Here is little update
I did following test for Delta 100 (with diffuse head enlarger):
- I figured out printing time that gives pure black
- Using that time, I printed my test negatives (I used graycard on black background as an test target)
- From these negatives I got right negative for zone I, ie. print where I could barely see difference between graycard and black background
- Then I checked which negative in my test series give IX that is just off the pure white
So that time (in my case, 9 min, 24°C, DiXactol Ultra) will give N-developing with full tonality scale.
The usable speed for Delta 100 is E.I. 80.
Then I measured densities of all zones. The most important zones were ofcourse zones I and VIII. The zone VIII I planned to use for an reference for testing developing times for N- and N+ developments.
Here is what I got:
Visual (above base fog):
And blue readings:
Does these values sound reasonable?
The suprise for me was how close the blue measurement get to the traditional diffuse reference values for zones I (0.09-0.11) and VIII (1.25-1.35).
Also I was suprised how the visual values are close to the reference values for condensor enlarger (I 0.08-0.10, VIII 1.15-1.25).
Now the big question. Are the reference values I got for zones I and VIII also usable with other staining pyrocathechin based developers (mainly Pyrocat-HD is in my mind).
I guess that they are.