On Thu, 07 Jun 2001 23:48:17 -0400 Isaac Crawford (firstname.lastname@example.org) wrote:
> Hmmm... was the scanner *adding* the dust and scratches? I would
> have a scanner that gets as much info off of the film as possible, and
> if there are dust and scratches on the film, they should be resolved...
> I'm funny that way...;-)
If you compare collimated vs. diffuse heads on an enlarger (ie all else
remains the same), the result on my Durst is about +1 grade harder from
the condenser head. There is no perceptible difference in image sharpness
at all, even using a loupe, but apparent image sharpness is enhanced by
greater contrast. You don't get any more information off the film. However
you *do* get genuinely sharper, better defined and uglier images of dust
and scratches from collimated light.
I can only resolve this paradox by thinking that the 3d nature of such
cack is the origin of the difference. Relative to film grains, detritus
and dust and scratches have significant depth and size. Illuminated from
all angles, the diffuser case, tends to mask them (soft light), whereas
collimated light shows them up magnificently. Film grains and clumps are
relatively minute, so exhibit little real loss of definition, but manifest
it as lowered contrast across the image.
IME this is also true of the Nikon LED lightsource, but to a lesser
degree. All filmscanners I've ever used have an alarming propensity to
hallucinate rubbish which vanishes in a diffuser enlarger head, but the
Nikons do elevate gunge discovery to an artform.
TBH I think this means there's *lots* of scope for scanner lightbox design
improvement, to give a proper diffused source. IME they just shine a tube
through the film and aren't all that diffuse at all. But such old
tech tricks have been outmoded by software ;)
http://www.halftone.co.uk - Online portfolio & exhibit; + film scanner
info & comparisons