تويت
التصوير الفوتوغرافي الحديث
التصوير بالألوان وحقائق حول المرشحات
الجزء الأول التصوير بالألوان
تجهيز فيلم ملون
PROCESSING COLOR FILM
POSITIVE COLOR FILM
All of the light - sensitive emulsions in color film are basically silver bromide So when color film is first developed , it is just as black as conventional panchromatic film . Now let us see how color is put into positive color film . This is done later in the processing operation .
This section on film processing is intended only as an explanation of the procedure . It is designed to give you a basic understanding of how color film is processed and how its color is achieved . We will deal here only in general terms , so our explanation will apply to all color film . Specific details will vary depending on the film .
In this Assignment we cannot give you instructions for processing any particular color film . If you want to do color processing , and some photographers do , you should get full instructions from the film manufacturer . Manufacturers supply detailed information and the special chemicals for the photographer who wants to do his own processing .
Home processing is not particularly difficult , but it is not recommended unless you are a very careful worker and shoot color film regularly . The processing solutions do not keep well and are quite expensive . The student who exposes only an occasional roll of color film will find it much cheaper to send his film to a commercial processing laboratory .
DEVELOPING . After exposure , the film is developed in a conventional type of developer . As a result of this development there will be three superimposed negatives in Layers 1 , 3 and 4. These negatives will differ slightly since each was produced by light of a different color . In each negative , the density will be proportional to the color to which the emulsion was sensitized .
SECOND EXPOSURE . The next step is to expose the developed but not fixed film to strong white light . This second exposure , in a sense , reverses the first . Where there is a dense area of silver produced by the first exposure and development , there is very little unused silver bromide left , so that the second exposure has practically no effect . On the other hand , if the first exposure produced no silver deposit in any area of the picture , all the silver bromide is still unchanged , and it will be strongly affected by the second exposure . This situation is very similar to that existing when photographic printing paper is exposed through a negative .
COLOR DEVELOPING . After the second exposure , the film is immersed in a special type of developer called a color developer . Remember , up to this point we have had no color . The first developed image is made of silver and is , therefore , black . A color developer is a special developer which can combine with certain chemical compounds in the various emulsions to form colors or dyes in direct proportion to the amount of silver being produced by the developing action . These compounds are called color couplers . What happens in color developing , then , is that colored dyes are formed in the emulsion that received the second exposure while the positive image is being developed .
There are three different color couplers , one in each of the emulsion layers . Layer 1 , the blue - sensitive layer , contains a color coupler which produces a yellow dye ; Layer 3 has a magenta color coupler ; Layer 4 has a cyan color coupler . Note that in each case , the dye produced is the complement to the color for which that emulsion was sensitized .
BLEACHING . After this second development , Layer 1 has a yellow dye image , Layer 3 has a magenta dye image , and Layer 4 has a cyan dye image . In addition , substantially all the silver bromide has been converted to silver so that the film as a whole is practically opaque . The next step is to bleach out the silver , leaving only the dye images . Finally , the bleached silver is fixed ( dissolved ) , and the film washed and dried .
FINAL COLOR RENDITION . Now let us see why we get correct natural color , even though our dyes were complementary , or opposite in color to the original subject . Let us assume that we photographed a blue flower . Layer 1 of our film , being sensitive to blue , produced a heavy silver deposit at the first exposure and development . Since practically all the light - sensitive silver bromide was used up in this development , no further silver was produced during second exposure and development . Since the second development is the one in which the color coupler adds dye to the developing emulsion , no yellow dye was formed . The top layer therefore , contains no color .
Layers 3 and 4 , however , had no density on the first development and , therefore , developed to full density on second development . In the second development , the positive image takes on the appropriate dyes . Layer 3 , therefore , has a strong magenta ( red plus blue ) image , and Layer 4 has a strong cyan ( green plus blue ) image . If we project white light through these superimposed magenta and cyan images , we will see that the green of the cyan will stop the red of the magenta , and the red of the magenta will stop the green of the cyan . Neither red nor green will , therefore , come through . Blue , however , will pass through , since both cyan and magenta transmit blue , as shown in Table I , page 20 and on Plate V opposite page 10. In other words , our blue flower will seen as blue , even though we used complementary colors to produce it . Go through this same reasoning procedure for any other colors or color mixtures , and you will see that they , too , are reproduced in a similar manner .
NEGATIVE COLOR AND POLAROID COLOR FILMS
Negative color film achieves its color in substantially the same manner , except that the color couplers are used in the first developers and there is no second developer to reverse density values . That is why you see the complementary colors rather than their primaries when you look at a color negative .
Polaroid color film is constructed in essentially the same way as conventional color film . The developing process , however , is much different . As with black - and -white , Polaroid film developing is done by the diffusion transfer process . A complementary negative is generated which produces a positive full - color print .
التصوير بالألوان وحقائق حول المرشحات
الجزء الأول التصوير بالألوان
تجهيز فيلم ملون
PROCESSING COLOR FILM
POSITIVE COLOR FILM
All of the light - sensitive emulsions in color film are basically silver bromide So when color film is first developed , it is just as black as conventional panchromatic film . Now let us see how color is put into positive color film . This is done later in the processing operation .
This section on film processing is intended only as an explanation of the procedure . It is designed to give you a basic understanding of how color film is processed and how its color is achieved . We will deal here only in general terms , so our explanation will apply to all color film . Specific details will vary depending on the film .
In this Assignment we cannot give you instructions for processing any particular color film . If you want to do color processing , and some photographers do , you should get full instructions from the film manufacturer . Manufacturers supply detailed information and the special chemicals for the photographer who wants to do his own processing .
Home processing is not particularly difficult , but it is not recommended unless you are a very careful worker and shoot color film regularly . The processing solutions do not keep well and are quite expensive . The student who exposes only an occasional roll of color film will find it much cheaper to send his film to a commercial processing laboratory .
DEVELOPING . After exposure , the film is developed in a conventional type of developer . As a result of this development there will be three superimposed negatives in Layers 1 , 3 and 4. These negatives will differ slightly since each was produced by light of a different color . In each negative , the density will be proportional to the color to which the emulsion was sensitized .
SECOND EXPOSURE . The next step is to expose the developed but not fixed film to strong white light . This second exposure , in a sense , reverses the first . Where there is a dense area of silver produced by the first exposure and development , there is very little unused silver bromide left , so that the second exposure has practically no effect . On the other hand , if the first exposure produced no silver deposit in any area of the picture , all the silver bromide is still unchanged , and it will be strongly affected by the second exposure . This situation is very similar to that existing when photographic printing paper is exposed through a negative .
COLOR DEVELOPING . After the second exposure , the film is immersed in a special type of developer called a color developer . Remember , up to this point we have had no color . The first developed image is made of silver and is , therefore , black . A color developer is a special developer which can combine with certain chemical compounds in the various emulsions to form colors or dyes in direct proportion to the amount of silver being produced by the developing action . These compounds are called color couplers . What happens in color developing , then , is that colored dyes are formed in the emulsion that received the second exposure while the positive image is being developed .
There are three different color couplers , one in each of the emulsion layers . Layer 1 , the blue - sensitive layer , contains a color coupler which produces a yellow dye ; Layer 3 has a magenta color coupler ; Layer 4 has a cyan color coupler . Note that in each case , the dye produced is the complement to the color for which that emulsion was sensitized .
BLEACHING . After this second development , Layer 1 has a yellow dye image , Layer 3 has a magenta dye image , and Layer 4 has a cyan dye image . In addition , substantially all the silver bromide has been converted to silver so that the film as a whole is practically opaque . The next step is to bleach out the silver , leaving only the dye images . Finally , the bleached silver is fixed ( dissolved ) , and the film washed and dried .
FINAL COLOR RENDITION . Now let us see why we get correct natural color , even though our dyes were complementary , or opposite in color to the original subject . Let us assume that we photographed a blue flower . Layer 1 of our film , being sensitive to blue , produced a heavy silver deposit at the first exposure and development . Since practically all the light - sensitive silver bromide was used up in this development , no further silver was produced during second exposure and development . Since the second development is the one in which the color coupler adds dye to the developing emulsion , no yellow dye was formed . The top layer therefore , contains no color .
Layers 3 and 4 , however , had no density on the first development and , therefore , developed to full density on second development . In the second development , the positive image takes on the appropriate dyes . Layer 3 , therefore , has a strong magenta ( red plus blue ) image , and Layer 4 has a strong cyan ( green plus blue ) image . If we project white light through these superimposed magenta and cyan images , we will see that the green of the cyan will stop the red of the magenta , and the red of the magenta will stop the green of the cyan . Neither red nor green will , therefore , come through . Blue , however , will pass through , since both cyan and magenta transmit blue , as shown in Table I , page 20 and on Plate V opposite page 10. In other words , our blue flower will seen as blue , even though we used complementary colors to produce it . Go through this same reasoning procedure for any other colors or color mixtures , and you will see that they , too , are reproduced in a similar manner .
NEGATIVE COLOR AND POLAROID COLOR FILMS
Negative color film achieves its color in substantially the same manner , except that the color couplers are used in the first developers and there is no second developer to reverse density values . That is why you see the complementary colors rather than their primaries when you look at a color negative .
Polaroid color film is constructed in essentially the same way as conventional color film . The developing process , however , is much different . As with black - and -white , Polaroid film developing is done by the diffusion transfer process . A complementary negative is generated which produces a positive full - color print .
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