QTR-Quadtone RIP

Thank you Ernst, that is an excellent summary!  Certainly much better 
than I could have provided. ;>)

The only thing I would add is that the Adobe Lightroom 2.0 Beta (and 
also version 1.2) have some wonderful tools for greyscale mixing.  They 
allow for subtle controls to emphasize, lighten, or darken greyscale  
values from color images.

I have been using color negative film in my 4x5 to allow me to use the 
Lightroom adjustments in post processing for B&W images.  But, most of 
my digital work and film work is in color.

Best,
Michael