Digital BW, The Print

Hi Jerry,

Are you including PMT scanners in your question?  They have a far greater
chance of reaching those "heights" than a CCD scanner, simply because they
have far less noise.

It's pretty much a matter of noise in the system.  I know that my Leafscan
can get over 3.2, and I've measured that (3.6 actually).  Some of the
sensors claim a dynamic range of >84db, and that translates into a dRange of
4.2...but I can't vouch for what the electronics (analog gain stage, plus
A/D converter) behind the sensor have for noise, but theoretically, it's not
unreasonable to get in the high 3s without too much difficulty...

I'd say that in most of the mid to low end desktop scanners, what you say is
probably more realistic, that they'd be hard pressed to really get 3.2...and
I believe it's safe to say they probably don't get near 4.

This is actually one issue that scanner manufacturers should be beaten up
on, rightly so.  What anyone who is claiming a dynamic range of 4.2 is
probably really saying, is they use 14 bit A/D converters, not that they
really have tested their system, and can substantiate the 4.2 dRange...so
just like the Bayer pattern BS, it's probably the same thing...marketing
mis-information.

Regards,

Austin



> -----Original Message-----
> From: Jerry Olson [mailto:jerryolson@...]
> Sent: Tuesday, February 19, 2002 11:55 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: Re: [Digital BW] Re: The Difital Revolution - WAS - AIPAD
> Galleries List
>
>
> Austin, you would seem to be the person who could accurately
> answer this question:
>
> I think the claims of some of the desktop scanners are bordering on
> fable-spinning.  What is the maximum density you could actually get out
> of a color slide? I've heard that no scanner in the world could actually
> get a 4.0 density range, and it is very difficult to actually get more
> than about 3.2.
>
> Jerry