Rob, I want IT-8 calibration because I'm color blind and I want to reduce the
number of variables I have to deal with. In theory, any of my calibrated
scanners can be used to scan the same slide and the final files will all be
nearly identical. As you imply, IT-8 calibration has its limitations because
a given target slide can only represent one type of transparency film. With
the exception of a gadget film like Velvia, most transparency films are
fairly similar and have less variability between them than you might find
between different brands of scanners. So IT-8 calibration can help with
consistent scanning of transparency film and get things a lot closer to a
common starting point for someone like me with poor color vision.
For negatives, I believe it was Ian Lyons who said that calibrating the
SS4000 and SilverFast with an IT-8 slide also had benefits for negatives. I
don't know why. But I can certainly see how information from an IT-8 slide
could be used to characterize the scanner's deviation from some norm so that
software could improve (make more consistent) negative scanning as well. For
example, if IT-8 calibration finds that the scanner's red channel has a weak
response when scanning transparency film and then makes an appropriate
correction, then it seems the red channel gain would have to be boosted just
as much when scanning negative film in order to get a "normal" scan. This is
speculation on my part.
Once again, my goal is to keep things as consistent as possible so that I can
do the final tweaking "by the numbers" without having to start with files in
which the color balance differs greatly from one another. That might not be
as important to someone with perfect color vision, but even they would
probably benefit from it if they had more than one film scanner since scans
from each scanner would have a starting point closer to one another.
Otherwise, each scan would be an adventure. I don't have time, nor the color
vision, for such adventures.
Someday I'd like to see the randomness taken out of the photo process and
brought under control so the photographer doesn't have to worry about it or
fight it all of the time. IT-8 calibration and color management are steps in
the right direction, but we've got a long way to go. Only when the
randomness from the scanning process is brought under control will the weenie
work be taken out of scanning and the photographer allowed to concentrate his
creative efforts on the task at hand.
Now that I've said all of that, I have to admit that I've been considering
buying Vuescan just to see if I could live with it. I'm not real happy with
SilverFast's price gouging.
In a message dated 8/5/2001 4:21:41 PM Pacific Daylight Time,
> Too bad Insight and Vuescan don't support IT-8 calibration.
> That's the only reason I've tolerating this SilverFast
For the purchase price of Vuescan it might be worth trying with the SS4000
just to see how much difference calibration really makes?
It occurs to me to wonder how much difference IT8 calibration on a film
scanner makes? Presumably the IT8 target is an ektachrome slide, so you'd
be calibrating for that type of film. What about negs? What about other
brands of slide? Is the calibration just introducing colour shifts that
will have to be corrected anyway?