hybrid screening

If I get a hybrid screen for my imagesetter will i be able to print 200lpi on my machine a roland 204 '98?Is it hard to print with hybrid screeens?Anyone with experience?
Thanks!

Hybrid means a combination of monette screening and AM screening?

Hi Luigi!

Even without a hybrid screen, your Roland 204 should be able to print 200 lpi. I say this because, during the time when my press was operational, we were printing 190 lpi on our 2 Komori Sprint 226's. (Your 204 is definitely a much better machine than the 226) We could easily have used 200 lpi; but 190 lpi was the maximum screen resolution of my imagesetter at the time.

The first thing I suggest you do is check if your platemaker can transfer the 200 lpi screen to the ps plate.

Do I have to decrease dot size from the imagesetter to compensate for the dot gain on the press?

The dot size in your film will have to be lower than the expected dot size; because, when you print, the dots will increase based on the dot gain of the printing process.

You can lower the dot value either in Photoshop or in the rip software.

Please take note that dot gain increases as the screen resolution increases.

We may want to linearize first our plate by creating a linearization curve in the RIP. If we have a reflective densitometer, why not go for gold and aim for ISO12647-2:2004?

FILE / FILM % (STIMULI)
10
15
20
30
40
50
60
70
80
85
90
95

ISO CMY when measured in Print (WANTED CMY)
14
20.9
27.6
40.7
53
64.3
74.5
83.4
90.7
93.7
96.3
98.4

ISO Black when measured in Print (WANTED BLACK)
15.6
23.1
30.2
43.7
56
67
76.6
84.9
91.5
94.3
96.6
98.5

HERE ARE THE STEPS:

Imagesetter: Print these tone patches (STIMULI) with the Linearization Curve ON, and Calibration Curve OFF.

Press: If we don't have a spectrophotometer, print these patches with the standard ink densities provided by our ink manufacturer.

Measurements of the patches (at least 10 sheets) are done 24 hours after. Use black backing. Average your values.

Go to the RIP in the Calibration Curve area and enter the above-mentioned ISO values as our WANTED Values. And then beside it, we enter the MEASURED values that we have averaged.

***CMY and K have different WANTED Values. Be careful.***

The RIP will compare these WANTED (ISO) values with the MEASURED values . The RIP will compensate by adding, or subtracting the difference so the next time we print our plate, adjustments have already been made in the film. Our plates will not be linear anymore.

After which, we turn Linearization Curve ON & Calibration Curve ON...and print the live job with the same densities. This should be okay....according to ISO...that is.

Hope this helps.