تويت
اختيار الورق .. المعالجة والطباعة .. كيفية التقاط وتطوير الصور بالأبيض والأسود
CHOOSING THE PAPER
Interestingly , printing papers are available in a wider range of characteristics than black - and - white film . Apart from size , printing papers come in different paper thicknesses , textures , tints , tones , types of coating and , probably most important of all , contrast grades . Speed , however , is not offered as a variable , but the way in which it is used renders such a choice unimportant . There is no difficulty in altering the exposure by almost any degree , unlike many camera situations . In order to allow workable exposure times of at least a few seconds , paper sensitivity to light is less than that of film .
CONTRAST GRADE
To compensate for low or high contrast in the negative , paper is available in several grades of contrast . The normal grade is 2 , low - contrast is 1 ( for con- trasty negatives ) , and high - contrast grades are 3 and 4 ( for flat negatives ) . This is the basic range , but some paper manufacturers produce a 0 grade - ex- tremely low contrast - and a 5 grade , which is very high , or ' hard ' .
An alternative is variable - contrast paper - a single type that will give a range depending on whether a bluish or yellowish filter is used in the enlarger . The advantage of this is that you need only buy one stock of paper .
WEIGHT
This is a measure of paper thickness . The most commonly available are single weight and double weight , the latter being better for significant enlargement because it has less tendency to crease or buckle .
TEXTURE
This refers to both the smoothness of the surface and to textural patterns introduced for special effect . The smoother the surface , the less scattering of light there is , and the deeper the blacks . So , for a good range of contrast and rich shadow tones , glossy paper is for many photographers the ideal . Except for resin - coated ( RC ) paper , this can be ' ferrotyped ' by drying it in contact with a smooth metal plate to give an even glossier effect , but an unglazed finish is more usual . Common alternatives to glossy are matte , lustre and pearl .
In addition , special papers are made to imitate the surface of an oil canvas , silk , and so on .
TINT
White paper is normal , giving the most brilliance in highlights , but slightly tinted stock , such as cream , is also available .
TONE
The mixture of chemicals in the emulsion determines the exact tone of the dark parts of the image , which can tend towards blue - black , brown - black , warm - black , or may just be neutral .
COATING
An alternative to standard , paper - base paper , and one that is becoming increas- ingly popular , is resin - coating . These papers have a water - resistant base that confines the processing chemicals to the emulsion and speeds up the fixing , washing and drying .
RIGHT While it is almost impossible to illustrate different paper finishes in print , the examples shown here may give some idea how great a difference the paper and finish can make to the final result , when development is the same for each print . One of the most obvious effects is the scattering of light on a textured surface ( such as the linen bases shown here ) which results in shallower blacks . For rich shadow tones , glossy papers are therefore preferred .
TOP , FROM RIGHT TO LEFT resin - coated glossy ; Kentmere textured matt ; Ilford Galerie ; ( middle ) fibre - based glossy , unglazed ; tinted linen base ; white linen ; ( bottom ) Chlorobromide fibre - based , matt ; fibre - based glossy , unglazed ; Chlorobromide fibre - based glossy , unglazed .
CHOOSING THE PAPER
Interestingly , printing papers are available in a wider range of characteristics than black - and - white film . Apart from size , printing papers come in different paper thicknesses , textures , tints , tones , types of coating and , probably most important of all , contrast grades . Speed , however , is not offered as a variable , but the way in which it is used renders such a choice unimportant . There is no difficulty in altering the exposure by almost any degree , unlike many camera situations . In order to allow workable exposure times of at least a few seconds , paper sensitivity to light is less than that of film .
CONTRAST GRADE
To compensate for low or high contrast in the negative , paper is available in several grades of contrast . The normal grade is 2 , low - contrast is 1 ( for con- trasty negatives ) , and high - contrast grades are 3 and 4 ( for flat negatives ) . This is the basic range , but some paper manufacturers produce a 0 grade - ex- tremely low contrast - and a 5 grade , which is very high , or ' hard ' .
An alternative is variable - contrast paper - a single type that will give a range depending on whether a bluish or yellowish filter is used in the enlarger . The advantage of this is that you need only buy one stock of paper .
WEIGHT
This is a measure of paper thickness . The most commonly available are single weight and double weight , the latter being better for significant enlargement because it has less tendency to crease or buckle .
TEXTURE
This refers to both the smoothness of the surface and to textural patterns introduced for special effect . The smoother the surface , the less scattering of light there is , and the deeper the blacks . So , for a good range of contrast and rich shadow tones , glossy paper is for many photographers the ideal . Except for resin - coated ( RC ) paper , this can be ' ferrotyped ' by drying it in contact with a smooth metal plate to give an even glossier effect , but an unglazed finish is more usual . Common alternatives to glossy are matte , lustre and pearl .
In addition , special papers are made to imitate the surface of an oil canvas , silk , and so on .
TINT
White paper is normal , giving the most brilliance in highlights , but slightly tinted stock , such as cream , is also available .
TONE
The mixture of chemicals in the emulsion determines the exact tone of the dark parts of the image , which can tend towards blue - black , brown - black , warm - black , or may just be neutral .
COATING
An alternative to standard , paper - base paper , and one that is becoming increas- ingly popular , is resin - coating . These papers have a water - resistant base that confines the processing chemicals to the emulsion and speeds up the fixing , washing and drying .
RIGHT While it is almost impossible to illustrate different paper finishes in print , the examples shown here may give some idea how great a difference the paper and finish can make to the final result , when development is the same for each print . One of the most obvious effects is the scattering of light on a textured surface ( such as the linen bases shown here ) which results in shallower blacks . For rich shadow tones , glossy papers are therefore preferred .
TOP , FROM RIGHT TO LEFT resin - coated glossy ; Kentmere textured matt ; Ilford Galerie ; ( middle ) fibre - based glossy , unglazed ; tinted linen base ; white linen ; ( bottom ) Chlorobromide fibre - based , matt ; fibre - based glossy , unglazed ; Chlorobromide fibre - based glossy , unglazed .
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