You are referring to the tone reproduction. This subject has been described in the Kodak Publication 'Kodak Professional Black and White Films, Negative Quality p. 2-7. second edition November 1976'. Later editions are available as well. The Kodak approach has a scientific base and is valid for modern high definition optics as well as older optics. This in contrast to the zone system approach which is valid for older low definition optics. [Modern lenses are often so detailed, that a zone does not exist anymore and another approach is required].
Originally Posted by markbarendt