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[filmscanners] RE: My best scanner/film combinations

> > > > > ...  Grain is a matter of resolution, not a
> > > > > matter of tonality.
> > > >
> > > >   ...  Assume 2 films ... both the same speed and
> > > > resolution, ...  To achive the same tonal range
> > > > by scanning, you need to ask the scan of the negative to
> > > > increase the contrast ... which will enhance the grain.
> > >
> > > Hi shAf,
> > >
> > > Certainly not if the scanner can't resolve the grain...  The
> increase in
> > > density range is handled by exposure time.  Nothing in the
> CCD-A/D path
> > > changes...just the time the light shines.  The light type the
> scanner uses
> > > also has a huge effect on grain, scratches etc.
> >
> >   I would agree to dissagree on that point.  That is, if you do
> anything to
> > stretch a film's D=2.5 to an equivelent 3.0, you'll enhance the
> grain ...
> > whether it's more light or a longer exposure time.
> This is what I think you are saying.....
> When you stretch a film's D=2.5 to 3.0 you are increasing the contrast.
> As the contrast between neighbouring grains/dye clouds increases they
> become more prominent thus the perception of a grainer image.
> Think of it this way......
> If i do a scan of a slide and a neg (both 100 speed film) using the
> scanner at full dynamical range I get 2 scans with the same grain
> appearance.  I have to increase the contrast on the neg image so it
> looks good for printing. This increases the contrast in neighbouring
> pixels which draws more attention to what people on this mailing list
> call grain. The grain does not get bigger i.e. you are not losing
> spatial resolution. Effectively there is less useful colour information
> in this scan now.
> Going back to the slide image, you do not have to do the increase in
> contrast so you do not have this problem.

Hi Anthony,

My contention is that is not the way scanners work.  They scan the same for
chromes as they do for negatives, just change the exposure time.  How it
works, is the range of data that you use out of the overall range is, of
course, different.  You are taking values of, say, 100-1640 for negative
film, and 100-4000 for positive film.  Now, does that in fact increase grain
"appearance"?  I do not believe so, but I'd have to think about it a
bit...but my experience tells me no, and that what people are seeing is more
a product of their development/film/scanner light source than of negative vs
slide film.


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