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معدات للغرفة المظلمة ..
مؤقتات للغرفة المظلمة ..
EQUIPMENT FOR THE DARKROOM
This Assignment does pretend to cover the full range of darkroom equipment , but it does discuss the more generally used items . You don't really need more to start with - you can get by with less .
DARKROOM TIMERS
Darkroom timers are of two types - those that simply keep time and those that ring a bell or close a switch at the end of some predetermined interval . To avoid confusion , we will call the first type darkroom clocks and the second , interval timers or simply timers .
Where 60 cycle AC power is available , you can use a large kitchen or wall - type , self - starting synchronous clock with a sweep second hand . It's a good idea to illuminate the dial as discussed earlier in this Assignment and place it where you can see the clock face clearly from any working position .
Where such a clock is not available , a simple spring - wound , darkroom clock with large minute and second hands will serve nicely . This is the type illustrated in Figure 17. The principal difficulty with a spring - wound clock is that it tends to rust and wear out rather quickly in the damp , chemical - laden air of the darkroom .
For short exposures - a half minute or less - you will probably find it more convenient and accu rate to count off the time instead of watching a clock . This is particu larly true if you have a complicated job of dodging to do while making an enlargement and must concentrate all your attention on the work instead of splitting it between the work and the clock .
Figure 17 Simple type of darkroom clock . Extremely useful for timing enlargements .
A favorite trick of old - time photographers is to have a spring - wound timer or a cheap alarm clock ticking away all the time . They can then count in step with the ticking and be sure of accurate timing . If you don't have a spring - wound timer that uses a standard alarm clock movement , get a cheap alarm clock with a good loud tick . With a little practice , you will soon learn to press the enlarger switch exactly on the tick and start your count with 0 instead of 1 .
Ordinary alarm clock movements and most spring - wound timers tick four times a second , so simply divide your count by four if you want the exposure in seconds . In actual practice , however , you will soon find that it is unimportant to know whether the exposure is , let us say , sixteen seconds or sixty - four ticks . After a little while , you will soon get into the habit of thinking of your exposures in terms of clock ticks and convert them into seconds only on the relatively rare occasions when your exposures get so long that you find it easier to watch the clock rather than to count into the hundreds .
Figure 18 Two types of interval timers . Timer to left rings a bell after a predetermined interval . Timer to right shuts off power after a predetermined interval .
In addition to the darkroom clock , you should have a good interval timer . When busily engaged in enlarging , you are likely to lose track of time and so tend to over - fix your prints . This means increased washing time for one thing and may also result in bleached and empty high lights in hot weather . Since an interval timer is prac tically an essential for negative developing any way , you might just as well get a good one and use it for print making too . For developing negatives , get the type that can be set in white light and started in total darkness . Figure 18 shows two types of interval timers . The one to the left is spring - wound and is very useful for timing film development since it can be started in total darkness . The interval timer to the right times short intervals only and is primarily intended for the accurate timing of exposures when printing .
When timing darkroom operations such as fixing or washing , don't rely on your memory to keep track of the time , but use an interval timer or jot down on a scrap of paper the exact time prints come out of the hypo or the wash water . It's surprising how easy it is to make the error of thinking your prints went to wash ten minutes before the hour , whereas they actually went in ten minutes after . The sad part of a mistake like this is that you never do find out your error until , several years later , some particularly important and irreplaceable prints start fading and there isn't anything you can do about it .
A very convenient gadget for keeping track of time is the clock type of sign used by doctors and dentists to tell waiting patients when they will be back . The sign consists of a clock face and a movable pointer that can be set to any hour . Place one of these signs above the hypo tray and another above the wash sink . Whenever a batch of negatives or prints goes into the hypo , simply set the pointer to indicate when fixing will be complete .
FOCUSING AIDS
When enlarging from a dense negative , it is sometimes difficult to see the projected image well enough for accurate focusing . Under such circumstances , focusing aids help considerably and are worth their cost . Most of them consist of a 45 - degree mirror and a groundglass so positioned that the projected image is reflected onto the groundglass by the mirror . Because you see the image by transmitted instead of reflected light , it is much brighter , and focusing is corre spondingly easier . The more elaborate focusing aids of this type contain magnifying lenses to permit even greater accuracy . ( See Figure 19. )
Figure 19 Extremely sharp enlargements are possible through the use of this type focusing aid .
You can make a simple focusing aid , which works on an entirely different principle out of a strip of heavy paper wound so as to form a very short tube . just big enough to slip over the enlarger lens as a lens cap . Mask off the central third of the lens opening , as illustrated in Figure 20 , with a strip of black masking tape . Now if you slip this cap over the enlarger lens , you will get a double image when the negative is out of focus . As you bring it into focus , the two images merge and become one , the improvement in sharpness and brilliance being more pronounced than in normal focusing Of course , after the negative is properly focused , you remove the cap and proceed in the usual way .
Figure 20 Homemade focusing aid .
if your negative is held securely between glass sheets , you can use a focusing target to advantage . This is a film with a very sharp and contrasty pattern of lines that can be easily focused . Simply focus this film , then remove it and insert your negative instead . This method , however , will not prove satisfactory with glassless negative carriers , which permit the film to buckle and change position so that each film must be individually focused .
Some enlargers have focusing targets built permanently into the negative carrier - but don't take the accuracy of a built - in focusing target for granted . To test it select a thin negative containing some sharp lines and in the carrier . Focus on the target with the lens wide open , and then shift to the negative . If you find that the negative requires refocusing , it is best to forget about the built - in focusing target .
معدات للغرفة المظلمة ..
مؤقتات للغرفة المظلمة ..
EQUIPMENT FOR THE DARKROOM
This Assignment does pretend to cover the full range of darkroom equipment , but it does discuss the more generally used items . You don't really need more to start with - you can get by with less .
DARKROOM TIMERS
Darkroom timers are of two types - those that simply keep time and those that ring a bell or close a switch at the end of some predetermined interval . To avoid confusion , we will call the first type darkroom clocks and the second , interval timers or simply timers .
Where 60 cycle AC power is available , you can use a large kitchen or wall - type , self - starting synchronous clock with a sweep second hand . It's a good idea to illuminate the dial as discussed earlier in this Assignment and place it where you can see the clock face clearly from any working position .
Where such a clock is not available , a simple spring - wound , darkroom clock with large minute and second hands will serve nicely . This is the type illustrated in Figure 17. The principal difficulty with a spring - wound clock is that it tends to rust and wear out rather quickly in the damp , chemical - laden air of the darkroom .
For short exposures - a half minute or less - you will probably find it more convenient and accu rate to count off the time instead of watching a clock . This is particu larly true if you have a complicated job of dodging to do while making an enlargement and must concentrate all your attention on the work instead of splitting it between the work and the clock .
Figure 17 Simple type of darkroom clock . Extremely useful for timing enlargements .
A favorite trick of old - time photographers is to have a spring - wound timer or a cheap alarm clock ticking away all the time . They can then count in step with the ticking and be sure of accurate timing . If you don't have a spring - wound timer that uses a standard alarm clock movement , get a cheap alarm clock with a good loud tick . With a little practice , you will soon learn to press the enlarger switch exactly on the tick and start your count with 0 instead of 1 .
Ordinary alarm clock movements and most spring - wound timers tick four times a second , so simply divide your count by four if you want the exposure in seconds . In actual practice , however , you will soon find that it is unimportant to know whether the exposure is , let us say , sixteen seconds or sixty - four ticks . After a little while , you will soon get into the habit of thinking of your exposures in terms of clock ticks and convert them into seconds only on the relatively rare occasions when your exposures get so long that you find it easier to watch the clock rather than to count into the hundreds .
Figure 18 Two types of interval timers . Timer to left rings a bell after a predetermined interval . Timer to right shuts off power after a predetermined interval .
In addition to the darkroom clock , you should have a good interval timer . When busily engaged in enlarging , you are likely to lose track of time and so tend to over - fix your prints . This means increased washing time for one thing and may also result in bleached and empty high lights in hot weather . Since an interval timer is prac tically an essential for negative developing any way , you might just as well get a good one and use it for print making too . For developing negatives , get the type that can be set in white light and started in total darkness . Figure 18 shows two types of interval timers . The one to the left is spring - wound and is very useful for timing film development since it can be started in total darkness . The interval timer to the right times short intervals only and is primarily intended for the accurate timing of exposures when printing .
When timing darkroom operations such as fixing or washing , don't rely on your memory to keep track of the time , but use an interval timer or jot down on a scrap of paper the exact time prints come out of the hypo or the wash water . It's surprising how easy it is to make the error of thinking your prints went to wash ten minutes before the hour , whereas they actually went in ten minutes after . The sad part of a mistake like this is that you never do find out your error until , several years later , some particularly important and irreplaceable prints start fading and there isn't anything you can do about it .
A very convenient gadget for keeping track of time is the clock type of sign used by doctors and dentists to tell waiting patients when they will be back . The sign consists of a clock face and a movable pointer that can be set to any hour . Place one of these signs above the hypo tray and another above the wash sink . Whenever a batch of negatives or prints goes into the hypo , simply set the pointer to indicate when fixing will be complete .
FOCUSING AIDS
When enlarging from a dense negative , it is sometimes difficult to see the projected image well enough for accurate focusing . Under such circumstances , focusing aids help considerably and are worth their cost . Most of them consist of a 45 - degree mirror and a groundglass so positioned that the projected image is reflected onto the groundglass by the mirror . Because you see the image by transmitted instead of reflected light , it is much brighter , and focusing is corre spondingly easier . The more elaborate focusing aids of this type contain magnifying lenses to permit even greater accuracy . ( See Figure 19. )
Figure 19 Extremely sharp enlargements are possible through the use of this type focusing aid .
You can make a simple focusing aid , which works on an entirely different principle out of a strip of heavy paper wound so as to form a very short tube . just big enough to slip over the enlarger lens as a lens cap . Mask off the central third of the lens opening , as illustrated in Figure 20 , with a strip of black masking tape . Now if you slip this cap over the enlarger lens , you will get a double image when the negative is out of focus . As you bring it into focus , the two images merge and become one , the improvement in sharpness and brilliance being more pronounced than in normal focusing Of course , after the negative is properly focused , you remove the cap and proceed in the usual way .
Figure 20 Homemade focusing aid .
if your negative is held securely between glass sheets , you can use a focusing target to advantage . This is a film with a very sharp and contrasty pattern of lines that can be easily focused . Simply focus this film , then remove it and insert your negative instead . This method , however , will not prove satisfactory with glassless negative carriers , which permit the film to buckle and change position so that each film must be individually focused .
Some enlargers have focusing targets built permanently into the negative carrier - but don't take the accuracy of a built - in focusing target for granted . To test it select a thin negative containing some sharp lines and in the carrier . Focus on the target with the lens wide open , and then shift to the negative . If you find that the negative requires refocusing , it is best to forget about the built - in focusing target .
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