Colorimeter: precision

[hairyotter]

Hi to everybody.

I'm an absolute beginner, both in color management and on this forum.

I was checking my R1800 printer (I had to convert from 3MK back to color) and I think that there is still some printhead cleaning to do:
Two copies of the first target, printed at a distance of one day, with the same paper and settings, show:

-some color patches (for example Deep Purplish Pink) have a DeltaE94 of 3.7 and it is evident, even to the naked eye, that they are different.

Being an engineer, I did a quick check to verify that the problem was indeed printer related and not, for example, paper-related.

-The two sheets of paper (Epson Luster) have a DeltaE94 of ~0.3
- If I take multiple measurements of the same spot (without moving the munki) the measurements I get are very consistent:
The DeltaE-94 is < 0.05
-If I move it, even just a little, the DeltaE can be anywhere from .2 to .4

So it seems that different areas of the paper can have color differences that the munki can appreciate.
Is this true ? What is the precision of the munki ?


Thanks, Marco.

[geotzo]

The precision of these instruments is very high. If you read at the manufacturers detailed specs, it should say in terms of dE, its precision. Differences like that are normal.

[madmanchan]

This is normal. For example, if I print black patches on my 3800, patches on the left side of the sheet are slightly lighter than on the right side. Uniformity is pretty even but there is definitely a systematic bias in some cases. (This is one reason why Bill Atkinson describes measuring targets by printing them out several times in different orientations, and averaging all the results together.)

[hairyotter]

[...] If you read at the manufacturers detailed specs, it should say in terms of dE, its precision. [...]

Thank you very much. Does anybody have the manufacturer specs ?
I could not find them on their web site.

Thanks, Marco.