> In a sense, it is three panchromatic sensors, receiving the light in
> parallel, but through different color filters.
Not with the Nikon. The Nikon uses the exact same sensor, but uses a
tri-color LED which cycles through the three colors before advancing
position. Actually, four, when you include the IR channel. So, the
sensor itself is a linear array of monochrome sensels with no filters
at all. The colors are derived by the cycling of the LED light source.
I scan B&W negs in color and do my monochrome conversion (actually, I
more often than not leave it as color, but desaturate the file), in
Picture Window Pro. The reason is that the film base itself is not
neutral gray. The three colors will achieve a slightly different
illumination. In essense, the negative does have a mask color. In the
case of Ilford XP2, the color is purple. If you derived the monochrome
from the green channel, chances are you'd get a reduced quality image.
The fact that you get a neutralized gray image on the screen in
VueScan doesn't mean anything because that is then a derived image and
doesn't actually optimize the scan itself, just the image file
post-scan.
When the film base is really neutral in color, I don't think it
matters much, but the more colored the base is, the more of a
difference it makes.
According to some of the more whacked out individuals in the hybrid
world, they ALWAYS scan in color and will get into all sorts of
interesting procedures--like taking one color channel and applying a
gaussian blur to it.
In VueScan, one really scary revelation is to go to the color tab and
change the first setting to "none". The screen takes you back to your
raw scan. After you pick yourself up off the floor, go back to the
first tab and go down to manual exposure...
Converting film to digital is sooooooo much fun.
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
--
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