[filmscanners] Re: over resolving scans

["Anthony Atkielski" <anthony@atkielski.com>]

Tony writes:

> I've seen this comment and similar ones regularly
> but I've never understood why these films are
> problematic to scan.

Slide films and black and white films can be very nearly opaque in their
darkest areas.  Since those areas can still contain detail, you need a very
sensitive scanner to pull those details out.  On B&W negatives, this equates
to detail in highlights; on slides, it equates to detail in shadows.

Color negatives present no problem, because they are never anywhere close to
opaque, and the range of densities on the negative is very small.  Just
about any scanner can see all of that with ease.

> The range of light that the film can handle (subject
> luminance range), whether very large or not, is mapped
> to a reasonably manageable density on the film, with
> dmax usually not exceeding 2.0.

Slides go higher than that, and so do (true) B&W films.

> Is it something peculiar to silver based films
> that causes difficulties?

Silver is a metal.  You can make the film pretty much opaque in its darkest
areas.  That's hard for a scanner to penetrate, much like the dark areas of
slides.

However, I have more trouble with slides than with B&W, but that may be
because so few B&W shots actually exploit the full density range of which
the negatives are capable.

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