تويت
عناصر التحكم في الطباعة .. المعالجة والطباعة .. كيفية التقاط وتطوير الصور بالأبيض والأسود
PRINT CONTROLS
The usual answer to high contrast , where the range of tones in the negative is beyond that of the print , is to change to a lower contrast grade of paper . This , however , affects the entire image , whereas often it is only local areas that need help . For instance , on an overcast day , in a landscape composed so that there is just a small area of sky , the brightness range below the horizon is likely to be fairly limited . So , for this principal part of the image , a contrast grade of 3 , or even 4 , would do well , yet the sky would come out a blank white in a straight- forward print . Changing to a softer grade of paper would bring the sky within the range of the print's tonal range , but at the serious cost of dullness elsewhere .
Another typical situation which causes uneven brightness across an image is an on - camera flash picture . Because of the position of the flash unit , nearer objects will be brighter than those in the background . If you have not already composed the photograph to take care of this , you will be left with a negative which , if printed normally , has too great a range of tones .
The solution to these and similar problems is to give selected areas of the print more or less exposure than normal , by moving your hands or a shaped piece of card in the path of light from the enlarger lens . Holding back the light from an area is called dodging or shading ; giving extra exposure is called burning - in or printing - in .
You can either make or buy printing tools . Dodging tools include large sheets of black card to cover big areas that run over an edge of the frame ( such as the sky ) and small discs , ovals and other shapes each attached to a length of wire for small areas inside the print ( such as faces ) . The wires are necessary to avoid shading more than a limited area , and in use a dodging tool must be moved constantly , otherwise the shadow of the wire rod will print distinctly .
Tools for burning - in are basically large sheets of black card , each cut with a hole of a particular shape . Again in use they must be moved around all the time to keep the edge projected by the hole soft and indistinct on the print . For this same reason , it is easier to blend the effect of burning - in , or dodging , if the printing tool is held at a distance from the print - the further away it is , the more out of focus the edges will be . Thus , if you are making your own tools , it is often better to keep them fairly small , as raising the tool away from the print will cause it to cover a larger area on the print .
With burning - in , always use a sheet of black card large enough to cover a bigger area than the print ; it is surprisingly easy when using this technique to be so absorbed in controlling the patch of light in the middle that you do not notice stray light at the edges of the print .
Rather than prepare several large sheets of black card for burning - in , an alternative is to make one with a fairly large central hole , and to stick over this
Shading - in Technique
1. Your hand may be used to shade the print , although keep it moving to prevent sharp contrasts between affected and unaffected areas .
2. Shading tools are commercially available , these being designed to shade specific areas .
3. Cupped hands may be used to control the size of the area during printing in .
BELOW The blocking out technique is very popular in industrial product photography , and involves holding back light from an area of the print to give a ' cut - out ' effect .
Despite their involving related techniques , blocking out and burning in produce dramatically different results , even with the same image Burning in ( above ) has lightened the atmosphere of the shot , while dodging ( left ) has lent a sinister mood to the picture .
ABOVE Printed straight , this picture sorely lacks impact the sky is the main culprit , being as it is bleached and devoid of detail .
NIGHT However , a simple process of burning in- selectively preventing light from reaching the print during exposure - restores sufficient contrast to the sky for the image to regain its punch .
ABOVE Burning in is more than a simple technique - it's a creative tool . And remember that you need not use specialized tools ; even your hand will serve as an adequate block between the light source and the printing paper .
one of a set of differently shaped apertures cut into smaller pieces of black paper .
Some darkroom workers prefer to use their hands rather than specially- prepared tools , although this method only works for burning - in and for sha- ding from the edge of the print inwards . You cannot successfully shade an isolated area within the image by using your hand - your wrist will shade adjacent parts also . In addition , you should be particularly careful when burning- in to avoid light catching the edges of the print . Nevertheless , using hands for printing controls has an advantage in that the shape of the edge can be formed by contorting your fingers , and this edge can be softened by finger movements almost like kneading dough ) .
Finally , for an edge that is convoluted but needs to be shaded precisely , you can cut around the image made on a test print - this will give an exact match .
VIGNETTING
Although not used for the same purposes , and more of a special effect , vignet- ting is a technique that is practised in essentially the same way as burning - in . The idea is to isolate the image entirely within the white background of the printing paper , usually in a soft - oval frame . Its main use has been in printing portraits . The technique requires an oval ( or other shape ) cut in a large sheet of black card . This tool should be used about halfway between the enlarger and the print to give a soft edge , and so the size of the cut hole needs to be calculated in advance . The entire exposure is then made through the cut hole , so that no light at all reaches the print from the edges of the negative . It too needs to be moved constantly , but kept central to the print .
PRINT CONTROLS
The usual answer to high contrast , where the range of tones in the negative is beyond that of the print , is to change to a lower contrast grade of paper . This , however , affects the entire image , whereas often it is only local areas that need help . For instance , on an overcast day , in a landscape composed so that there is just a small area of sky , the brightness range below the horizon is likely to be fairly limited . So , for this principal part of the image , a contrast grade of 3 , or even 4 , would do well , yet the sky would come out a blank white in a straight- forward print . Changing to a softer grade of paper would bring the sky within the range of the print's tonal range , but at the serious cost of dullness elsewhere .
Another typical situation which causes uneven brightness across an image is an on - camera flash picture . Because of the position of the flash unit , nearer objects will be brighter than those in the background . If you have not already composed the photograph to take care of this , you will be left with a negative which , if printed normally , has too great a range of tones .
The solution to these and similar problems is to give selected areas of the print more or less exposure than normal , by moving your hands or a shaped piece of card in the path of light from the enlarger lens . Holding back the light from an area is called dodging or shading ; giving extra exposure is called burning - in or printing - in .
You can either make or buy printing tools . Dodging tools include large sheets of black card to cover big areas that run over an edge of the frame ( such as the sky ) and small discs , ovals and other shapes each attached to a length of wire for small areas inside the print ( such as faces ) . The wires are necessary to avoid shading more than a limited area , and in use a dodging tool must be moved constantly , otherwise the shadow of the wire rod will print distinctly .
Tools for burning - in are basically large sheets of black card , each cut with a hole of a particular shape . Again in use they must be moved around all the time to keep the edge projected by the hole soft and indistinct on the print . For this same reason , it is easier to blend the effect of burning - in , or dodging , if the printing tool is held at a distance from the print - the further away it is , the more out of focus the edges will be . Thus , if you are making your own tools , it is often better to keep them fairly small , as raising the tool away from the print will cause it to cover a larger area on the print .
With burning - in , always use a sheet of black card large enough to cover a bigger area than the print ; it is surprisingly easy when using this technique to be so absorbed in controlling the patch of light in the middle that you do not notice stray light at the edges of the print .
Rather than prepare several large sheets of black card for burning - in , an alternative is to make one with a fairly large central hole , and to stick over this
Shading - in Technique
1. Your hand may be used to shade the print , although keep it moving to prevent sharp contrasts between affected and unaffected areas .
2. Shading tools are commercially available , these being designed to shade specific areas .
3. Cupped hands may be used to control the size of the area during printing in .
BELOW The blocking out technique is very popular in industrial product photography , and involves holding back light from an area of the print to give a ' cut - out ' effect .
Despite their involving related techniques , blocking out and burning in produce dramatically different results , even with the same image Burning in ( above ) has lightened the atmosphere of the shot , while dodging ( left ) has lent a sinister mood to the picture .
ABOVE Printed straight , this picture sorely lacks impact the sky is the main culprit , being as it is bleached and devoid of detail .
NIGHT However , a simple process of burning in- selectively preventing light from reaching the print during exposure - restores sufficient contrast to the sky for the image to regain its punch .
ABOVE Burning in is more than a simple technique - it's a creative tool . And remember that you need not use specialized tools ; even your hand will serve as an adequate block between the light source and the printing paper .
one of a set of differently shaped apertures cut into smaller pieces of black paper .
Some darkroom workers prefer to use their hands rather than specially- prepared tools , although this method only works for burning - in and for sha- ding from the edge of the print inwards . You cannot successfully shade an isolated area within the image by using your hand - your wrist will shade adjacent parts also . In addition , you should be particularly careful when burning- in to avoid light catching the edges of the print . Nevertheless , using hands for printing controls has an advantage in that the shape of the edge can be formed by contorting your fingers , and this edge can be softened by finger movements almost like kneading dough ) .
Finally , for an edge that is convoluted but needs to be shaded precisely , you can cut around the image made on a test print - this will give an exact match .
VIGNETTING
Although not used for the same purposes , and more of a special effect , vignet- ting is a technique that is practised in essentially the same way as burning - in . The idea is to isolate the image entirely within the white background of the printing paper , usually in a soft - oval frame . Its main use has been in printing portraits . The technique requires an oval ( or other shape ) cut in a large sheet of black card . This tool should be used about halfway between the enlarger and the print to give a soft edge , and so the size of the cut hole needs to be calculated in advance . The entire exposure is then made through the cut hole , so that no light at all reaches the print from the edges of the negative . It too needs to be moved constantly , but kept central to the print .
تعليق