Rob,
negs and slides are very alike. Both use silver halides, and multiple layer
design (2-3 layers for one band, varied speed). Even films like Astia 100 -
3 yellow, 3 magenta, 3 cyan, plus auxiliary. This is a common concept.
Spectral sensitivity varies between films, so the spectral properties of an
image dyes. However, for a given information content, negs carry more
clouds - due to masking dyes. In a slide film components are colorless, in
negs they are colored. So, even if the component does not form some part of
the image (sort of negative to negative), it can be seen as a part of an
orange mask. To be exact - green-sensitive layer with yellow colored
magenta forming coupler, or red sensitive magenta colored cyan formed
coupler. But it is my speculation. For the record - the excellent film
Reala does have 4th (cyan sensitive) layer which is image forming, it is
not filtering layer as some insist. It does change the spectral sensitivity
of the film to more accurately mimic a human vision, or make it more
forgiving for illumination mismatches.
Our problems with LS30 may be caused by "colimated" light of LEDs, as
oposite to diffuse illumination in most scanners. In similar manner as in
enlargers with point light source vs. diffused.
Roman
At 17:43 29/11/2000 +1000, you wrote:
>Guy wrote:
> > Yeah, but isn't that because most negative films have tons of
> > latitude?
>
>I'm not sure if anyone with more knowledge of film chemistry confirmed this
>suspicion of mine - that the graininess of print film of a given rated speed
>compared to slide film was precisely due to multiple emulsion layers with
>varying grain sizes (and speeds)?
>
>Rob
>
>
>Rob Geraghty [EMAIL PROTECTED]
>http://wordweb.com
"Don't worry about the world coming to an end today. It's already tomorrow
in Australia".
