Digital BW, The Print

Bob,

>Some days prints of the same image with the same adjustments and printing
>curves come out much denser than others.  ...

At least with the desktop Epson printers, all that I have used have at least
a 0.03 density variance just from warming up during the day, and it might be
much more than this.  Luckily, the ratios of the "color" inks seem to stay
the same, so this inconsistency does not appear to affect the hue of the
print.  Then there seems to be weather-related changes, paper-batch
variances, ink-batch differences (all manufacturers I've tested), individual
printer differences, and probably lots of others.  

I'm told that the "professional" large format printers are more stable and
consistent.  I have not tried to measure the differences in them.

Part of what I try to do in the inkset and curves designs is make them as
tolerant of the variances as I can.  The B&W inksets are all, in part, a
response to the printers' inability to consistently control high-gamut
colors.  The variable-tone approach, for example, by pre-mixing the toners
and having them the lowest gamut that can do the job helps hide the
variances.  The UT2 inkset, by relying on the Epson driver cross-overs more
than the previous versions also helps avoid the problems associated with all
the inconsistencies.  For the 1160 I recently made what I call a "mild"
partitioning curve for use with the UT-FS inksets.  I'm hopeful this will
also help deal with inconsistencies.

Those who want the best output should also consider tweaking the existing
curves to match their specific printer.  Professional color printers
generally use custom profiles, not canned ones.

In the darkroom I'd always have to do a test strip just before making a
large print even if I'd precisely recorded all my exposure information
during the last time the negative was printed.  So, it's all relative.

Paul
www.PaulRoark.com