[filmscanners] RE: Scanning negs vs. slides

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

> Theoretically, any
> difference with slides should be attributed to their optical
> density and the
> possible number of f/stops.  Slides are usually attributed with an optical
> density of not much more than '3', which limits the number of f/stops to
> ~10.  Negatives, on the other hand, are claimed to have the potential for
> ~14 f/stops.

Hey Michael,

Optical density and "number of f-stops" that film records aren't directly
related.  You say that negative film, which has a LOWER optical density,
records more f-stops...so how is the optical density limiting the number of
f-stops?

The scene optical density doesn't directly translate into film optical
density (relatively it does, as in something darker in the scene will be
"darker" on film, but not absolutely, as in something 2x darker in the scene
won't be 2x "darker" on film)...you can have a very wide density scene, and
compress it to a very narrow density range on negative film...

Regards,

Austin

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