[filmscanners] RE: Scanning negs vs. slides

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

> he turned to negatives solely claiming that he found
> the results to be better scanning negatives in case of wide dynamic range
> captured on the film.

It IS true that negative film has a wider dynamic range than slide film...

> He states that the image with
> featuring high contrast (night scenic for example) will be rendered much
> better by the scanner in terms of the details in dark, while
> highlights are
> still well preserved, whilst with slides often the dark details
> are missing
> being still resolved visually on light table under loupe.

That is not a dynamic range issue, but a density range issue (they are not
the same, though in the imaging world, for some reason, people use them
interchangeably, more likely because the word sounds cool and they don't
really know what it means ;-).

Slides DO have a wider density range than negative film, simply because the
image density range is from clear to black for positive film, where on
negative film, it's from film base to black...but that's only half the
equation.  Another reason that negatives don't have blocked shadows on a
"regular" scanner is because negative shadow detail is on the LOW end of the
density scale, and highlights are on the high end of the density scale.
Positives have the shadows on the high end of the density scale, requiring a
higher dMax to get to the shadows.

> Is that correct ?
> I usually prefer to shoot slides for anything except people-related stuff,
> but if is opinions have much to reflect the reality, I would
> probably switch
> to negatives for outdoors also.

Two issues with slides.  One is the have a far narrower exposure latitude
then negative film, and the second, the dynamic range (basically the amount
of tonality they can capture over the density range) of positive film is
lower than negative film.

Austin

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