تويت
الأخطاء والطوارئ - ١ - المعالجة والطباعة .. كيفية التقاط وتطوير الصور بالأبيض والأسود
FAULTS & EMERGENCIES
- When things go wrong , the time to discover them is usually at the end of the processing . The first check that you should make when the film is dry and ready to handle is for gross errors . The transparent edges of black - and - white negative film called the rebates - make it a little easier to spot mistakes than on colour transparency film , as does the contrast range , which is generally lower . Unwanted exposure , such as light leaks and flaring , appear as dark areas on the negative , while parts that have been blocked from the light appear clear . Because commercial processing is now geared to colour film , black - and - white development by other people , when you can find it , is not infrequently at a lower standard ; this is one of the strongest arguments for doing your own processing .
Faults can occur in three areas of the photography , and it is important to identify which applies to a particular error . The three areas are : the condition of the film ; the exposure ; and the processing . The first of these is the least
ABOVE A bad case of over - exposure during printing such as this can be easily rectified ... by throwing away and making another print !
LEFT If a print is found to suffer from blurring , such as here , there are two potential causes . The first is that the camera may have moved during the original exposure , and unfortunately there is no easy cure here -unless you're willing to enter into a lengthy retouching exercise ! The other possible cause is that the enlarger may have been jolted . Fortunately , the cure here is quite simple - make another print .
LEFT When corresponding to the positioning of the sprockets on the film strip , light leaks ( top of the print ) can be turned to your advantage . This can be done by " burning in ' ; darkening an area of the print during the enlarging process by placing a block between light source and paper .
Evaluating the Negative
In the first shot 1 , the meter has been misled by the bright highlight behind , and , as a result , the negative is underexposed . There is more detail in 2 , and it would be much easier to print , 3 and 4 have a 2 - stop exposure difference between them . Note how the piano player , who is virtually invisible in 3 , appears when the exposure has been opened up . The metering has been misled by the small , brightly lit scene in the centre of 5 , resulting in overexposure . The photographer compensated in 6 , by stopping down , but underdevelopment has aggravated the problem , causing burned out highlights . Negative 7 has a heavy sky ( it was blue ) and would print flat white . The sky area in 8 would print much darker because the photographer had fitted a red filter to the lens .
An ill - defined dark area is characteristic of accidental exposure to light . Here , this includes the rebate , suggesting that the leak occurred outside the camera ( top ) . Two adjacent pieces of the film stuck together in developing tank , preventing full exposure to the processing solutions ( above ) .
likely , but includes manufacturing defects and bad storage . While photo- graphers , and even some camera manufacturers , are ready to identify the film makers as the culprits in many situations , the truth is that defects are very rare . More often than not , the cause of the fault lies in the camera , the way it is used , and in the darkroom .
The examples that follow are some of the most typical , and are intended to help you identify ones that you may come across . There are not many general- izations that are useful , but one is this : if the blemish , or whatever form the fault takes , extends beyond the rectangle of the picture frame , it has almost certainly not occurred during the exposure . The rebates themselves can offer quite a lot of information , particularly about the processing . These rebates carry printed frame numbers and the film's name , and as this has been pre- exposed by the manufacturer , it is consistent . In other words , if this lettering appears either weak or dense , it indicates a processing , rather than an expo- sure , error .
Processing errors usually happen because the photographer was not paying full attention , or through inexperience . Always make an effort to find out exactly what happened - the only positive value of a mistake is that you can in future avoid doing the same thing .
Some faults can be cured or concealed , by retouching , special treatment , or in the printing . Only throw away a damaged negative if you are absolutely sure that you can make nothing of it .
FAULTS & EMERGENCIES
- When things go wrong , the time to discover them is usually at the end of the processing . The first check that you should make when the film is dry and ready to handle is for gross errors . The transparent edges of black - and - white negative film called the rebates - make it a little easier to spot mistakes than on colour transparency film , as does the contrast range , which is generally lower . Unwanted exposure , such as light leaks and flaring , appear as dark areas on the negative , while parts that have been blocked from the light appear clear . Because commercial processing is now geared to colour film , black - and - white development by other people , when you can find it , is not infrequently at a lower standard ; this is one of the strongest arguments for doing your own processing .
Faults can occur in three areas of the photography , and it is important to identify which applies to a particular error . The three areas are : the condition of the film ; the exposure ; and the processing . The first of these is the least
ABOVE A bad case of over - exposure during printing such as this can be easily rectified ... by throwing away and making another print !
LEFT If a print is found to suffer from blurring , such as here , there are two potential causes . The first is that the camera may have moved during the original exposure , and unfortunately there is no easy cure here -unless you're willing to enter into a lengthy retouching exercise ! The other possible cause is that the enlarger may have been jolted . Fortunately , the cure here is quite simple - make another print .
LEFT When corresponding to the positioning of the sprockets on the film strip , light leaks ( top of the print ) can be turned to your advantage . This can be done by " burning in ' ; darkening an area of the print during the enlarging process by placing a block between light source and paper .
Evaluating the Negative
In the first shot 1 , the meter has been misled by the bright highlight behind , and , as a result , the negative is underexposed . There is more detail in 2 , and it would be much easier to print , 3 and 4 have a 2 - stop exposure difference between them . Note how the piano player , who is virtually invisible in 3 , appears when the exposure has been opened up . The metering has been misled by the small , brightly lit scene in the centre of 5 , resulting in overexposure . The photographer compensated in 6 , by stopping down , but underdevelopment has aggravated the problem , causing burned out highlights . Negative 7 has a heavy sky ( it was blue ) and would print flat white . The sky area in 8 would print much darker because the photographer had fitted a red filter to the lens .
An ill - defined dark area is characteristic of accidental exposure to light . Here , this includes the rebate , suggesting that the leak occurred outside the camera ( top ) . Two adjacent pieces of the film stuck together in developing tank , preventing full exposure to the processing solutions ( above ) .
likely , but includes manufacturing defects and bad storage . While photo- graphers , and even some camera manufacturers , are ready to identify the film makers as the culprits in many situations , the truth is that defects are very rare . More often than not , the cause of the fault lies in the camera , the way it is used , and in the darkroom .
The examples that follow are some of the most typical , and are intended to help you identify ones that you may come across . There are not many general- izations that are useful , but one is this : if the blemish , or whatever form the fault takes , extends beyond the rectangle of the picture frame , it has almost certainly not occurred during the exposure . The rebates themselves can offer quite a lot of information , particularly about the processing . These rebates carry printed frame numbers and the film's name , and as this has been pre- exposed by the manufacturer , it is consistent . In other words , if this lettering appears either weak or dense , it indicates a processing , rather than an expo- sure , error .
Processing errors usually happen because the photographer was not paying full attention , or through inexperience . Always make an effort to find out exactly what happened - the only positive value of a mistake is that you can in future avoid doing the same thing .
Some faults can be cured or concealed , by retouching , special treatment , or in the printing . Only throw away a damaged negative if you are absolutely sure that you can make nothing of it .
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