Re: What is the best Spectrophotometer for reading canvas
Re: What is the best Spectrophotometer for reading canvas
- Subject: Re: What is the best Spectrophotometer for reading canvas
- From: "Abe Hayhurst" <email@hidden>
- Date: Thu, 3 Apr 2003 15:05:15 -0800
- Organization: We Do Graphics Inc.
I have built profiles using data from integrating sphere spectros. It
works just fine. I did a comparison beween the X-Rite SP64 and Gretag
Macbeth Color Eye XTH sphere spectros before purchasing. The X-Rite's
use a gas filled tungsten bulb for the instruments illumination. The
Gretag uses a xenon flash bulb. I measured a variety of substrates and a
variety of different colorants with each of them. They consistently
measured within 1 Delta E of each other EXCEPT for materials with
obtical brighteners. The xenon flash bulb in the Gretag excites the UV
brighteners and causes them to fluoresce significantly more than the gas
filled tungsten bulb in the X-Rite. Measuring a fabric with optical
brighteners in it would produce values of about L94 A1 B4 on the X-Rite
SP64, but would measure L94 A2 B8 on the Gretag Color Eye.
After I purchased the instrument, I compared the X-Rite SP64 to a Gretag
Spectrolino/Spectroscan that I had at the time. If you compared the
spectral reflectance values/curves from the two instruments you could
generalize by saying that the sphere measures higher reflectance values
than the 0/45 instrument. In LAB terms this would mean that the sphere
spectro would measure a higher L value (2 to 5 points on average) and
lower A and B values in almost exactly the same ratio as the 0/45
spectro. In LCH terms this would mean that the sphere measures the same
hue as the 0/45 spectro but lighter and less chromatic. The X-Rite SP60,
SP62, and SP64 are almost identical except for extra functionality built
into the display of the instrument. If I remember correctly, the SP60 is
about $5,000 the SP62 is about $7,000 and the SP64 is about $9,000. The
SP62 and SP64 are supposed to be more accurate than the SP60.
Good luck,
Abe Hayhurst
We Do Graphics Inc.
1150 N. Main St.
Orange, CA 92867
714-997-7390
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