[filmscanners] Re: Scanning negs vs. slides

["Anthony Atkielski" <anthony@atkielski.com>]

Austin writes:

> Slide film has a lower dynamic range (which loosely
> translates into the number of tones the film
> can capture...it's a little more involved than that,
> but that's the basics of it) than negative film,
> therefore negative film gives you more tonality.

So why don't slide images posterize?  After all, if they can capture far
fewer tones than negative film, I'd expect to see more abrupt transitions
between different tones.

I'd also like you to explain why slide film would have less dynamic range,
given that it is essentially the same technology as negative film.

> Slide film has a larger DENSITY range than negative
> film.

If it has a larger density range, but a lower dynamic range, I'd expect to
see posterization.  Where is it?

> Slides DO have more contrast for a number of reasons.

The reason is that density varies more quickly with light exposure than on
negative film.  The density and dynamic ranges are the same, but they are
compressed over a smaller range of light exposures.  This increases contrast
and resolution in the midtones, but diminishes resolution in the highlights
and shadows.



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