Dev control for b/w filmsgreenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I know b/w developing is contingent on the shooting/printing style of the photographer, but... Is there a manufacturer spec for 18% grey in terms of statusM density? Like a LAD for color? For example, if I develop PlusX (exposed normal) in D76 straight, 18% grey should yield a density of 1.20 or something? B/w is not like color as there are many variables, but the manufacture must come up with suggested times of development of various stocks using some sort of aim middle grey density.
-- Doug Delaney (email@example.com), November 01, 2000
Errm, 18% grey is 18% grey. By definition, it's a neutral tone that diffusely reflects 18% of the light falling on it.
It isn't a density.
The 'claim to fame' of this standard is that light meters are calibrated to give an exposure that's 4 stops up from the nominal 'toe' of the film D/logE curve when metering an 18% reflective surface. What density this results in on film depends on the development given, and only results in a density of ~1.2 (+base +fog), when the film is developed to a bar gamma of 1.
A gamma of 1 is a bit too high for most pictorial work in practise though, and a gamma of 0.8, giving a density closer to 1, would be a more sensible value to aim for.
Anyway, IMHO, what's much more important pictorially is the relationship of all the other tones in the print to this arbitrary 'reference'.
-- Pete Andrews (firstname.lastname@example.org), November 02, 2000.