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.

Any ideas?

-- Doug Delaney (ddelaney1@hotmail.com), November 01, 2000

Answers

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 (p.l.andrews@bham.ac.uk), November 02, 2000.