Hi Frank,
There are a couple of questions to ask in terms of these specifications.
A/D bit conversion is correlated to dynamic range. In theory, a higher
bit depth in the conversion, should result in a better (higher) dynamic
range. But the truth is, it isn't that simple, and the quoted results
may be based upon the mathematical theory, rather than empirical
measured results.
In the case you mention, that is exactly what happened.
In a perfect (and unachievable) world, a 14 bit A/D converter would
result in 16,384 values which in log form is 4.2, likewise, 16 bit A/D
could convert to 65,536 levels or log 4.8.
Can either exist in the real world of scanners? No.
All sorts of problems enter into the equation, such as the amount of
noise a CCD sensor will generate in darkest areas, which determines
where the noise floor may overcome the ability to record accurate image
data); at what point the whites may blow out and cannot recover
information, how accurate or linear the values are, etc.
A very good quality CCD sensor used in conjunction with a 14 bit A/D
converter may supply a superior result to a poorer CCD with a 16 A/D
converter. The same exact CCD sensor in both circumstances may show
minimal improvement with a 16 bit A/D converter if it is not able to
provide low noise scans in the darker areas.
If you will be scanning slides, which tend to be quite dense, and
which are not inverted for luminosity as negs do, having a low noise CCD
and higher bit depth can be very valuable to "claim" all the shadow
detail. If you are mainly using negs, which tend to have less density
overall, and which get their luminosity inverted, a scanner with less
dynamic range may be just fine.
However, since the numbers being quoted are not actual reading of real
world conditions of either scanner, it is not possible to determine if
the extra money is providing you with significant improvement. You may
wish to try to get results from both scanners and see if you can verify
the difference is great enough to justify the price difference.
For more information on Dynamic Range you might want to go to the
following URL.
Art
Frank & Lila Mullins wrote:
> I am in the process of purchasing my first film scanner. Although, I will,
> at times, use the scanner to make 8 x 10 or larger prints, my primary goal
> is to convert my 35mm slide collection to digital. At present, am tending
> toward the Nikon Coolscan V. However, at a local photographic supply store,
> the salesperson basically told me I was wasting my money and should buy the
> Super Coolscan 5000 (at a cost of about $500 more!!).
>
> As best I can determine, there are two MAJOR differences between the two
> scanners:
> The Coolscan V has a dynamic range of 4.2 while the Super Coolscan
> 5000 has a dynamic range of 4.8.
> The Coolscan V has a 14-bit A/D converter
> while the Super Coolscan 5000 has a16-bit A/D converter.
>
> My questions is this: Do these two differences justify the added expense of
> $500 or will the less expensive scanner meet my needs?
>
> Thanks for your input.
>
> Frank
>
>
----------------------------------------------------------------------------------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or
body
