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مبادئ الإضاءة ..
التحكم في جودة الإضاءة الخارجية
CONTROLLING THE QUALITY OF OUTDOOR ILLUMINATION
Outdoor illumination is extremely variable , not only as to strength but as to direction , contrast and quality . The photographer who works in daylight must know how to control it to meet his requirements . The type lighting which may be extremely effective for black - and - white film may be completely wrong for color film , and vice versa . The type of lighting which may be ideal for an architectural subject may be all wrong for a group photograph . Perfect outdoor lighting for showing a steel worker may be impossibly bad for a fashion model . the commercial photographer who is sent out on a specific assignment has to produce a good picture regardless of any other consideration . It is not often that he can postpone his picture taking until the light is just right . He must know how to control his light so that he can get good results regardless .
Figure 21 Same scene as Figure 20 but given a highly dramatic impact by printing for a silhouette effect .
There are quite a number of ways in which daylight illumination can be controlled . Usually the problem is one of contrast . The light is either too . contrasty or not contrasty enough . Because of this , we will discuss contrast control first .
CONTROLLING LIGHT FOR CONTRAST . Direct sunlight is often too contrasty , particularly when it comes to the photography of people . Changing the direction of light will exercise some control . For example , if the subject is faced into the light so that you have front lighting with a relatively low sun , the shadows on the face may be small enough so as not to cause trouble . Then by tilting the head right , left , up or down , the shadows may be placed where they will do the least amount of harm . The exposure can then be carefully adjusted to produce the best modeling . Usually this means keeping the exposure on the low side , since overexposure will block up the highlights and destroy modeling .
Figure 22 The silhouetted skaters and their long shadows provide the main interest here , so the only fill - in light is that which is reflected from the ice on which the figures are skating . Courtesy of Swiss National Tourist Office .
With some types of subjects , shifting the subject or the camera angle . radically so as to produce backlighting will provide a satisfactory answer . The subject , being mainly in shadow , will therefore have very low contrast even though the sun is shining brightly . With this type of lighting , however , it is important to note two things : 1. The brightly highlighted areas which are reached by the sun must be small and relatively unimportant . Otherwise , they will appear to be the main subject material and the whole purpose of the picture will be lost . 2. Enough light must reach the key subject area so that it will have sufficient contrast to make a satisfactory picture . This secondary light may be reflections from a light foreground , such as the sand in a beach scene , from a sidewalk on a city street , or from neighboring white buildings . If nothing else is available and the subject does not cover too large an area , newspapers spread on the ground just out of the camera view may throw enough light into the shadows to provide the necessary detail . See Figures 22 and 23 .
USING THE REFLECTOR . Many photographers overlook the use of reflectors or reflecting surfaces to improve their pictures . Reflectors are inexpensive , easy to use , and easy to carry with you . They fill in shadows with a soft diffused light which is both natural and pleasing .
Almost any white surface of suitable size may be used as a reflector . A sheet , a newspaper , a piece of white cardboard , even a white shirt or a couple of handkerchiefs will suffice in an emergency . For outdoor use , you can make a very good portable reflector out of two sheets of cardboard or hardboard about 10x12 inches in size , and two sheets of aluminum foil about two inches larger each way than the cardboard . First crumple the aluminum foil and smooth it out again to break up the smooth surface . This crumpling procedure is necessary because a large mirror - like reflector will throw a sharply outlined beam which may be strong enough to cast its own shadow and produce a bad , double lighting effect .
Figure 23 This is primarily an informal portrait of the two boys with their dog so their faces must be proper ly lighted The fill - in was strong enough to give very . good illumination of the faces , but not too strong , so that the sunlight serves as a very good accent light for their heads as well as lighting the background . Actually flash was used for the fill - in light source .
Now cover one side of each cardboard with this aluminum foil . The extra length and width of the aluminum should be folded around the back , thus serving to hold it in place without adhesive . This will give you two small aluminum reflectors . Finally use adhesive or surgical tape to hinge them together so they can be folded , with the aluminum surfaces in , and you have a portable reflector .
The effective working distance of such a reflector is from 1 to 1½ times its diagonal . A 12x20 inch reflector can , therefore , be used from 20 to 36 inches from the subject . For small subjects and closer distances , fold the reflector to the 10x12 size . You will find this type of reflector particularly valuable for such subjects as close - ups of flowers and outdoor portraits . To cover larger areas , increase the size of the reflector correspondingly .
USING FLASH FOR FILL - IN . Quite often the simplest way for filling in empty shadows is by using auxiliary flash . The subject of flash photography is covered in detail in a later Assignment so we will touch on it only briefly here . Basically , the
idea is to give just enough flash exposure to bring the shadows up to the desired level . This requires a careful calculation of the exact flash exposure since you are working at the low exposure end of the exposure curve , and latitude is at a minimum there . If you don't use enough flash exposure , the shadows will still be empty - if you use too much , they will become as bright as the main areas and the lighting balance will be completely destroyed .
There are a number of ways to calculate the correct flash exposure , but perhaps the easiest is to determine the normally correct exposure and then simply cut it in half by draping a clean white handkerchief over the flash lamp . A double thickness of handkerchief , or two handkerchiefs , will reduce the strength of the flash to one - fourth its full brilliance .
GETTING OUT OF THE BRIGHT SUN . The fact that the sun is the main source of illumination does not necessarily mean that you must be in direct sunlight . Quite the contrary . It is often desirable to get out of the sun where the lighting contrast is much more manageable . You can often do this in making outdoor portraits or model shots . Look for a suitable location in the light shade just out of direct reach of the sun . If you are outdoors in open country , in a park or other recreational area , look for some large trees to furnish the shade . In the city , the shady side of a building may serve quite nicely . In any event , stay away from the deep shade because the light is almost certain to be too soft and lifeless . Instead , try to find a spot where the light is still quite directional so that you get soft 45 ° . 45 ° lighting or a reasonable approximation thereto , and proceed with your picture taking .
With black - and - white film , that is about all there is to it , but in color film you have a more complicated situation . The light in the shade is not direct sunlight , but reaches the subject because it is reflected from its surroundings . Its color value is , therefore , determined to a considerable degree by its surroundings . For example , if the subject is placed on green grass under the shade of some green trees , the light will be noticeably green , and flesh tones will be rather unnatural and certainly unpleasant . Even this trap for the unwary is avoided by placing the subject in neutral gray or white surroundings , the flesh tones may still be tinged with blue for the very simple reason that the light may be reaching the subject from a blue sky and such light is not white - it is blue .
Daylight color film is balanced for an average mixture of direct sunlight which is slightly yellowish and overhead sky which is bluish . If you omit the yellow of the sun and shoot under the blue illumination of the sky , your subject may have a noticeable bluish tinge . Fortunately , this situation can be corrected through the use of the proper color correction filters .
We will not pursue this further this Assignment since the subjects of color photography as well as color filters are covered in a later Assignment where they will receive the thorough treatment they deserve . However , while we are on the subject of color photography , we may as well go on to the next means of controlling lighting contrast , since it deals primarily with color film .
مبادئ الإضاءة ..
التحكم في جودة الإضاءة الخارجية
CONTROLLING THE QUALITY OF OUTDOOR ILLUMINATION
Outdoor illumination is extremely variable , not only as to strength but as to direction , contrast and quality . The photographer who works in daylight must know how to control it to meet his requirements . The type lighting which may be extremely effective for black - and - white film may be completely wrong for color film , and vice versa . The type of lighting which may be ideal for an architectural subject may be all wrong for a group photograph . Perfect outdoor lighting for showing a steel worker may be impossibly bad for a fashion model . the commercial photographer who is sent out on a specific assignment has to produce a good picture regardless of any other consideration . It is not often that he can postpone his picture taking until the light is just right . He must know how to control his light so that he can get good results regardless .
Figure 21 Same scene as Figure 20 but given a highly dramatic impact by printing for a silhouette effect .
There are quite a number of ways in which daylight illumination can be controlled . Usually the problem is one of contrast . The light is either too . contrasty or not contrasty enough . Because of this , we will discuss contrast control first .
CONTROLLING LIGHT FOR CONTRAST . Direct sunlight is often too contrasty , particularly when it comes to the photography of people . Changing the direction of light will exercise some control . For example , if the subject is faced into the light so that you have front lighting with a relatively low sun , the shadows on the face may be small enough so as not to cause trouble . Then by tilting the head right , left , up or down , the shadows may be placed where they will do the least amount of harm . The exposure can then be carefully adjusted to produce the best modeling . Usually this means keeping the exposure on the low side , since overexposure will block up the highlights and destroy modeling .
Figure 22 The silhouetted skaters and their long shadows provide the main interest here , so the only fill - in light is that which is reflected from the ice on which the figures are skating . Courtesy of Swiss National Tourist Office .
With some types of subjects , shifting the subject or the camera angle . radically so as to produce backlighting will provide a satisfactory answer . The subject , being mainly in shadow , will therefore have very low contrast even though the sun is shining brightly . With this type of lighting , however , it is important to note two things : 1. The brightly highlighted areas which are reached by the sun must be small and relatively unimportant . Otherwise , they will appear to be the main subject material and the whole purpose of the picture will be lost . 2. Enough light must reach the key subject area so that it will have sufficient contrast to make a satisfactory picture . This secondary light may be reflections from a light foreground , such as the sand in a beach scene , from a sidewalk on a city street , or from neighboring white buildings . If nothing else is available and the subject does not cover too large an area , newspapers spread on the ground just out of the camera view may throw enough light into the shadows to provide the necessary detail . See Figures 22 and 23 .
USING THE REFLECTOR . Many photographers overlook the use of reflectors or reflecting surfaces to improve their pictures . Reflectors are inexpensive , easy to use , and easy to carry with you . They fill in shadows with a soft diffused light which is both natural and pleasing .
Almost any white surface of suitable size may be used as a reflector . A sheet , a newspaper , a piece of white cardboard , even a white shirt or a couple of handkerchiefs will suffice in an emergency . For outdoor use , you can make a very good portable reflector out of two sheets of cardboard or hardboard about 10x12 inches in size , and two sheets of aluminum foil about two inches larger each way than the cardboard . First crumple the aluminum foil and smooth it out again to break up the smooth surface . This crumpling procedure is necessary because a large mirror - like reflector will throw a sharply outlined beam which may be strong enough to cast its own shadow and produce a bad , double lighting effect .
Figure 23 This is primarily an informal portrait of the two boys with their dog so their faces must be proper ly lighted The fill - in was strong enough to give very . good illumination of the faces , but not too strong , so that the sunlight serves as a very good accent light for their heads as well as lighting the background . Actually flash was used for the fill - in light source .
Now cover one side of each cardboard with this aluminum foil . The extra length and width of the aluminum should be folded around the back , thus serving to hold it in place without adhesive . This will give you two small aluminum reflectors . Finally use adhesive or surgical tape to hinge them together so they can be folded , with the aluminum surfaces in , and you have a portable reflector .
The effective working distance of such a reflector is from 1 to 1½ times its diagonal . A 12x20 inch reflector can , therefore , be used from 20 to 36 inches from the subject . For small subjects and closer distances , fold the reflector to the 10x12 size . You will find this type of reflector particularly valuable for such subjects as close - ups of flowers and outdoor portraits . To cover larger areas , increase the size of the reflector correspondingly .
USING FLASH FOR FILL - IN . Quite often the simplest way for filling in empty shadows is by using auxiliary flash . The subject of flash photography is covered in detail in a later Assignment so we will touch on it only briefly here . Basically , the
idea is to give just enough flash exposure to bring the shadows up to the desired level . This requires a careful calculation of the exact flash exposure since you are working at the low exposure end of the exposure curve , and latitude is at a minimum there . If you don't use enough flash exposure , the shadows will still be empty - if you use too much , they will become as bright as the main areas and the lighting balance will be completely destroyed .
There are a number of ways to calculate the correct flash exposure , but perhaps the easiest is to determine the normally correct exposure and then simply cut it in half by draping a clean white handkerchief over the flash lamp . A double thickness of handkerchief , or two handkerchiefs , will reduce the strength of the flash to one - fourth its full brilliance .
GETTING OUT OF THE BRIGHT SUN . The fact that the sun is the main source of illumination does not necessarily mean that you must be in direct sunlight . Quite the contrary . It is often desirable to get out of the sun where the lighting contrast is much more manageable . You can often do this in making outdoor portraits or model shots . Look for a suitable location in the light shade just out of direct reach of the sun . If you are outdoors in open country , in a park or other recreational area , look for some large trees to furnish the shade . In the city , the shady side of a building may serve quite nicely . In any event , stay away from the deep shade because the light is almost certain to be too soft and lifeless . Instead , try to find a spot where the light is still quite directional so that you get soft 45 ° . 45 ° lighting or a reasonable approximation thereto , and proceed with your picture taking .
With black - and - white film , that is about all there is to it , but in color film you have a more complicated situation . The light in the shade is not direct sunlight , but reaches the subject because it is reflected from its surroundings . Its color value is , therefore , determined to a considerable degree by its surroundings . For example , if the subject is placed on green grass under the shade of some green trees , the light will be noticeably green , and flesh tones will be rather unnatural and certainly unpleasant . Even this trap for the unwary is avoided by placing the subject in neutral gray or white surroundings , the flesh tones may still be tinged with blue for the very simple reason that the light may be reaching the subject from a blue sky and such light is not white - it is blue .
Daylight color film is balanced for an average mixture of direct sunlight which is slightly yellowish and overhead sky which is bluish . If you omit the yellow of the sun and shoot under the blue illumination of the sky , your subject may have a noticeable bluish tinge . Fortunately , this situation can be corrected through the use of the proper color correction filters .
We will not pursue this further this Assignment since the subjects of color photography as well as color filters are covered in a later Assignment where they will receive the thorough treatment they deserve . However , while we are on the subject of color photography , we may as well go on to the next means of controlling lighting contrast , since it deals primarily with color film .
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