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ASSESSING THE RESULTS
Professional laboratories use control strips of pre - exposed film to monitor their processing . If you process your own films individually and occasionally , however , you should examine the results carefully to make sure that there have been no mistakes . If there is anything wrong with the film , it could have occurred either during the processing or earlier , when taking the photographs .
Of the two types of film , negative and slide , the first is more difficult to judge . Slide film , once processed , carries its image as it should be seen , and can be assessed by using a light - box , projector or slide - viewer . In a colour negative , however , both the tones and the colours are reversed . In addition , a built - in orange mask is included by the manufacturer to improve print quality . This mask overlays everything .
A well - exposed colour negative looks rather denser than an equivalent black- and - white negative . If you view it through an orange filter ( such as an 85B or similar ) , this will give a better idea of the tones . Nothing short of a print , however , will show what the colours will look like . One of the most common faults is under - exposure ; others are fogging because of a light leak , stains due to chemical contamination , and scratches . Fogging appears as a dark area , and extends over the rebates ( the perforated margins of 35mm film ) ; it can occur during the loading of the tank , by failing to seal the tank's lid properly , or even earlier , if the camera back is accidentally opened before the film has been completely re - wound . If you develop one film at a time , you may have some opportunity to correct mistakes after the first has been processed . With the C - 41 process , if you know that the films have been underexposed by one stop , increase the development time by one third . This is really an emergency procedure , as colour negative films are not designed to perform as well as slide films do when push - processed .
Mistakes in processing slide film are easier to spot . Look for over - exposure and under - exposure , but realize that this may have been a mistake during shooting . Strong colour casts and stains are probably due to chemical contam- ination ; just a drop or two of bleach or fixer in the developer will have disastrous results .
TOP LEFT AND ABOVE Colour slide film is far more critical of exposure than colour negative film , a fact that must be remembered when assessing your prints from slides . Much of the time , slight under- or overexposure may be the fault of the original transparency . However , stains and noticeable colour casts may well be due to chemical contamination ; a mere drop or two of bleach or fixer in the developer will have disastrous consequences . One thing you can't do much about , however , is an image which is simply out- of - focus . This can be spotted if you look carefully at the slide .
LEFT A well - exposed negative looks rather denser than an equivalent black and white negative . Viewing the negative through an orange filter , such as an 85B , will give a better idea of tones .
LEFT AND ABOVE A high - contrast scene such as this could be ruined completely by the common fault of print under - exposure ; all detail in the foreground subject could easily be lost altogether .
BELOW Crimp marks show up as pinkish or bluish crescents on transparencies . These are most often caused by buckling the film before processing . Take care when separating the film from the spool and loading it into the developing tank .
ASSESSING THE RESULTS
Professional laboratories use control strips of pre - exposed film to monitor their processing . If you process your own films individually and occasionally , however , you should examine the results carefully to make sure that there have been no mistakes . If there is anything wrong with the film , it could have occurred either during the processing or earlier , when taking the photographs .
Of the two types of film , negative and slide , the first is more difficult to judge . Slide film , once processed , carries its image as it should be seen , and can be assessed by using a light - box , projector or slide - viewer . In a colour negative , however , both the tones and the colours are reversed . In addition , a built - in orange mask is included by the manufacturer to improve print quality . This mask overlays everything .
A well - exposed colour negative looks rather denser than an equivalent black- and - white negative . If you view it through an orange filter ( such as an 85B or similar ) , this will give a better idea of the tones . Nothing short of a print , however , will show what the colours will look like . One of the most common faults is under - exposure ; others are fogging because of a light leak , stains due to chemical contamination , and scratches . Fogging appears as a dark area , and extends over the rebates ( the perforated margins of 35mm film ) ; it can occur during the loading of the tank , by failing to seal the tank's lid properly , or even earlier , if the camera back is accidentally opened before the film has been completely re - wound . If you develop one film at a time , you may have some opportunity to correct mistakes after the first has been processed . With the C - 41 process , if you know that the films have been underexposed by one stop , increase the development time by one third . This is really an emergency procedure , as colour negative films are not designed to perform as well as slide films do when push - processed .
Mistakes in processing slide film are easier to spot . Look for over - exposure and under - exposure , but realize that this may have been a mistake during shooting . Strong colour casts and stains are probably due to chemical contam- ination ; just a drop or two of bleach or fixer in the developer will have disastrous results .
TOP LEFT AND ABOVE Colour slide film is far more critical of exposure than colour negative film , a fact that must be remembered when assessing your prints from slides . Much of the time , slight under- or overexposure may be the fault of the original transparency . However , stains and noticeable colour casts may well be due to chemical contamination ; a mere drop or two of bleach or fixer in the developer will have disastrous consequences . One thing you can't do much about , however , is an image which is simply out- of - focus . This can be spotted if you look carefully at the slide .
LEFT A well - exposed negative looks rather denser than an equivalent black and white negative . Viewing the negative through an orange filter , such as an 85B , will give a better idea of tones .
LEFT AND ABOVE A high - contrast scene such as this could be ruined completely by the common fault of print under - exposure ; all detail in the foreground subject could easily be lost altogether .
BELOW Crimp marks show up as pinkish or bluish crescents on transparencies . These are most often caused by buckling the film before processing . Take care when separating the film from the spool and loading it into the developing tank .
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