Digital BW, The Print

Hello Brian,

>If I set (this is an extreme example, I know) the cyan slider to 
>-25 and the magenta to +25 the tones in the 70-90 range are about 
>equal and there's a clear break to pure black around 95%. 

I printed an entire set of symmetrical CM +/- and -/+  ramps at
increments of 5, on Dourian (like PR, medium warm at 0/0), and it's
easy to see what happens.  The practical limit seems to be about 15 in
either direction.  Up to there it holds a fairly normal ramp.  After
that the ramp gets pretty messed up. 


>I know there's a curve that would correct for this (to get back to 
>a normal step wedge) but I can't seem to wrap my mind around what 
>it should look like. 

Even at 0/0/0, R2 tends to lower contrast and density a bit, so I
always expect to add an adjustment curve.  In your example the curve
would need to restore contrast (steeper slope) in that 70-90 zone.  
However, it may not be practically possible without getting
posturization or other weird effects.  But if you stay within the 15
limit, I've found so far that it's easily controlled.


>...I was basically trying to find out what the warmest print I 
>could get from the set was.  

In the above set of ramps on Dourian, with CM +15/-15 being the
coolest and -15/+15 the warmest, it's quite a nice range between the
extremes.  There is a greater difference between 0/0 and the warm one
than the cool one, something like this, just to give an idea:

 Cool +15/-15 ------- 0/0 ------------ -15/+15 warm

The same settings printed on Kayenta, a cold paper, are relatively the
same result, but much cooler.  The Kayenta 0/0 print is cooler than
the cool PR print, and the warm Kayenta is a close match to the PR
0/0.  Sort of like this (sorry for the dots, it's because of the html):

.....................C------- PR ------------W
.......C------- KY ------------W

and I assume a super warm paper like Wm. Turner would do something
similar on the warm end (I don't have any on hand to test).

So I still see the paper choice as the main determiner of the general
tone, and R2 as a way to nudge it warmer or cooler from there.  

Hope this helps...I think I'll go add this to the article.

Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm