تويت
التصوير الفوتوغرافي الحديث
التصوير الفوتوغرافي ٣٥ مم
مطورو الحبوب الدقيقة
تعويض المطورين
FINE - GRAIN DEVELOPERS
For best results , thin - emulsion films should be developed in vigorous , quick - acting developers . The regular , fine - grain developers are not suited to such films ; ultra - fine grain developers should never be used . Let us see why this is so .
Fine - grain developers all contain a chemical agent which slowly dissolves a part of each silver bromide crystal while the rest of it is being developed . This silver bromide solvent may be nothing more than an excess of sodium sulfite some sodium sulfite is used as a preservative in practically all developers ) or it may be some chemical specifically added for that purpose . This slow dissolving action , occurring simultaneously with development , retards the clumping of the fine silver particles and thus reduces grain .
The silver bromide crystals of thin - emulsion films are much smaller than in the more conventional films , and when developed , produce much finer clumps of silver . It is , therefore , not necessary to use the standard type of fine - grain developer with their silver - solvent action to minimize grain . As a matter of fact , such fine - grain developers should be avoided because thin - emulsion films use the least amount of silver consistent with good negative density . Any loss of silver due to solvent action causes a loss of sharpness as well as a reduction in speed . This is particularly true of the slow , soft - working , ultra - fine grain developers in which solvent action and loss of film speed are greatest .
Thin - emulsion films develop quickly . The thinness of the emulsion promotes the penetration of developer , and the smaller silver bromide crystals take less time to develop . If development is too rapid , however , it is difficult to time accurately . The time required to pour the solution in and out of the tank , for example , may constitute a rather large part of the total time . It is , therefore , general practice to use somewhat more dilute developers with thin - emulsion films and , in that way , keep the development time within the range of three to five minutes . This is about the minimum practical time for accurate control .
COMPENSATING DEVELOPERS
Another point to consider in using vigorous developers for 35mm work is that many such developers build up density to very high values in areas of overexposure . For example , in outdoor pictures where part of the subject is in shadow and part in sunlight , the sunlit areas may build up so much density as to block up and lose detail . Faces in the sun become chalk white when printed .
To retain good detail in both the shadows and highlights under contrasty . lighting , a special type of developer called a compensating developer is recommended . In a compensating developer , development starts normally and proceeds much as usual . However , after density in the highlight areas has built up appreciably , development in those areas gradually slows down , while development in other normally exposed areas proceeds at the normal rate . As a result , the heavily exposed highlight areas do not block up as they would with a normal developer .
Figures 21 and 22 illustrate the benefits to be derived from the use of compensating developers . Figure 21 was made from a negative processed in an ordinary vigorous developer extreme contrast - shadows are empty and highlights paper white . On the other hand , the negative from which Figure 22 was printed , was given slightly more exposure , but developed in a compensating developer . The shadows have more detail , and the highlights are no longer blocked up .
Figure 21 Negative was developed in a vigorous developer . Note blocked - up highlights and deep shadows .
Figure 22 Similar to Figure 21 , but the negative was developed in a com pensating developer . Detail was retained in both high lights and shadows .
A certain amount of compensating quality has been built into some of the more modern , general the manufacturer often designates these as compensating developers . While their compensating qualities are not as great as the developers specifically designed to have this property , they are , nevertheless , adequate for all ordinary use .
التصوير الفوتوغرافي ٣٥ مم
مطورو الحبوب الدقيقة
تعويض المطورين
FINE - GRAIN DEVELOPERS
For best results , thin - emulsion films should be developed in vigorous , quick - acting developers . The regular , fine - grain developers are not suited to such films ; ultra - fine grain developers should never be used . Let us see why this is so .
Fine - grain developers all contain a chemical agent which slowly dissolves a part of each silver bromide crystal while the rest of it is being developed . This silver bromide solvent may be nothing more than an excess of sodium sulfite some sodium sulfite is used as a preservative in practically all developers ) or it may be some chemical specifically added for that purpose . This slow dissolving action , occurring simultaneously with development , retards the clumping of the fine silver particles and thus reduces grain .
The silver bromide crystals of thin - emulsion films are much smaller than in the more conventional films , and when developed , produce much finer clumps of silver . It is , therefore , not necessary to use the standard type of fine - grain developer with their silver - solvent action to minimize grain . As a matter of fact , such fine - grain developers should be avoided because thin - emulsion films use the least amount of silver consistent with good negative density . Any loss of silver due to solvent action causes a loss of sharpness as well as a reduction in speed . This is particularly true of the slow , soft - working , ultra - fine grain developers in which solvent action and loss of film speed are greatest .
Thin - emulsion films develop quickly . The thinness of the emulsion promotes the penetration of developer , and the smaller silver bromide crystals take less time to develop . If development is too rapid , however , it is difficult to time accurately . The time required to pour the solution in and out of the tank , for example , may constitute a rather large part of the total time . It is , therefore , general practice to use somewhat more dilute developers with thin - emulsion films and , in that way , keep the development time within the range of three to five minutes . This is about the minimum practical time for accurate control .
COMPENSATING DEVELOPERS
Another point to consider in using vigorous developers for 35mm work is that many such developers build up density to very high values in areas of overexposure . For example , in outdoor pictures where part of the subject is in shadow and part in sunlight , the sunlit areas may build up so much density as to block up and lose detail . Faces in the sun become chalk white when printed .
To retain good detail in both the shadows and highlights under contrasty . lighting , a special type of developer called a compensating developer is recommended . In a compensating developer , development starts normally and proceeds much as usual . However , after density in the highlight areas has built up appreciably , development in those areas gradually slows down , while development in other normally exposed areas proceeds at the normal rate . As a result , the heavily exposed highlight areas do not block up as they would with a normal developer .
Figures 21 and 22 illustrate the benefits to be derived from the use of compensating developers . Figure 21 was made from a negative processed in an ordinary vigorous developer extreme contrast - shadows are empty and highlights paper white . On the other hand , the negative from which Figure 22 was printed , was given slightly more exposure , but developed in a compensating developer . The shadows have more detail , and the highlights are no longer blocked up .
Figure 21 Negative was developed in a vigorous developer . Note blocked - up highlights and deep shadows .
Figure 22 Similar to Figure 21 , but the negative was developed in a com pensating developer . Detail was retained in both high lights and shadows .
A certain amount of compensating quality has been built into some of the more modern , general the manufacturer often designates these as compensating developers . While their compensating qualities are not as great as the developers specifically designed to have this property , they are , nevertheless , adequate for all ordinary use .
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