تويت
ملخص تقنية الكاميرا .. المرشد خطوة بخطوة للتصوير الفوتوغرافي
SUMMARY Camera technique
Focusing
A camera with an adjustable lens extends the range of distances you can be from your subject and allows you to choose which parts of the subject you want sharp . By moving the lens away from the film plane you can focus on closer subjects . and by racking it closer , more distant subjects become sharp .
Aperture and shutter speed
Adjusting the size of the aperture alters the quantity of light that is admitted ; the shutter speed controls the time for which light is admitted .
Aperture size is given in " f numbers " . The higher the number the smaller the aperture . and therefore the less light is admitted .
The shutter can be opened and closed for precise , preset periods . If the time that the shutter is open is relatively long , and the subject or the camera move , then this movement will be recorded as blur in the image .
Depth of field
The size of the aperture changes the depth of field recorded by a camera . The higher the f number , the greater the zone of accep- tably sharp detail in front of and behind the focused subject . The lower the f number . the more isolated the subject in focus will became . With subjects further than about 3 feet ( 0.9 m ) away depth of field extends further behind the focused subject than in front of it .
Exposure
Exposing the film correctly means combin- ing the right aperture with the right shutter speed . For each exposure you can choose between letting light pass through a smaller aperture for a longer time , or through a larger aperture for a shorter time .
Once you have chosen the right size film for your camera , and the number of exposures you require , your main consider . ation will be to choose the right speed of film , as shown by the ASA or DIN number . The higher the number the quicker the emulsion reacts to light because of its large grain size . The lower the number the slow- er the emulsion reacts to light because of its small grain size . Detail is recorded more sharply on fine - grained emulsion .
Light meters
Make sure that your meter " sees " a representative area of the subject . Take your readings from those areas of the subject that are most important , and if necessary , average out the light and dark areas .
The subject
Try not to let the choice of controls come between you and your subject . It is some- times advisable to set your camera controls in advance to a probable shutter speed and aperture so that you can take a quick pic- ture without making further adjustments .
The diagram below shows a typical sequence of decisions necessary when taking a photo- graph . It is not meant to be com- prehensive or invariable . Your camera may have slightly differ-ent controls or you may prefer to set the aperture or shutter before you focus . A similar procedure applies if you are using a hand- heid meter or if you have an aperture priority camera .
1. Film loading Always load and unload film in the shade . Set the film ASA rating on the exposure meter .
2. Focus Select your view- point and focus on the main part of your subject .
3. Shutter Set a shutter speed . remembering the effect of movement and camera shake .
4. Aperture Set the exposure according to the weather symbols .
4. Aperture Using the meter . take a reading from an appropriate area of the subject . Alter the aperture until the meter read - out shows the correct exposure .
5. Expose Check the com- position and , with the camera steady . choose the right moment to gently press the shutter release . Wind on the film .
SUMMARY Camera technique
Focusing
A camera with an adjustable lens extends the range of distances you can be from your subject and allows you to choose which parts of the subject you want sharp . By moving the lens away from the film plane you can focus on closer subjects . and by racking it closer , more distant subjects become sharp .
Aperture and shutter speed
Adjusting the size of the aperture alters the quantity of light that is admitted ; the shutter speed controls the time for which light is admitted .
Aperture size is given in " f numbers " . The higher the number the smaller the aperture . and therefore the less light is admitted .
The shutter can be opened and closed for precise , preset periods . If the time that the shutter is open is relatively long , and the subject or the camera move , then this movement will be recorded as blur in the image .
Depth of field
The size of the aperture changes the depth of field recorded by a camera . The higher the f number , the greater the zone of accep- tably sharp detail in front of and behind the focused subject . The lower the f number . the more isolated the subject in focus will became . With subjects further than about 3 feet ( 0.9 m ) away depth of field extends further behind the focused subject than in front of it .
Exposure
Exposing the film correctly means combin- ing the right aperture with the right shutter speed . For each exposure you can choose between letting light pass through a smaller aperture for a longer time , or through a larger aperture for a shorter time .
Once you have chosen the right size film for your camera , and the number of exposures you require , your main consider . ation will be to choose the right speed of film , as shown by the ASA or DIN number . The higher the number the quicker the emulsion reacts to light because of its large grain size . The lower the number the slow- er the emulsion reacts to light because of its small grain size . Detail is recorded more sharply on fine - grained emulsion .
Light meters
Make sure that your meter " sees " a representative area of the subject . Take your readings from those areas of the subject that are most important , and if necessary , average out the light and dark areas .
The subject
Try not to let the choice of controls come between you and your subject . It is some- times advisable to set your camera controls in advance to a probable shutter speed and aperture so that you can take a quick pic- ture without making further adjustments .
The diagram below shows a typical sequence of decisions necessary when taking a photo- graph . It is not meant to be com- prehensive or invariable . Your camera may have slightly differ-ent controls or you may prefer to set the aperture or shutter before you focus . A similar procedure applies if you are using a hand- heid meter or if you have an aperture priority camera .
1. Film loading Always load and unload film in the shade . Set the film ASA rating on the exposure meter .
2. Focus Select your view- point and focus on the main part of your subject .
3. Shutter Set a shutter speed . remembering the effect of movement and camera shake .
4. Aperture Set the exposure according to the weather symbols .
4. Aperture Using the meter . take a reading from an appropriate area of the subject . Alter the aperture until the meter read - out shows the correct exposure .
5. Expose Check the com- position and , with the camera steady . choose the right moment to gently press the shutter release . Wind on the film .
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