Color temperature of lights - demo (C) D Friedman Light bulb (lamp) color temperature & brightness compared & illustrated
     

  • BULB COLOR TEMPERATURE COMPRARISONS - CONTENTS: Comparative Examples of Color Temperature and Color Rendering Index for Indoor Light Bulbs (lamps). Comparing the Appearance of Color Temperatures of Different Bulb Types. Halogen Lamp (light bulb) Color. emperatures & Properties. Photo guide to the effects of varying color temperatures of different light bulbs & lamps. Halogen Lamp (light bulb) Color Temperatures & Properties. Comparing Light Output using LED Flashlights for an Example. Sorting out Definitions of Color Temperature of light, Light Brightness, Watts & the Wavelength of Light: What's the Difference? Table of Color Temperatures of Various Artificial & Natural Light Source
  • POST a QUESTION or READ FAQs about about lamp or light bulb color temperature or brightness, applications, & uses.
  • REFERENCES

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Light bulb color comparison examples, photos:

LED & Halogen colors & brightness: this article describes the variations in perceived color and color temperature of different indoor-use bulb types compared with sunlight. We illustrate both interior lighting bulbs (incandescent, three types of fluorescent bulbs, halogen lamps, and LED bulbs) comparing both color temperature (color rendition) and brightness.

We illustrate what different object colors look like under different types of lamps (bulbs) including incandescent, all types of compact fluorescent bulbs, halogen lighting, and LED lighting. We include comparisons of types of LED bulb brightness using flashlights for an example.

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Comparative Examples of Color Temperature and Color Rendering Index for Indoor Light Bulbs (lamps)

Globe bulbs illustrate temperature differences (C) D FriedmanAt Color Temperature and CRI for Indoor Lights we introduced and defined color temperature and CRI.

Here we provide additional details and photo examples of variations in perceived color and color temperature of different bulb types compared with sunlight.

We illustrate both interior lighting bulbs (incandescent, three types of fluorescent bulbs, halogen lamps, and LED bulbs) comparing both color temperature (color rendition) and brightness.

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Skin tones look best under lamps rated from 2700K (standard A-bulb) to 3500K and with a CRI over 80. Residential lamps range as high as 7500K for continuous spectrum fluorescents, such as GE’s Chroma 50 or 75. These simulate daylight and are good for detailed work where color accuracy is critical, but they give skin an unflattering greenish tone.

Comparing the Appearance of Color Temperatures of Different Bulb Types

At Color Temperature and CRI for Indoor Lights we include a table comparing the color temperatures of the most common types of lamps used indoors.

The display below, available at many Home Depot stores, compares lighting among four bulb color types, from left to right

Color temperature of lights - demo (C) D Friedman
  • Incandescent bulb
  • Soft white compact fluorescent bulb
  • Bright white compact fluorescent bulb
  • Daylight compact fluorescent bulb

The accuracy of color rendition of different lights and the CRI scale are explained at Color Temperature and CRI for Indoor Lights.

The four lamps (bulbs) described above are shown inside the display, below. We kept the camera on the same "automatic" white balance setting for all four bulb color photographs.

These colors are not exactly what your eye will see, nor do they consider the effects of the colors of surroundings, but you can see the color temperature differences among these light bulbs.

Color temperature of lights - demo (C) D Friedman Color temperature of lights - demo (C) D Friedman Color temperature of lights - demo (C) D Friedman Color temperature of lights - demo (C) D Friedman

The display, which includes a spot for you to insert your hand to observe what each light does to the perceived color of your skin, also describes the applications for these bulb color temperatures (corresponding to left-to-right above) as:

  • Incandescent - general purpose light source. Standard incandescent bulbs give off light at 2700o Kelvin and produced a reddish light that is best where comparatively low levels of light are desired. These bulbs produce the lowest frequency or color temperature compared with outdoor daylight which is described as 6500o Kelvin.
  • Soft White - a warm full glow light ideal "lifestyle" light. Color corrected fluorescent bulbs operate at about 3600o K and skin tones look somewhat normal under these lights.
  • Bright white - a crisp, white light ideal for kitchen and task areas.
  • Daylight - simulates natural sunlight, ideal for reading & detail oriented activities. Full spectrum fluorescent bulbs operate at about 5000o K, producing lighting simulating daylight but with skin tones slightly greenish. Bliss points out that these lights are popular in art galleries & jewelry stores.

Watch out: if you didn't notice, the compact fluorescent bulbs such as the models shown above include a warning printed on the bulb base indicating that these bulbs are intended for dry locations, and are not for use in luminaires controlled by a dimmer or totally enclosed recessed lighting fixtures. Check the specifications on lamps you are buying if you have other needs than those that fit these restrictions.

Photo guide to the effects of varying color temperatures of different light bulbs & lamps

Colors of Objects in Indirect Sunlight

Glass soap dish in sunlight (C) D FriedmanRecognizing that the human eye does not see light and color exactly the same as any camera, film or digital, we set our camera to a white-balance setting based on white typing paper in indirect sunlight to begin the light color temperature comparison photographs shown here.

Each photograph was taken with a glass soap dish placed on plain white typing paper. The white balance of the camera was set to normal for the white typing paper alone, in sunlight.

We take the first soap dish color photograph as our reference standard, as this image was taken in outdoor sunlight.

At below left a string of eight (4 shown) mini globe incandescent bulbs give the glass soap dish a pink hue that is very close to the color we found in sunlight.

You can see that the soap dish as a very light pink-purple color in the reference photo. Actually outdoors, to the human eye, we saw this dish as more "pink" than did our camera.

Comparing Colors of Objects in Incandescent & Fluorescent Light Indoors

We set our camera white balance to the same white paper under incandescent lighting indoors (below left) and then for compact fluorescent bulbs in an overhead light fixture (below right). You will observe that the indoor incandescent shifts the original image towards red/pink hues while the compact fluorescent lighting shifts the image towards blue-green.

Color temperature of lights - demo (C) D Friedman Color temperature of lights - demo (C) D Friedman

At below right we illustrate what these same objects look like under a standard (long tube) fluorescent lamp. Compare that photo (below right) with the compact fluorescent lamp lighting photo (above right) and you can see a shift towards green.

At below left we illustrate our darkroom test set-up for light source comparisons, in this case with a "blacklight" or UV ultraviolet light bulb (Woods lamp) installed in our test fixture using a 13W bulb produced by Feit Electric.[5] (280-410nm usually narrowed to 368-371 nm wavelength light). Some septic system and building inspectors use UV lamps to detect the presence of septic test dye that contains fluroscein, or to screen for animal urine stains.

Color temperature of lights - demo (C) D Friedman Color temperature of lights - demo (C) D Friedman

See UV LIGHT BLACK LIGHT USES for definitions of fluoresence, UV light, black light, and the use of UV lights in buildings to track down different substances including animal urine or even blood. Also see BLOOD in ART WORKS, TESTING FOR.

Halogen Lamp (light bulb) Color Temperatures & Properties

As explained at explained at Color Temperature and CRI for Indoor Lights, the color rendering index (CRI) of light bulbs provides a scale of 1 to 100 where a bulb rated at 100 closely matches a reference light source.

Colors of Objects under a Halogen Lamp

Halogen lamps such as the bulb we show at below left operate at around 3000K and give off a whiter light than incandescents and most fluorescents. At below right we include an example photograph of our color references used above, but here, illuminated by a halogen lamp. Comparing this result (below left) with our example from daylight (above) you will see that the halogen image is rendered rather close in color temperature to daylight.

Halogen work light (C) Daniel Friedman Color temperature of lights - demo (C) D Friedman
  • For incandescent lamps and all others with a color temperature of 5000K or less, the reference used to state the CRI of those bulbs is an incandescent or halogen bulb, which are both assigned CRIs of 100.
  • For lamps with a color temperature of over 5000K, the reference is natural daylight, which also has a CRI of 100 or "perfect" color rendition.

Comparing Light Output using LED Flashlights for an Example

At Lumens, Definition, comparisons we defined Lumens as

a measure of the amount of light contained within an area or within a defined beam or angle emitted from the light source. Lumens is further defined as the total amount of visible light emitted by a source.

Here we offer a more subjective comparison of the brightness of light emitted by LED bulbs, using flashlights as an example. Take a look at the rated light output in lumens when you can find that information. It is both useful and very interesting. For example when purchasing LED-designed flashlights, you will usually observe that the very inexpensive units may look exactly like others that cost five to ten times as much.

Fluorescent lamp (C) Daniel Friedman Fluorescent lamp (C) Daniel Friedman Fluorescent lamp (C) Daniel Friedman

But the light output of the low-priced units is often 1/10th the light output of the costly versions. Brighter LED's cost more. And if the flashlight marketing information on the package does not tell you the light output of the device... well that tells you something, right?

And our digital camera "sees" light differently than the human eye - a fact that can add difficulties when photographing some subjects, as our three comparison photographs of light beams from two LED flashlights illustrate above. All three photos are of the same two LED flash light units. But depending on external variables our eye and the camera see different brightness.

From left, with no flash the right-hand LED flashlight looks brighter shining on blue ceramic tile. With a flash to eliminate dark background, the bulbs look about equal. With no flash and shining the two LED flashlights onto a darkened wall, the left-hand LED flashlight looks brighter (and less diffuse, which confuses the matter). [Click any image to see a larger version.]

Color Temperatures of Various Artificial & Natural Light Sources

As Bliss points out in Color Temperature and CRI for Indoor Lights, the comparison standards for color temperatures of lights produced by different types of lamps are not uniform. Quoting:

For incandescent lamps and all others with a color temperature of 5000K or less, the reference is an incandescent or halogen bulb, which are both assigned CRIs of 100. For lamps with a color temperature of over 5000K, the reference is natural daylight, which also has a CRI of 100.

CRI numbers are best used to compare lamps with color temperatures within about 300K of each other. Colors will look very different under a 3000K lamp and a 6000K lamp with the same CRI.

Sorting out Definitions of Color Temperature of light, Light Brightness, Watts & the Wavelength of Light: What's the Difference?

Do not confuse color temperature (in degrees Kelvin) with brightness. The table below describes color temperature (or you could say "hue", not the brightness of the light source.

  • Color temperature - Kelvin: the color temperature of a light source (visible to humans) is the temperature measured in Kelvin of a theoretical idealized black-body radiator that emits light of a matching color hue to that of the light source we are actually observing.

    Higher color temperature numbers in Kelvin (over 5,000 oK ) are cooler, more blue in hue. Lower color temperature numbers (2,700-3,000 oK) are warmer or more red colors. Our table below gives the color temperatures of many types of light sources, both artificial and natural.
  • Light brightness - Lumens: We measure the brightness of light in Lumens or equivalents. Lumens is a measure of the amount of visible (to humans) light observed / measured within an area or within a defined beam or angle emitted from the light source. Lumens is further defined as the total amount of visible light emitted by a source.

    One lumen is (at one steridian) equivalent to one candela in light intensity. Typical narrative describes as a practical example that one "birthday cake candle" emits one lumen if its light is measured at a distance of one foot from the light source.
  • Visible light (to humans) - measured in wavelength: light visible to humans is a form of energy (or photos if you like) emitted in the 380-780 nanometer wavelength range. The wavelength of light and its color temperatures are inversely related. That is, higher wavelengths (bigger numbers) are lower or cooler color temperatures. [9][13]
    • 7,831 oK = 370 nm wavelength light
    • 6,585 oK = 440 nm wavelength light
    • 6,300 oK = 460 nm wavelength light
    • Formula: [Peak] light wavelength in meters [actually nanometers or nm] lambda Max = b/t where T= light temperature in Kelvin or oK and b = Wien's displacement constant of proportionality = 2.897 768 5(51) × 10–3 m K
  • Color Rendering Index (CRI) is a rating on a scale of 1 to 100 of how accurately a lamp shows colored objects. The higher the CRI, the closer the colors look to a standard reference.
  • Watts as a measure of light brightness Because watts, the traditional standard of brightness of incandescent light bulbs no longer expresses the total light output of other types of bulbs (CFs and LEDs for example), we use lumens as a better measure of bulb light output. Properly, watts are a measure of a rate energy conversion or transfer (one watt is defined as one joule per second) not specifically a measure of light output.

Table of Color Temperatures of Various Artificial & Natural Light Source

Light Source or Type

Color Temperature in oK

Comments

Match flame 1,700 oK - 1850 oK Very low color temperatures, more warm or red in hue.

Candlelight - flame from a single candle
Gaslight
Sunrise or sunset

2,000 oK

Candle flames are 1850-1930 oK. Some sources say 1,800oK Notes 2, 3

Sunrise/Sunset color temperature range is 2000 oK to 3000 oK

Horizon light (simulating daylight) 2,300 oK Note 4.
Standard incandescent bulb, 15-watt 2,470 oK Tungsten filament household bulb
Standard incandescent bulb, "soft white"
2,700 oK

Living areas. Typical incandescent bulb color temperatures range from 2,700oK to 3,300oK

(Incandescent tungsten filament household bulbs range from 2,470 to 2,900 oK depending on bulb wattage)

Krypton bulb, 500W 2,900  
Halogen bulb
Soft white compact fluorescent bulb
3,000 oK Other sources rate halogens at 3,400 oK Note 3.
Projector type bulbs, filament 3,100 oK  

Photo floodlamps, studio lamps
Quartz lights and floodlights
Tungsten 2k Lamp

3,200 oK

Quartz lights range from 3,200 to 3,500 oK

Tungsten 5k or 10k Lamps have a higher color temperature of 3380 oK

3,200 oK is a common reference color temperature for expressing RGB values used to simulate the colors of images captured on "indoor" photographic film. 6.

Studio "CP" light
3,350 oK  
Halogen bulbs 3,400 oK  
Fluorescent bulb, color corrected 3,500 oK Fluorescent light color temperatures range from 3,200 to 7,500 oK
"Bright white" bulbs 3,500 oK - 4100 oK Kitchens, bathrooms
Projector bulbs, carbon arc (traditional movie) 3,900 oK  
Fluorescent bulb, cool white
Moonlight (natural, full moon, clear night)
Xenon arclamps
4,100 oK Some sources put moonlight at 4,200 oK 3.
Cool white fluorescent "store lights" 4,150 oK Note 4.
Daylight, with industrial smog conditions 4,700 oK Note 3.

Cool White or "Daylight" CF bulbs
Daylight, at the horizon
Fluorescent bulb, full-spectrum
Sunlight, sun directly overhead (Noon)

5,000 oK

Fluorescent lamps rated as "artificial daylight" have color temperatures of 5,000 oK or 7,500 oK Note 4.

Noon sunlight range: 5,000 5,400 oK

Dayligt (sunlight) under hazy conditions 5,100 oK

Color temperatures over 5,000 oK are considered cool colors and are more blue-white in hue.

Sunlight through clouds or thick haze range from 5,500 to 6,500 oK

Notes 2, 3.

Daylight - sunlight
Electronic flash (cameras, pocket)
5,500 - 6,100oK

Sunlight at 30 deg. over the horizon is typically 5,500 oK while sunlight at 50 deg. over the horizon may be 6,100 oK.

Daylight ranges given as 5,500 to 6,500 under a clear sky

Electronic flash from larger photo-flash devices may be rated at 6,700 oK 3.

Daylight: sunlight at mid-day 6,500 oK Whitest light. Some sources rate this as "overcast light" 2
Fluorescent bulb, "daylight" rated 6,500 oK Reading, close-work
Daylight (sunlight) through overcast sky or in indirect light 6,500 oK - 7,500 oK

More blue than sunlight.

Some sources put overcast sky daylight at 7,400 oK 3.

Electronic flash (cameras) 6,700 oK Note 3.
Daylight (sunlight) measured in a shaded area 7,000 - 8,000 oK  
Daylight (sunlight) measured under a partly clouded sky 8,000 - 10,000 oK  
Daylight: foggy conditions 8,300 oK Note 3. [further study needed-Ed.]
Computer monitors, LCD or CRT screens 6,300 - 9,300 oK Note 2. Adjustable on many devices. Most RGB monitors, measured by examining a white point, are 6,500 - 7,000 oK
Sunlight, 5 Meters under water, near the equator 14,000 - 20,000 oK Note 5.

Notes to the table of light source color temperatures

1. Also see Table 5-23, "Color Temperatures of Common Lamps" found in Lamp & Bulb Abbreviations & Type
2. cf reference [9] at the end of this article.
3. cf reference [10] at the end of this article. The Kelvin color temperatures offered by this source and included among those in our table above may involve both accurate measurements and some subjectivity about the actual weather conditions at the time, such as "hazy" or "industrial smog" that would require more careful definition. The color temperatures of most common sources of visible light range from 1,800 to 160,000 oK
4. cf reference [11] at the end of this article.
5. cf reference [12] at the end of this article.
5. cf references [14] [16] [17] at the end of this article.

Reader Question: What are ANSI-coded light bulbs (lamps) & where can I find a table of the ANSI bulb codes?

I have heard of ANSI coded bulbs but do I need to worry about these codes? Where can I find what the ANSI bulb codes mean? - Anon. 5/14/12

Reply:

ANSI (American National Standards Institute) codes for light bulbs[8] permit a standard definition for bulb shape, design, electrical connections, light output, and other parameters. ANSI has defined approximately 100 bulb codes, typically 3-letter designations such as

  • BAB (BAB Light Bulb - MR16 20W 12V Flood Halogen Open Face)
  • DYS (DYS 120V 600W Projector Light Bulbs)
  • ESD (ESD 120V 150W Projector lamp)
  • FTC (FTC MR11 12V 20W Narrow Flood- front glass covered, Halogen bulb)
  • etc. - more than we want to try listing here.

Many bulb (lamp) producers and distributors provide an extensive index to lamps by ANSI bulb codes and bulb types or applications. Perhaps because ANSI standards are sold you won't find it easy to obtain the details of most ANSI standards at ANSI's own website. A website that does an excellent job of illustrating the various ANSI bulb codes, bulbstock.com explains:

ANSI (American National Standards Institute) coded light bulbs meet specific industry standards for light output, bulb shape, base type, beam spread and other lamp specifications. If a manufacturer offers a light bulb with an ANSI designation, that bulb should be identical to a similarly ANSI designated bulb from other manufacturers. [7]

Light Bulb & LampTypes Articles

 

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