Ever since I was back at Ansel’s in the late ’70’s, I had been faithfully calibrating my high values at Zone VIII, targeting a density of about 1.25 above filmbase-fog.
Since 2004 or so, however, I’ve been thinking more and more that it makes more sense to calibrate to Zone IX, with a target density of about 1.45.
True, Zone VIII is supposed to be the high end of the “textural range”, but then Zone II-1/2 to III is generally considered the low end, and we don’t use THAT as a film speed point.
For me, Zone IX prints on a “medium contrast” paper as not quite a paper white. THIS is the end of “normal” photographic scale and I think it’s ultimately the most useful calibration point, in the same manner that we use Zone I for film speed (0.07 to 0.10 above Fb-F).
The Zone IX calibration point calls for more modest changes in development time and/or dilution to get useful Plus and Minus development. There also is less tendency for Minus development to “block-up” values which fall higher than Zone IX.
If you’d like to see a larger version of these theoretical curves showing why I like this idea, or if they don’t display on your browser, email me and I’ll send a pdf pdq!