ElectricLadyland said:
..... is there a way to use the N development or highlights to find the proper development for midtones? .....
Yep. It is easy-peasy.
Using contemporary tools and materials, we have certain advantages over previous photographers.
I use an incident meter for most of my portraiture ( which is about 80% of my work ) for the simple reason I want faces to fall where they naturally fall.
( I DO use a spot meter to check the background... but it isn't THAT hard ! )
With certain developers and films, we can get box film speed, a long straight line ( density proportional to exposure ) and a splendid balance of all the other virtues.
Using Kodak's XTOL and TMY, you can simply expose for Zone V or VI, and adjust the development to give you the density you want. Chances are, it will be very close to Kodak's .58 CI suggestion. Since the combination of film and developer does not produce funny dips and dives in the curve, you can literally expose for ANYTHING and get everything else to fall where it can be retrieved later.
For the record, this combination yields a straight line from .15 to 2.3.
In normal use, with a camera with an electronic shutter like my Nikon F5, it is no big deal to make negatives with routine precision beyond Ansel's wildest dreams.
Other developers that make life easy include Aculux 2 from Paterson, and Ilford's DDX. Films such as FP4, Tri X, Plus X, Delta 100.... perform quite similarly.
Of course, you COULD spend a lot of time tinkering. But Kodak's Xtol data is wonderfully good and will bring you to the starting line very quickly, and you can expose for Zone V reliably and cheerfully.
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