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التقاط الصور والرؤية .. مبادئ التصوير الفوتوغرافي .. المرشد خطوة بخطوة للتصوير الفوتوغرافي
Taking photographs and seeing
If you compare the camera with the human eye , you will at first find many similarities . Your eye admits light through the cornea and the pupil , with a variable iris to adjust brightness ; it uses a tissue lens to give a sharp image , and a light - sensitive area - the retina to receive it . The camera admits light through the lens aperture , which is adjusted by a variable diaphragm ( or iris ) ; it uses a glass lens , and a light - sensitive film . Both lenses can be focused for different distances , and both form miniature upside- down images of the scene .
But here the likeness ends . You cannot assume the camera sees as you do . There are basic differences between seeing and photography which you should understand - otherwise your pictures may look very different from the scene you remember . With practice you can learn to anticipate what the camera will see , and adjust your photography accordingly .
Selective vision :
Human vision is controlled partly by the eye , partly by the brain . This arrangement gives you selective vision - you can " notice " important images on the retina and disregard others . For example the words you are now reading appear sharp and clear , whereas the words surrounding them are less distinct . Selective vision eliminates distracting elements . The camera cannot do this it records what is there , with objects at the same distance all appearing equally clear . So photography often records too much -the unimportant along with the important . You must get used to scanning your viewfinder frame thoroughly for unwanted elements , particularly around the edges . You can usually exclude them by changing your viewpoint or framing .
The eye seldom presents you with an out - of - focus image . If you glance up from this book to look at a door or window across the room , the detail will look equally sharp . Your eyes have refocused for the new distance automatically . Only if you hold your book up in line with the door or window , and try to see both at once , will you discover that focusing on one causes the other to appear unsharp . You can alter the focus of a camera lens in the same way . But if you take a picture with , say , the book sharp and the room out - of - focus , this situation is fixed within the photograph . You cannot then move your eye from one to the other to see both clearly . So you must show a particular part of the scene in focus when you shoot the picture . This selective focus is useful for directing attention in your pictures .
The photographed scene :
Looking through the camera viewfinder you see a picture framed by hard edges and corners . But the scene your eyes see is limited only by your attention , as your eyes regularly scan and move across it . A photograph is taken from a fixed viewpoint , which determines what is included . The proportions of the frame affect how the elements in your picture relate to each other . Try looking around you in terms of rectangles - horizontal or upright . How would the scene appear ?
The camera reduces the three - dimensional world to a two- dimensional image . The picture formed at the back of your eye is also two - dimensional , but you see in three dimensions . This is partly because you have two eyes and so see everything from two slightly different viewpoints . Look through your left eye only , and line up a close subject with one much further away . Without moving your head , now look through your right eye only - the relationship of the two objects will change . Your brain interprets these differences to judge space , distance , and depth . You can also estimate distance by changing your viewpoint -notice how near objects appear to shift more than those further away . In a two - dimensional photograph you have to communicate depth by creating perspective , by overlapping near and far objects and by choosing lighting that shows three - dimensional form .
A photograph isolates and records a moment of time . The skill lies in choosing the moment that expresses the essence of the changing scene or event you are looking at . You must learn to anticipate , to see only what the camera will see at the moment of exposure . Your eyes see motion as change : in a still photograph , you can only imply motion , perhaps by blurring the image .
How the human eye works :
The human eye is a sphere about one inch ( 2.5 cm ) across , with a precision optical system at the front which projects a sharp image upside - down on to the curved back wall , or retina . Here light - sensitive cells receive the image and convey it directly to the brain . Light reaching the eye first passes through the cornea which bends and focuses the light to pass through a small hole , the pupil . The size of the pupil can be altered by the tiny muscles of the iris , to adjust the brightness of light entering the eye . Within the eye , the light passes through a flexible lens . The lens is fixed in position , but can expand or contract to focus objects at different distances on the retina .
How the camera works :
The camera includes similar elements . but is much cruder than the human eye . It has an optical system at the front , to project a sharp , upside - down image on to the film held flat at the back . Here light - sensitive chemicals record the image . Light first enters the camera through the compound lens , a series of glass elements that bend and focus the light . The amount of light entering is controlled by an aperture , usually formed by a ring or diaphragm of adjustable metal leaves within the lens body . Unlike the eye . the camera uses a shutter between lens and film to determine when and for how long light acts on the film . The camera lens focuses objects at different distances by moving backward or forward , not , as in the human eye , by changing its shape .
Eye and film sensitivity :
Your eyes alter their response to light in different conditions . but film is less flexible . You see colors most strongly in bright light . When very little light is present under moonlight , for example - you see almost entirely in black , white and grays . When it is very dark , you gradually " get used to the dark " as the retina increases its sensitivity by hundreds of times . Film sensitivity is more fixed . But , unlike the eye , film will accumulate light , so you can give a long exposure and overcome dim conditions this way . Film will exaggerate the contrast between the light and dark parts of a scene . If you are inside on a sunny day , you can usually see details of a bright scene outside the window just as clearly as details of the darker scene indoors . But film cannot cope with such a range . You must choose between exposing the interior detail correctly , and allowing the outside to appear too pale ; or exposing the outside correctly , and leaving the interior almost black . You can estimate how film will respond by half closing your eyes and looking through your eyelashes .
Film possesses neither the same light - sensitivity as the retina , nor the power of the brain to interpret what it sees . The eye functions equally well in semi - darkness or bright sunlight . But there is no one film that can cope with such a range of light intensity . Films therefore come in a variety of speeds - the speed denotes the sensitivity of the film to light . Fast film requires less light to record an image and can therefore be used in dimmer conditions ; slow film has a relatively low sensitivity to light and so requires bright lighting . In color photography , you will also have to consider the color of your light source . If , for instance , you take a color picture by artificial lighting with a film intended for outdoor use , your result will be tinged with red . The film has recorded the fact that the light source had a higher proportion of red than natural daylight , while your eyes registered the scene according to the brain's preconception of how a scene lit by white light should look .
These differences between seeing and photography are the " ground rules " of a photographer . When you work through the section on Picture Building ( pp . 45-64 ) you will find that many of these differences can be turned to your advantage .
The camera cannot discriminate Pictures often turn out cluttered . because your eyes showed you only the element you were concentrating on in a scene , whereas the camera recorded everything equally clearly . Always look carefully at the subject in your viewfinder , and try to simplify it . The photograph . left . for example , includes important and unimportant elements without discriminating between them . The subject could have been isolated by changing the viewpoint or using selective focus .
The camera must be focused Wherever you look , you see a sharply rendered scene . You are not aware of your eyes adjusting to focus at different distances . So it is easy to forget that the camera will only render the focused distance sharply , as shown in the picture . left . You must set your chosen subject distance on the camera lens , so that the subject you wish to emphasize is rendered sharply . As you can see from this photograph . selective focus is a powerful tool for isolating a subject .
Film exaggerates contrast When viewing the scene shown in the picture , left , the photographer saw detail in both the bright daylit balcony and the dark interior . But film exaggerates extremely light and dark tones if they are present in the same picture . So for a scene like this , you may have to decide whether to expose dark parts correctly so that detail elsewhere is bleached white by overexposure , or expose light areas correctly and accept that dark areas will be solid black .
A photograph is two - dimensional A photograph is a flat image with height and width but no depth . So you have to learn to suggest the third dimension , depth , experienced in human vision . The picture shown left does so by using strong perspective lines , and lighting that exaggerates the three - dimensional form of the train . The part of the train on the right - hand side of the picture appears much closer to you than the woman in the center , though both lie in a two- dimensional picture .
Taking photographs and seeing
If you compare the camera with the human eye , you will at first find many similarities . Your eye admits light through the cornea and the pupil , with a variable iris to adjust brightness ; it uses a tissue lens to give a sharp image , and a light - sensitive area - the retina to receive it . The camera admits light through the lens aperture , which is adjusted by a variable diaphragm ( or iris ) ; it uses a glass lens , and a light - sensitive film . Both lenses can be focused for different distances , and both form miniature upside- down images of the scene .
But here the likeness ends . You cannot assume the camera sees as you do . There are basic differences between seeing and photography which you should understand - otherwise your pictures may look very different from the scene you remember . With practice you can learn to anticipate what the camera will see , and adjust your photography accordingly .
Selective vision :
Human vision is controlled partly by the eye , partly by the brain . This arrangement gives you selective vision - you can " notice " important images on the retina and disregard others . For example the words you are now reading appear sharp and clear , whereas the words surrounding them are less distinct . Selective vision eliminates distracting elements . The camera cannot do this it records what is there , with objects at the same distance all appearing equally clear . So photography often records too much -the unimportant along with the important . You must get used to scanning your viewfinder frame thoroughly for unwanted elements , particularly around the edges . You can usually exclude them by changing your viewpoint or framing .
The eye seldom presents you with an out - of - focus image . If you glance up from this book to look at a door or window across the room , the detail will look equally sharp . Your eyes have refocused for the new distance automatically . Only if you hold your book up in line with the door or window , and try to see both at once , will you discover that focusing on one causes the other to appear unsharp . You can alter the focus of a camera lens in the same way . But if you take a picture with , say , the book sharp and the room out - of - focus , this situation is fixed within the photograph . You cannot then move your eye from one to the other to see both clearly . So you must show a particular part of the scene in focus when you shoot the picture . This selective focus is useful for directing attention in your pictures .
The photographed scene :
Looking through the camera viewfinder you see a picture framed by hard edges and corners . But the scene your eyes see is limited only by your attention , as your eyes regularly scan and move across it . A photograph is taken from a fixed viewpoint , which determines what is included . The proportions of the frame affect how the elements in your picture relate to each other . Try looking around you in terms of rectangles - horizontal or upright . How would the scene appear ?
The camera reduces the three - dimensional world to a two- dimensional image . The picture formed at the back of your eye is also two - dimensional , but you see in three dimensions . This is partly because you have two eyes and so see everything from two slightly different viewpoints . Look through your left eye only , and line up a close subject with one much further away . Without moving your head , now look through your right eye only - the relationship of the two objects will change . Your brain interprets these differences to judge space , distance , and depth . You can also estimate distance by changing your viewpoint -notice how near objects appear to shift more than those further away . In a two - dimensional photograph you have to communicate depth by creating perspective , by overlapping near and far objects and by choosing lighting that shows three - dimensional form .
A photograph isolates and records a moment of time . The skill lies in choosing the moment that expresses the essence of the changing scene or event you are looking at . You must learn to anticipate , to see only what the camera will see at the moment of exposure . Your eyes see motion as change : in a still photograph , you can only imply motion , perhaps by blurring the image .
How the human eye works :
The human eye is a sphere about one inch ( 2.5 cm ) across , with a precision optical system at the front which projects a sharp image upside - down on to the curved back wall , or retina . Here light - sensitive cells receive the image and convey it directly to the brain . Light reaching the eye first passes through the cornea which bends and focuses the light to pass through a small hole , the pupil . The size of the pupil can be altered by the tiny muscles of the iris , to adjust the brightness of light entering the eye . Within the eye , the light passes through a flexible lens . The lens is fixed in position , but can expand or contract to focus objects at different distances on the retina .
How the camera works :
The camera includes similar elements . but is much cruder than the human eye . It has an optical system at the front , to project a sharp , upside - down image on to the film held flat at the back . Here light - sensitive chemicals record the image . Light first enters the camera through the compound lens , a series of glass elements that bend and focus the light . The amount of light entering is controlled by an aperture , usually formed by a ring or diaphragm of adjustable metal leaves within the lens body . Unlike the eye . the camera uses a shutter between lens and film to determine when and for how long light acts on the film . The camera lens focuses objects at different distances by moving backward or forward , not , as in the human eye , by changing its shape .
Eye and film sensitivity :
Your eyes alter their response to light in different conditions . but film is less flexible . You see colors most strongly in bright light . When very little light is present under moonlight , for example - you see almost entirely in black , white and grays . When it is very dark , you gradually " get used to the dark " as the retina increases its sensitivity by hundreds of times . Film sensitivity is more fixed . But , unlike the eye , film will accumulate light , so you can give a long exposure and overcome dim conditions this way . Film will exaggerate the contrast between the light and dark parts of a scene . If you are inside on a sunny day , you can usually see details of a bright scene outside the window just as clearly as details of the darker scene indoors . But film cannot cope with such a range . You must choose between exposing the interior detail correctly , and allowing the outside to appear too pale ; or exposing the outside correctly , and leaving the interior almost black . You can estimate how film will respond by half closing your eyes and looking through your eyelashes .
Film possesses neither the same light - sensitivity as the retina , nor the power of the brain to interpret what it sees . The eye functions equally well in semi - darkness or bright sunlight . But there is no one film that can cope with such a range of light intensity . Films therefore come in a variety of speeds - the speed denotes the sensitivity of the film to light . Fast film requires less light to record an image and can therefore be used in dimmer conditions ; slow film has a relatively low sensitivity to light and so requires bright lighting . In color photography , you will also have to consider the color of your light source . If , for instance , you take a color picture by artificial lighting with a film intended for outdoor use , your result will be tinged with red . The film has recorded the fact that the light source had a higher proportion of red than natural daylight , while your eyes registered the scene according to the brain's preconception of how a scene lit by white light should look .
These differences between seeing and photography are the " ground rules " of a photographer . When you work through the section on Picture Building ( pp . 45-64 ) you will find that many of these differences can be turned to your advantage .
The camera cannot discriminate Pictures often turn out cluttered . because your eyes showed you only the element you were concentrating on in a scene , whereas the camera recorded everything equally clearly . Always look carefully at the subject in your viewfinder , and try to simplify it . The photograph . left . for example , includes important and unimportant elements without discriminating between them . The subject could have been isolated by changing the viewpoint or using selective focus .
The camera must be focused Wherever you look , you see a sharply rendered scene . You are not aware of your eyes adjusting to focus at different distances . So it is easy to forget that the camera will only render the focused distance sharply , as shown in the picture . left . You must set your chosen subject distance on the camera lens , so that the subject you wish to emphasize is rendered sharply . As you can see from this photograph . selective focus is a powerful tool for isolating a subject .
Film exaggerates contrast When viewing the scene shown in the picture , left , the photographer saw detail in both the bright daylit balcony and the dark interior . But film exaggerates extremely light and dark tones if they are present in the same picture . So for a scene like this , you may have to decide whether to expose dark parts correctly so that detail elsewhere is bleached white by overexposure , or expose light areas correctly and accept that dark areas will be solid black .
A photograph is two - dimensional A photograph is a flat image with height and width but no depth . So you have to learn to suggest the third dimension , depth , experienced in human vision . The picture shown left does so by using strong perspective lines , and lighting that exaggerates the three - dimensional form of the train . The part of the train on the right - hand side of the picture appears much closer to you than the woman in the center , though both lie in a two- dimensional picture .
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