Digital BW, The Print

----- Original Message ----- 
From: "Anton Pickard" <lightworx@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Monday, May 26, 2003 7:35 PM
Subject: RE: [Digital BW] Re: Scanning


> Does this imply that if I am using B&W film (not C-41) where I have some
> control over development times etc, that I should calibrate the
> exposure/development time of the film optimally for the scanner’s
> sensitivity range in order to maximize the tonal range? If this is the
case,
> are there any guidelines for doing this?

Anton,

This could be done in a traditional Zone System approach. You would need to
first determine the maximum density you scanner can work with. This is done
by scanning a known density wedge from Kodak or Stouffer
(http://www.stouffer.net). You would then adjust your film development so
that your Zone IX or X values matched the maximum the scanner can read. This
is much the same way you would work with step-wedges, film and silver paper
to determine optimum exposures and development

However this would not be useful. Some general numbers: drum scanners max
out at optical densities of 3.0 to 3.4, high end CCD scanners such as the
Imacon and Nikon 8000 round 2.7 with flatbeds falling in at 2.6 and below.
Traditional Zone System densities for Zone VIII are around 1.20 to 1.50 and
Zone X hitting ~1.80. So scanners can punch through some pretty high film
densities.

Unfortunately placing Zone X up at 2.6 is not going to work well. Even
though the scanner can read it you will have exceeded the films ability to
clearly render detail due to light scatter within the emulsion during
exposure, grain bloom during development and other effects. You will be
exceeding the intended useful range of the film. The scanner gives you a
better margin of error in the highlights but doesn't free you from the need
to make good decisions regarding exposures and development. Blocked up
highlights are not just a matter of density.

A good test might be to photograph a resolution target at progressively
higher exposures and developments to determine the point where resolution
begins to degrade when scanned. This along with a scan of the resolution
target itself would give you a good idea of the maximum usable density the
film and scanner can work with. You also might want to photograph calibrated
step wedges and tone ramps along with the resolution target so that you can
check for tonal compressions.

Martin Wesley