I have also seen this phenomena and tried it on a few
units a while back (they were all Revision-A at the time).
Some units are more sensitive than others, and some seemed
to be immune to it. The drift is always upward. If you
calibrate when hot, then all your other measurements can
be low if the device had time to cool, as you saw.
When I do high precision single patch measurements, I
always wait a (fixed amount) few seconds betwen each
measurement. When measuring patch strips, I make a few
practice rows before re-calibrating and making the final
measurements.
I suspect the problem is due to lamp filament movement,
when heated. This problem should go away with LED
illumination (and new ones pop in!).
Danny Pascale
email@hidden
www.BabelColor.com
On Fri, 23 Feb 2007 11:59:20 +1100
Graeme Gill <email@hidden> wrote:
Roberto Michelena wrote:
- better agreement with the Eye-One, nowadays handheld
spectro of
choice. is this so? I mean, is the sensor really the
same as an
Eye-One?
I've been taking a look at a Rev A Eye-One Pro, and
notice
one not so nice thing about it's accuracy - it seems to
drift significantly as it gets hot. If I read the white
calibration reference several times in quick succession
for instance,
I see the L* value drift upwards by up to 0.7 delta E by
the
end of the run. If I let it cool down again, it drops
back.
Does anyone know if this effect is similar with latter
revision
Eye-One Pro's, or are they a bit better behaved ?
Graeme Gill.
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