Oh yeah.  It is a big time problem that is getting worse.  The old original
scanners had a depth of field of almost an inch.  I scanned a Lambis
truncatus once, worked great.  These early scanners worker pretty much like
old cameras with a pin hole aperture.  As higher resolutions were demanded
for photographs and such, they had to install lenses.  The higher the
magnification available through the lens, the shorter the depth of field.  I
have been through five scanners in the last decade and can really see the
difference.  A digital camera works great, but for many applications a
scanner was better.  No special lighting required, shells are all imaged in
the same position, immediate hook up to computer photo programs, etc.  The
older scanners are still sometimes available, but need an older computer
operating system to match the out-of-date drivers.

--------------------------------------------------
From: "David Kirsh" <[log in to unmask]>
Sent: Sunday, February 21, 2010 9:53 PM
To: <[log in to unmask]>
Subject:      [CONCH-L] scanners

> No, not the movie.
>
> I recently got a Lexmark copier/fax/scanner with high resolution that
> works well...everything except for the fact that I can't scan shells the
> way I did on an older scanner. I used to be able to scan shells down to
> about 10mm at high resolution and be able to enlarge the images with good
> results.
>
> The Lexmark images have virtually no depth of field so that any
> 3-dimensional object will be out of focus and pixilated where it's not
> touching the glass. Yet a flat document can be enlarged quite a bit and
> remain sharp.
>
> Has anyone encountered or solved this problem with a recent scanner?
>
> David Kirsh
> Durham, NC
>
> "When you're chewing on life's gristle, DON'T grumble. Give a
> whistle!" --from Life of Brian
>
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