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نسخ السلبيات والمطبوعات .. المعالجة والطباعة .. كيفية التقاط وتطوير الصور بالأبيض والأسود
COPYING NEGATIVES AND PRINTS
Making copies of important photographs is a basic skill that has several uses in caring for and restoring images . For instance , a duplicate negative can be insurance against loss or damage , or it may simply make printing easier if you enlarge it , making the dodging and burning - in corrections at this stage . Copy- ing a print may be the only way of saving an image if the original negative has gone missing or been destroyed , and is also useful if you have already done considerable difficult retouching to a print , or have made a photo - montage by sticking parts of different prints together .
COPY NEGATIVES
The technique for copying negatives is different in principle from the slide duplicating procedures used for transparencies . Because the original is a nega- tive , normal black - and - white emulsions are not suitable , as they produce nega- tive images , and the result would be a transparent positive . The material needed is a direct duplicating film , and this is normally exposed in the enlarger . The normal procedure is to make the copy negative onto a large sheet of this film large enough for contact printing later ( this avoids one more optical stage ) . The obvious difference in exposing a sheet of direct duplicating film and a sheet of printing paper is that with the former , shorter exposures give denser images . Dodging and burning - in are possible , but the effects are re- versed . The film speed is similar printing papers , and develop- ment is in a standard dish .
COPY PRINTS
This is a relatively straightforward procedure , involving normal black - and- white film . The three most important things to consider are alignment , light- ing and contrast .
Alignment means getting the print absolutely straight in relation to the camera ; any slight tilt of either the print or the camera will cause what is known
ABOVE Copying prints is a fairly simple process once a tripod fitted with a horizontal arm is employed . Ensure that the tripod legs will not appear in the picture !
Negative Copying
1. Place the original negative in the enlarger's carrier , in exactly the same way as for printing .
2. Using a regular printing easel , focus and frame the image .
3. Using a weak red safelight ( the duplicating film is sensitive only to blue light ) , expose the film . A test strip may be necessary to calculate the exact exposure time and aperture setting . Here , the shadowy areas are shaded to hold detail Develop for about 2 to 22 minutes in a dish . ( The actual time will depend on the developer and on the level of contrast desired ) . Rinse in water for 30 seconds . Fix for 5 to 10 minutes , agitating frequently . Wash for 20 to 30 minutes in running water . After a weak bath of wetting agent , hang to dry .
ABOVE With the 50mm enlarger lens stopped down to 111 for maximum sharpness this 35mm negative was exposed for 30 seconds and the 8x 10 inch ( 20x24cm ) copy negative developed for two minutes in Kodak D- 163 .
LEFT Enlarging a 35mm ) negative onto 8 x 10 inch ( 20 x 24cm ) duplicating film involves a magnification of about eight times , but this is no more than is necessary for a normal print , and although the graininess becomes much more obvious . and the resolution appears to deteriorate , the final result , by contact- printing the enlarged duplicate negative , is no different from what would have been achieved by making a straightforward print enlargement .
as ' key - stoning ' , in which the rectangular image becomes a trapezoid with two of the sides converging . If you lay the print flat and point the camera vertically down , the easiest method of alignment is to use a two - way spirit level on both the print and the camera back . Vertical copying like this is probably the most convenient method of all , and can be done either with a purpose - built copying stand , or with a tripod ( if the latter , be careful that the legs are not in the way of the lighting , or they will cast a shadow over the print ) . A slightly more complex , but very efficient alternative is to use your enlarger , placing an unexposed strip of film in the negative carrier and the print on the baseboard ; with this tech- nique , another negative must first be used in order to focus the enlarger at the right distance .
A second method of alignment to place a small flat mirror on the print , in the middle . The camera lens is then re - focused and the camera angle adjusted antil the reflection of the lens is centred in the viewfinder . This is extreemly accurate . Adjust the focus again before making the exposure . If your camera has the facility for interchangeable viewing screens , you might consider fitting one that has a checked grid pattern . This pattern will make it clear when the camera and print are properly aligned , although you must then leave a small distance surrounding the print in the viewfinder .
When lighting a print in order to make a copy , the two key factors are even coverage and avoiding reflections . For even lighting , arrange two lamps , at equal distance from the print and on opposite sides . To avoid a ' hot spot ' in the centre , aim each lamp towards the opposite edge of the print ; the two beams will cross and the light will be evenly distributed . If you have only one light , this can be used when copying a fairly small print , provided that you place a strong reflector , such as crumpled foil , on the side opposite .
As a test of lighting evenness , use a hand - held meter fitted with a plastic dome for incident readings , and measure the light level in each corner . Another , more rough - and - ready technique is to cover the print with a sheet of plain white paper , and hold a pencil vertically over the middle so that its tip is just touching : the two shadows cast should be of equal length and density .
Reflections in the print's surface are possible , particularly if the surface sheen is glossy . First make sure that the print lies flat , weighing down the corners or placing it in the enlarger easel . Then make sure that the lamps are at a sufficiently acute angle to the print - 45 degrees or less . The most certain way of blocking reflections is to support a large sheet of black.card or paper just in front of the camera , with a hole cut in it just large enough for the lens .
ABOVE The viewing prism can be detached from certain , top - of - the - range SLRs , and this makes the business of focusing far easier .
TOP When using your SLR on a copying stand , attach a cable release . This will prevent the camera from shaking during exposure , thus ensuring the sharpest possible results .
A lamp at each corner ( below ) is the ideal lighting for copying .
Using two lamps ( above ) , a flat surface can be evenly lit by aiming each at the opposite edge . The strength of the two shadows cast by a pencil held up to the surface will show if the illumination is equal . Shade the camera lens ( right ) from the direct lamp light with pieces of card .
COPYING NEGATIVES AND PRINTS
Making copies of important photographs is a basic skill that has several uses in caring for and restoring images . For instance , a duplicate negative can be insurance against loss or damage , or it may simply make printing easier if you enlarge it , making the dodging and burning - in corrections at this stage . Copy- ing a print may be the only way of saving an image if the original negative has gone missing or been destroyed , and is also useful if you have already done considerable difficult retouching to a print , or have made a photo - montage by sticking parts of different prints together .
COPY NEGATIVES
The technique for copying negatives is different in principle from the slide duplicating procedures used for transparencies . Because the original is a nega- tive , normal black - and - white emulsions are not suitable , as they produce nega- tive images , and the result would be a transparent positive . The material needed is a direct duplicating film , and this is normally exposed in the enlarger . The normal procedure is to make the copy negative onto a large sheet of this film large enough for contact printing later ( this avoids one more optical stage ) . The obvious difference in exposing a sheet of direct duplicating film and a sheet of printing paper is that with the former , shorter exposures give denser images . Dodging and burning - in are possible , but the effects are re- versed . The film speed is similar printing papers , and develop- ment is in a standard dish .
COPY PRINTS
This is a relatively straightforward procedure , involving normal black - and- white film . The three most important things to consider are alignment , light- ing and contrast .
Alignment means getting the print absolutely straight in relation to the camera ; any slight tilt of either the print or the camera will cause what is known
ABOVE Copying prints is a fairly simple process once a tripod fitted with a horizontal arm is employed . Ensure that the tripod legs will not appear in the picture !
Negative Copying
1. Place the original negative in the enlarger's carrier , in exactly the same way as for printing .
2. Using a regular printing easel , focus and frame the image .
3. Using a weak red safelight ( the duplicating film is sensitive only to blue light ) , expose the film . A test strip may be necessary to calculate the exact exposure time and aperture setting . Here , the shadowy areas are shaded to hold detail Develop for about 2 to 22 minutes in a dish . ( The actual time will depend on the developer and on the level of contrast desired ) . Rinse in water for 30 seconds . Fix for 5 to 10 minutes , agitating frequently . Wash for 20 to 30 minutes in running water . After a weak bath of wetting agent , hang to dry .
ABOVE With the 50mm enlarger lens stopped down to 111 for maximum sharpness this 35mm negative was exposed for 30 seconds and the 8x 10 inch ( 20x24cm ) copy negative developed for two minutes in Kodak D- 163 .
LEFT Enlarging a 35mm ) negative onto 8 x 10 inch ( 20 x 24cm ) duplicating film involves a magnification of about eight times , but this is no more than is necessary for a normal print , and although the graininess becomes much more obvious . and the resolution appears to deteriorate , the final result , by contact- printing the enlarged duplicate negative , is no different from what would have been achieved by making a straightforward print enlargement .
as ' key - stoning ' , in which the rectangular image becomes a trapezoid with two of the sides converging . If you lay the print flat and point the camera vertically down , the easiest method of alignment is to use a two - way spirit level on both the print and the camera back . Vertical copying like this is probably the most convenient method of all , and can be done either with a purpose - built copying stand , or with a tripod ( if the latter , be careful that the legs are not in the way of the lighting , or they will cast a shadow over the print ) . A slightly more complex , but very efficient alternative is to use your enlarger , placing an unexposed strip of film in the negative carrier and the print on the baseboard ; with this tech- nique , another negative must first be used in order to focus the enlarger at the right distance .
A second method of alignment to place a small flat mirror on the print , in the middle . The camera lens is then re - focused and the camera angle adjusted antil the reflection of the lens is centred in the viewfinder . This is extreemly accurate . Adjust the focus again before making the exposure . If your camera has the facility for interchangeable viewing screens , you might consider fitting one that has a checked grid pattern . This pattern will make it clear when the camera and print are properly aligned , although you must then leave a small distance surrounding the print in the viewfinder .
When lighting a print in order to make a copy , the two key factors are even coverage and avoiding reflections . For even lighting , arrange two lamps , at equal distance from the print and on opposite sides . To avoid a ' hot spot ' in the centre , aim each lamp towards the opposite edge of the print ; the two beams will cross and the light will be evenly distributed . If you have only one light , this can be used when copying a fairly small print , provided that you place a strong reflector , such as crumpled foil , on the side opposite .
As a test of lighting evenness , use a hand - held meter fitted with a plastic dome for incident readings , and measure the light level in each corner . Another , more rough - and - ready technique is to cover the print with a sheet of plain white paper , and hold a pencil vertically over the middle so that its tip is just touching : the two shadows cast should be of equal length and density .
Reflections in the print's surface are possible , particularly if the surface sheen is glossy . First make sure that the print lies flat , weighing down the corners or placing it in the enlarger easel . Then make sure that the lamps are at a sufficiently acute angle to the print - 45 degrees or less . The most certain way of blocking reflections is to support a large sheet of black.card or paper just in front of the camera , with a hole cut in it just large enough for the lens .
ABOVE The viewing prism can be detached from certain , top - of - the - range SLRs , and this makes the business of focusing far easier .
TOP When using your SLR on a copying stand , attach a cable release . This will prevent the camera from shaking during exposure , thus ensuring the sharpest possible results .
A lamp at each corner ( below ) is the ideal lighting for copying .
Using two lamps ( above ) , a flat surface can be evenly lit by aiming each at the opposite edge . The strength of the two shadows cast by a pencil held up to the surface will show if the illumination is equal . Shade the camera lens ( right ) from the direct lamp light with pieces of card .
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