Hi JP,
The Ryobi presses are very good (as are many other brands). Are you getting a new one?
The DPX is very good, but is restricted by the polyester plate. This struggles to hold a 2x2 20 micron hilite dot at 2540 dpi. If everything is setup perfectly, then on a good day you might be able to, but I'd not like to try that. The plate also struggles to hold open a 3x3 30 micron shadow dot at 2540 dpi, depending on the gain you have on your press.
An uncalibrated 2x2 20 micron dot pretty much corresponds to a 2% of a 175 lpi screen at 2540 and a 3x3 30 micron dot to a 4%. That means you're really only getting an uncalibrated range of 3-96%. So really a 175 is the highest you'd want to go. I'd not really want to try 200 lpi on a DPX.
if you go to metal violet plates with the best plates, you can hold a 2x2 hilite dot and a 3x3 (or even 2x2) shadow dot. If you go to most thermal plates, you can hold a 2x2 hilite dot and most will hold a 2x2 shadow dot.
What Terry says about stochastic screening is not 100% correct.
For a stochastic screen to work you need to have a min dot size of 3x3 pixels, 30 microns at 2540 dpi on the DPX (or it drops dots), which means more like a 4% tint. It is a little large, but of course that assumes you have square dots...
The quality you also get depends on how well you control gain (which no FM screen does) and the dot size - it's not how big it is that matters, but what you do with it that counts...
I don't know if you saw the Press Release that went out last week about Auraia-II -
AURAIA II ACHIEVES HOLY GRAIL OF STOCHASTIC SCREENING ... - our DM (Digitally Modulated) screen, which is quite different from an FM screen.
With this we have perfected stochastic screening. If you can hold a 2x2 20 micron dot at 2400/2540 dpi, we can generate prints that have no noise in them whatsoever, with detail of circa 400-500 lpi. This works on both violet and thermal devices. Nothing else comes close, especially on violet. In fact flat tints with Auraia-II are so smooth, they are smoother than conventional screening and much smoother than high lpi (250+) conventional screens.
The other key thing about Auraia-II is that it has none of the drawbacks of FM screens. Yes Auraia has more gain than conventional screening, but about half that of FM screens - in one test we did Staccato gained by about 20% at 50%, whereas Auraia only gained by about 10% (Stacatto was also very noisy and Auraia was very smooth, but that's another discussion).
However, that's no good for the DPX, which needs a larger min dot. For this we have a Medium Quality (MQ) screen that uses a min dot of 3x3, 30 microns at 2540 dpi and this looks pretty good, but you could debate with me if it's smooth enough. That's not good enough for me.
So to perfect this we've therefore developed three special screens which use a dot size 'smaller' than a 3x3, but 'larger' than a 2x2 (e.g. 2x5 / 5x2, 2x4, 4x2, 2x3, 3x2, ...). We are currently testing this at a printer and results so far are very positive - they've been using it for a couple of weeks now without any problems. We're planning to run this for a little longer (another month) and will then put it on general release. If anyone else wants to try it though, by all means contact me.
And yes this also generates image quality of around 400-500 lpi. On a DPX - yup, for real.
So, I have to say that yes there is no way of using an FM screen to get what you want, but with Auraia-II, there is a DM screen that will.
PS If anyone doesn't believe me, contact me off-line and I can send you lots of samples which prove it. Or ask Gordon Prichard or Andy Tribute who have seen some.
Best Regards,
Andy.
Andy Cave,
Chief Executive Officer,
Hamillroad Software Limited.
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