Can anyone provide real world feedback on using the Sublima and/or Crystal Raster screening to resolve moires in fabric and other patterns? We are in the process of installing Apogee 6 and Agfa is pushing these as the replacement for our current stochastic screening. I would like to hear feedback from someone who uses this on a fairly consistent basis to see how well it fits the bill and if there are any challenges with it.
Agfa :CrystalRaster and :Sublima should not be compared against each another since :CrystalRaster is an FM screen while :Sublima is basically an AM screen (Agfa ABS). Instead they should be compared against screens in their respective families, i.e. :CrystalRaster against other FM screens (Staccato, Satin, HDS, etc.) and :Sublima against other AM/XM screens (ABS, Maxtone, HQS, etc.)
This is what :CrystalRaster looks like close up (2400 dpi):
This is what :Sublima looks like close up (2400 dpi):
As a comparison, here is what Agfa ABS - a "conventional" AM screen looks like (2400 dpi)
:CrystalRaster is Agfa's implementation of a "First Order" FM screen. :Sublima is their implementation of a hybrid AM screen (a.k.a. XM screen).
Because :CrystalRaster is a 1st order FM screen it shares many of the issues of that class of screening. Grainy flat tint areas as well as being problematic in plate imaging and possibly on press due to the small size of the dots that propagate through the tone scale. On the plus side, when reliably imaged it will eliminate rosettes and subject moiré (i.e. the moiré thant can occur with fabric)
At its heart :Sublima is ABS screening - Agfa's core AM screening technology. However, at the extreme highlight and shadow dots the actual smallest dot size is restricted to the minimum dot size that can be reproduced by the imaging system (CtP, plate, and/or press). Typically it's the 2%/98%, or 3%/97% dot that is specified as the minimum allowable dot size. It recovers the tones that would otherwise be lost by varying the number of same-size AM dots in those tones rather than their size. That is the "FM" part of the screen. It is a screening solution to an imaging resolution problem. This class of screening is most often used in flexo applications due to the low resolution of the majority of flexo plates. Because only the 2%/98%, or 3%/97% dots are affected there are no magical properties presswork properties that are not also available with conventional AM screening (including Agfa's).
Because :Sublima is at its core Agfa ABS (AM) screening it performs identically to a conventional AM screen as far as moiré is concerned. What it does allow is higher than 200 lpi screening on Afga systems (other vendor systems may not need this resolution limitation work around for their metal plate CtP). Higher lpi AM/XM screening may avoid subject moiré - depending on the frequency of the subject's pattern. But it is an lpi moiré solution rather than a dot pattern solution.
Make sense?
You don't say how much of Agfa's equipment you've switched to (workflow, plates, CtP ?), however if you've jumped ship completely from your current vendor to Agfa, my suggestion would be to avoid :CrystalRaster for production work - although you may find it worthwhile to experiment with it. Instead use ABS at 200 lpi and if you need to got to higher lpi, then you have no choice but to use :Sublima.
(PS In addition to a great deal of background, I was a beta site for Agfa :CrystalRaster and wrote the BRIDG's guide to screening technology whose content was vetted by all of the major vendors including Agfa).
best gordon p
