Sparpitti. Isn't he that eco-terrorist guy?

Hey, I was going to say that!!! :-)

Whatever you do, don't listen to those who say don't listen to me.
they're all a bunch of sour pusses!

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FROM KODAK:
Negative Quality
It is axiomatic that if optimum print quality is to be obtained, the
negative must also be of optimum quality. Unfortunately, there is no
simple yet completely comprehensive answer to the question of what is
a good negative, which leads back again to the generalization that a
good negative is one which makes a good print.

Regardless of the type of photography involved, there is a definite
production advantage in producing negatives of consistent quality.
Ideally, the photographer's goal should be to make all his negatives
so that they will give a consistently high quality when printed on the
same grade of paper. To do this, it is important to maintain fairly
accurate control over film processing conditions. The temperature of
the developer, the method and frequency of agitation, and the time of
development should be held as constant as possible and close to
recommendations, if consistently good, reproducible results are to be
obtained. Even with Kodak Developer DK-50 diluted l to 1 as an aid in
stabilizing development times, a difference of only one minute of
extra development means an increase of about 20 percent in gamma, or
the amount of contrast increase equivalent to one full paper grade.

Negatives made by professional photographers can be divided into two
general classifications, portrait and commercial, for a study of
their desired characteristics.

THE PORTRAIT NEGATIVE
What is a portrait negative? Certainly not every picture in which a
person appears. For the purpose of this discussion, a portrait is,
generally, a formal, indoor picture taken with medium-to low-key
lighting and covers the range of head-and-shoulders close-ups to
three-quarter views. The desired printing characteristics of negatives
of high-key portraits, group pictures, outdoor portraits, and pictures
of teen-agers or younger people are more closely akin to those of
commercial negatives.

Consider for a moment the desired characteristics of a medium low-key
portrait. Customers, particularly men, find this style of lighting
quite pleasing or, at any rate, "less revealing," than a moderately
high-key lighting. From the photographer's standpoint, therefore, the
majority of the subject tones will be shadow areas. The center of
attention should be, of course, the subject's face with its carefully
placed highlight emphasis. The portrait photographer is interested in
the subject's face to the extent that he is willing to accept
intentional distortion of the shadows if this will add by comparison
to the facial emphasis. Photographically the problem resolves itself
to rendering the shadows with low contrast, and the facial highlights
with sufficient contrast. How should this be accomplished?

For many years a popular adage among portrait photographers has been,
"You can read a newspaper through a good negative." And, as a general
guide to portrait-negative quality, this adage seems to be true. It is
a "rule of thumb" which helps the portrait photographer to achieve
negatives with proper printing characteristics and to avoid production
annoyances, such as dense negatives which print with excessively long
enlarging times. A negative "through which a newspaper can be read"
should be exposed so that it has a fairly low average density, and
should be developed so that facial tones are slightly transparent with
the exception of the most dense diffuse highlights on the forehead.
These highlights should be just dense enough so that printing cannot
be seen through them. This assumes average subject reflectances and a
normal portrait lighting ratio of about 3 to l.

Aside from the subject arrangement, the lighting, and the type of film
used, the printing characteristics of the negative are controlled both
by the amount of exposure and degree of development. Although exposure
and development are interrelated in their effect on density, it is
simpler to consider their actions separately. Primarily, the exposure
affects the density obtainable in both the shadows and highlights,
while the degree of development, as indicated by gamma, affects the
density of the highlights more than that of the shadows.

Exposure.
It has been found that a portrait negative yields best-quality prints
if the exposure locates the shadow point on the toe of the
characteristic curve not lower than the ASA gradient speed point.
Briefly, the shadow point in the negative represents the darkest area
of the subject in which detail is desired in the print. The speed
point described in the Standard is the point on the characteristic
curve where the gradient is 0.3 of the average gradient over 1.5 log
exposure range. 1f further clarification of these sensitometric
concepts is desired, pages 4, 5, and 6 of the Data Book "Kodak Films"
are recommended for supplementary reading.

Recommended exposure meter techniques using either reflected-light or
incident-light readings have an exposure safety factor of about 2 ½
times. This means that a normal meter reading will result in an
exposure which will place the shadow point about one lens stop above
the ASA gradient speed point. In other words, if the meter is used
correctly, there is an exposure latitude from the indicated reading to
one stop less than this where the shadow point of an excellent
portrait negative should be located. Underexposure of more than one
stop will place the shadow point down too far on the characteristic
curve, and the darkest areas of the subject will be represented in the
negative by insufficient density differences. This means that a shadow
detail will not be discernible in the print.

It has also been found that if a portrait negative with optimum
printing quality is desired, it is important with most portrait films
not to expose the film enough to place the shadow point appreciably
above the ASA gradient speed point. With some films, however, such as
Kodak Super-XX, this can be a fairly large factor; in some cases two
or four times seems satisfactory. The important consideration is that
the highlight densities at the other end of the density scale should
not be recorded by the shoulder portion of the characteristic curve.
The curve gradient here is decreasing as the density increases, which
means that the facial highlights, if recorded, will be rendered with
insufficient tonal separation.

Here, then, is how and why a portrait negative should be exposed: The
darkest shadow areas should be well down on the toe of the
characteristic curve, the middle tones should be on the central
portion of the toe, while the highest diffuse facial highlights should
be on the straight-line portion of the curve. Ideally, these
highlights should have density values of about 0.8 to 1.0. For most
portrait films, this value should not be above 1.2. A negative which
has been exposed in this manner will result in a print which, most
observers agree, is of better quality than the best obtainable print
made from negatives with appreciably less or more exposure. This ideal
negative has, accordingly, highlights which have appreciably more
brilliant tonal separation than the shadows. This evidently helps to
concentrate observer attention on the most important area of the
portrait, the face, while subordinating the shadows with a lower
printing contrast.

In other words, in portraiture, a more pleasing picture may be
obtained if toe densities represent the shadows in spite of the fact
that it may be a less literal reproduction of the subject. Thus, from
a pictorial standpoint, retention of shadow detail may be unimportant.

There is another factor which influences the tolerance of the film's
exposure latitude, and that is the type of film which is used.
Remember that it is desirable to keep the facial highlights from being
recorded by the shoulder portion of the characteristic curve. It
happens that some films normally "shoulder" sooner than others as the
higher densities are approached. It follows, therefore, that the
longer the straight-line portion of the curve, the more "portrait"
latitude a particular film has. Of course, too long a negative scale
cannot be compressed within the ability of a photographic paper to
reproduce its entire spread. For films customarily used in
portraiture, and which have a shoulder starting at a density of about
1.5, the negative should be on the "thin side." However, excellent
prints can be made even from fairly dense negatives on Kodak Super-XX
Film which has an unusually long "straight-line curve."

There is, of course, an upper limit of useful exposure which is
governed by increased graininess, loss of definition, and the
practical difficulty of printing very dense negatives long before the
upper limit of the negative exposure scale is reached.

It should not be inferred that a film with a long straight-line curve
is better for portraiture than one which shoulders off at a lower
density. Portrait films with a long sweeping toe have both a very
desirable toe shape and sufficient straight line to record the
highlights brilliantly. It's just that a longer straight-line curve
permits a greater "portrait-subject" exposure latitude.

Development.
The photographer's style of lighting in terms of lighting ratios, his
enlarging equipment, and the Kodak Opal Paper on which he makes his
prints are relatively fixed features among the variables controlling
print contrast. The simplest method of controlling contrast is,
accordingly, by adjusting the degree of negative development. Because
individual working conditions and techniques vary widely, it means,
practically, that every photographer should develop his negatives to a
gamma which best suits his particular conditions. Thus, any gamma
which results subsequently in best-quality prints is the correct gamma
to use. Development recommendations are therefore to be regarded as a
basis for trial from which a departure may be needed. The Kodak
Developing Dataguide will be found helpful in working out a uniform
development procedure best suited to a photographer's particular
needs. As an example, take a portrait photographer using a certain
lighting contrast, type of enlarger, etc. He might find that the most
appropriate film developing time corresponds to the "Lower Contrast"
arrow on the Dataguide. If he changes film or developer, or the
developer temperature changes, he can obtain negatives of the same
printing quality by developing for the time which again appears at the
"Lower Contrast" arrow. In any case, having once found the degree of
development that gives excellent prints on the desired paper, he
should stick to it. This degree of development may come above or below
the recommended one, but it is the right one for the photographer's
conditions.

THE COMMERCIAL NEGATIVE
Commercial photography encompasses almost all subjects not included
under the portrait category previously discussed. Commercial negatives
would be typified by normal negatives of product illustrations for
advertising, display, or catalogue purposes, press shots, and many
types of industrial photography.

Whereas in portraiture the photographer is primarily concerned with
the reproduction of facial tones, in commercial photography he is
interested equally in both highlights and shadows. In other words, the
commercial photographer wants to reproduce all important portions of
his subject with a minimum of tonal value distortion. In general, this
means a slightly more dense negative in order to avoid the tonal
distortion of shadows occurring in the toe portion of the
characteristic curve. Many commercial photographers feel that these
conditions are fulfilled if the average commercial negative receives
about one stop more than the average portrait negative. Thus, the
recommended technique for making a meter reading by either reflected
light or incident light will produce negatives of the desired exposure
level.

It has been customary for commercial negatives to be developed
somewhat more than portrait negatives. However, there is no
photographic reason why an average commercial negative should be
developed to a higher gamma than a portrait negative.

As the portrait photographers have their adage, so also do the
commercial photographers who say, "Expose for the shadows and develop
for the highlights." Is this sound advice? First, let us examine this
statement more closely. Admittedly, adequate exposure is desirable to
record the important shadow tones. But to "develop for the highlights"
implies that the time of development, or in other words, the gamma,
should be varied in accordance with the brightness range of the scene.
The idea is, of course, to prevent overdevelopment of highlights, so
the scale of tones can be kept within that which photographic paper
can render. Thus, should a negative of a short scale subject, such as
an average building exterior taken on an overcast day, be developed to
a higher gamma than a negative of the same scene taken in brilliant
sunlight? The answer is generally no; both negatives should be
developed alike. This is probably contrary to the practice which some
professional photographers advocate. The reasoning for this answer
follows: Although photographers speak of "important highlights" and
"important shadows," for the most part it is actually the middle tones
which are most important of all. Middle tones are, of course, the
range of grays between highlights and shadows. Stated differently,
middle tones of a negative or print are those densities which are not
associated with toe or shoulder areas of the characteristic curve.

It has been found through a series of comprehensive tests that for the
great majority of scenes the middle tones should be reproduced at a
gradient of 1.0 on a tone reproduction curve. This curve is a plot of
densities in the print versus the logarithms of the luminances or
"brightnesses" of corresponding areas in the scene. A gradient of 1.0
means that if there is a 10 percent difference between two tones in
the scene, then these same tones should be reproduced with a 10
percent difference in the print. Generally speaking, the middle tones
should be reproduced with a gradient of 1.0, even if this can be done
only at a sacrifice of gradient in the highlights and shadows.
In other words, the majority of people want the middle tones of the
print to reproduce most original subjects as closely as possible,
regardless of the lighting conditions that prevailed when the pictures
were taken. To do this, all negatives should be developed to the same
contrast or gamma for the same printing conditions and paper grade.

There are exceptions, of course. The "majority" of outdoor subjects in
the tests mentioned previously included about 85 percent of
picture-taking situations, such as portraits, landscapes, and
architectural pictures taken in sunlight, in shade, and on overcast
days. The remaining 15 percent of the scenes had, for the most part,
large and very deep shadow areas which comprised an important part of
the subject. It was these latter scenes which the majority of
observers thought were best printed on a paper one grade softer than
normal. Thus, even for subjects with a long scale of brightnesses, it
was found satisfactory to develop the negative as though for a normal
scene and to let the range of paper grades compensate for the unusual
nature of the subject. In other words, the varying lighting conditions
may demand the use of a paper grade other than No.2 for best results.

However, unusual subjects in which heavy shadows may either be present
or actually predominate the scene are usually treated differently by
professional photographers than they are by amateur photographers. The
professional uses fill-in flash illumination, whereas the amateur does
them without the benefit of supplementary illumination. The flash
converts an "unusual" subject into a "normal" subject, and as such
requires a normal negative development and will print on a normal
grade of paper.

The degree of negative development for some subjects naturally depends
on the photographer's "artistic intent." For example, suppose he were
to photograph a sailboat at anchor during foggy weather. If it is
thought that the fog lends a desirable pictorial effect to the scene,
then it can be reproduced as the eye saw it with a normal negative
development and a print on No.2 grade paper. If, on the other hand, a
clear record picture of the boat was the photographer's object, and
the exposure could be made only under a fog condition, then the
negative should receive more than normal development to compensate for
the contrast-reducing action of the fog particles. In this case,
overdevelopment of the negative is desirable only if a print from a
normally developed negative on No.4 paper grade would contain
insufficient contrast. Accordingly, in view of the desirability of
reproducing most scenes with a gradient of 1.0, and because of the
wide control over contrast possible with various paper grades, it is
highly advisable for the professional photographer to develop the
great majority of his negatives to the same gamma.

A sensible approach to planning a standard photographic technique,
including the degree of negative development, is to strive for a
negative that will print best on a normal grade of paper. Although
there is no necessity to confine oneself to anyone gamma if several
paper grades are available, it is only logical to aim for No.2 paper.
If this is done successfully, the printing problem is simplified by
using one grade of paper for most negatives. At the same time, the
photographer is protected on both sides of normal by papers with
greater or less contrast capacity, should an underdeveloped or
overdeveloped negative accidentally result.

Kodak processing recommendations for film are generally based on the
use of diffusion-type enlargers, or on contact printing which results
in prints of approximately the same contrast, everything else being
equal. Obviously, these same processing recommendations should be
modified by a reduction of 15 to 20 percent in gamma to suit
condenser-type enlargers if prints of the same contrast are to be
obtained.

Individual preferences are shown in a survey made of several
individual newspapers and the principal news photo services. The
results showed that films were developed to gammas ranging from 0.62
to 1.18, with an average of 0.85; that Kodak Developer DK-60a was the
most popular of the developers, although a number of others were used;
and that developing times ranged all the way from 4 ½ to 8 minutes.
The photographers who preferred the lower range of gammas used
condenser enlargers. The ones who developed films in the intermediate
range used tungsten-source, diffusion enlargers, and those using the
highest gammas employed mercury-vapor enlargers. In a similar manner,
commercial and, to a lesser extent, portrait photographers also modify
the basic development recommendations according to individual
conditions.

(From: Negative Making for Professional Photographers, Eastman Kodak,
1956.)

No. You not need one. Get the book: "Way Beyond Monochrome"  by Ralph W.
Lambrecht and
Chris Woodhouse. It will save you money in the short run.

A step wedge is a good piece of equipment, but most suitable
for large format film testing opposed to 35mm although
the wedge can be made to work with the Zone system and 35mm, its a good
piece of equipment if you want to calibrate film and paper....but you
can use the wedge to just calibrate your paper and process.

What I want to know is where is it most important to control the process.
i.e. Camera, Film Developing, Printing. Which practices can I use as a means
of eliminating errors from the whole process. Calibrating the shutter speed
and aperture on my camera for example. Is this easy or hard? Is it worth
doing even? How about processing my negs. This seems to me the area with the
most room for error. If my thermometer is out a bit I could be plus or minus
10 to 20 per cent. But how would I even know? What tells me this. A test
image of some sort on the neg perhaps. That's why I was wondering about the
step wedges.

That's essentially what I said. It's impossible, in principle, because
no two batches of film, water, paper, chemistry, etc., are identical,
and no shutter is 100% consistent, and even the sunlight varies from
moment to moment.  All you can do is to determine your 'normal' paper
grade (#3 for 35mm, #2 for sheet film), and try to get most of your
negatives to print properly on that paper.