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تقنيات الطباعة المتقدمة
المزيد عن تطوير الطباعة
توقيت التنمية
MORE ABOUT PRINT DEVELOPMENT
In discussing the routine step by step processing of a print , we have covered only the basic principles of print development because we thought it inadvisable to digress for too long an interval into a discussion of the fine points of print development . However , these points are quite important , since they afford the photographer a considerable degree of control . We will , therefore , discuss such matters now .
TIMING DEVELOPMENT
If there is one invariable rule for making good prints that should never be forgotten , it is this : always develop by the clock . If you time your print developing accurately , you need not worry about getting the correct exposure the appearance of the print will automatically tell you whether exposure is correct or not . The use of a clock to time development is not a sign of inexperience ; it indicates the user is a good technician .
A print must be developed for the correct length of time if good print quality is expected . You cannot save a badly overexposed print by underdeveloping it and still get good quality . An overexposed and underdeveloped print will range from a poor brown to an unpleasant olive color . It will be flat and muddy , with mottled , streaky shadows . On the other hand , an underexposed print will have chalky , empty highlights with sickly gray shadows . With vigorous developers , underexposed and overdeveloped prints may be fogged ; with slow - working or partially exhausted developers , they may be stained .
EFFECT OF DEVELOPMENT TIME ON CONTRAST . You can vary the contrast of a print to a noticeable degree by regulating both the exposure and length of development . This characteristic is much more pronounced with some papers than with others , but it is true to a greater or lesser degree with all . The warm toned slow chloro - bromides , which are available in a single contrast grade only , exhibit it more markedly than the bromides or fast chloro - bromides .
You can increase the contrast of your print by prolonging its development , provided of course , you reduce the exposure so it doesn't get too dark during the longer development period . You can , within narrow limits , reduce contrast by cutting down development time and increasing exposure to give you satisfactory density for this shorter development period .
It is seldom safe to develop for less than three - fourths the recommended time . If exposures are so heavy that shorter development time is called for , the image builds up so rapidly that the diffusion of the solution through the gelatin is too slow to prevent streaky and uneven prints . You can overcome this tendency toward uneven development of badly overexposed prints by wetting the exposed . paper in ordinary water just before development . This , in effect , dilutes the developer as it diffuses into the emulsion and slows up development so it doesn't get out of hand .
EFFECT OF DEVELOPMENT TIME ON TONE . Ordinarily , the basic color of a silver print is black . If the silver particles making up the image are relatively coarse , the black may have a noticeable blue tinge . On the other hand , if the particles of silver are unusually fine , they are deep brown rather than black . Putting it another way , the larger the silver grains the bluer their color ; the smaller the particles , the browner . Let us see how this works out in print making .
If a print is given a fairly short exposure , a relatively small number of silver halide crystals are made developable . It will take a long time in the developer to build up this small number of silver particles to provide correct picture density , and the particles themselves will have to be quite large . Such an underexposed and overdeveloped print will , therefore , be colder in tone ( bluer black ) than normal . On the other hand , if the exposure is heavy , there will be a large number of developable silver grains . It will take but a short development time for these many silver particles to produce correct print density , so that they will be quite small in size . An overexposed print , because it is made up of a large number of very fine silver particles , will be warm toned ( brown or brown - black ) .
DILUTED VERSUS CONCENTRATED SOLUTIONS . Concentrated solutions . generally give slightly higher contrast than diluted solutions of the same developer . For example , D - 72 ( or Dektol ) stock solution is generally diluted 1:21 for average results . You may dilute it 1 : 4 to reduce contrast or use it 1 : 1 or even full strength to increase contrast . If you are printing a number of negatives and only one needs more contrasty treatment , develop it first in the concentrated solution and then add water to give normal dilution for the remaining prints .
Diluting the developer by adding two to three times the normal quantity of water will reduce contrast slightly , and is a very simple technique to follow when the desired contrast change is very minor . You may find it necessary to add more potassium bromide to prevent fogging because the amount of bromide needed to prevent fogging depends upon the total volume of solution , and not upon its strength . However , don't add restrainer unless test strips show definite fogging , and then add only enough to keep the highlights clear , since restrainers increase contrast .
With greatly increased dilution , the time of development is increased to such a point that it becomes necessary to overexpose to speed up development to a more reasonable value . This increase in exposure also reduces contrast , so that we have a double effect .
A more convenient method than diluting the developer is to wet the print before development . This has two advantages ; it doesn't spoil the developer for the next print , and it permits you to change dilution almost at will . After exposure , and just before development , soak the print in plain tap water until it is limp , drain it well , and then transfer it to the developer . The water that has been absorbed by the print dilutes the developer as it diffuses into the emulsion and so , in effect , you are using a diluted developer for the initial stages of the developing process .
تقنيات الطباعة المتقدمة
المزيد عن تطوير الطباعة
توقيت التنمية
MORE ABOUT PRINT DEVELOPMENT
In discussing the routine step by step processing of a print , we have covered only the basic principles of print development because we thought it inadvisable to digress for too long an interval into a discussion of the fine points of print development . However , these points are quite important , since they afford the photographer a considerable degree of control . We will , therefore , discuss such matters now .
TIMING DEVELOPMENT
If there is one invariable rule for making good prints that should never be forgotten , it is this : always develop by the clock . If you time your print developing accurately , you need not worry about getting the correct exposure the appearance of the print will automatically tell you whether exposure is correct or not . The use of a clock to time development is not a sign of inexperience ; it indicates the user is a good technician .
A print must be developed for the correct length of time if good print quality is expected . You cannot save a badly overexposed print by underdeveloping it and still get good quality . An overexposed and underdeveloped print will range from a poor brown to an unpleasant olive color . It will be flat and muddy , with mottled , streaky shadows . On the other hand , an underexposed print will have chalky , empty highlights with sickly gray shadows . With vigorous developers , underexposed and overdeveloped prints may be fogged ; with slow - working or partially exhausted developers , they may be stained .
EFFECT OF DEVELOPMENT TIME ON CONTRAST . You can vary the contrast of a print to a noticeable degree by regulating both the exposure and length of development . This characteristic is much more pronounced with some papers than with others , but it is true to a greater or lesser degree with all . The warm toned slow chloro - bromides , which are available in a single contrast grade only , exhibit it more markedly than the bromides or fast chloro - bromides .
You can increase the contrast of your print by prolonging its development , provided of course , you reduce the exposure so it doesn't get too dark during the longer development period . You can , within narrow limits , reduce contrast by cutting down development time and increasing exposure to give you satisfactory density for this shorter development period .
It is seldom safe to develop for less than three - fourths the recommended time . If exposures are so heavy that shorter development time is called for , the image builds up so rapidly that the diffusion of the solution through the gelatin is too slow to prevent streaky and uneven prints . You can overcome this tendency toward uneven development of badly overexposed prints by wetting the exposed . paper in ordinary water just before development . This , in effect , dilutes the developer as it diffuses into the emulsion and slows up development so it doesn't get out of hand .
EFFECT OF DEVELOPMENT TIME ON TONE . Ordinarily , the basic color of a silver print is black . If the silver particles making up the image are relatively coarse , the black may have a noticeable blue tinge . On the other hand , if the particles of silver are unusually fine , they are deep brown rather than black . Putting it another way , the larger the silver grains the bluer their color ; the smaller the particles , the browner . Let us see how this works out in print making .
If a print is given a fairly short exposure , a relatively small number of silver halide crystals are made developable . It will take a long time in the developer to build up this small number of silver particles to provide correct picture density , and the particles themselves will have to be quite large . Such an underexposed and overdeveloped print will , therefore , be colder in tone ( bluer black ) than normal . On the other hand , if the exposure is heavy , there will be a large number of developable silver grains . It will take but a short development time for these many silver particles to produce correct print density , so that they will be quite small in size . An overexposed print , because it is made up of a large number of very fine silver particles , will be warm toned ( brown or brown - black ) .
DILUTED VERSUS CONCENTRATED SOLUTIONS . Concentrated solutions . generally give slightly higher contrast than diluted solutions of the same developer . For example , D - 72 ( or Dektol ) stock solution is generally diluted 1:21 for average results . You may dilute it 1 : 4 to reduce contrast or use it 1 : 1 or even full strength to increase contrast . If you are printing a number of negatives and only one needs more contrasty treatment , develop it first in the concentrated solution and then add water to give normal dilution for the remaining prints .
Diluting the developer by adding two to three times the normal quantity of water will reduce contrast slightly , and is a very simple technique to follow when the desired contrast change is very minor . You may find it necessary to add more potassium bromide to prevent fogging because the amount of bromide needed to prevent fogging depends upon the total volume of solution , and not upon its strength . However , don't add restrainer unless test strips show definite fogging , and then add only enough to keep the highlights clear , since restrainers increase contrast .
With greatly increased dilution , the time of development is increased to such a point that it becomes necessary to overexpose to speed up development to a more reasonable value . This increase in exposure also reduces contrast , so that we have a double effect .
A more convenient method than diluting the developer is to wet the print before development . This has two advantages ; it doesn't spoil the developer for the next print , and it permits you to change dilution almost at will . After exposure , and just before development , soak the print in plain tap water until it is limp , drain it well , and then transfer it to the developer . The water that has been absorbed by the print dilutes the developer as it diffuses into the emulsion and so , in effect , you are using a diluted developer for the initial stages of the developing process .
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