Bob wrote:
>I think what you may have here derives in part from the sky and other nominally
>bright parts of images on negatives being the darkest -- most dense --
in
>the film. So sky in negs can be more difficult and show grain and/or noise
>much like dark shadow areas of slides are the difficult parts to scan and
>image.
I believe that for some reason there is more CCD noise in the blue channel
than other channels. It may be that the effect of Nikon's collimated light
is more pronounced in the blue channel than elsewhere - certainly shorter
wavelengths might show different focus than longer wavelengths. However,
the negative has the blue channel inverted doesn't it? :) I'm not hugely
concerned about what the source of the effect may be - the fact is that
on my LS30, all slide films scan far better in terms of apparent grain than
the neg films I've tried.
AFAICS slide grain is far more homogenous than neg film - which I presume
is also why negs have much more latitude than slides.
Rob
Rob Geraghty harper@wordweb.com
