[filmscanners] Re: Dynamic range question

["" <lists@lazygranch.com>]

I think it would be important to get a scanner where averaging can be
done without moving the sensor. Vuescan can do averaging, but with my
Artixscan 4000, the the image must be scanned multiple times. This is
from scratch, i.e .the whole image is scanned multiple times, moving the
film over the sensor on each scan. With the Polaroid version of my
scanner, the scan line itself can be averaged without moving the line
sensor. That is, for each line that is scanned, the CCD is read multiple
times. This allows the noise to be reduced without adding blur due to
imperfections in the repeatability of the scanner in term of position.

Incidentally, I've gone to Astia 100F to get around blowing the
highlights. It is less contrasty, but on average, I get better shots in
situations where I really can't control things like specular highlights
that often go to white on Provia 100F. Even when Astia is pushed one
stop, I think the contrast is still a little less than Provia 100F.


Paul D. DeRocco wrote:

>>From: Andrew Skretvedt
>>
>>In evaluating a film scanner, one should consider its dynamic range. How
>>deep can a scanner reach in and pull out shadow details from a very
>>contrasty slide, for example. What about one that might have been
>>underexposed a bit as you tried to keep from blowing out highlights?
>>
>>I've seen some dynamic ranges posted for certain scanners here and
>>elsewhere, many appear to be measured figures. But for the Minolta
>>DiMAGE Scan Dual III and IV, the posted figure is 4.8 (calculated).
>>
>>That figure appears to be the theoretical dynamic range for the bit
>>depth of the capture. Of course this is not going to be its true range.
>>Does anyone know the actual range of these scanners? How is dynamic
>>range measured?
>>
>>
>
>Dynamic range is limited by noise in the sensor. You rarely see specs on
>this, even though a meaningful spec standard could certainly be devised.
>
>--
>
>Ciao,               Paul D. DeRocco
>Paul                mailto:pderocco@ix.netcom.com
>
>
>
>
>

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