[filmscanners] Re: Density vs Dynamic range

["Todd Flashner" <tflash@earthlink.net>]

on 6/12/02 12:19 PM, Austin Franklin wrote:

>> What would constitute that
>> noise?
>
> I believe it's because of the negative films ability to record a higher
> overall scene density range, it simply has more dynamic range, given the
> same amount of noise in both.

Hi Austin,

Well, this gets back to my problem with discussing the dynamic range of a
material as opposed to a process. You are saying a piece of slide film, a
frame of exposed film, has a lower dynamic range than negative film BECAUSE
neg film can conceivably hold a greater scene luminosity range.

But on the other hand, if the materials were chosen to match the luminosity
range range of the scene properly I don't believe you can make the same
assumption. For example, if your luminosity range contains a 6 stop range,
which is within the tolerance of slide film, and you shoot the scene on
slide film and neg film, of the two frames of film I believe the slide frame
would be the one with the higher dynamic range. It would be taking the same
luminosity, but spreading it across a larger density range than neg film,
without clipping, and with the same noise. The neg film would be compressing
the relatively short luminosity into a lower density range.

IOW, once the film exists as a photo, and the luminosity or the original
scene is no longer relevant, the dynamic ranges of the two pieces of film
itself would be different than that of the capability of the films under
different original conditions.

I don't know if that makes sense, but the baby is crying, Gotta run. ;-)

Todd

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