Photography Tutorial, Black and White Tone Reproduction 1, f8 Pro Photo

Seeing the work of the ‘old masters’ Adams & Evans to name but two has often been the inspiration to fine art photographers particularly those working in black and white but, a question arises - could these old masters produce the same results now with modern film emulsions?
With smaller image formats the quest for finer grain and definition has led to shallower film emulsions and high acutance, surface acting developers, both at the expense of tonal range - that illusive quality within the image that stands out before sharpness or fine detail.
For this tutorial digital photographers can take a siesta in their Adobe’s while we dabble in that dark room of densitometry trying to get the most out of the materials we’ve got.

First it must noted here, the likes of Adams and Evans did a lot of their work on 10x8 inch monchrome sheet film. Edward Weston, who inspires me still, used 14x11 inch sheet film. A display size print can be contact printed from these huge negatives. Moreover, qualities such as fine grain, resolution of detail and sharpness of image where attributes hardly worth consideration being intrinsic to the large negative. These old boys could concentrate more on tonal quality and back then, as now, it was in the darkroom that these images came to life.

The essence of black and white photography is the transposing of colour into tones of grey, tone reproduction is the term we use for it and three variables control it, exposure then time and temperature of development.
   Submitting the negative to a Densitometer, that projects a light beam through the negative’s tonal density to display a value, these three variables can be plotted from the negative onto a graph that becomes the Characteristic Curve of that negative.
   Exposure, measured as the quanta of illumination that the negative receives from varying subject brightness levels, is converted to a logarithm for ease of scaling and is then known as the Relative Logarithm of Exposure (R.log E) measured along the horizontal axis of a graph against the negative’s actual density levels up the vertical axis.
   A theoretically perfect negative will plot as a perfectly straight lined slope on which each and every measurable tone would be equidistant from the next yielding perfectly even tone separation.

The curve itself, shown in red, is the actual Characteristic Curve of Ilford FP4 film normally developed in Paterson Acutol solution, normal dilution, normal agitation and for 6½ mins. at 68 deg. Fahrenheit.
The curved sections occupy the shadow end or toe (lower left) and the highlight end or shoulder (top right).
In these areas separate tones are not equidistant but compressed.

With perfection seemingly unobtainable in the photographic world the optimum negative should yield all it’s relevant information upon the straight line portion of the curve so ensuring optimum tonal separation - a concept that bypasses creativity in favour of reproducing the most technically accurate rendition of the scene photographed but, the resulting optimum print may be a disappointment.

Without the deep blacks, (that press photographers in particular used to prefer) due to the compression or merging of the lowest intensities into one solid black tone on the toe of the curve, and the same merging of the brightest highlights into a bright sparkle on the shoulder, the print may look flat, without depth so, incorporating toe and shoulder detail into the image will therefore produce a more pleasing print and other terminology, describing measurements gleaned from the curve, can encompass this.

Next: Under & Over Exposure & Development

text & graphics C steve rostron 2007

Photography. Free Resource for Photography, Cameras, Digital Cameras, Tutorials and Black and White Photography, f8 Pro Photo
f8 Logo, Text, Graphic Design and all Original Photography herein, Copyright 2007/2008 f8prophoto.com except
Submitted Work Copyright Accredited Photographers, Authors and Designers
Reproduction in Whole or in Part strictly prohibited