تويت
التصوير الفوتوغرافي الحديث
التقنيات المهنية المتقدمة
إعادة لمس السلبية
باستخدام سكين الحفر
USING THE ETCHING KNIFE
Up to this point we have discussed pencil retouching only , even though an experienced retoucher uses the etching knife first and the retouching pencil next . We have reversed the normal procedure for two reasons . By far the greater part of all your retouching will be with the pencil because it is unnecessary to use the etching knife on many negatives that will require a good deal of pencil work . The pencil , moreover , is much easier for the student to control and for that reason is the logical starting point .
It is suggested that you practice pencil retouching until you are fairly adept at it , before you tackle the etching knife . The confidence you acquire in that way will be essential to successful work , for there is this important difference between these two techniques : if you make an error with the pencil you can erase it and start over again . If you make an error with the etching knife , the negative is permanently damaged .
You can buy etching knives especially made for the purpose of retouching negatives . They vary considerably in price and quality . It is always advisable to buy the best , since none of them are very expensive .
The real secret to successful etching is to get the right type of cutting edge . In etching a negative , you do not cut the gelatin - you scrape it away . The cutting edge must not have the very acute angle of a cutting tool like a knife or razor , but the obtuse angle of a scraping tool , like the floor scrapers used by carpenters . To get this type of cutting edge , you will need a fine carborundum stone and a small hard Arkansas oil stone .
A good etching knife is sharpened on one side only like a chisel . Put a few drops of oil on the carborundum stone and sharpen the blade on one side only . To prevent the formation of a burr or featheredge which would ruin its cutting properties , hold the blade against the stone as shown in Figure 23 and sharpen on the pull stroke , as though you were trying to shave the stone . Every few seconds lay the blade flat on the stone , sharpened surface up , and give it a few strokes to clean up the burr or featheredge . ( Figure 24 ) .
When the edge is as sharp as you can get it with the carborundum stone , switch to the Arkansas stone , using exactly the same technique and plenty of oil .
When your knife blade is as sharp as a razor , it is ready for its final cutting edge . Hold the blade almost at right angles to the oil stone , but tilted just a few degrees toward the beveled side ( Figure 25 ) , and stroke it across the stone a half dozen times or so . This will take down the very acute angle of the razor edge and produce the obtuse angle of the scraper edge . The razor type of cutting edge has a strong tendency to dig into the work and gouge out chunks of material , making its use quite difficult , whereas the obtuse angle of the scraping tool penetrates only far enough to permit the scraping away of a thin surface layer . Figure 26 shows how this blade scrapes away the emulsion when it is used for retouching .
An etching knife becomes dull rather quickly , and it must be re - sharpened frequently to do good work . To re - sharpen it , simply draw it across the hard Arkansas oil stone at the obtuse angle you used to obtain the final cutting edge .
Figure 23 The first step in sharpening an etching knife is putting on the chisel edge with a fine carborundum stone .
Figure 24 Removing the burr or feather edge of the blade ..
Figure 25 Putting on the final scraping edge on the blade with a fine Arkansas oil stone .
Greatly enlarged diagrams showing the correct cutting edge for an etching knife .
Only a few strokes are necessary , but as the steel is worn down and the cutting edge becomes too broad ( as shown in Figure 27 ) , completely re - sharpen the knife to thin down the edge .
KNIFE POSITION . The way you hold the knife depends a good deal on the kind of knife you are using and the kind of work you want to do with it . The edge of the blade should be nearly at right angles to the film , the angle in front of the knife being a little more acute than the angle at the back . The etching should be done on the downward stroke only and just in one direction . Each stroke must be very , very light , the very thinnest possible shaving of emulsion being pared or scraped off . An extremely gentle scraping motion is used . If the knife is in the proper condition and is very sharp , it will shave down the surface without tearing it .
Etching is somewhat like the operation of planing a piece of wood with a carpenter's plane that takes off successive thin shavings until the thickness of the wood has been sufficiently reduced . However , the angle at which the etching knife is held in relation to the negative is just the opposite of the angle of the plane with the wood .
The width of the cut can be varied at will by changing the angle between knife and negative . If the knife is held almost vertically , only the sharp tip will contact the negative and a very fine line will be etched . By lowering the handle so that more of the curve of the blade is in use , a wider shaving will be removed .
PRACTICE . You will have to practice before using the knife a negative of value . Practice making fine lines as well as broad erasures . Get the lines uniform in width , evenly spaced , and with softened edges . Practice making them of various densities , but be very careful never to cut right through the emulsion down to the film base .
See how little of the film you can remove with one stroke , not how much you can remove . Try to do the work so that the film surface is just as smooth after etching as before .
You will find that the silver deposit of a negative is largely on the surface of the emulsion instead of being uniformly distributed throughout it . A very slight amount of knife work is usually all that is needed in most ordinary retouching .
Sometimes , it is true , if you photograph a woman dressed in white against a very dark background and then have to make her appear about forty to fifty pounds lighter than she really is , you may have to etch pretty deep in order to slenderize the figure , but even then you should not go right through to the film base .
Any etching or knife work needed on a negative must always be done before the retouching medium is rubbed on . It is much more difficult to etch the emulsion evenly after it has been doped .
Some skill is needed to use an etching knife successfully , but the knack can be acquired by practice . If you make any mistakes in using the pencil or the spotting brush , it is easy to rub off the work and start over again , but you cannot do this when using the knife . If you etch too deeply and reduce the density of the negative too much , you can patch it up afterwards with the retouching pencil , but if you go so far that you etch right through to the base , it is very difficult , if not impossible , to cover up your error .
In using a pencil on the negative , the point is so sharp and so long that you can see easily where the lead is being applied , but in using a knife it is not so easy . to tell just where the edge of the knife is in contact with the film and whether it is in exactly the right position . Practice and experience will help in this respect . If you are not sure of the correct angle at which to hold the knife , test it on a part of the negative that will not show before actually working on the part you want to etch .
Wrinkles in the clothing , a coat collar that does not fit snugly , and slight modifications in the lines of a dress are the kinds of things that most frequently call for the use of the knife . Sometimes in pictures of children , the edge of a white undergarment shows below a short dress . Sometimes a little modification of the outlines of the figure is needed to make the subject appear slimmer . Such modifications as these should not offer any difficulty after you have gained experience in the use of the knife .
If you do etch a little too much , you can usually hide all traces of it by careful work with a pencil after the negative has been doped . If you expect to do any pencil work on an area that you have etched , you should always stop the etching just a shade short of the desired effect because the retouching dope will make the etched surface a trifle more transparent .
In reducing contours and modifying the outlines of a figure , work in from the background toward the figure . Try to make the new outline just as natural and as much like the rest of the outline as possible so that the change will not be apparent in the print . Do not go too far in this or the results will be noticeable . Your retouching should never show in the print .
The smoothing of wrinkles in the clothing will be a combination of knife work and pencil work ; highlights will need to be etched and shadows filled in . Do all the necessary etching first , then apply the medium and fill in the light places with the pencil .
Sometimes in profile portraits , it is necessary to improve the outline of the chin and neck a little , but use a good deal of restraint in doing this .
FACE WORK . Any etching on the face in a portrait must be done very carefully . Fortunately , it seldom is necessary . If there is more than one source of light , there probably will be two or more catchlights in the eyes and it may be necessary to etch out the catchlights caused by the secondary or fill - in lights . This should not be difficult with a good knife . Do not etch out a pair of catchlights , however , until you have made a print and have painted them out , leaving only one in each eye . Then you can be sure which to remove and which to leave alone ..
If the eyebrows are unusually light and do not show in the picture , it may be necessary to etch them in very lightly . If the nose needs straightening , it can usually be done with the pencil and it is seldom necessary to use the knife as well . If the head is turned just a little too much toward the camera in a three - quarter view of the face , the tip of the ear may show beyond the outline of the cheek . It is usually best to remove the ear tip altogether with the etching knife .
Such things as straightening crossed eyes are quite possible . An experienced retoucher would not find this too difficult . Before you try to do such retouching , it is advisable to practice for a time on things that do not call for quite so much skill .
If the hair is strongly lighted with a spotlight or an overhead light and the subject is posed against a dark background , any stray hairs that are out of place will show prominently against the background and may need to be etched out .
التقنيات المهنية المتقدمة
إعادة لمس السلبية
باستخدام سكين الحفر
USING THE ETCHING KNIFE
Up to this point we have discussed pencil retouching only , even though an experienced retoucher uses the etching knife first and the retouching pencil next . We have reversed the normal procedure for two reasons . By far the greater part of all your retouching will be with the pencil because it is unnecessary to use the etching knife on many negatives that will require a good deal of pencil work . The pencil , moreover , is much easier for the student to control and for that reason is the logical starting point .
It is suggested that you practice pencil retouching until you are fairly adept at it , before you tackle the etching knife . The confidence you acquire in that way will be essential to successful work , for there is this important difference between these two techniques : if you make an error with the pencil you can erase it and start over again . If you make an error with the etching knife , the negative is permanently damaged .
You can buy etching knives especially made for the purpose of retouching negatives . They vary considerably in price and quality . It is always advisable to buy the best , since none of them are very expensive .
The real secret to successful etching is to get the right type of cutting edge . In etching a negative , you do not cut the gelatin - you scrape it away . The cutting edge must not have the very acute angle of a cutting tool like a knife or razor , but the obtuse angle of a scraping tool , like the floor scrapers used by carpenters . To get this type of cutting edge , you will need a fine carborundum stone and a small hard Arkansas oil stone .
A good etching knife is sharpened on one side only like a chisel . Put a few drops of oil on the carborundum stone and sharpen the blade on one side only . To prevent the formation of a burr or featheredge which would ruin its cutting properties , hold the blade against the stone as shown in Figure 23 and sharpen on the pull stroke , as though you were trying to shave the stone . Every few seconds lay the blade flat on the stone , sharpened surface up , and give it a few strokes to clean up the burr or featheredge . ( Figure 24 ) .
When the edge is as sharp as you can get it with the carborundum stone , switch to the Arkansas stone , using exactly the same technique and plenty of oil .
When your knife blade is as sharp as a razor , it is ready for its final cutting edge . Hold the blade almost at right angles to the oil stone , but tilted just a few degrees toward the beveled side ( Figure 25 ) , and stroke it across the stone a half dozen times or so . This will take down the very acute angle of the razor edge and produce the obtuse angle of the scraper edge . The razor type of cutting edge has a strong tendency to dig into the work and gouge out chunks of material , making its use quite difficult , whereas the obtuse angle of the scraping tool penetrates only far enough to permit the scraping away of a thin surface layer . Figure 26 shows how this blade scrapes away the emulsion when it is used for retouching .
An etching knife becomes dull rather quickly , and it must be re - sharpened frequently to do good work . To re - sharpen it , simply draw it across the hard Arkansas oil stone at the obtuse angle you used to obtain the final cutting edge .
Figure 23 The first step in sharpening an etching knife is putting on the chisel edge with a fine carborundum stone .
Figure 24 Removing the burr or feather edge of the blade ..
Figure 25 Putting on the final scraping edge on the blade with a fine Arkansas oil stone .
Greatly enlarged diagrams showing the correct cutting edge for an etching knife .
Only a few strokes are necessary , but as the steel is worn down and the cutting edge becomes too broad ( as shown in Figure 27 ) , completely re - sharpen the knife to thin down the edge .
KNIFE POSITION . The way you hold the knife depends a good deal on the kind of knife you are using and the kind of work you want to do with it . The edge of the blade should be nearly at right angles to the film , the angle in front of the knife being a little more acute than the angle at the back . The etching should be done on the downward stroke only and just in one direction . Each stroke must be very , very light , the very thinnest possible shaving of emulsion being pared or scraped off . An extremely gentle scraping motion is used . If the knife is in the proper condition and is very sharp , it will shave down the surface without tearing it .
Etching is somewhat like the operation of planing a piece of wood with a carpenter's plane that takes off successive thin shavings until the thickness of the wood has been sufficiently reduced . However , the angle at which the etching knife is held in relation to the negative is just the opposite of the angle of the plane with the wood .
The width of the cut can be varied at will by changing the angle between knife and negative . If the knife is held almost vertically , only the sharp tip will contact the negative and a very fine line will be etched . By lowering the handle so that more of the curve of the blade is in use , a wider shaving will be removed .
PRACTICE . You will have to practice before using the knife a negative of value . Practice making fine lines as well as broad erasures . Get the lines uniform in width , evenly spaced , and with softened edges . Practice making them of various densities , but be very careful never to cut right through the emulsion down to the film base .
See how little of the film you can remove with one stroke , not how much you can remove . Try to do the work so that the film surface is just as smooth after etching as before .
You will find that the silver deposit of a negative is largely on the surface of the emulsion instead of being uniformly distributed throughout it . A very slight amount of knife work is usually all that is needed in most ordinary retouching .
Sometimes , it is true , if you photograph a woman dressed in white against a very dark background and then have to make her appear about forty to fifty pounds lighter than she really is , you may have to etch pretty deep in order to slenderize the figure , but even then you should not go right through to the film base .
Any etching or knife work needed on a negative must always be done before the retouching medium is rubbed on . It is much more difficult to etch the emulsion evenly after it has been doped .
Some skill is needed to use an etching knife successfully , but the knack can be acquired by practice . If you make any mistakes in using the pencil or the spotting brush , it is easy to rub off the work and start over again , but you cannot do this when using the knife . If you etch too deeply and reduce the density of the negative too much , you can patch it up afterwards with the retouching pencil , but if you go so far that you etch right through to the base , it is very difficult , if not impossible , to cover up your error .
In using a pencil on the negative , the point is so sharp and so long that you can see easily where the lead is being applied , but in using a knife it is not so easy . to tell just where the edge of the knife is in contact with the film and whether it is in exactly the right position . Practice and experience will help in this respect . If you are not sure of the correct angle at which to hold the knife , test it on a part of the negative that will not show before actually working on the part you want to etch .
Wrinkles in the clothing , a coat collar that does not fit snugly , and slight modifications in the lines of a dress are the kinds of things that most frequently call for the use of the knife . Sometimes in pictures of children , the edge of a white undergarment shows below a short dress . Sometimes a little modification of the outlines of the figure is needed to make the subject appear slimmer . Such modifications as these should not offer any difficulty after you have gained experience in the use of the knife .
If you do etch a little too much , you can usually hide all traces of it by careful work with a pencil after the negative has been doped . If you expect to do any pencil work on an area that you have etched , you should always stop the etching just a shade short of the desired effect because the retouching dope will make the etched surface a trifle more transparent .
In reducing contours and modifying the outlines of a figure , work in from the background toward the figure . Try to make the new outline just as natural and as much like the rest of the outline as possible so that the change will not be apparent in the print . Do not go too far in this or the results will be noticeable . Your retouching should never show in the print .
The smoothing of wrinkles in the clothing will be a combination of knife work and pencil work ; highlights will need to be etched and shadows filled in . Do all the necessary etching first , then apply the medium and fill in the light places with the pencil .
Sometimes in profile portraits , it is necessary to improve the outline of the chin and neck a little , but use a good deal of restraint in doing this .
FACE WORK . Any etching on the face in a portrait must be done very carefully . Fortunately , it seldom is necessary . If there is more than one source of light , there probably will be two or more catchlights in the eyes and it may be necessary to etch out the catchlights caused by the secondary or fill - in lights . This should not be difficult with a good knife . Do not etch out a pair of catchlights , however , until you have made a print and have painted them out , leaving only one in each eye . Then you can be sure which to remove and which to leave alone ..
If the eyebrows are unusually light and do not show in the picture , it may be necessary to etch them in very lightly . If the nose needs straightening , it can usually be done with the pencil and it is seldom necessary to use the knife as well . If the head is turned just a little too much toward the camera in a three - quarter view of the face , the tip of the ear may show beyond the outline of the cheek . It is usually best to remove the ear tip altogether with the etching knife .
Such things as straightening crossed eyes are quite possible . An experienced retoucher would not find this too difficult . Before you try to do such retouching , it is advisable to practice for a time on things that do not call for quite so much skill .
If the hair is strongly lighted with a spotlight or an overhead light and the subject is posed against a dark background , any stray hairs that are out of place will show prominently against the background and may need to be etched out .
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