Kodak provides various raster file targets to aid in exposure setting. These high-resolution 1-bit TIFFs can be used without having to configure and run test files through the Prinergy/Evo workflow system. They are composed of a single-angle separation at representative line frequencies, rendered at the two most common resolutions of 2540 dpi (100 dpm) and 2400 dpi (94 dpm). These can be used before the Prinergy workflow is set up, to determine media settings.
The table below lists the targets produced in raster format.
Round dot at 37.5°/2400 dpi | Round dot at 37.5°/2540 dpi |
|---|---|
65 | 65 |
85 | 85 |
100 | 100 |
110 | 110 |
120 | 120 |
133 | 133 |
150 | 150 |
175 | 175 |
Figure 1. Exposure test target
Figure 2. Exposure test marked off to change UV exposure times for each target
There are suggested face exposure times above the individual step targets. If desired, the vector PDF can be opened in Adobe Illustrator, and the text edited if the media representative wants to use and record different face exposure times. This target is provided only as a potential aid—media representatives may prefer to use their own.
The media representative will examine the exposure tests to determine which face and back exposure times produce the best combination of print quality and time efficiency.
Figure 3. Halftone dots showing effects of longer exposures—clockwise from top left, 2.5, 5, 10, and 15 minutes respectively
After a certain point, increased UV exposure times will not result in a larger dot, even if you use very long exposure times. Longer UV exposure times will increase the cross-linking, and may increase the strength of the polymer bonds. However, longer exposure times can also result in brittle dots that may break off under impression.
See Also