupted by the reflected 600nm red light. In making a bulb with high CRI the bulb manufacturer is attempting to add enough of other colors to the bulb's radiation that when shone against an object the native reflection wavelengths of that object being is not corrupted by the basic wavelength of the bulb. So in photography we sometimes want to capture the native wavelengths that our objects reflect. In a studio, if I'm taking a picture of a blonde person I want to capture that hair color, and if my flash is too red, the blonde hair color will be corrupted. So my flash needs to have a high CRI.

When we look at a lawn at high noon, much of the reflections are of blue light because full daylight has so much blue. But we know that a lawn is green so our visual cortex communicates with other parts of our cerebrum to filter out much of the blue - so the lawn is perceived as bright green. This combination of lighting plus cerebral manipulation, because it's so prevalent and overwhelming, then becomes the standard by which we judge all other lighting and is therefore called "neutral". Any light that subsequently reproduces or simulates this optical illusion is also judged to be "neutral" or natural. As a result, daylight at high noon has become our reference even though it's harsh and ugly.

Neither of these parameters have anything to do with the way plants use light energy. Plants can use any color light and they have mechanisms to reject harmful wavelengths such as UV. As long as the radiation is in the visible spectrum it can be used. Neither color temperature nor CRI has any effect on the plants and furthermore, neither of these parameters can tell us how pretty we as individuals will perceive the colors reflected in the tank.

There are a lot of myths out there about how blue wavelengths cause algae and how certain Kelvin temperature bulbs are more ideal than others. This is all complete rubbish. Vendors perpetuate these myths in order to program the population so that they can charge 30 quid for a light bulb. Now, certainly there are bulb phosphor formulations which produce wavelength combinations that many people find more pleasing than others. If one chooses to purchase these bulbs at a higher price based on aesthetics then that's fine, but we should be fully aware that we are paying money for something that pleases us, not because we are being duped into thinking that we are paying 30 quid because the bulbs are somehow "ideal" for plant growth. A 2 quid bulb from Tesco will grow the plant just as well but may not "look" as nice. 8)

Cheers,

 

Haha easy, just light your entire world with those goofy pink bulbs and your central processing unit will make pink disappear. 8)

Now do you see what a mess was created by the marketing departments of bulb vendors :?: I reckon it's just a matter of trying a lot of different bulbs to see what combinations you like the best. Glad you found something that works for you!

Cheers,