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كتاب التصوير الفوتوغرافي المغلق
Depth of field
Depth of field is the zone in front of and behind the plane of focus where the image appears sharply defined . Being able to understand and exploit depth of field to the maximum is essential when taking close - ups , since the more you magnify a subject the smaller the depth of field becomes ( see p . 161 ) . It is also decreased by opening up the lens aperture ; conversely , reduction of image size or the lens aperture increases the depth of field . When taking close ups , I invariably aim to use a macro lens at one stop above the smallest aperture to retain good definition ; for example , f22 with an f32 lens . When working in available light with a slow speed color film , small apertures are possible only if a slow shutter speed is used , or if the light level is boosted by additional lighting .
The way in which the depth of field changes with the aperture can be seen either by stop ping down a non - automatic lens or depressing the depth of field preview button with an auto matic lens . When a subject is 3.5 feet away , or closer , the depth of field increases almost equally on each side of the plane of focus . You can therefore ensure the best use of the depth of field available by focusing slightly beyond that part of the subject nearest to the camera This should bring the subject completely into focus as the lens is stopped down . For a sharply defined image the precise plane of focus will need to be selected for each subject depend ing on the chosen magnification and aperture , but you can always check the depth of field either by viewing the subject through a stopped - down lens , or by using a macro lens which has a close - up depth of field scale printed on the lens barrel .
A useful way of isolating a close - up subject from a confusing background is to throw the background out of focus , which may mean decreasing the depth of field by opening up the aperture . If you wish to isolate one object among many similar ones , you can do this by means of differential focus whereby with car ful focusing and aperture selection everything else is thrown out of focus so the eye is auto matically led toward the defined subject .
A single plane ▷ I collected these crab's - eye seeds in Barbados and carefully grouped them in a shallow petri dish so they would create a greater impact in a mass . I took the picture with the camera mounted overhead , using a spirit level to check that the film plane was parallel with the layer of seeds . It was then easy to ensure the seed mosaic was sharply defined within the one plane . Lens 55mm micro - Nikkor Mag . on film × 0.5 Mag . on page × 3
Selective focus
I wanted to draw attention to the first open pussy willow catkin on this branch , so I stopped down the lens and then while keeping the depth of field button depressed I slowly . opened up the lens . In this way I could see precisely how many catkins were sharply in focus . I also deliberately chose to off center the point of focus . Lens 105mm micro - Nikkor Mag . on film × 0.4 Mag . on page × 2
Improving the definition Using a pair of spotlights , I took a group of marbles on a solitaire board with the lens set on the widest aperture at f4 . The result can be seen in the top left picture , where only the red marble appears sharply in focus . Keeping the camera position and lighting constant , I then stopped the lens down to f8 ( center left ) which brought each marble on either side of the red one into focus . It also reduced the size of the highlights in the marbles which are out of focus . Finally , I stopped the lens down to f32 to bring all the marbles into focus and reduce the highlights still further . The set - up below illustrates the extent of the depth of field ( shaded in gray ) for each aperture . Lens Hasselblad 150mm + 103mm ( 55 + 32 + 16 ) extension
Mag on film x0.6
Mag on page ×7
التشريح عن قرب ..
كتاب التصوير الفوتوغرافي المغلق
Depth of field
Depth of field is the zone in front of and behind the plane of focus where the image appears sharply defined . Being able to understand and exploit depth of field to the maximum is essential when taking close - ups , since the more you magnify a subject the smaller the depth of field becomes ( see p . 161 ) . It is also decreased by opening up the lens aperture ; conversely , reduction of image size or the lens aperture increases the depth of field . When taking close ups , I invariably aim to use a macro lens at one stop above the smallest aperture to retain good definition ; for example , f22 with an f32 lens . When working in available light with a slow speed color film , small apertures are possible only if a slow shutter speed is used , or if the light level is boosted by additional lighting .
The way in which the depth of field changes with the aperture can be seen either by stop ping down a non - automatic lens or depressing the depth of field preview button with an auto matic lens . When a subject is 3.5 feet away , or closer , the depth of field increases almost equally on each side of the plane of focus . You can therefore ensure the best use of the depth of field available by focusing slightly beyond that part of the subject nearest to the camera This should bring the subject completely into focus as the lens is stopped down . For a sharply defined image the precise plane of focus will need to be selected for each subject depend ing on the chosen magnification and aperture , but you can always check the depth of field either by viewing the subject through a stopped - down lens , or by using a macro lens which has a close - up depth of field scale printed on the lens barrel .
A useful way of isolating a close - up subject from a confusing background is to throw the background out of focus , which may mean decreasing the depth of field by opening up the aperture . If you wish to isolate one object among many similar ones , you can do this by means of differential focus whereby with car ful focusing and aperture selection everything else is thrown out of focus so the eye is auto matically led toward the defined subject .
A single plane ▷ I collected these crab's - eye seeds in Barbados and carefully grouped them in a shallow petri dish so they would create a greater impact in a mass . I took the picture with the camera mounted overhead , using a spirit level to check that the film plane was parallel with the layer of seeds . It was then easy to ensure the seed mosaic was sharply defined within the one plane . Lens 55mm micro - Nikkor Mag . on film × 0.5 Mag . on page × 3
Selective focus
I wanted to draw attention to the first open pussy willow catkin on this branch , so I stopped down the lens and then while keeping the depth of field button depressed I slowly . opened up the lens . In this way I could see precisely how many catkins were sharply in focus . I also deliberately chose to off center the point of focus . Lens 105mm micro - Nikkor Mag . on film × 0.4 Mag . on page × 2
Improving the definition Using a pair of spotlights , I took a group of marbles on a solitaire board with the lens set on the widest aperture at f4 . The result can be seen in the top left picture , where only the red marble appears sharply in focus . Keeping the camera position and lighting constant , I then stopped the lens down to f8 ( center left ) which brought each marble on either side of the red one into focus . It also reduced the size of the highlights in the marbles which are out of focus . Finally , I stopped the lens down to f32 to bring all the marbles into focus and reduce the highlights still further . The set - up below illustrates the extent of the depth of field ( shaded in gray ) for each aperture . Lens Hasselblad 150mm + 103mm ( 55 + 32 + 16 ) extension
Mag on film x0.6
Mag on page ×7
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