تويت
التصوير الفوتوغرافي الحديث
طرق الحفاظ على الجودة
الحفاظ على الجودة مع الفيلم الأسود والأبيض
WAYS TO MAINTAIN QUALITY
The available light photographer must always bear in mind the subject of picture quality . He is usually working under extremely adverse lighting conditions . He may have to shoot with the lens wide open instead of stopping it down to its best aperture . He may have to push development to get greater effective film speed . He may have to accept lighting which is basically wrong for the best presentation of his subject .
He must constantly compromise among conflicting requirements in order to get the best possible picture under extremely difficult circumstances . He can make the best compromise only if he understands how quality is affected by each of the elements which determine the quality of the finished picture . Let us consider some broad general rules for black - and - white film .
Figure 24 English library interior . illuminated by daylight coming through windows . Courtesy of G. Maling
MAINTAINING QUALITY WITH BLACK - AND - WHITE FILM
CORRECT SPEED RATING . Use the correct film speed rating when setting your exposure meter before taking light readings . The film speed rating for any film will vary to some extent , depending on your meter , the type of film , the developer you use , and whether you prefer maximum shadow detail or like somewhat darker shadows for greater dramatic effect . The true film speed for the available light photographer generally ranges from the manufacturer's published figure to twice that ..
For example , a film rated at ASA 160 may have a useable speed for available light from 160 to 320. However , it is generally best to base your exposure on a film speed of not over 200. While it is possible to push film in development to provide greater effective speed , it is not a good idea to do so except in an emergency . More on that subject later .
WORK FOR NORMAL NEGATIVE DENSITY . Work for normal density in your negatives . Using the correct film speed permits you use normal developing techniques . Normal developing usually produces normal negative density . Excessive density , whether due to overexposure or overdevelopment , increases grain and cuts down image sharpness . It is also likely to degrade tone separation in the finished picture .
FOLLOW RECOMMENDATIONS . Don't push the film beyond the manu facturer's recommendations except in emergencies . Do your best to limit such emergencies . This applies both to exposure and development . When you increase the film speed rating , you aren't really doing anything to the film itself , you are simply underexposing it . Calling that fact by another name doesn't change it .
The normal speed rating of a film results in exposures which produce a reasonable amount of shadow detail . As exposure is reduced , the deeper shadows lose detail first , and as the exposure is progressively reduced , more and more of the shadows go black . Doubling the speed rating is equivalent to halving the exposure and this will empty the deeper shadows . If the lighting is flat and there are no really deep shadows , this reduction in exposure will still produce a good negative . However , if the lighting is contrasty to begin with , the shadows are quite dark , so that losing additional shadow detail may hurt the picture badly .
Pushing up the speed rating beyond a certain point will also reduce overall negative contrast . You may compensate for this to a limited degree by increasing development or by using a more vigorous developer . This technique has undesirable aspects , too . Increasing development always increases grain . Excessive development also produces excessive contrast and blocked highlights in those parts of the picture which are more strongly lighted . For the student who is likely to have a wide range of subjects on a single roll , special processing to favor some of the exposures on a roll may ruin the others .
USE THE CORRECT DEVELOPER . Use the correct developer for the film and type of subject . The proper choice of developers may make a considerable difference in the final result . Some developers bring out the maximum speed of a film , but they may produce contrasty negatives . Others bring out maximum detail , but they may lose speed , contrast and sharpness . Many fine grain developers are of this type For many subjects , it is better to use one of the standard developers , even though such a developer will produce somewhat more pronounced grain . The difference between developers is discussed more fully later in this Assignment .
طرق الحفاظ على الجودة
الحفاظ على الجودة مع الفيلم الأسود والأبيض
WAYS TO MAINTAIN QUALITY
The available light photographer must always bear in mind the subject of picture quality . He is usually working under extremely adverse lighting conditions . He may have to shoot with the lens wide open instead of stopping it down to its best aperture . He may have to push development to get greater effective film speed . He may have to accept lighting which is basically wrong for the best presentation of his subject .
He must constantly compromise among conflicting requirements in order to get the best possible picture under extremely difficult circumstances . He can make the best compromise only if he understands how quality is affected by each of the elements which determine the quality of the finished picture . Let us consider some broad general rules for black - and - white film .
Figure 24 English library interior . illuminated by daylight coming through windows . Courtesy of G. Maling
MAINTAINING QUALITY WITH BLACK - AND - WHITE FILM
CORRECT SPEED RATING . Use the correct film speed rating when setting your exposure meter before taking light readings . The film speed rating for any film will vary to some extent , depending on your meter , the type of film , the developer you use , and whether you prefer maximum shadow detail or like somewhat darker shadows for greater dramatic effect . The true film speed for the available light photographer generally ranges from the manufacturer's published figure to twice that ..
For example , a film rated at ASA 160 may have a useable speed for available light from 160 to 320. However , it is generally best to base your exposure on a film speed of not over 200. While it is possible to push film in development to provide greater effective speed , it is not a good idea to do so except in an emergency . More on that subject later .
WORK FOR NORMAL NEGATIVE DENSITY . Work for normal density in your negatives . Using the correct film speed permits you use normal developing techniques . Normal developing usually produces normal negative density . Excessive density , whether due to overexposure or overdevelopment , increases grain and cuts down image sharpness . It is also likely to degrade tone separation in the finished picture .
FOLLOW RECOMMENDATIONS . Don't push the film beyond the manu facturer's recommendations except in emergencies . Do your best to limit such emergencies . This applies both to exposure and development . When you increase the film speed rating , you aren't really doing anything to the film itself , you are simply underexposing it . Calling that fact by another name doesn't change it .
The normal speed rating of a film results in exposures which produce a reasonable amount of shadow detail . As exposure is reduced , the deeper shadows lose detail first , and as the exposure is progressively reduced , more and more of the shadows go black . Doubling the speed rating is equivalent to halving the exposure and this will empty the deeper shadows . If the lighting is flat and there are no really deep shadows , this reduction in exposure will still produce a good negative . However , if the lighting is contrasty to begin with , the shadows are quite dark , so that losing additional shadow detail may hurt the picture badly .
Pushing up the speed rating beyond a certain point will also reduce overall negative contrast . You may compensate for this to a limited degree by increasing development or by using a more vigorous developer . This technique has undesirable aspects , too . Increasing development always increases grain . Excessive development also produces excessive contrast and blocked highlights in those parts of the picture which are more strongly lighted . For the student who is likely to have a wide range of subjects on a single roll , special processing to favor some of the exposures on a roll may ruin the others .
USE THE CORRECT DEVELOPER . Use the correct developer for the film and type of subject . The proper choice of developers may make a considerable difference in the final result . Some developers bring out the maximum speed of a film , but they may produce contrasty negatives . Others bring out maximum detail , but they may lose speed , contrast and sharpness . Many fine grain developers are of this type For many subjects , it is better to use one of the standard developers , even though such a developer will produce somewhat more pronounced grain . The difference between developers is discussed more fully later in this Assignment .
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