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كتاب التصوير الفوتوغرافي المغلق
Extension tubes
Extension tubes can be used in conjunction with any single lens reflex camera which has a detachable lens ; the lens has to be removed so that the tubes can be fitted between the camera body and the lens ( see p . 148 ) . There fore whenever extension tubes are used , the lens - to - film distance is greater than it would be without tubes . This reduces the amount of light reaching the film . Such a light loss is de tected by a through - the - lens meter , but you must allow for it when using a light meter remote from the camera ( see p . 160 ) .
Extension tubes may be manual or auto matic . Manual tubes are cheaper , but they have to be stopped down to the required aper ture by hand . Automatic tubes couple the lens diaphragm to the camera body . This facility allows the maximum lens aperture to be re tained for viewing and metering until the moment the shutter is released , when the diaphragm automatically closes down to a selected aperture . Although manual tubes can be made to function automatically by using a Z ring and a double cable release ( see p . 148 ) , automatic tubes are more convenient to use .
Within the 35mm format , extension tubes may come in sets of three or five tubes of vari able lengths and can be used in any combina tion to gain the desired magnification . A set is usually designed to give a magnification of up to life - size ( x1 ) with a standard 50mm lens on a 35mm format . Additional tubes can always be added if greater magnifications are required , although it may be more convenient to use a bellows extension ( see p . 28 ) at magnifications of much greater than × 1.5 .
Extension tubes can be used with longer focal length lenses ( 90mm , 105mm , 135mm or 200mm ) for taking close - ups of more distant objects which are out of range of a 50mm lens with tubes . The magnification gained on 35mm film and a 50mm extension will change with the focal length of the lens : with a 50mm lens it is x 1 , whereas with a 100mm lens it is × 0.5 .
Painting pattern
My young son made this pattern by sweeping a plastic comb back and forth across wet paint on cerise - colored paper . After the painting had dried , I laid it on a table beside a window and photographed part of it by indirect available light . Lens 50mm Nikon + 14mm extension Mag . on film × 0.3 Mag . on page × 1.5
Plant power ▷ If roots of perennial plants such as this bracken . extend beneath hard surfacing , the force of the upward - growing new shoots is strong enough to fracture and ultimately to break through the hard surface . I took this picture in my garden by setting up the camera on a tripod close to the ground . Focusing at this low - level viewpoint was made easier by using a right - angle viewfinder . Lens 50mm Nikon + 14mm extension Mag . on film × 0.3 Mag . on page × 2.5
التشريح عن قرب ..
كتاب التصوير الفوتوغرافي المغلق
Extension tubes
Extension tubes can be used in conjunction with any single lens reflex camera which has a detachable lens ; the lens has to be removed so that the tubes can be fitted between the camera body and the lens ( see p . 148 ) . There fore whenever extension tubes are used , the lens - to - film distance is greater than it would be without tubes . This reduces the amount of light reaching the film . Such a light loss is de tected by a through - the - lens meter , but you must allow for it when using a light meter remote from the camera ( see p . 160 ) .
Extension tubes may be manual or auto matic . Manual tubes are cheaper , but they have to be stopped down to the required aper ture by hand . Automatic tubes couple the lens diaphragm to the camera body . This facility allows the maximum lens aperture to be re tained for viewing and metering until the moment the shutter is released , when the diaphragm automatically closes down to a selected aperture . Although manual tubes can be made to function automatically by using a Z ring and a double cable release ( see p . 148 ) , automatic tubes are more convenient to use .
Within the 35mm format , extension tubes may come in sets of three or five tubes of vari able lengths and can be used in any combina tion to gain the desired magnification . A set is usually designed to give a magnification of up to life - size ( x1 ) with a standard 50mm lens on a 35mm format . Additional tubes can always be added if greater magnifications are required , although it may be more convenient to use a bellows extension ( see p . 28 ) at magnifications of much greater than × 1.5 .
Extension tubes can be used with longer focal length lenses ( 90mm , 105mm , 135mm or 200mm ) for taking close - ups of more distant objects which are out of range of a 50mm lens with tubes . The magnification gained on 35mm film and a 50mm extension will change with the focal length of the lens : with a 50mm lens it is x 1 , whereas with a 100mm lens it is × 0.5 .
Painting pattern
My young son made this pattern by sweeping a plastic comb back and forth across wet paint on cerise - colored paper . After the painting had dried , I laid it on a table beside a window and photographed part of it by indirect available light . Lens 50mm Nikon + 14mm extension Mag . on film × 0.3 Mag . on page × 1.5
Plant power ▷ If roots of perennial plants such as this bracken . extend beneath hard surfacing , the force of the upward - growing new shoots is strong enough to fracture and ultimately to break through the hard surface . I took this picture in my garden by setting up the camera on a tripod close to the ground . Focusing at this low - level viewpoint was made easier by using a right - angle viewfinder . Lens 50mm Nikon + 14mm extension Mag . on film × 0.3 Mag . on page × 2.5
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