Kodak on Variable Film Development: NO!

Discussion in 'Kodak' started by Michael Scarpitti, Aug 1, 2004.

  1. I should see the statement in context, because that amount of
    variation seems excessive for any reasonable purpose.
     
    Michael Scarpitti, Aug 10, 2004
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  2. I see problems with several of these images, quite frankly.
    That's not what zs dogma asserts, and if the variation in dev time is
    significant enough to cause the mid-tones to veer wildly from 1:1, the
    eye immediately recognizes it. That's why I can spot zs manipulations
    so easily. In some cases (unusual subject matter) it may be more
    difficult to spot.
    No. The shadows SHOULD be on the toe, because the shape of the curve
    of the paper (which is the inverse) will correct for it better. This
    is explained quite clearly in 'The Science of Photography' by Baines,
    rev. by Bomback, pages 181-186. These photographers may be doing what
    they are doing because they are incorrectly exposing their film, and
    not letting the paper curve complement the film curve. Their variable
    film development may be an attempt to cure a problem that they are
    causing themselves.
    Kodak points out in the 'Negative Making' that the 1:1 ratio of tone
    in the scene to tone in the print is most important for mid-tones.

    ------------------------------------------------------------------------

    "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.)
     
    Michael Scarpitti, Aug 12, 2004
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