Re: Solux Bulb color temperature
Re: Solux Bulb color temperature
- Subject: Re: Solux Bulb color temperature
- From: Robin Myers <email@hidden>
- Date: Tue, 17 Feb 2009 20:57:23 -0800
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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