RE: Solux Bulb color temperature
RE: Solux Bulb color temperature
- Subject: RE: Solux Bulb color temperature
- From: Roger <email@hidden>
- Date: Wed, 18 Feb 2009 07:32:27 -0500
Robin,
Your findings agree with my humble findings. I don't have the data with me
but, if memory serves, I could *not* get a better D50 spectrum out of the
5000K bulbs, even when driven at my regular 13 to 15 volts level. As as
matter of fact, my conclusion at the time was that the 4700K bulbs were
better than the 5000K bulbs, no matter what I'd try. So, it was a big
disappointment. Same price, you'll say, for either bulbs, but why bother
with the 5000K units, I figured?
Lucky you, with your PR-655! Isn't the 655 giving 5nm resolution only, btw?
Roger
>
> Here are the CCT results from measuring a Solux 4700K bulb, and two
> Solux 5000K bulbs (one with clear sides, one with black sides). The
> measurements were made 1 m from the front of the fixture to the
> measuring devices aperture.
>
> i1 Pro with Ambient filter
>
> Solux 4700 50W 36-degree 4304K +-4K
> Solux 5000 35 W 36-degree Clear 3974K +- 3K
> Solux 5000 35 W 36-degree Black 4428K +-7K
>
>
> PR-655 with CR-655 Cosine Corrector
>
> Solux 4700 50W 36-degree 4431K +-2K
> Solux 5000 35 W 36-degree Clear 4025K +- 4K
> Solux 5000 35 W 36-degree Black 4528K +-2K
>
>
> With only one sample each of the 5000K bulbs, it was not possible to
> double-check the 5000K Clear bulb, but it is apparent that the 5000K
> bulb is not right. I suspect it is a mismarked lower Kelvin bulb or a
> bad bulb.
>
> Otherwise, the i1 Pro and the PR-655 agree. There were two different
> setups, at two different locations but the light fixture was the same
> and the bulbs were the same for both sets of tests. The CCT was
> calculated with SpectraShop 3 (to be released later this week,
> hopefully) and the CCT results of 5 to 6 measurements of each bulb
> were averaged.
>
> The calculated CCTs do not agree with the expectation based on the
> manufacturer's marketing.
>
> In comparing the emission spectrums, the i1 Pro and PR-655 agree
> fairly well. Both of them have a general shape similar to the D50
> curve, but much smoother. There are several small peaks in the D50
> spectrum absent from the measured Solux spectra. The manufacturer has
> claimed a spectral shape similar to D50 and it is a reasonable
> approximation.
>
> In Ken Fleisher's original post, he reported a CCT of 4450K for the
> Solux 4700K bulbs and the results above agree with the lower than
> claimed CCT value (if you believe the "4700 Kelvin" on the bulb's box
> means CCT).
>
> Robin Myers
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