تويت
التصوير الفوتوغرافي الحديث
فن النسخ
نسخ الصور، نسخ التباين
عمل نسخ بالأسود والأبيض من الأصول الملونة
COPYING PHOTOGRAPHS
Prints made especially for copying should be on glossy paper , somewhat lower in contrast than ordinary prints , and have full detail in shadows and highlights . The lightest whites should be slightly grayed over , while the darkest blacks should not be as deep as the paper can produce . Prints of this character can be copied with the minimum loss of highlight and shadow detail . The negatives should be developed to slightly higher - than - normal contrast by increasing the development time . This will compensate for the lower contrast of the original .
Rough surfaced , creased or wrinkled prints usually show troublesome reflections . These can be avoided to a large extent if the print is flattened in a printing frame and copied through the glass .
Black - and - white photographic prints in good condition , either on smooth or glossy paper , present no particular difficulty to the copyist . Simply expose correctly and develop for the right contrast as determined by trial and error . However , copies from ordinary photographs will generally not be so good as copies from photographs that were made especially for reproduction .
COPYING FOR CONTRAST
The secret of copying for contrast - such as copying manuscripts , newspaper clippings , maps , or legal documents - is to keep in mind that you want the reproduced copy to have black lines on a white background . The exposure must be long enough to get good density in the white background , but not so long that the transparent lines in the negative will become gray or fogged . If the negative is overexposed and the lines or letters are slightly veiled , the negative can be improved by slight reduction with potassium ferricyanide reducer . On the other hand , underexposure of the negative will give a thin negative without enough contrast .
When you are copying pencil drawings , you may have some difficulty in getting good contrast . This is because pencil lines are not black but gray . Furthermore , if the drawing is on rough paper , the lines are broken and uneven . The film and processing technique you use to copy such material must , therefore , be geared to obtaining maximum contrast .
You may be asked to copy a half - tone reproduction , which , as you may . know , is composed of a series of very fine dots with white interspaces . ( If you never have done so , examine any of the half - tone illustrations in this Assignment through a magnifying glass and you will see the screen effect very plainly . ) If the copy is to be life size or smaller so that the dots are not unduly exaggerated , you can treat the half - tone as you would any high contrast black - and - white original and copy it with a reasonably high contrast film . This is the correct procedure . because half - tones of this kind do not really contain any half tones and , therefore , if you reproduce the black dots accurately , you will get the correct half - tone effect . It is essential with this technique to expose very accurately and to get maximum sharpness so that the black dots will not blur to the point where detail is lost .
Another method of copying such half - tone illustrations is to throw the copy very slightly out of focus , which will blur the dots and the spaces between them so they will appear to merge into a more even tone .
In copying tracings or drawings on very thin paper , you should back up the tracing with a piece of white cardboard . If you have to copy some printed matter and the printing on the reverse side shows through , you can hide this printing by backing it up with black cardboard .
When copying from a book , be careful not to break the binding of the book . The easiest way to set up the original is to have a shelf attached to the easel . Open the book at the desired page and place it on the shelf so that the page to be copied and the stiff cover behind it can be held flat against the easel by means of a rubber band or a string tied firmly around the book and the easel . If the rubber band or the string shows in the negative , it can be blocked out with opaque or retouched with a soft pencil ..
MAKING BLACK - AND - WHITE COPIES OF COLORED ORIGINALS
If there is color in the original , your copy technique will depend upon whether you want to emphasize the color , minimize it , or reproduce it in its correct value .
You can copy a colored original and reproduce the colors in their correct tonal value by using ordinary panchromatic film . There are times , however , when you have to falsify the colors for some specific purpose . Suppose , for instance , that you want to copy a light sepia print and get a good snappy negative . In such a picture , the highlights are white , but the half - tones and shadows are yellowish - brown . If you use a panchromatic film to reproduce the light sepia color truthfully , you will get a flat washed - out copy with very little contrast . If the sepia is photographed to appear darker , you would gain contrast and get a much better copy . So you use an orthochromatic film which tends to ake yellow - brown photograph dark and you get a much better negative .
In the same way , faded prints in which the original black silver image has faded badly or has turned yellow and low in contrast , should be photographed with an orthochromatic film .
فن النسخ
نسخ الصور، نسخ التباين
عمل نسخ بالأسود والأبيض من الأصول الملونة
COPYING PHOTOGRAPHS
Prints made especially for copying should be on glossy paper , somewhat lower in contrast than ordinary prints , and have full detail in shadows and highlights . The lightest whites should be slightly grayed over , while the darkest blacks should not be as deep as the paper can produce . Prints of this character can be copied with the minimum loss of highlight and shadow detail . The negatives should be developed to slightly higher - than - normal contrast by increasing the development time . This will compensate for the lower contrast of the original .
Rough surfaced , creased or wrinkled prints usually show troublesome reflections . These can be avoided to a large extent if the print is flattened in a printing frame and copied through the glass .
Black - and - white photographic prints in good condition , either on smooth or glossy paper , present no particular difficulty to the copyist . Simply expose correctly and develop for the right contrast as determined by trial and error . However , copies from ordinary photographs will generally not be so good as copies from photographs that were made especially for reproduction .
COPYING FOR CONTRAST
The secret of copying for contrast - such as copying manuscripts , newspaper clippings , maps , or legal documents - is to keep in mind that you want the reproduced copy to have black lines on a white background . The exposure must be long enough to get good density in the white background , but not so long that the transparent lines in the negative will become gray or fogged . If the negative is overexposed and the lines or letters are slightly veiled , the negative can be improved by slight reduction with potassium ferricyanide reducer . On the other hand , underexposure of the negative will give a thin negative without enough contrast .
When you are copying pencil drawings , you may have some difficulty in getting good contrast . This is because pencil lines are not black but gray . Furthermore , if the drawing is on rough paper , the lines are broken and uneven . The film and processing technique you use to copy such material must , therefore , be geared to obtaining maximum contrast .
You may be asked to copy a half - tone reproduction , which , as you may . know , is composed of a series of very fine dots with white interspaces . ( If you never have done so , examine any of the half - tone illustrations in this Assignment through a magnifying glass and you will see the screen effect very plainly . ) If the copy is to be life size or smaller so that the dots are not unduly exaggerated , you can treat the half - tone as you would any high contrast black - and - white original and copy it with a reasonably high contrast film . This is the correct procedure . because half - tones of this kind do not really contain any half tones and , therefore , if you reproduce the black dots accurately , you will get the correct half - tone effect . It is essential with this technique to expose very accurately and to get maximum sharpness so that the black dots will not blur to the point where detail is lost .
Another method of copying such half - tone illustrations is to throw the copy very slightly out of focus , which will blur the dots and the spaces between them so they will appear to merge into a more even tone .
In copying tracings or drawings on very thin paper , you should back up the tracing with a piece of white cardboard . If you have to copy some printed matter and the printing on the reverse side shows through , you can hide this printing by backing it up with black cardboard .
When copying from a book , be careful not to break the binding of the book . The easiest way to set up the original is to have a shelf attached to the easel . Open the book at the desired page and place it on the shelf so that the page to be copied and the stiff cover behind it can be held flat against the easel by means of a rubber band or a string tied firmly around the book and the easel . If the rubber band or the string shows in the negative , it can be blocked out with opaque or retouched with a soft pencil ..
MAKING BLACK - AND - WHITE COPIES OF COLORED ORIGINALS
If there is color in the original , your copy technique will depend upon whether you want to emphasize the color , minimize it , or reproduce it in its correct value .
You can copy a colored original and reproduce the colors in their correct tonal value by using ordinary panchromatic film . There are times , however , when you have to falsify the colors for some specific purpose . Suppose , for instance , that you want to copy a light sepia print and get a good snappy negative . In such a picture , the highlights are white , but the half - tones and shadows are yellowish - brown . If you use a panchromatic film to reproduce the light sepia color truthfully , you will get a flat washed - out copy with very little contrast . If the sepia is photographed to appear darker , you would gain contrast and get a much better copy . So you use an orthochromatic film which tends to ake yellow - brown photograph dark and you get a much better negative .
In the same way , faded prints in which the original black silver image has faded badly or has turned yellow and low in contrast , should be photographed with an orthochromatic film .
تعليق