[OM] lens "contrast"; keystoning; SCSI card

Subject: [OM] lens "contrast"; keystoning; SCSI card
From: William Sommerwerck <williams@xxxxxxxxxx>
Date: Fri, 10 Nov 2000 19:15:16 -0800
"When scanning pictures, it's easy to increase contrast digitally, but if
shadow and/or highlight detail has been lost due to excessive contrast, you
can't recover it."


It is impossible for a lens to have "excessive" contrast -- that is, to render
a wider range of tones than exist in the original image. All a lens can do is
degrade the original tonal range, by scattering light into the darker areas.

I, for one, do not like "muddy" shadow areas. All other things being equal, I
would use the lens that rendered the scene more accurately. There are better
ways to rationally adjust the tonal range of the final image than by letting
the lens degrade it in an unpredictable and uncontrollable fashion.

Keystoning is not distortion. It's unfortunate that keystoning and perspective
exaggeration (or flattening) -- which are part of the normal behavior of a
rectilinear lens -- are considered "errors." They are not.

The default interrupts for a SCSI card are 10 and 11. Check to be sure at least
one is not in use, and that the card is set to that interrupt.

If you install a "famous name brand" SCSI card (such as Adaptec), Windows 95 or
98 should recognize it at start-up and install the correct driver. If it
doesn't, it's probably because the Acer isn't recognized.

I strongly recommend tossing the Acer in the trash and buying a cheap Adaptec.
I did this several years ago (because HP refused to provide drivers for their
old card that would run under Windows 95), and I had no problems.

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