Re: Solux Bulb color temperature
Re: Solux Bulb color temperature
- Subject: Re: Solux Bulb color temperature
- From: "dpascale" <email@hidden>
- Date: Tue, 17 Feb 2009 12:23:21 -0500
Hello Clemens,
Let's do it practicaly:
1. Take your spectro with an ambient head.
2. Measure the the bulb
3. Load the measurement in Excel, Openffice Calc or what ever
4. Scale the measurements and compare it to you reference spectrum
This is what was done in the paper I wrote with Roger, except for step 3,
which is not required when you use BabelColor CT&A.
I agree that to just use the Kelvin value is wrong, as you and Andrew
mentioned, but it is a starting point. When you combine this info with the
chromaticity accuracy (u'v' in CIE 1976), plus the CRI info, which is also
almost useles when used alone, plus the Metamerism Index (MI) based on CIE S
012, which is much more critical when comparing an unknown source, plus a
direct comparison of the measured spectrum vs the theoretical D-series
spectrum OR vs the equivalent blackbody (and at the same illuminance), then
you get a pretty good picture of the light under test. I think that this is
what Ken did since he mentioned the exact same test results (Chromaticity
error, CRI, and MI)
Danny
----- Original Message -----
From: "Beisch Clemens" <email@hidden>
To: "colorsync-users List" <email@hidden>
Sent: Tuesday, February 17, 2009 11:40 AM
Subject: Re: Solux Bulb color temperature
I'm not refering to the paper of D. Pascale and R. Breton, becuase I
didn't knew that it exists ;-)
The only thing I wanted to clarify is, that Kelvin is the wrong method
for this kind of work.
Let's do it practicaly:
1. Take your spectro with an ambient head.
2. Measure the the bulb
3. Load the measurement in Excel, Openffice Calc or what ever
4. Scale the measurements and compare it to you reference spectrum
Than you will see which one works better for you.
Btw.: I don't know which bulb is better and don not say that one is
better than the other.
A few years ago a had a customer who had trouble with his viewing box.
After cleaning the box inside and outside everything was fine.
Just because you like Kelvin, after cleaning the box the measurements
gave about 500K more ;-)
Regards,
Clemens Beisch
Am 17.02.2009 um 16:50 schrieb Fleisher, Ken:
The 5000K bulb is closer to D50 as far as I understand it and as shown
by
the improved CRI and MI (although it is only "slightly" better, it's
certainly not worse). If you are using D. Pascale and R. Breton's paper
as a
guide, keep in mind that the comparison on page 25 compares the 5000K
bulb
with the 4700K bulb (with over-driven DC current to obtain closer to
5000K).
I still don't see any reason why the 4700K bulb used at normal wattage
(assuming you would not want to over-drive it due to greatly decreasing
bulb
life) would be preferred over the 5000K bulb.
Also, when talking about using this for a soft-proofing application, a
difference of 500K between proof light and monitor white point can make
a
big difference for critical color matching, so I don't see this as
insignificant. (500K because our 4700K bulbs actually measured at
4450K.)
If I am missing something, please be specific.
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