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#271
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"Frank Pittel" wrote in message
... I wish I could afford a T1!! Right now I'd settle for a decent DSL connection. I live in the Chicago area which is a major hub for the Internet connections in the US and only a few miles from the Illinois "Technology corridor" and the best I can get is idsl. :-( With a max. throughput of 144Kbps I'm not putting a image files scanned in a way to do them justice. Actually, I lost the T1 connection. Forgot that. I do have a 100mb line to our lab, however. It will have to suffice. |
#272
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Kodak on Variable Film Development: NO!
Michael Scarpitti wrote:
: Frank Pittel wrote in message ... : Michael Scarpitti wrote: : : Frank Pittel wrote in message ... : : Michael Scarpitti wrote: : : : Frank Pittel wrote in message ... : : : Jim Phelps wrote: : : : : : : : "Michael Scarpitti" wrote in message : : : : om... : : : : So, the very clearly stated piece by Kodak, which acknowledges the : : : : MOTIVES for variable film development and DISMISSES them as mistaken, : : : : means nothing to you? Then you're STUPID.... : : : : : A writing that is almost 50 years old! : : : : : : Since it says what scapitti wants to hear he's going to hold it up as holy writing with : : : more authority then anything from even Kodak stating anything different. : : : : This is based on reaearch, which is cited in the text. It is precisely : : : the opposite of 'holy writ'. : : : : The Zone System was developed over years of scientific research aided by Kodak and : : experimentation. : : : False statement. Kodak has never endorsed the zoan sistum. : : No one ever claimed they did. Still trying to change the subject I see. : Several people here have claimed that. Such as?? -- Keep working millions on welfare depend on you ------------------- |
#273
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Michael Scarpitti wrote:
: Frank Pittel wrote in message ... : Michael Scarpitti wrote: : : Frank Pittel wrote in message ... : : Michael Scarpitti wrote: : : : Frank Pittel wrote in message ... : : : Jim Phelps wrote: : : : : : : : "Michael Scarpitti" wrote in message : : : : om... : : : : So, the very clearly stated piece by Kodak, which acknowledges the : : : : MOTIVES for variable film development and DISMISSES them as mistaken, : : : : means nothing to you? Then you're STUPID.... : : : : : A writing that is almost 50 years old! : : : : : : Since it says what scapitti wants to hear he's going to hold it up as holy writing with : : : more authority then anything from even Kodak stating anything different. : : : : This is based on reaearch, which is cited in the text. It is precisely : : : the opposite of 'holy writ'. : : : : The Zone System was developed over years of scientific research aided by Kodak and : : experimentation. : : : False statement. Kodak has never endorsed the zoan sistum. : : No one ever claimed they did. Still trying to change the subject I see. : Several people here have claimed that. Such as?? -- Keep working millions on welfare depend on you ------------------- |
#274
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Kodak on Variable Film Development: NO!
"jjs" wrote in message ...
"Michael Scarpitti" wrote in message om... Leigh Marrin/KM6JE wrote in message ... Sigh... In a 1970s edition of the Kodak Master Darkroom Dataguide, Kodak clearly states on pages 8 and 9 that Kodak Tri-X can be developed in D-76 1:1 from 5.5 minutes to 12 minutes as needed for higher or lower contrast. That refers to varying contrast to adjust for one's enlarger, etc., not scene contrast. Good gosh, more than _doubling_ or halfing development time is a huge adjustment and certainly more than is necessary to make up for variations in enlarger contrast. I should see the statement in context, because that amount of variation seems excessive for any reasonable purpose. Anyway, I'm out of this thread. If I read any more of it, I'll have to search for some kind of Darkroom Twelve Step Program. It's really gone out of control. |
#275
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"jjs" wrote in message ...
"Michael Scarpitti" wrote in message om... Leigh Marrin/KM6JE wrote in message ... Sigh... In a 1970s edition of the Kodak Master Darkroom Dataguide, Kodak clearly states on pages 8 and 9 that Kodak Tri-X can be developed in D-76 1:1 from 5.5 minutes to 12 minutes as needed for higher or lower contrast. That refers to varying contrast to adjust for one's enlarger, etc., not scene contrast. Good gosh, more than _doubling_ or halfing development time is a huge adjustment and certainly more than is necessary to make up for variations in enlarger contrast. I should see the statement in context, because that amount of variation seems excessive for any reasonable purpose. Anyway, I'm out of this thread. If I read any more of it, I'll have to search for some kind of Darkroom Twelve Step Program. It's really gone out of control. |
#276
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ENOUGH - Kodak on Variable Film Development: NO!
Christopher A. Cline wrote in message news:fR8Sc.236791$%_6.13336@attbi_s01...
On Tue, 10 Aug 2004 10:34:13 -0600, jjs wrote (in article ): "Michael Scarpitti" wrote in message m... "jjs" wrote in message ... Enough will survive to serve far better than words can. I'm not too confident of that. I have scanned many of my B&W and they don't have the same impact. Another trouble, is that scanning can be varied to look different in contrast and tonality from the originals. Ah, but the whole objective of the Middle-Tones goal is to have something that looks good regardless. Believe me, web viewing is good enough _for this particular_ venue. It's not good enough for a show, of course. I will certainly offer up my meager online images http://people.westminstercollege.edu...os/photos.html but I think looking at Don Kirby's online images would be much more representative of what can be done using variable film development, along with variable contrast paper and a lot of work in the darkroom. http://www.santafephotogallery.com/a....php?artist=DK I see problems with several of these images, quite frankly. Of the modern practitioners of the Zone System that I have talked to (Don Kirby, Bruce Barnbaum, Ray McSavaney, John Sexton, Stu Levy), they are not using it in the way that Mr. Scarpitti appears to be representing it. Instead of varying the development times to fit the scene contrast range onto the negative and to the paper, they vary development times to get good local contrast and good tonal separation within the scene. 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. To over simplify a little, give the negative enough exposure to get the shadows off of the toe (I place them on zone IV), don't worry too much about the highlights (particularly with TMax, which doesn't have a shoulder for most practical purposes), and develop to get good tonal separation. 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. If the highlights will end up being way too dense (but still with good tonal separation), then you can also use other developing techniques, such as stand development or diluted developers. Of course, they all recognize that you very rarely get a perfect negative, so there is still a lot of work to be done in the darkroom, using variable contrast paper and other techniques to further work on the local contrast in different regions of the print. The goal is to make the print "sing", give it that "snap" and luminosity. Perhaps this is what Mr. Scarpitti means by making sure the midtones are appropriate? 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.) |
#277
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Christopher A. Cline wrote in message news:fR8Sc.236791$%_6.13336@attbi_s01...
On Tue, 10 Aug 2004 10:34:13 -0600, jjs wrote (in article ): "Michael Scarpitti" wrote in message m... "jjs" wrote in message ... Enough will survive to serve far better than words can. I'm not too confident of that. I have scanned many of my B&W and they don't have the same impact. Another trouble, is that scanning can be varied to look different in contrast and tonality from the originals. Ah, but the whole objective of the Middle-Tones goal is to have something that looks good regardless. Believe me, web viewing is good enough _for this particular_ venue. It's not good enough for a show, of course. I will certainly offer up my meager online images http://people.westminstercollege.edu...os/photos.html but I think looking at Don Kirby's online images would be much more representative of what can be done using variable film development, along with variable contrast paper and a lot of work in the darkroom. http://www.santafephotogallery.com/a....php?artist=DK I see problems with several of these images, quite frankly. Of the modern practitioners of the Zone System that I have talked to (Don Kirby, Bruce Barnbaum, Ray McSavaney, John Sexton, Stu Levy), they are not using it in the way that Mr. Scarpitti appears to be representing it. Instead of varying the development times to fit the scene contrast range onto the negative and to the paper, they vary development times to get good local contrast and good tonal separation within the scene. 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. To over simplify a little, give the negative enough exposure to get the shadows off of the toe (I place them on zone IV), don't worry too much about the highlights (particularly with TMax, which doesn't have a shoulder for most practical purposes), and develop to get good tonal separation. 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. If the highlights will end up being way too dense (but still with good tonal separation), then you can also use other developing techniques, such as stand development or diluted developers. Of course, they all recognize that you very rarely get a perfect negative, so there is still a lot of work to be done in the darkroom, using variable contrast paper and other techniques to further work on the local contrast in different regions of the print. The goal is to make the print "sing", give it that "snap" and luminosity. Perhaps this is what Mr. Scarpitti means by making sure the midtones are appropriate? 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.) |
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