تويت
الخطوة 3: التكبير / المكبر .. المعالجة والطباعة بالأبيض والأسود .. المرشد خطوة بخطوة للتصوير الفوتوغرافي
STEP 3 : ENLARGING / The enlarger
So far we have only used the enlarger as a handy light source for making contact prints . Before making enlargements we really need to know more about what this equipment does and how it works .
An enlarger is a projection printer , simi- lar to a slide projector but mounted vertically and with a much less brilliant lamp . Like a slide projector , it has a condenser ( which consists simply of one or two converging lenses ) that concentrates the light source into an even , focused beam ( some enlargers use a plastic diffuser for this ) . Below the condenser , the film is held by its edges in a carrier that has its central area cut out in a rectangle the size of one negative . When an exposure is made , the lamp above the carrier projects the image down through the enlarging lens so that it appears en- larged on a sheet of light - sensitive paper laid on the baseboard below .
Components of the enlarger
Although the enlarger is basically a very simple device , it is as important for pro- ducing a quality print as a good camera . The lamp must illuminate the negative evenly ; a central bright spot or dark corner , for example , will give greatly exaggerated dark or light areas on all your prints . In addition , the lamphouse must prevent light escaping through the ventilation holes as this might fog the paper on the baseboard . The carrier should hold the negative absolutely flat , otherwise parts of the picture will appear out of focus or distorted . For the same reason , the lamp must not over - heat and distort the film . The enlarging lens , which normally has a longer focal length than the lens on a camera , must be the best quality that you can afford . If you have a good quality lens on your camera , the detail it gives will be lost if you enlarge through a poor quality enlarging lens .
Controls on the enlarger
There are three main controls on the enlarger the position of the enlarging head , the focus , and the aperture . Move the whole enlarging head toward or away from the baseboard along the column to alter the size of the enlargement ; the column should be large enough to allow the biggest print you will normally want . For even larger images , some heads can be swung around the column to project on to a distant surface such as a wall or floor . The second main control on the enlarger is the focus ; it should give a smooth , fine focus of the image on the baseboard . The lens must not slip out of focus when , for example , you are adjusting its aperture or when swinging over the red filter . The third control is the aperture , which with the timer determines the ex- posure of the print ; its stops follow the same sequence as the f numbers on your camera .
The enlarger and accessories
Column
Lamphouse
Filter drawer
Negative carrier Focusing knob
Enlarging lens
Red filter
Height adjustment knob
Masking easel
Baseboard
Focus magnifier
To see if the image on the base- board is exactly in focus , a focus magnifier , shown below , can be used . A small mirror reflects light up to an internal focusing screen that can be closely studied through a magnifier .
Timer
An electric timer , shown below . is a useful accessory : wired between the electricity supply and the enlarger , it will automatically switch the enlarger on for the set exposure time .
Types of enlarger
Lamphouse
Enlarger bulb
Condenser lens
Negative carrier
Enlarging lens
Direct lamphouse
Most enlargers are of this kind . The light from the enlarger bulb is concentrated by a condenser ( consisting of one or two lenses ) or scattered by a diffuser , so that the negative is evenly illuminated through the enlarging lens .
Lamphouse
Enlarger bulb
Mirror at 45 °
Condenser lens
Negative carrier
Enlarging lens
Reflex lamphouse
Illumination from the enlarger bulb is reflected by a 45 ° angle mirror in a reflex system , thereby reducing the lamphouse height . A condenser , of one or two lenses , concentrates the light before it reaches the negative . ( On some enlargers the light is evenly distributed by a diffuser . )
STEP 3 : ENLARGING / The enlarger
So far we have only used the enlarger as a handy light source for making contact prints . Before making enlargements we really need to know more about what this equipment does and how it works .
An enlarger is a projection printer , simi- lar to a slide projector but mounted vertically and with a much less brilliant lamp . Like a slide projector , it has a condenser ( which consists simply of one or two converging lenses ) that concentrates the light source into an even , focused beam ( some enlargers use a plastic diffuser for this ) . Below the condenser , the film is held by its edges in a carrier that has its central area cut out in a rectangle the size of one negative . When an exposure is made , the lamp above the carrier projects the image down through the enlarging lens so that it appears en- larged on a sheet of light - sensitive paper laid on the baseboard below .
Components of the enlarger
Although the enlarger is basically a very simple device , it is as important for pro- ducing a quality print as a good camera . The lamp must illuminate the negative evenly ; a central bright spot or dark corner , for example , will give greatly exaggerated dark or light areas on all your prints . In addition , the lamphouse must prevent light escaping through the ventilation holes as this might fog the paper on the baseboard . The carrier should hold the negative absolutely flat , otherwise parts of the picture will appear out of focus or distorted . For the same reason , the lamp must not over - heat and distort the film . The enlarging lens , which normally has a longer focal length than the lens on a camera , must be the best quality that you can afford . If you have a good quality lens on your camera , the detail it gives will be lost if you enlarge through a poor quality enlarging lens .
Controls on the enlarger
There are three main controls on the enlarger the position of the enlarging head , the focus , and the aperture . Move the whole enlarging head toward or away from the baseboard along the column to alter the size of the enlargement ; the column should be large enough to allow the biggest print you will normally want . For even larger images , some heads can be swung around the column to project on to a distant surface such as a wall or floor . The second main control on the enlarger is the focus ; it should give a smooth , fine focus of the image on the baseboard . The lens must not slip out of focus when , for example , you are adjusting its aperture or when swinging over the red filter . The third control is the aperture , which with the timer determines the ex- posure of the print ; its stops follow the same sequence as the f numbers on your camera .
The enlarger and accessories
Column
Lamphouse
Filter drawer
Negative carrier Focusing knob
Enlarging lens
Red filter
Height adjustment knob
Masking easel
Baseboard
Focus magnifier
To see if the image on the base- board is exactly in focus , a focus magnifier , shown below , can be used . A small mirror reflects light up to an internal focusing screen that can be closely studied through a magnifier .
Timer
An electric timer , shown below . is a useful accessory : wired between the electricity supply and the enlarger , it will automatically switch the enlarger on for the set exposure time .
Types of enlarger
Lamphouse
Enlarger bulb
Condenser lens
Negative carrier
Enlarging lens
Direct lamphouse
Most enlargers are of this kind . The light from the enlarger bulb is concentrated by a condenser ( consisting of one or two lenses ) or scattered by a diffuser , so that the negative is evenly illuminated through the enlarging lens .
Lamphouse
Enlarger bulb
Mirror at 45 °
Condenser lens
Negative carrier
Enlarging lens
Reflex lamphouse
Illumination from the enlarger bulb is reflected by a 45 ° angle mirror in a reflex system , thereby reducing the lamphouse height . A condenser , of one or two lenses , concentrates the light before it reaches the negative . ( On some enlargers the light is evenly distributed by a diffuser . )
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