[filmscanners] RE: 12 vs 16-bit A/D conversion. Was: WinXP and Dimage Scan Dual II and more

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

> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Preston Earle
> Sent: Tuesday, November 12, 2002 8:23 PM
> To: austin@darkroom.com
> Subject: [filmscanners] 12 vs 16-bit A/D conversion. Was: WinXP and
> Dimage Scan Dual II and more
>
>
> Curt Degler wrote: "Anyone with experience running  the Scan Dual II run
> with Win XP? Its not listed in the scanner specs."
>
> and "Arthur Entlich" <artistic-1@shaw.ca> answered: "The Minolta DUal
> Scan II may be good value if it is being heavily discounted.  The
> Minolta Scan III sounds like it may be worth a few extra bucks however,
> due to an improved interface (USB 2.0) and a higher A/D converter (16
> rather than 12).  It also appears to have new software."
> ------------------
>
> I don't know nothing about no stinking electronics, but if you're saying
> that a 16-bit A/D converter will give the Scan Dual III better
> performance, I'd take issue with it. I guess theoretically a 12-bit
> conversion will yield 1024 distinct values, while a 16-bit conversion
> will give 16k values. But I'd say the Scan Dual III's ccd's have trouble
> reliably measuring 4 good bits of data in dark, shadow areas, and in any
> other "photographic image", the 13th-16th bits have the same value that
> loose change has to Bill Gates. The USB 2.0 interface is probably a real
> benefit over the Scan Dual II, but I don't know about that A/D stuff. I
> have a Scan Dual II and think it's a wonderful $300-$400 scanner, but
> it's no high-end device.
>
> Preston Earle
> PEarle@triad.rr.com

Preston,

You're absolutely right.  The extra bits do in no way mean the scanner gives
better results, and in fact, you may get better results from a 12 bit
scanner.

The spec sheet says that the dynamic range is "4.8 (computed)", which
basically means nothing.  This is one of the issues David from Polaroid
talked quite a bit about, that there is no standardized testing for dynamic
range (at that time that is), and one of the issues the ISO is in fact
addressing.  I am surprised that Minolta didn't adopt the new ISO proposal
for testing dynamic range, and use those results as the basis for their
spec, instead of simply stating the dynamic range that 16 bits can hold.

Regards,

Austin

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