Tomasz wrote:
> Why do scans of color negatives appear grainier
> than those from slides?
>From what I've read on this list, it's related to the exposure latitude
of colour negs. To get greater latitude, the grain in neg film varies in
size much more than in slide film. The very narrow exposure latitude of
slide film results in more consistent grain.
My experience with a 2700spi scanner is that the larger elements of the
neg grain cause aliasing and makes the grain appear to be "worse" than it
really is. Scanners with collimated light sources like the Nikons will
tend to see grain more than those with diffuse light sources like the Polaroids.
I haven't used a 4000spi scanner enough to know for myself, but other such
as Tony Sleep have said that "apparent grain" in negs is a lot less with
a 4000spi scanner like the SS4000 than with a Nikon scanner.
Tony (and others I think) have also mentioned about the visibility of different
sized grain patterns depending on how the film is exposed and developed,
but I think that's an issue better covered by someone who understand the
chemistry.
> I have always read and experienced myself that color negs
> are less grainy, especially in high ISO emulsions and that
> in slides everything above ISO 100 shows pronounced grain
> (ok - naow we have Provia 400F).
I think virtualyl all my slide films are ISO100. As far as I can remember,
I've shot one or two rolls of Kodak Extachrome push film at EI1600, and
a roll of Provia 400F. I didn't mind the grain in the Provia. Ah- I've
also used a couple of rolls of Kodak 320T and they were very grainy, but
I expected that under the circumstance (dark stage lighting).
> I'm just curious what's so peculiar in film structures
> that different effects are achieved although both types
> of film use dye clouds.
FWIW the different dye clouds seem to behave quite differently with light.
Colour neg film grain seems to look sharper and more coarse, while slide
film grain seems to look smoother. I've seen photomicrographs of Provia
100F and it looks quite amorphous.
Rob
Rob Geraghty harper@wordweb.com
