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تحويل الألوان إلى درجات - ١ - الصورة أحادية اللون .. كيفية التقاط وتطوير الصور بالأبيض والأسود
COLOURS INTO TONES
Because black - and - white film converts from real life into tones , these tones can be altered , more or less at will . All that is needed is a set of coloured filters - coloured more strongly than the correction and light balancing filters common to colour photography . By choosing an appropriate filter , you can selectively manipulate the various shades of grey in an image . This freedom to experiment with the tonal relationships in a scene is one of black - and - white photography's strong appeals .
Often , however , a filter may be needed simply to compensate for a deficiency in the way that a monochrome film records light . The shade of grey in which a particular colour records depends on both the intensity of the light and on the spectral sensitivity of the film . Red , for instance , records paler than normal on the negative because film is relatively insensitive to it ; in the print , therefore , it appears dark . At the other end of the spectrum , blue , to which film is more sensitive than our eyes are , exposes strongly onto film , and so appears pale in the print .
RIGHT Filters allow the photographer to manipulate toner and compensate for the deficiencies in the way that monochrome film records light . Because film is more sensitive to blue light than red , then red , yellow or orange filters can be used to compensate . Neutral density filters ( top left and centre ) can reduce the overall exposure - if , for example , you are using fast film on a bright day . Graduated filters ( centre right ) are excellent for ' deepening ' a sky while not affecting the tones below the horizon .
Filtering Colours into Tones
Each of the four distinct colours in this still life- green , red , blue and yellow are susceptible to alteration by filters . With no filter used , the over- sensitivity of normal black- and - white film to blue and its under - sensitivity to red give pale tones to the cigarette packet and a too- dark version of the red Dutch cheese on the left of the picture . A yellow filter lightens the yellow cheese and darkens the blue design on the cigarette packet . An orange filter performs a similar function to the yellow , but more strongly . A red filter dramatically lightens the red cheese and darkens . the blue packet . A blue filter turns the yellow cheese almost black . A green filter lightens the tone of the apple , but makes the red cheese appear black .
No filter
Wratten 8 yellow
Wratten 16 orange
Wratten 25 red
Wratten 47 blue
Wratten 58 green
COLOURS INTO TONES
Because black - and - white film converts from real life into tones , these tones can be altered , more or less at will . All that is needed is a set of coloured filters - coloured more strongly than the correction and light balancing filters common to colour photography . By choosing an appropriate filter , you can selectively manipulate the various shades of grey in an image . This freedom to experiment with the tonal relationships in a scene is one of black - and - white photography's strong appeals .
Often , however , a filter may be needed simply to compensate for a deficiency in the way that a monochrome film records light . The shade of grey in which a particular colour records depends on both the intensity of the light and on the spectral sensitivity of the film . Red , for instance , records paler than normal on the negative because film is relatively insensitive to it ; in the print , therefore , it appears dark . At the other end of the spectrum , blue , to which film is more sensitive than our eyes are , exposes strongly onto film , and so appears pale in the print .
RIGHT Filters allow the photographer to manipulate toner and compensate for the deficiencies in the way that monochrome film records light . Because film is more sensitive to blue light than red , then red , yellow or orange filters can be used to compensate . Neutral density filters ( top left and centre ) can reduce the overall exposure - if , for example , you are using fast film on a bright day . Graduated filters ( centre right ) are excellent for ' deepening ' a sky while not affecting the tones below the horizon .
Filtering Colours into Tones
Each of the four distinct colours in this still life- green , red , blue and yellow are susceptible to alteration by filters . With no filter used , the over- sensitivity of normal black- and - white film to blue and its under - sensitivity to red give pale tones to the cigarette packet and a too- dark version of the red Dutch cheese on the left of the picture . A yellow filter lightens the yellow cheese and darkens the blue design on the cigarette packet . An orange filter performs a similar function to the yellow , but more strongly . A red filter dramatically lightens the red cheese and darkens . the blue packet . A blue filter turns the yellow cheese almost black . A green filter lightens the tone of the apple , but makes the red cheese appear black .
No filter
Wratten 8 yellow
Wratten 16 orange
Wratten 25 red
Wratten 47 blue
Wratten 58 green
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