RE: Sorry to ask again but...
You are correct. But tests have shown that there is or can be an optimum
height for scanning film above the platen due to variations of scanner
That's why variable height film holders are sold.
Look at the BEtterScanning.com web page for examples.
From: etienne garbaux [mailto:email@example.com]
Sent: Wednesday, August 30, 2006 12:05 AM
Subject: RE: Sorry to ask again but...
> Of course the issue is DOF for film scans which maybe quite a bit less
> than document scanners.
The scanners most folks seem to be talking about (Epson, Umax, etc.)
use the same optics for reflective and transmissive media -- they just
illuminate from above rather than below in transparency mode. So, the
depth of field should be the same.