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التصوير الفوتوغرافي الحديث
صنع الطباعة ..
عمل الطباعة الموسعة ..
إجراء التوسيع - ١ -
ENLARGING PROCEDURE
Dust the negative gently with a very soft camel hair brush to remove lint and dust ( Figure 21 ) . This eliminates tedious work later on the finished print , touching up blemishes with a brush and spotting color . In using your dusting brush , draw it across the negative slowly and lightly . If you brush too vigorously , you will generate a charge of static electricity on the negative , which will only attract dust and make matters worse . In winter , when the air is very dry and film becomes electrically charged very easily , it is best not to use a brush at all . A small , rubber ear syringe is much better . Simply aim it at the negative and blow the dust off with short , sharp puffs . When the negative is clean , place it in the negative carrier with the emulsion ( dull ) side down and insert it in the enlarger as shown in Figure 22 .
Figure 20 A test print of the negative is made in order to study picture content and to decide on cropping .
Figure 21 Next the negative is placed in the carrier . and brushed lightly and care fully to remove lint and dust .
Figure 22 Then the negative carrier is put into the enlarger with the emulsion side of the film facing down towards the enlarging lens .
SETTING UP THE ENLARGING EASEL . Adjust the marginal masks of the enlarging easel for the size of printing paper you are going to use . Don't put the paper in at this point . Instead , insert a plain sheet of white paper which will serve for preliminary focusing . A wasted print of the size you are going to use is just right for this purpose . Otherwise , any smooth , white paper will do . Put this focusing sheet in the easel and set it under the enlarger .
Incidentally , don't try to make it easy for yourself by painting the surface of the easel white to eliminate the use of a separate focusing sheet . It is true that such easels have been made and sold , but if you have one , cover it with a piece of black paper , or paint it a dull black . Single weight enlarging paper is far from opaque . Whenever you make an enlargement , some of the light you project onto the paper goes all the way through to the easel . If the easel is painted a dull black , the light is absorbed there . However if the easel is white , this light is reflected back through the paper . By the time it gets back to the emulsion , it is badly diffused . Its main effect then is to fog the print and gray the highlights in the neighborhood of deep shadows .
PROJECTING THE NEGATIVE . Switch on the enlarger and run it up or down until the projected image is about the correct size . Focus the negative roughly - you shouldn't do the final accurate focusing until the very last minute . Shift the easel to get the exact framing you want . Don't guess . A projected negative doesn't look at all like the final print . Don't try to frame the picture from memory . Use the marked print you made as a guide .
There is a good reason for putting off the final accurate focusing until the last minute . The negative will absorb enough heat from the enlarger lamp to increase its temperature considerably in a matter of seconds . The warmed - up negative will expand , and this may cause it to buckle . If buckling occurs before exposure , the print will be out of focus or blurred in spots . If this occurs suddenly part way through the exposure , you will get a double image . For that reason , you should always refocus on the most important section of the picture just before making the exposure . This precaution is unnecessary if the negative is held between glass and cannot buckle .
If the negative is very dense or the enlarger not very efficient , the projected image may be so dim that you will have some trouble focusing . There are a number of fairly inexpensive focusing aids you can buy ( Figure 23 ) . This subject will be discussed later .
STOPPING DOWN THE LENS . After final focusing , the next step is to stop down the lens . In brief , you stop down the enlarging lens for three reasons :
1. to improve the corredtion ( sharpness ) of the lens .
2. To increase depth of field .
3. To establish the most convenient exposure .
Let us examine each of these reasons in detail .
Figure 23 Project negative and focus carefully . A focusing aid is very helpful at this point .
1. Improving Lens Corrections . Due to practical limitations in design , no photographic lens will give its sharpest image when it is used wide open . A good lens needs to be stopped down only one f / number from maximum aperture ; a poor lens may have to be stopped down even further for sharp detail .
There may be times when you don't want the sharpest possible print . If you are making a twenty diameter enlargement from a 35mm negative which has noticeable grain , you can enlarge with the lens wide open and rely on the slight diffusion you get this way to kill most of the grain . Or you may have a negative that is just little too harsh and contrasty for your favorite paper . A wide - open lens may soften the print just enough to make it perfect . Ordinarily , however , you will want maximum sharpness from your negative . Using good judgment in simple things little things like this is what distinguishes a fine technician from just another darkroom hand ..
2. Increasing Depth Of Focus . The usual glassless negative carrier supports the negative around the edges only . When the negative warms up and expands under the heat of the enlarger light , it may buckle and go slightly out of focus . As you will recall , when you stop down a lens , you increase its depth of focus . With a greater depth of focus , a slight shift in negative position will not affect the sharpness of the projected image .
Of course , if the negative is held between two sheets of glass it can't buckle or shift , and so you don't have to worry about depth of focus as long as you focus accurately . But it's still a good idea to stop down the lens slightly , just to be on the safe side . In spite of your best efforts , it may be that you haven't hit the correct focus . It is often very difficult to be sure your focusing is perfect if the projected image is dim , or if the negative has no sharp lines .
3. Establishing The Most Convenient Exposure . This is where your own judgment is the deciding factor . If you are trying to make the best possible . enlargement and intend holding back ( keeping light from ) some areas to make them lighter , or printing - in ( exposing longer ) other areas to make them darker , stop your lens down to allow an exposure of at least ten or fifteen seconds . This gives you enough time to exercise the necessary printing control . On the other hand , suppose you have a roll of 35mm negatives and you want to make a small test projection print of each . Since your only interest is in seeing what your pictures look like so you can select the best ones to enlarge properly , leave the lens fairly wide open to keep the exposure time as short as possible .
Considering the three factors mentioned earlier , f / 11 is a good basic setting for average enlargements with paper of average speed . You might start there . Give your focusing a final check , see that the picture is framed in the easel just as you want it , then set your lens stop . Swing the red filter of the enlarger in front of the lens so it is projecting only a faint red image . This will not expose your paper . Remove the white focusing sheet from the easel and switch off the light . Now you are ready to enlarge . Your first enlargement , however , will be a test strip to help you select the correct length of exposure and to verify your selection of the correct f / stop .
DETERMINING EXPOSURE TIME . The best way to determine the proper length of exposure is by systematic trial and error , using a test strip . Exposure time may range from as little as a second or two , to as much as two minutes or more , depending upon the degree of enlargement , the density of the negative and the speed of the printing paper . To help you make your first trial somewhere close to the correct exposure time , let us review the facts that effect exposure .
In enlarging , if you are using large apertures , you require less exposure time than if you are using small apertures . Dense , dark negatives require more exposure than thin underexposed negatives . High - speed papers require less exposure time than low - speed papers . Small enlargements require less exposure time than big enlargements . The wattage of your light source , of course , has an important bearing on the length of exposure . The brighter the bulb , the shorter the exposure . If you are making enlargements in which all of these factors seem to be average , then two good test exposure times would be 5 and 10 seconds . By . examining the prints exposed at these two times , you get a good idea what your correct exposure should be for the first enlargement .
The Test Strip . Switch off all the white light in your darkroom , leaving only the safelight illumination . Pull out a sheet of the enlarging paper you are going to use , and cut off a strip long enough to take in a fair sample of the picture including both shadows and highlights . Use a big enough strip to give a pretty fair idea of the overall picture . Put the remaining paper back into its light - tight package at once . You can never tell when you may want to switch on the light to look at something , and it is easy to forget to cover the paper then . The only photographer who never fogs any paper is the photographer who never leaves paper uncovered - even in the dark .
Make sure the red filter is in position in front of the lens , then turn on the enlarger . Place the test strip emulsion side up on the easel so it is ready to receive the exposure . With some dull - surfaced papers , it may be a little difficult to tell which is the emulsion side . If the paper has a slight curl , you can be sure the emulsion side curls inward . If the paper has not been kept flat , it may have a decided wave , so you cannot be sure which side is which . In that case , hold the paper at eye level and sight along the surface toward the safelight . The emulsion side will generally show a slight sheen even for dead matte papers . If this test fails , moisten your lips slightly and bite down on a corner of the test strip with your moistened lips for a second or two . When you open your mouth , the side that sticks is the emulsion side .
Some photographers make a test print using a large number of different exposures covering a wide range of exposure time . They start at the top of the sheet and move down a short distance every second or two through 20 to 30 seconds . This method may be satisfactory for a uniformly illuminated subject . It may be necessary for someone who has no idea at all how to estimate correct . exposure . In actual practice , however , such a horizontal test print is of little value and most photographers can guess better than that . The average print has its main interest in a relatively small area . It is this area we have to expose correctly in order to make our decision . A long series of graduated exposures is not only unnecessary and time - consuming , but often meaningless . Most likely , the center of interest will fall into the incorrectly exposed portions of the test print , while the correctly exposed section may fall in the sky or somewhere else where there is nothing to tell whether the exposure is correct or not .
The experienced photographer usually makes his test strips long and narrow . This gives him a fairly representative coverage of the more important elements of the picture , yet does not waste paper . He then estimates his exposure and gives the test strip two or three different exposures . One exposure will be for his estimated time , one for a longer and one for a shorter time .
papers paper has paper has The advantage of a long test strip is illustrated in the mountain scene of Figure 24. The actual test strip used to determine the correct exposure is shown in Figure 25. There are sky and mountains in the background , light - flecked water in the middle distance , and a figure in the foreground . The test strip must be long enough to stretch across the sky , the mountains , the water and the figure , if possible . If the strip is so small that it covers only one or two of these elements , it may give very misleading information .
For example , in this picture , if we use a short rectangular test strip taking in the trees and lake only , it may have told us what exposure would reproduce them best , but this exposure would give us a chalky sky with no clouds at all .
To make your test strip , have a sheet of cardboard ready to cover part of the paper . You will usually find a sheet in every envelope of enlarging paper which works fine . Now swing the filter out . the way , and start clocking the exposure time . At exactly five seconds , cover half of the test strip with the masking card . Continue the exposure another five seconds , and then switch off the light . This allows a 10 - second exposure for one half of the test strip and a five second exposure for the other half . Now , before you forget , turn the test strip over and write the exposure time and f / stop setting for each test on the back . Next , develop the strip to see how correctly you guessed the exposure .
صنع الطباعة ..
عمل الطباعة الموسعة ..
إجراء التوسيع - ١ -
ENLARGING PROCEDURE
Dust the negative gently with a very soft camel hair brush to remove lint and dust ( Figure 21 ) . This eliminates tedious work later on the finished print , touching up blemishes with a brush and spotting color . In using your dusting brush , draw it across the negative slowly and lightly . If you brush too vigorously , you will generate a charge of static electricity on the negative , which will only attract dust and make matters worse . In winter , when the air is very dry and film becomes electrically charged very easily , it is best not to use a brush at all . A small , rubber ear syringe is much better . Simply aim it at the negative and blow the dust off with short , sharp puffs . When the negative is clean , place it in the negative carrier with the emulsion ( dull ) side down and insert it in the enlarger as shown in Figure 22 .
Figure 20 A test print of the negative is made in order to study picture content and to decide on cropping .
Figure 21 Next the negative is placed in the carrier . and brushed lightly and care fully to remove lint and dust .
Figure 22 Then the negative carrier is put into the enlarger with the emulsion side of the film facing down towards the enlarging lens .
SETTING UP THE ENLARGING EASEL . Adjust the marginal masks of the enlarging easel for the size of printing paper you are going to use . Don't put the paper in at this point . Instead , insert a plain sheet of white paper which will serve for preliminary focusing . A wasted print of the size you are going to use is just right for this purpose . Otherwise , any smooth , white paper will do . Put this focusing sheet in the easel and set it under the enlarger .
Incidentally , don't try to make it easy for yourself by painting the surface of the easel white to eliminate the use of a separate focusing sheet . It is true that such easels have been made and sold , but if you have one , cover it with a piece of black paper , or paint it a dull black . Single weight enlarging paper is far from opaque . Whenever you make an enlargement , some of the light you project onto the paper goes all the way through to the easel . If the easel is painted a dull black , the light is absorbed there . However if the easel is white , this light is reflected back through the paper . By the time it gets back to the emulsion , it is badly diffused . Its main effect then is to fog the print and gray the highlights in the neighborhood of deep shadows .
PROJECTING THE NEGATIVE . Switch on the enlarger and run it up or down until the projected image is about the correct size . Focus the negative roughly - you shouldn't do the final accurate focusing until the very last minute . Shift the easel to get the exact framing you want . Don't guess . A projected negative doesn't look at all like the final print . Don't try to frame the picture from memory . Use the marked print you made as a guide .
There is a good reason for putting off the final accurate focusing until the last minute . The negative will absorb enough heat from the enlarger lamp to increase its temperature considerably in a matter of seconds . The warmed - up negative will expand , and this may cause it to buckle . If buckling occurs before exposure , the print will be out of focus or blurred in spots . If this occurs suddenly part way through the exposure , you will get a double image . For that reason , you should always refocus on the most important section of the picture just before making the exposure . This precaution is unnecessary if the negative is held between glass and cannot buckle .
If the negative is very dense or the enlarger not very efficient , the projected image may be so dim that you will have some trouble focusing . There are a number of fairly inexpensive focusing aids you can buy ( Figure 23 ) . This subject will be discussed later .
STOPPING DOWN THE LENS . After final focusing , the next step is to stop down the lens . In brief , you stop down the enlarging lens for three reasons :
1. to improve the corredtion ( sharpness ) of the lens .
2. To increase depth of field .
3. To establish the most convenient exposure .
Let us examine each of these reasons in detail .
Figure 23 Project negative and focus carefully . A focusing aid is very helpful at this point .
1. Improving Lens Corrections . Due to practical limitations in design , no photographic lens will give its sharpest image when it is used wide open . A good lens needs to be stopped down only one f / number from maximum aperture ; a poor lens may have to be stopped down even further for sharp detail .
There may be times when you don't want the sharpest possible print . If you are making a twenty diameter enlargement from a 35mm negative which has noticeable grain , you can enlarge with the lens wide open and rely on the slight diffusion you get this way to kill most of the grain . Or you may have a negative that is just little too harsh and contrasty for your favorite paper . A wide - open lens may soften the print just enough to make it perfect . Ordinarily , however , you will want maximum sharpness from your negative . Using good judgment in simple things little things like this is what distinguishes a fine technician from just another darkroom hand ..
2. Increasing Depth Of Focus . The usual glassless negative carrier supports the negative around the edges only . When the negative warms up and expands under the heat of the enlarger light , it may buckle and go slightly out of focus . As you will recall , when you stop down a lens , you increase its depth of focus . With a greater depth of focus , a slight shift in negative position will not affect the sharpness of the projected image .
Of course , if the negative is held between two sheets of glass it can't buckle or shift , and so you don't have to worry about depth of focus as long as you focus accurately . But it's still a good idea to stop down the lens slightly , just to be on the safe side . In spite of your best efforts , it may be that you haven't hit the correct focus . It is often very difficult to be sure your focusing is perfect if the projected image is dim , or if the negative has no sharp lines .
3. Establishing The Most Convenient Exposure . This is where your own judgment is the deciding factor . If you are trying to make the best possible . enlargement and intend holding back ( keeping light from ) some areas to make them lighter , or printing - in ( exposing longer ) other areas to make them darker , stop your lens down to allow an exposure of at least ten or fifteen seconds . This gives you enough time to exercise the necessary printing control . On the other hand , suppose you have a roll of 35mm negatives and you want to make a small test projection print of each . Since your only interest is in seeing what your pictures look like so you can select the best ones to enlarge properly , leave the lens fairly wide open to keep the exposure time as short as possible .
Considering the three factors mentioned earlier , f / 11 is a good basic setting for average enlargements with paper of average speed . You might start there . Give your focusing a final check , see that the picture is framed in the easel just as you want it , then set your lens stop . Swing the red filter of the enlarger in front of the lens so it is projecting only a faint red image . This will not expose your paper . Remove the white focusing sheet from the easel and switch off the light . Now you are ready to enlarge . Your first enlargement , however , will be a test strip to help you select the correct length of exposure and to verify your selection of the correct f / stop .
DETERMINING EXPOSURE TIME . The best way to determine the proper length of exposure is by systematic trial and error , using a test strip . Exposure time may range from as little as a second or two , to as much as two minutes or more , depending upon the degree of enlargement , the density of the negative and the speed of the printing paper . To help you make your first trial somewhere close to the correct exposure time , let us review the facts that effect exposure .
In enlarging , if you are using large apertures , you require less exposure time than if you are using small apertures . Dense , dark negatives require more exposure than thin underexposed negatives . High - speed papers require less exposure time than low - speed papers . Small enlargements require less exposure time than big enlargements . The wattage of your light source , of course , has an important bearing on the length of exposure . The brighter the bulb , the shorter the exposure . If you are making enlargements in which all of these factors seem to be average , then two good test exposure times would be 5 and 10 seconds . By . examining the prints exposed at these two times , you get a good idea what your correct exposure should be for the first enlargement .
The Test Strip . Switch off all the white light in your darkroom , leaving only the safelight illumination . Pull out a sheet of the enlarging paper you are going to use , and cut off a strip long enough to take in a fair sample of the picture including both shadows and highlights . Use a big enough strip to give a pretty fair idea of the overall picture . Put the remaining paper back into its light - tight package at once . You can never tell when you may want to switch on the light to look at something , and it is easy to forget to cover the paper then . The only photographer who never fogs any paper is the photographer who never leaves paper uncovered - even in the dark .
Make sure the red filter is in position in front of the lens , then turn on the enlarger . Place the test strip emulsion side up on the easel so it is ready to receive the exposure . With some dull - surfaced papers , it may be a little difficult to tell which is the emulsion side . If the paper has a slight curl , you can be sure the emulsion side curls inward . If the paper has not been kept flat , it may have a decided wave , so you cannot be sure which side is which . In that case , hold the paper at eye level and sight along the surface toward the safelight . The emulsion side will generally show a slight sheen even for dead matte papers . If this test fails , moisten your lips slightly and bite down on a corner of the test strip with your moistened lips for a second or two . When you open your mouth , the side that sticks is the emulsion side .
Some photographers make a test print using a large number of different exposures covering a wide range of exposure time . They start at the top of the sheet and move down a short distance every second or two through 20 to 30 seconds . This method may be satisfactory for a uniformly illuminated subject . It may be necessary for someone who has no idea at all how to estimate correct . exposure . In actual practice , however , such a horizontal test print is of little value and most photographers can guess better than that . The average print has its main interest in a relatively small area . It is this area we have to expose correctly in order to make our decision . A long series of graduated exposures is not only unnecessary and time - consuming , but often meaningless . Most likely , the center of interest will fall into the incorrectly exposed portions of the test print , while the correctly exposed section may fall in the sky or somewhere else where there is nothing to tell whether the exposure is correct or not .
The experienced photographer usually makes his test strips long and narrow . This gives him a fairly representative coverage of the more important elements of the picture , yet does not waste paper . He then estimates his exposure and gives the test strip two or three different exposures . One exposure will be for his estimated time , one for a longer and one for a shorter time .
papers paper has paper has The advantage of a long test strip is illustrated in the mountain scene of Figure 24. The actual test strip used to determine the correct exposure is shown in Figure 25. There are sky and mountains in the background , light - flecked water in the middle distance , and a figure in the foreground . The test strip must be long enough to stretch across the sky , the mountains , the water and the figure , if possible . If the strip is so small that it covers only one or two of these elements , it may give very misleading information .
For example , in this picture , if we use a short rectangular test strip taking in the trees and lake only , it may have told us what exposure would reproduce them best , but this exposure would give us a chalky sky with no clouds at all .
To make your test strip , have a sheet of cardboard ready to cover part of the paper . You will usually find a sheet in every envelope of enlarging paper which works fine . Now swing the filter out . the way , and start clocking the exposure time . At exactly five seconds , cover half of the test strip with the masking card . Continue the exposure another five seconds , and then switch off the light . This allows a 10 - second exposure for one half of the test strip and a five second exposure for the other half . Now , before you forget , turn the test strip over and write the exposure time and f / stop setting for each test on the back . Next , develop the strip to see how correctly you guessed the exposure .
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