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Thread: Fun with a Sekonic C-7000 Spectrometer For Kelvin, CRI & Other Measurements of LED's

  1. #1
    *Flashaholic* BVH's Avatar
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    Default Fun with a Sekonic C-7000 Spectrometer For Kelvin, CRI & Other Measurements of LED's

    Picked up a new toy.............. or rather an indispensable measuring tool today. I've been what I call a connoisseur of light for a decade or so now. My sweet spot is 5500K. I've just not been able to get into the neutral or warm Whites. There is only 1 incan bulb in my house. Everything else is LED 5000K or 5500K. Now I can precisely measure all of my home, car, searchlight and other lights' color temps and the REAL CRI, not just the averaged number usually quoted for marketing purposes. I've learned quite a bit over the last week while researching my purchase. The typical CRI number we see is the calculated average of 8 colors chosen decades ago by a Body in France, the name escapes me now. It represents how close a light source comes to the spectrum emitted by Tungsten incandescent light. CRI of Tungsten light is 100 on the CRI Scale. Extended CRI adds another 7 colors to the mix and the Sekonic 7000 meter has the capability to measure and display the additional 7 additional colors. The more color samples that are taken, the more accurate your CRI is going to be. But even CRI is a bit outdated and there have been and are processes in-motion to use another standard or two. There's a lot more to it but i won't get that deep. Suffice to say that below, the first 2 pics are of readings of the Sun. The first shows the Color temp in Kelvin (Tcp on the meter) of the Sun at 3:15 PM. Don't pay attention to any of the lux reading as I did not set up for a precise Lux measurement. The next pic shows the CRI RA average of the Sun calculated on only the first 8 colors in the bar graph but it also shows specific individual CRI readings from all 15 samples. The higher the bar graph and number to the left, the higher the CRI of each of the sample colors and the closer to the Tungsten standard the measured light source is.

    The 3rd and 4th pics are of the same type of measurements of the Group Buy GT I recently received on HIGH, not Turbo. The 5th and 6th pics are of the GT on Turbo. Notice how the R9 Red is absent from the GT and is actually a minus number.



    Sol at 3:15 PM Dec 12 Text Mode Kelvin Temp (Tcp)




    Sol at 3:15 PM Dec 12 Bar Graph Mode CRI RA




    GT at Top of Ramp Text Mode Kelvin Temp (Tcp)




    GT at Top of Ramp Bar Graph CRI RA




    GT at Turbo Text Mode Kelvin Temp (Tcp)




    GT at Turbo Bar Graph Mode CRI RA

    Last edited by BVH; 01-13-2018 at 11:59 AM.
    WWII 60" Carbon Arc (Sold), 1.6KW NightSun, 1KW VSS-3A, .8KW TrakkaBeam, 600W M-134 Light, 500W X-500-14s, 500W Starburst, 500W A120b, 450 Watt AEG German Leopard 1 Tank Light, 300W Locators, Megaray, 150W Communicator, Maxabeam Gen3, Pichel 75W Mini-Novas

  2. #2
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    Congratulations on the meter. I had access to the C700U Sekonic. It did more than I needed as does your C7000.

    I preferred the Gossen Mavospec base due being able to get spot readings. Both are great tools, but it comes down to personal preference.
    Those that can, do. Those that can't, teach.

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    Flashaholic* Modernflame's Avatar
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    This thread is full of potential. Thank you for the informative readings! I'm hoping to see the measurements taken from other flashlights.
    “May it be a light to you in dark places, when all other lights go out.”
    J.R.R. Tolkien, The Fellowship of the Ring

  4. #4
    *Flashaholic* BVH's Avatar
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    I'm under the impression that typical XBO/Xenon Short Arc lamps have CRI's in the 90's. It will be fun to confirm this on my searchlights.

    I would be more than happy to measure lots of light sources for people if they send them to me. Send complete lights, bare LED's, commercial bulbs, whatever you might want measured. I have programmable current limiting power supplies so I can power up bare sources so to speak. Example: LED's on stars as long as I can get a reasonable sized contact area or u attach wires to it. I can provide Kelvin and CRI/extended CRI measurements and, although I do not quite understand them yet, info on where the source is in relation to:

    CIE1976
    CIE1931(CIE1964)
    XYZ
    xyz
    u'v'
    λp (Peak wavelength)
    λd (Dominant wavelength)
    Pe (Purity)
    PPFD

    Maybe a database/repository of sources and their measurements could be kept on the site.
    WWII 60" Carbon Arc (Sold), 1.6KW NightSun, 1KW VSS-3A, .8KW TrakkaBeam, 600W M-134 Light, 500W X-500-14s, 500W Starburst, 500W A120b, 450 Watt AEG German Leopard 1 Tank Light, 300W Locators, Megaray, 150W Communicator, Maxabeam Gen3, Pichel 75W Mini-Novas

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    *Flashaholic* BVH's Avatar
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    Yesterday, the Sun at 3:45P was 5001K and 99.5 CRI. Today at 10:45 it's 5401K and 99.4 CRI.
    WWII 60" Carbon Arc (Sold), 1.6KW NightSun, 1KW VSS-3A, .8KW TrakkaBeam, 600W M-134 Light, 500W X-500-14s, 500W Starburst, 500W A120b, 450 Watt AEG German Leopard 1 Tank Light, 300W Locators, Megaray, 150W Communicator, Maxabeam Gen3, Pichel 75W Mini-Novas

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    Flashaholic* maukka's Avatar
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    Good to see the GT has a nice rosy tint. Thanks for the measurement!

  7. #7
    *Flashaholic* BVH's Avatar
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    Todays 10:45 Sun was 5409K and 99.4 CRI
    Todays 12-noon Sun was 4901K and 94.1 CRI
    Todays 2 PM Sun was 5999K and 94.2 CRI
    Last edited by BVH; 01-13-2018 at 03:56 PM.
    WWII 60" Carbon Arc (Sold), 1.6KW NightSun, 1KW VSS-3A, .8KW TrakkaBeam, 600W M-134 Light, 500W X-500-14s, 500W Starburst, 500W A120b, 450 Watt AEG German Leopard 1 Tank Light, 300W Locators, Megaray, 150W Communicator, Maxabeam Gen3, Pichel 75W Mini-Novas

  8. #8

    Default Re: Fun with a Sekonic C-7000 Spectrometer

    This is neat.
    I wonder if the less than 100% CRI of the sunlight comes down to limitations of the machine, or if a giant mass of hydrogen fusing into helium isn't a proper "black body", or if atmosphere and particulate are filtering out some wavelengths and reducing the CRI?
    The brighter the light, the darker the shadow.

  9. #9
    *Flashaholic* BVH's Avatar
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    Default Re: Fun with a Sekonic C-7000 Spectrometer

    I'm not an expert but it seems from what I've read, that CRI is based on Tungsten filament lamps so a Tungsten lamp produces 100 CRI and all other light sources, including the Sun are rated against it.
    WWII 60" Carbon Arc (Sold), 1.6KW NightSun, 1KW VSS-3A, .8KW TrakkaBeam, 600W M-134 Light, 500W X-500-14s, 500W Starburst, 500W A120b, 450 Watt AEG German Leopard 1 Tank Light, 300W Locators, Megaray, 150W Communicator, Maxabeam Gen3, Pichel 75W Mini-Novas

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