What are the specific
problems with getting a good scan of Kodachrome.
Unlike what some have reported, I haven't ever had a problem with my
scanner not being able to "penetrate" a Kodachrome slide or the scans
coming out particularly dark (relative to other emulsions). For me,
scanning Kodachorme is pretty much like scanning any other positive
film, at least in that respect. Instead, the big issue whith
Kodachrome is the effectiveness of infrared dust cleaning (FARE in my
case, as I have a Canon scanner), which tends to produce strange
artifacts. It seems that the infrared "sees" crystal patterns in the
emulsion and tries to correct them, as if they were dust. The
resulting artifacts, if too pronounced, tend to make the IR cleaning
not worth the effort. But the problem varies a lot. Some report that
it depends on the specific Kodachorme emulsion you have and it may
even vary from one slide to the next in a given roll. In some cases
the IR cleaning will render the scan unusable, while in others the
artifacts may so minimal as to be insignificant. I think the bottom
line is that it really depends on how dirty your slides are, and how
much custom spotting you are willing to do. It may also depend
somewhat on the resolution of your scan and how much detail you are
trying to bring out (you probably won't see the artifacts at lower
resolution).
Hope that helps!
Jeff