Epson printers - 2400 vs. 4800 ??

"David Nebenzahl" wrote in message
.com...

Right; seems to me the fibers in the paper are going to be *much* coarser
than that claimed high resolution. Anyone know for sure?


You're not printing on fibers. There are about a half-dozen
layers on top of the fiber, and you're printing on the topmost
of those. It's likely to be kaolin or microcrystalline, or maybe
a swellable polymer. But definitely not fibers.


rafe b
www.terrapinphoto.com

rafe b spake thus:

"David Nebenzahl" wrote in message
.com...

Right; seems to me the fibers in the paper are going to be *much*
coarser than that claimed high resolution. Anyone know for sure?

You're not printing on fibers. There are about a half-dozen
layers on top of the fiber, and you're printing on the topmost
of those. It's likely to be kaolin or microcrystalline, or maybe
a swellable polymer. But definitely not fibers.

Well, OK; you're right. But even a kaolin (clay-coated) surface isn't
going to be smooth enough to make 5670 dpi anything but an inverifiable
marketing claim.

I'd like to see something like a scanning electron microphoto of the
surface.


--
The only reason corrupt Republicans rule the roost in Washington
is because the corrupt Democrats can't muster any viable opposition.

David Nebenzahl wrote:
rafe b spake thus:

"David Nebenzahl" wrote in message
.com...

Right; seems to me the fibers in the paper are going to be *much*
coarser than that claimed high resolution. Anyone know for sure?


You're not printing on fibers. There are about a half-dozen
layers on top of the fiber, and you're printing on the topmost
of those. It's likely to be kaolin or microcrystalline, or maybe
a swellable polymer. But definitely not fibers.


Well, OK; you're right. But even a kaolin (clay-coated) surface isn't
going to be smooth enough to make 5670 dpi anything but an inverifiable
marketing claim.

I'd like to see something like a scanning electron microphoto of the
surface.



The dot gain alone would be far higher. Best I have heard from inkjet
(ColorSpan) was about an 8 µm dot, but I have not directly tested that
claim.

"David Nebenzahl" wrote in message
s.com...
rafe b spake thus:

You're not printing on fibers. There are about a half-dozen
layers on top of the fiber, and you're printing on the topmost
of those. It's likely to be kaolin or microcrystalline, or maybe
a swellable polymer. But definitely not fibers.

Well, OK; you're right. But even a kaolin (clay-coated) surface isn't
going to be smooth enough to make 5670 dpi anything but an inverifiable
marketing claim.

I'd like to see something like a scanning electron microphoto of the
surface.


I think most of us know that the contone resolution
is far lower than the advertised resolution.

That said, I received my Epson R1800 yesterday
and am pretty impressed with how fine and well-
placed the dots are, especially in "RPM" mode.
(RPM is Epson's acronym for their super-hi-res
photo mode.)

I've got an LF (4x5) shot taken with a 90mm,
printed at 8x10." With a loupe, you can clearly
make out some fence posts about 1/4 mile away.
The fence posts have a cross-section of around
1.5 inches -- you know, those stamped-metal posts
used for barbed wire and drift fences.


rafe b
www.terrapinphoto.com

"Gordon Moat" wrote in message
...

The dot gain alone would be far higher. Best I have heard from inkjet
(ColorSpan) was about an 8 µm dot, but I have not directly tested that
claim.


I don't think there's any appreciable dot gain
on a modern coated paper (eg. Epson Premium
Glossy.)

None except the "gain" you'd get from a spherical
droplet impacting on the paper's surface. It's
not going to spread much, after that.

IIRC, the dots in the best current Epson desktop
printers (R1800, R2400) are around 1.5 or 2
picoliters in volume. If my calcs are right, a 2 pl
drop has a diameter of around 15 microns,
assuming a density equal to water. I'm not
sure what it would look like after it hits the
paper and flattens out. At 2400 dpi, the dot
spacing is 106 microns, so that's an upper limit.


rafe b
www.terrapinphoto.com

rafe b wrote:
"Gordon Moat" wrote in message
...


The dot gain alone would be far higher. Best I have heard from inkjet
(ColorSpan) was about an 8 ?m dot, but I have not directly tested that
claim.



I don't think there's any appreciable dot gain
on a modern coated paper (eg. Epson Premium
Glossy.)

None except the "gain" you'd get from a spherical
droplet impacting on the paper's surface. It's
not going to spread much, after that.


All ink has a property called tack. Commercial printing inks are fairly
low tack inks, even if sometimes slightly less tack might produce a
smoother tone. Inkjet inks are largely very low tack, which basically
means they spread more. Paper absorption can either help or hurt that
spreading.



IIRC, the dots in the best current Epson desktop
printers (R1800, R2400) are around 1.5 or 2
picoliters in volume. If my calcs are right, a 2 pl
drop has a diameter of around 15 microns,
assuming a density equal to water. I'm not
sure what it would look like after it hits the
paper and flattens out. At 2400 dpi, the dot
spacing is 106 microns, so that's an upper limit.



That is about what I would have guessed on for a picolitre to micron
conversion. However, it seems to me that 15 to 20 would match 1.5 to
2.0. Anyway, I think it makes the ColorSpan claim not very easy to believe.

It bugs me about the picolitre usage, when the commercial printing
industry and major paper companies don't use such numbers. Also, while I
managed to get paper samples from Epson, getting specifications anything
near like what I would get from International Paper, Sappi,
Weyerhaeuser, or any other paper company didn't happen . . . the best I
could manage was incomplete data on weights, largely without whiteness,
brightness, nor surface finish. Sorry for the rant.

Also, 2400 for each colour, with an overlap and with some inkjet
printers an offset of droplets. I always was told the dpi quotes were
for dot placement, and that was across the board from every company.
Variable dot is a different matter, though the specifications can
indicate accuracy of dot placement.

Ciao!

Gordon Moat
A G Studio
http://www.allgstudio.com

Kennedy McEwen wrote:
In article w9bvf.7874$V.6727@fed1read04, Mark²
writes

I contend that there isn't ANY media capable of showing a benefit of
dpi that high.

There are plenty of such media, they just aren't papers. :-)

Who said anything about papers?
I still challenge anyone to produce evidence that ANY media will show the
useful exhibition of 9600dpi from an ink jet type printer.

Gordon Moat wrote:

rafe b wrote:
"Gordon Moat" wrote in message
...


The dot gain alone would be far higher. Best I have heard from inkjet
(ColorSpan) was about an 8 ?m dot, but I have not directly tested that
claim.



I don't think there's any appreciable dot gain
on a modern coated paper (eg. Epson Premium
Glossy.)

None except the "gain" you'd get from a spherical
droplet impacting on the paper's surface. It's
not going to spread much, after that.


All ink has a property called tack. Commercial printing inks are fairly
low tack inks, even if sometimes slightly less tack might produce a
smoother tone. Inkjet inks are largely very low tack, which basically
means they spread more. Paper absorption can either help or hurt that
spreading.

In other words it called giclee, or sprayed ink
and it definitely spreads. And at some point too
high a dpi is overkill...

But don't try to tell that to uniformed digital
geeks who think resolution is unlimited for both
ppi and dpi and limitations like dot gain don't
exist...

Kennedy McEwen spake thus:

In article w9bvf.7874$V.6727@fed1read04, Mark²
writes

I contend that there isn't ANY media capable of showing a benefit of
dpi that high.

There are plenty of such media, they just aren't papers. :-)

Like what--stainless steel? Precision-buffed to a high gloss?


--
The only reason corrupt Republicans rule the roost in Washington
is because the corrupt Democrats can't muster any viable opposition.

Mark² wrote:

I still challenge anyone to produce evidence that ANY media will show the
useful exhibition of 9600dpi from an ink jet type printer.

The dpis aren't there because someone might actually see
the resolution, they are there because the inkjet dot
is not a '24-bit' dot. The printer has to dither - and the
more dpi, the better it can do this.

So you have to divide the stated dpi by the number of inks
and then further by number of 'levels' you want to have
from one ink (depending on whether the inkjet can modulate
the size of the dot or not this really matters or not).
A 5760x1440 dpi printer with 8 inks is in reality 720x1440
for one ink color. Divide the 720 by two and you get 360 lpi -
something that is not far away from what one can see with
bare eye.

My previous printer was a several years old 1200x2400 3-ink
dpi HP all-in-one. The photos from it were good enough for
a 8 x 11 print that you don't look at closely, but were
unacceptable for regular 4 x 6 in - the dithering was clearly
visible when holding from a normal viewing distance.

My current photo-printer is a 5760x1440 Epson R1800 and
it is fantastic. I think one could construct an example
that makes its limits visible, but for normal use it
is amazingly good.

--
Stano