Re: new eye one ruler question
Re: new eye one ruler question
- Subject: Re: new eye one ruler question
- From: Marco Ugolini <email@hidden>
- Date: Wed, 22 Feb 2006 23:23:32 -0800
In a message dated 2/22/06 2:28 AM, Liane May wrote:
> Hello,
>
> The slightly higher distance to the material is intended to avoid scratches.
>
> In principle you are right, a too high distance to the material would produce
> errors in the measurements but the new ruler does not have a too high
> distance! Even if you see the remitted light of the Eye-One head, you can
> expect correct measurements.
Hi Liane.
I got my EyeOne Pro Rev B recently too, and noticed right away the higher
positioning of the spectro's head above the paper, compared to the previous
version of the ruler.
I get reliable and consistent readings most of the time with the new ruler,
which I have put through several rounds of testing to reassure myself that
it performs to my satisfaction.
But I would like to introduce another consideration here:
My room is not usually very bright; the rainy weather in the SF Bay Area has
added to the darkness lately. But I noticed one day the other week, when it
was nice and very sunny outside, with bright sunlight coming in through the
window, that I was getting some wildly variable readings from one
measurement session to the next on some of the patches in a printed
1780-patch ECI2002CMYK testchart. A few patches (usually darker ones, some
of them green) jumped around from one reading to the next to the tune of 18
Delta E 2000, even! (I calculated those Delta E values by comparing
measurement sessions with the Comparing tool in MeasureTool).
It's my impression (and please let me emphasize that *I may be wrong* about
this) that, when measuring testcharts with the new ruler, the readings may
be adversely affected by ambient lighting that is *too bright* (and how
bright is too bright I cannot say). Bright ambient lighting may be strong
enough to to influence the reading if some of it makes its way into the
spectro's head through the slight opening between the head and the paper.
Also, additional ambient light may be be entering the spectro's head by
bouncing off the internal reflections in the ruler itself, which is made of
clear plastic.
Am I off the mark to think this? Does anyone else get that impression?
> The new ruler is designed within a tolerance of a
> maximum deviation of 0.3 in L, compared to the old ruler.
What was the maximum deviation with the old ruler?
> When using the new ruler, please make sure, that the Eye-One is positioned
> correctly to the black carriage. Then you will get precise measuring data.
I believe you mean to say that the EyeOne Pro ought to be *properly seated*
on the black carriage, with the 2 upright pins in the carriage locking into
the the corresponding holes in the spectro's base, correct? That is the way
I have done all my test measurement sessions for the Rev B.
One last observation: though my EyeOne Pro is properly seated on the new
ruler's carriage, when I slide it across the testchart page it seems to
stick a bit, offering slight resistance here and there, enough to make my
motion somewhat uneven. Is that normal?
Thank you, and best regards.
--------------
Marco Ugolini
Mill Valley, CA
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