[filmscanners] RE: scanner dmax discussion

["Austin Franklin" <austin@darkroom.com>]

> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Paul D. DeRocco
> Sent: Saturday, July 12, 2003 1:47 PM
> To: austin@darkroom.com
> Subject: [filmscanners] RE: scanner dmax discussion
>
>
> > From: Karl Schulmeisters
> >
> > Except Austin, that's not how these devices are calibrated or
> tested.  The
> > universal (I have yet to see another one used but I am willing to be
> > corrected) approach is to use a step tablet with density
> increments of 1/3
> > of a stop and the 'dynamic range' is measured by seeing where
> the scanner
> > ceases to differentiate between two adjacent steps.
>
> I would assume that that limit would always be on the dark end, and that
> instead of running out of bits, the steps would just disappear into the
> noise. So noise would be the limiting factor, not the A/D resolution. Am I
> wrong?

Paul,

That is true only if the scanner is designed with the A/D resolution being
greater than the noise, obviously.

What he is bringing up is how to measure the scanner density range...which
really has nothing to do with what we were talking about, so I'm not sure
why he brought it up.

Regards,

Austin

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