Digital BW, The Print

From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Tuesday, August 20, 2002 5:56 AM
Subject: RE: [Digital BW] Dmax and drivers was Getting perfect neutral
prints from Epson 7600/9600 etc


>
> > Austin,
> >
> > I simply created a square in PS and filled it with 100% black. I printed
> > with the Piezo driver on one end of the paper then turned the paper
around
> > and printed the square again with the Epson driver on the other end. I
let
> > the print out settle for 24 hours and then took measurements. So same
> > printer, same ink, and same paper. The difference is definitely
> > greater than
> > the variability of my Spectrocam.
> >
> > Martin
>
> Martin,
>
> Thank you for describing your "experiment".  That goes a long way towards
> understanding what's going on, for me.  You didn't happen to look under a
> high powered scope to see what caused the difference?  Can you send me the
> file, and I'll try the same thing.  I have a 90x scope that I can get a
good
> look at what's going on with.
>
> I'd love to get an "explanation" for this from Jon ;-)

This is simply a different degree of ink limitation per given papersetting.
I can flood the canvas with black ink if necessary. The RIP allows that. In
a less open driver you can not control that amount but the software people
made that decision for you and the amount of black is more or less arbitrary
depending on what they think how much bleeding is allowed. Sometimes more
ink doesn't deliver more density though. It would be nice if in a given
maximum print time per square foot the black ink lay down is equally
distributed for any unit of time. The drying between each additional droplet
makes bleeding less. I don't know whether that is used to the maximum in all
drivers. Some weaving techniques will be better than others on this I guess.
Hard to see that with a microscope.
Best way is to stop a print when it isn't finished and then look how the
weaving is done. A high speed camera and slow motion projection is another
option. The Germans call that a 'Zeit Loupe'. Nice term.

Ernst

From: "Austin Franklin" <darkroom@...>
To: "Digital B&W Mailing List"
<DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Monday, August 19, 2002 8:20 PM
Subject: RE: [Digital BW] Getting perfect neutral prints from Epson
7600/9600 etc


(snip)
>
> My point is, there should be NO mix with dMax...it should only be using
the
> one black position for ink, period!  There also should be no dithering.
>
> > Getting a sharp, non bleeding
> > result with
> > smooth gradients through the dark tones is always a challenge
> > with heavier
> > blacks, but simply laying down more ink is easy. On some media,
> > adding more
> > ink may not make the resulting patch darker, on others it may.
>
> Understood, and agreed...but I'm simply, again, talking about black at the
> max.
>
> > I'll admit;
> > paper white is pretty much a fixed limit... but max black is not.
>
> Well...it depends.  If you change inks, then it should be the ink that
> changes the max.  If you have the same ink, just different "software",
then,
> I believe, there is something wrong with the software if it doesn't use
just
> black for max black.
>
> Of course, there is an issue with amount of in, on a printer that has that
> control.  But, on a printer that puts a fixed ink drop amount/size, this
> should not be an issue.

Austin,

I haven't a clue about the theory here but I have demonstrated to myself
with the original Piezo and the new PiezoTone inks that the Epson driver
produces a 100% level black square about 0.1 density units darker than the
Piezo driver. Antonis reported that IP4 pushed the same ink about another
0.03 units darker than the Epson. So for whatever reason, the driver does
play a practical role in the level of Dmax that is actually achieved.

Martin

From: "Austin Franklin" <darkroom@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Monday, August 19, 2002 8:45 PM
Subject: RE: [Digital BW] Dmax and drivers was Getting perfect neutral
prints from Epson 7600/9600 etc


> > Austin,
> >
> > I haven't a clue about the theory here but I have demonstrated to myself
> > with the original Piezo and the new PiezoTone inks that the Epson driver
> > produces a 100% level black square about 0.1 density units darker than
the
> > Piezo driver. Antonis reported that IP4 pushed the same ink about
another
> > 0.03 units darker than the Epson. So for whatever reason, the driver
does
> > play a practical role in the level of Dmax that is actually achieved.
> >
> > Martin
>
> Hi Martin,
>
> I assume you used the same inks with different drivers, right?
>
> If that is true, then, IMO, the driver is done poorly.  Something is fishy
> here.  I'll try a Piezo "black" and an Epson black, Epson driver using
> simply the single ink Epson B&W output...as it'll simply give me black ink
> only.
>
> Another thing, were the test all printed at the same time, on the same
paper
> (same batch, and same image), with the same ink (meaning the EXACT same
> ink), and done multiple times, and measured after the same amount of time
> (preferably immediately)?  I know this sounds anal, but I have found SO
much
> variance in these damn inks...the same print, printed tomorrow, will have
a
> variance of .1 density units from the one I printed today!  I've also
> noticed that the inks in the bottles aren't always fully mixed.  Sorry,
this
> stuff bugs me...
>
Austin,

I simply created a square in PS and filled it with 100% black. I printed
with the Piezo driver on one end of the paper then turned the paper around
and printed the square again with the Epson driver on the other end. I let
the print out settle for 24 hours and then took measurements. So same
printer, same ink, and same paper. The difference is definitely greater than
the variability of my Spectrocam.

Martin