One of the important features of light is the way it allows us to accurately perceive colors. To explain this, we'll touch briefly on why we see things in color.
Visible light from the sun contains all the wavelengths that our brains interpret as color. Initially we would perceive this as pure white light; but when this light strikes an object, that object may absorb certain wavelengths and reflect others. We only receive and interpret the wavelengths that are reflected toward us. So if a flower absorbs several wavelengths but reflects a wavelength that we interpret as red, we would call that a red flower.
Now imagine that same flower was only lit with a light that lacked "red" wavelengths. (Those that we see as red.) In this case, the flower couldn't reflect red toward us, so if we could see the flower, it would look black to us.
This is a simple example and represents a perfect scenario, but it tells us enough to talk about LEDs, color rendering, and an LED comparison with incandescent bulbs.
Since sunlight includes all the wavelengths we need for accurately seeing a color, it is given a 100 rating on the CRI scale. This same rating is given to incandescent and halogen bulbs, which also provide all wavelengths of light. But according to this chart from "Popular Mechanics," incandescent bulbs emphasize red and orange wavelengths over blues and greens.
Compare this on the chart with the color wavelengths produced by compact fluorescent (CFL) and LED light bulbs. CFLs are a hit and miss on all sorts of colors while LEDs emphasize deep blue and green wavelengths even more so than incandescents, though they have less in the way of red wavelengths.
(We should note that any specific bulb may show up differently on a chart like this.)
Still, this doesn't mean that other wavelengths are completely lacking in either CFLs or LEDs, but that we would be able to perceive some colors better or worse in comparison with other types of bulbs.
The traditional Color Rendering Index (CRI) is supposed to tell us how well a light source will let us perceive colors. And this index rates CFLs and LEDs well below the 100 rating of incandescent bulbs, usually in the low 80s. (Specific bulbs, however, are designed for a high CRI rating.) At a glance, this suggests that you'll most accurately see objects under incandescent lighting, and in that sense, incandescents are superior.
But clearly, when you look at the color chart above, CFLs could theoretically render certain colors very well; and LEDs, with a smooth color curve of their own, should render most colors very nicely, surpassing incandescents on greens and blues. And this is exactly why the lighting industry is now working on a new way of measuring color rendering.
HOW WE RAN OUR TEST
We did our own test to demonstrate LED lights against incandescent lights. The test looked at colored candies in a room with overhead lights turned off. The only lighting source was a single light bulb -- either incandescent or LED (two types were tested). We used a 60 watt incandescent and LEDs that are designed to replace 60 watt incandescents. The camera was set to not adjust the image and the flash was not used, so these images only represent how the colors appeared under the respective light bulbs.
Please note that we have shown the same incandescent image twice so you can more easily compare that to the LED bulbs we tested.
The Philips "Warm Glow" bulb is one that actually gets warmer (in color temperature, not in actual heat) when you dim it. This mimics the effect of a dimmed incandescent bulb.
WHAT WE SEE IN THE PICTURES
To our eyes, while rendering the background (table) with a little less red, the warm glow bulb provides a similar lighting level to the incandescent. It also seems to render colors almost identically in the candies. If we're to get really picky about it, we feel that the greens, yellows, and oranges are slightly more vivid under the warm glow light, while the reds have the edge under the incandescent.
Meanwhile, comparing the TCP LED, we feel the TCP is overall brighter so this may give us the sense of more vivid colors. That said, this time we perceive the blues, yellows, greens, and oranges to all be more vivid under the LED, while again the slight edge in red goes to the incandenscent.
Based on the color curves shown above, it absolutely makes sense that the incandescent would render reds better while the other colors might do better under LED lighting. That's what we're experiencing.
In any case, you may see what a subtle difference this is, and why the traditional CRI model doesn't make a lot of sense when buying LEDs. These bulbs do provide us with an excellent sense of color, and may be superior in some ways.
So what are your eyes telling you? We'd love your feedback as to which light you think provides the best image of these candies.
A lot of people are passionate about their plants, and they get an early start on the season by growing seedlings indoors when outdoor temperatures are still low. Many of these people look to 6500K CFLs as their solution.
We thought we'd take a moment to explain light bulbs used for growing plants; to mention what options you have besides CFLs; and to showcase our own selection of 6500K CFLs.
Traditional wisdom in regards to light and plant growth is that cooler color temperatures (more blue wavelengths) assist with seedling growth while warmer color temperatures (more red wavelengths) help with the flowering process.
Based on this, if you're planning to move your plants outdoors when the weather warms, you can focus on lamps (lights) that emphasize blue wavelengths. That means lamps with color temperatures of 5000K or up, and especially 6500K lamps.
What many people don't realize is that even these lamps will have some of the warmer colors (red wavelengths) within their light, and may still help plants with flowering. However, those who grow plants from seed to flower indoors typically recommend full spectrum lamps or a mixture of high and low color temperature bulbs. (Full spectrum and "grow" lights are fairly expensive, though, and people have plenty of success by mixing color temperatures to create their own "full spectrum" effect.) Based on reported results, we would suggest perhaps two 6500K lamps for every one 2700K or 3000K lamp; some people simply use a 1-to-1 ratio of these two color temperatures.
As for lamp types, CFL bulbs aren't your only option, but they are a popular choice because many of them have a standard ("medium" or "Edison") base that screws into fixtures most people are familiar with. Some, however, will choose a shop fixture for fluorescent tubes, or may even upgrade to long-lasting LEDs. It's generally recommended to not use incandescent or halogen lights because of how much heat they emit. If you do use these, make sure to set them further from the seedlings.
If you do stick with CFLs, some experts would recommend using reflectors to help provide more even light across all the seedlings and from all directions. This is true with tubes as well, but their length across all plants (on a shelf, for instance) may already help in balancing out lighting.
In some cases, LEDs are programmable and could be made to provide sunrise and sunset effects for plants. Given the success people have had without such advancements, though, it's unclear how much value this would offer for the additional cost. Importantly, though, any light used should be on a timer rather than left on continuously. The amount of time may vary by plant and brightness of the lights, but a rule of thumb for seedlings is 16-18 hours a day of lighting.
If 6500K CFLs are your lamp of choice for seedlings, we offer several to choose from, including the most likely candidates pictured below. (Click on an image to see it online.)
You've probably seen them in plenty of places, like coffee shops, bars, and restaurants and anywhere else that wants to add a touch of nostalgia to its atmosphere.
Edison bulbs -- those historic looking light bulbs with swirling, looping filaments that create a piece of glowing art and cast a dim, warm glow. For comparison purposes, your standard incandescent bulb provides light at about 2700K, which is already a warm color temperature. Fluorescent lighting in an office setting is typically 3500K and above (much cooler, or whiter). An Edison bulb clocks in at a super warm 2200K or so, with a possible range of about 1800K to 2400K.
While they're not a great idea for general lighting (roughly half the light produced of a traditional incandescent bulb for the same wattage), Edison bulbs are widely embraced for decorative purposes, helping to drive a calming and retro ambiance.
Also sometimes called "carbon filament bulbs," these antique styled bulbs normally use modern tungsten filaments to reproduce the look of early light bulbs, which did indeed use carbon filaments. And to recreate that look, the bulbs are formed in historic shapes and the filaments are strung out in patterns like those of early bulbs. This can include filaments with double, triple, or quad loops; hairpin or horseshoe patterns; or the very popular "squirrel cage" option like in the bulb shown here.
While you should verify with the details on a website or packaging before buying, most Edison light bulbs come with a medium (E26) base, which is the common base in the United States. So it's easy to simply replace a standard light bulb with one of these. But again, you should only do so for decorative purposes: they're not ideal for general or task lighting since they're not as bright and don't have the same ability as other bulbs to render colors properly.
While there are several places where you can buy Edison bulbs, we think you will love the pricing and selection available at Lighting Supply. We work hard to give you an easy user experience on our website; we offer help by phone; and in-stock products ship same business day when you order by 5 p.m. EST.
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