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This article describes the recommended aperture sizes for color measurements of screened samples.


There is a correlation between the lineature of printed samples and the aperture of a spectrophotometer that will give you error-free measuring. The following aperture sizes are recommended:

  • 1.5 mm instrument, for 2mm patches, for screening of 175 l/inch, 69 l/cm or above
  • 2 mm instrument, for 3 to 5 mm patches, for screening of 133 l/inch, 52 l/cm or above
  • 4 mm instrument. for 5 to 6 mm patches, for screening of 65l/inch, 26 l/cm or above
  • 6 mm instrument for large patches (e.g. in packaging)

You notice that it is not recommended to measure samples with a ruling less than 65 LPI with spectrophotometers like a X-Rite i1 which has a 4.5mm aperture.

The eXact has different Aperture sizes to meet all applications: With a choice 1.5, 2, 4 or 6 mm, the instrument can measure across a range of application in print and packaging. For each eXact aperture size, the target window is 1mm (radius) larger than the spot measurement area size. This 1 mm over illumination of the measurement area is required by ISO5/4. The White area around the patch does not influence the measurement data, but does require the operator to center the measurement sample in the target window opening.

The information provided here comes from X-Rite.
Article information
Applies toColor Engine Pilot 12.x
Last revised 
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