Digital BW, The Print

Austin,

I may be fuzzy in my understanding of how PMT scanners work.  I am using a
Howtek 4500 and have also scanned with Polaroid and Scitex flatbed and film
scanners.  The one thing I've noticed about all these scanners and their
software is that they are very imprecise about resolution.  In most cases,
as I mentioned, the terminology comes from the pre-press world, where %
enlargement based on 300 DPI was the norm.  It's often very difficult to
determine the actual scanning resolution.

As I understand it, with Howtek (and other PMT?) scanners, "native
resolution" is determined by the selected orifice size (is that the right
term?).  Where I guess I'm unclear is how intermediate resolutions are
achieved.  I had thought that for, say, 3250 DPI, the scanner would actually
scan at 4000 DPI and then interpolate down to 3250 DPI.  Are you saying it's
done differently?

Bill

on 3/21/02 9:50 PM, Austin Franklin wrote:

> Mike, I'm not sure I'm following you.  Are you scanning the negative @364
> DPI or is the 20x20 print @ 364 DPI?

Bill,

He's talking about a different beast then you are probably used to.  I'm not
saying he's right or wrong, as I don't know his scanner, but PMT scanners
(Photo Multiplier Tube), AKA drum scanners, aren't subject to the resolution
issues CCD scanners are.  They only use a single element sensor, and an
aperture.  The aperture is typically selected such that the width of the
resolution is covered.  It's the drum that moves in an XY pattern,
illuminated from within for film, to scan the media.

Regards,

Austin


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