[filmscanners] RE: Black and white scans on LS4000 ED andotherissues

["Austin Franklin" <darkroom@ix.netcom.com>]

Bob,

> Enlargers can have interchangeable diffuse light sources and
> parallel light
> sources. The former give soft images with less contrast, while the latter
> give sharper images with higher contrast.

That's absolutely NOT true.  You do NOT get softer images with less contrast
from a diffuse (typically called "cold") light source.

There has always been a controversy about the merits of
cold-lights.  Careful tests have proven that exactly the same tonal
rendition can be attained with either a cold-light or a conventional
condenser when the contrasts of the film/paper are adjusted to match.

The contrast difference between condenser and diffusion sources is
due to "Callier" effect which is scattering of light by the grains of
the film.  The thinner the emulsion and the finer the grain, the less
Callier effect there is.  For color film, where the image is composed
of very small dye particles, there is practically no difference between
them.  The diffused source will tend to show blemishes less so is
commonly used for color printing.

Personally, I believe cold light heads give better tonality for B&W chemical
darkroom printing, having spend some 25+ years printing fine art B&W
prints...

Austin

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