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color temperature of light bulbs

Discussion in 'Open Gear Talk' started by Luke, Jun 9, 2015.

  1. Luke

    Luke Super Moderator

    Nov 11, 2011
    Milwaukee, WI USA
    Luke
    Hey all,
    I've replaced a fair number of bulbs in our house with LED replacements, but last time I replaced some, my wife was VERY unhappy about the difference in color temperature. I'm sure there's a proper match for nearly every bulb and application by this point in time. But she has nixed any of my further energy reduction bulb purchases because she thinks all the modern replacements are "too white" or "too blue". I'm sure if I err on the other end of the spectrum, I'll hear about it that the new ones are "too yellow".

    So my question to the great minds here in the lounge is....... how can I use my camera and it's fancy WB function to find out what color temperature my current blubs are? Most new bulbs will tell you what color temperature they are, but how do I figure out what I already have? Can I do it without owning a gray card? Do I try various color temperature settings and see what photos most accurately reflect the lighting to the human eye?
     
  2. davidzvi

    davidzvi SC Regular

    180
    Apr 18, 2014
    David
    Here is an image from a GE lighting page:
    fluorescent-color-chart.
    For image editing I work in a room with bulbs in the 4100-5000K. If I had to guess I'd think the bulbs you got are at least 4100k or above. Typical incandescent bulbs were in the 3000-3500k range.
     
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  3. ajramirez

    ajramirez SC All-Pro

    Jul 9, 2010
    Caguas, Puerto Rico
    Antonio
    Grey card would be best, but a white piece of paper would work as well. Use it to set a custom white balance. Open the RAW file in ACR (or Lightroom) and the software will tell you the color temperature set by the camera.

    However, I do not think you need to go through the trouble. As David said above, most standard incandescents are in the vicinity of 3000K. Get something close, if available.

    Cheers,

    Antonio
     
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  4. Luke

    Luke Super Moderator

    Nov 11, 2011
    Milwaukee, WI USA
    Luke

    Well, there's many different bulbs that need replacing....funky old large spots in the bathroom and some weird halogens in the living room, etc...... Thanks for the tip about Lightroom
     
  5. ReD

    ReD SC Hall of Famer

    Mar 27, 2013
    IMO there is a big difference between what manuf's claim & what the temp is in reality so its trial & error (with emphasis on error).
    as a rule of thumb aim for an LED with min 5-7 watt or higher and check the lumen level - some are quite low and only suitable for desk lights etc
     
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  6. Luke

    Luke Super Moderator

    Nov 11, 2011
    Milwaukee, WI USA
    Luke
    Thanks for the tip Roger. You made me learn what a lumen is. Seems we should be buying bulbs based on lumens (light output volume), not watts (energy consumption).
     
  7. Boid

    Boid SC All-Pro

    Dec 15, 2011
    Bangalore, India
    Rajiv
    Hey Luke, it's unfortunately not as simple as finding out the color temperature of your light fitting (bulb) or it's intensity (lumens). The quality of light has a lot more to do with it's CRI (color rendition index, http://en.wikipedia.org/wiki/Color_rendering_index) than it has to do with simply color temperature. CRI is expressed on a scale of 1-100, with higher numbers representing a higher ability of the light source to render colors accurately. LEDs have a very poor CRI index, unless you pay a lot of money for them. The Japanese made Nichia LEDs come to mind, which in some cases achieve CRI indexes of 85-90. A regular incandescent bulb, which makes light by burning a filament, achieves a CRI pretty close to 100.

    Here's another write-up that can help you out - http://www.topbulb.com/color-rendering-index

    Found a better article - http://lowel.tiffen.com/edu/color_temperature_and_rendering_demystified.html

    What your wife (very astutely I might add) might be pointing out is not that she's just uncomfortable with the color temperature, but the fact that the quality of the LEDs/florescent bulbs are just not nice enough.
     
    Last edited: Jun 10, 2015
  8. Luke

    Luke Super Moderator

    Nov 11, 2011
    Milwaukee, WI USA
    Luke
    Thanks Rajiv. That's a lot of information to take in. I kind of understood (without knowing the science behind it) that there was more to the quality of a light than the color temperature (there was a reason I used to spend triple the money on the bulbs for my aquarium). But now I understand the science a little more.

    So I'll probably need to spend a fortune to match the quality of light I'm getting from those hot halogen bulbs that I hate. :frown:
     
  9. Boid

    Boid SC All-Pro

    Dec 15, 2011
    Bangalore, India
    Rajiv
    It's an issue I end up grappling with quite a lot. Sometimes cheaper LED alternatives are used in projects, with poor CRI properties, and the space becomes very difficult to photograph. Our brains usually make up for poor lighting, but pictures show up all the faults. The cove lights are the wrong LEDs in the subsequent image, and throw up a greenish tinge.

    LegveWX.
     
  10. Luke

    Luke Super Moderator

    Nov 11, 2011
    Milwaukee, WI USA
    Luke
    who cares about a greenish tinge.....where can I get those mod looking dining chairs?
     
  11. Djarum

    Djarum SC All-Pro

    Jul 10, 2010
    Huntsville, AL
    Jason
    Thing about color temperature is that it only describes the amount of "blue". For example, I've picked up 10000K aquarium bulbs. Some are more green while others are more magenta. Same goes for household bulbs. I've got 2700K CFLs from two different companies. Some are more orange than others.

    http://en.wikipedia.org/wiki/Color_temperature#/media/File:PlanckianLocus.png

    As you can see, the line across the color temperature spreads as the bulb gets cooler and cooler. The warmer the K the less variation for the same Kelvin bulb.

    Cree has their "TW" series which are supposed to have a CRI >90.

    Feit also has some with CRI >90 as well.

    Some of the led remote phosphor bulbs were supposed to improve CRI, but I'm not sure how far they got.
     
    Last edited: Jun 11, 2015
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