Photography made-easy


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Photography made-easy

  2. 2. PHOTOGRAPHY MADE EASY CONTENTSIntroductionHow a camera works Controlling the light Providing additional light Automatic controlsTypes of camerasPhotographyThe photographic process Capturing light rays Focusing the image Exposing the film Developing the filmTaking photographs Composition Light Color FocusingExposure Controlling exposure Setting the exposurePhotographic equipment Cameras Film Lighting equipment Artificial lighting devices FiltersDeveloping and printingInstant processingColor depends chiefly on lightHistory Early developments The beginnings of modern photography Technical improvements Artistic advances The photographic revolutionCareers Commercial photography Portraiture Photojournalism
  3. 3. IntroductionCamera is an instrument used for taking photographs or making motion pictures. Theword camera comes from a Latin term meaning dark chamber. A camera is a dark boxthat holds a light-sensitive device or material--usually film--at the back. Light reflectsoff the scene that is being photographed and enters the camera through a small hole ora lens at the front. The light exposes the film to make a picture.How a camera worksAll cameras--those that take photographs and those that make motion pictures--use thesame basic principles. Light reflects from the scene being photographed and strikes thelens of the camera. The light passes through the lens and forms an upside down imageon the film at the back of the camera. The image can be sharpened by adjusting thedistance between the lens and the film. Many cameras have a focusing mechanism bywhich the photographer moves the lens a short distance to sharpen the image.In addition, most cameras have a viewfinder, a sighting instrument that thephotographer looks through to frame the subject. Most cameras also have a filmadvance. With this device, the photographer winds the film through the camera to putunexposed film in position to take a picture. After each picture has been taken, the filmadvance moves the exposed film out of the way. The film advances automatically inmany cameras.Controlling the lightTo take good pictures, a camera must let the proper amount of light reach the film.Two devices control the light: (1) the shutter, a movable set of blades or curtains thatopen to let light into the camera, and (2) the diaphragm, an adjustable ring thatexpands or contracts the aperture, the opening through which light enters. The speedof the shutters opening and closing determines how long the film is exposed to light.The size of the aperture determines how much light reaches the film during that time.Many cameras have adjustable shutter speeds, ranging from 30 seconds to 1/12,000 of asecond. Many cameras also have an adjustable aperture. The various sizes of anaperture are often called f-stops.The settings for shutter speed and aperture are interrelated. Suppose you wanted to"freeze" a fast-moving object. You would need a fast shutter speed--in other words, ashort exposure time. To let in enough light during this brief time, you would need alarge aperture.Now, suppose you wanted to photograph a sweeping landscape. To bring into sharpfocus all parts of the landscape that were at various distances from the camera, you
  4. 4. would need a small aperture. To let in enough light through this narrow opening forproper exposure, you would need a slow shutter speed.Providing additional lightMany cameras have a built-in or attachable electronic flash unit that provides anyadditional light needed to take a picture. The flash unit provides a short burst of lightsynchronized with the opening of the shutter.Automatic controlsMany cameras also have built-in devices that perform various parts of the picture-taking process automatically. A tiny built-in computer called a central processing unit(CPU) or microprocessor determines the correct settings for picture taking. Sensorsinside the camera tell the CPU what speed of film is in the camera and how bright thelight is. The CPU processes this information and either adjusts the camera settingsitself or displays the information so that the photographer can set the camera by hand.The two chief automatic features are (1) automatic exposure control and (2) automaticfocusing.Automatic exposure control, also called auto exposure, helps ensure proper exposure ofthe film. A feature called aperture-priority automation enables the photographer to setthe f-stop, while the camera chooses the shutter speed. Shutter-priority automationdoes the opposite. It lets the photographer set the shutter speed while the cameraselects the aperture for proper exposure. Many cameras offer programmed exposure,in which the camera chooses both the shutter speed and the f-stop.All automatic exposure systems rely on readings from a built-in light meter. Thecameras CPU interprets these readings according to a metering pattern, a set ofinstructions that tells the CPU how to react to different amounts of brightness inspecific parts of the scene. Some cameras offer a choice of metering patterns. Using thereadings and a metering pattern, exposure systems can compensate for muchunevenness in lighting, such as a scene with a bright background behind a dark subject.Automatic focusing, also called auto focus, adjusts the lens focus automatically toprovide sharp photographs. There are two chief types of automatic focusing systems:(1) active and (2) passive.An active system bounces an infrared (heat) ray or an ultrasound wave off the subject--that is, whatever object is within brackets or a box in the viewfinder. Sensors measurethe angle at which the infrared beam returns to the camera or how long it takes theultrasound wave to return. The system uses the measurement to determine how faraway the subject is and where the lens should focus.
  5. 5. A passive auto focus system analyzes the sharpness of the image entering the lens. Inmost systems, sensors behind the lens measure the contrast of lines or edges in thesubject. This contrast is highest when the camera is sharply focused on the subject.The system adjusts the focus to achieve the maximum contrast.Some auto focus systems can sense if a subject is moving. These systems makeadjustments so that the subject is in focus during the instant the shutter is open.Types of camerasFixed-focus cameras, the most basic of all cameras, have a nonadjustable lens. Mostmodels have a single aperture setting and only one or two shutter speeds. Most fixed-focus cameras, including many inexpensive, pocket-sized models, use 110-size, 126-size,or 35-millimeter film.In general, a fixed-focus camera can take satisfactory photographs in ordinary daylightbut not in dim light, because its aperture does not admit much light. The camera mayproduce a blurred picture if the subject is moving or is less than 6 feet (1.8 meters)away. Many fixed-focus cameras can take flash pictures.Disposable or recyclable cameras are a kind of fixed-focus camera that combines aplastic lens, a shutter, and film in one small box. The entire camera is brought to thephoto lab when the roll of film has been exposed.Single-lens reflex cameras appeal to skilled amateur photographers and to professionalphotographers. The cameras name refers to its viewing system. The photographerviews the subject through the camera lens rather than through a separate viewing lens.A mirror between the lens and the film reflects the image to the viewfinder. When theshutter release button is pressed to take a picture, the mirror lifts out of the way toallow the light to expose the film. Thus, the photographer sees almost the exact imagethat is recorded on the film. Most single-lens reflex cameras use 35-millimeter film.The photographer can adjust the focus, select the shutter speed, and control theopening of the diaphragm. Many new models can also adjust the focus and control thelight exposure automatically.The standard lens of the single-lens reflex camera can be replaced by special-purposelenses that change the size and depth relationship of objects in a scene. These lensesinclude wide-angle lenses, telephoto lenses, and zoom lenses. A wide-angle lens providesa wider view of a scene than a standard lens does. A telephoto lens makes objectsappear closer. A zoom lens combines features of standard, wide-angle, and telephotolenses.Twin-lens reflex cameras have a viewing lens directly above the picture-taking lens.The image in the viewfinder appears on a flat screen built into the top of the camera.Photographers find such a screen helpful in composing a picture. Photographers do nothold the viewfinder to the eye, as they do with a fixed-focus, point-and-shoot, or single-lens reflex camera. They usually hold it at the chest or waist and look down into the
  6. 6. viewfinder. The image appears reversed from left to right. Most such cameras use filmthat produces negatives measuring 21/4 by 21/4 inches (5.7 by 5.7 centimeters).Point-and-shoot cameras have many automatic features that make them easy to use.Electronic devices inside the cameras automatically adjust the focus, set the lightexposure and the shutter speed, and advance and rewind the film. A built-in electronicflash automatically supplies light when too little light reflects off the subject. Point-and-shoot cameras use 35-millimeter film. These cameras are popular among amateurphotographers. Some of them have a zoom lens.View cameras are the largest and most adjustable type of camera. Most have anaccordion like body, with a replaceable lens in front. They have a large viewing screeninstead of a viewfinder. Most models have an adjustable diaphragm and shutter speed.View cameras must be mounted on a stand for efficient operation.A photographer focuses a view camera by moving the lens end or the back end of thecamera forward or backward to produce a sharp image on the viewing screen.Adjustments in the tilt of the camera give the photographer great control over theimage. A view camera can provide artistic distortions of a subject more effectively thanany other kind of camera.Many professional photographers use a view camera for portraits and other subjects.A view camera uses sheets of film that range from 21/4 by 31/4 inches (57 by 83millimeters) to 11 by 14 inches (279 by 356 millimeters).Instant cameras use film that provides a print without first being developed into anegative. The cameras produce a print 15 seconds to 2 minutes after the photographertakes a picture. The time varies according to the camera and the type of film. Instantcameras use film that provides pictures ranging in size from 27/8 by 35/8 inches (73 by92 millimeters) to 20 by 24 inches (508 by 610 millimeters). Special types of film forinstant cameras also provide negatives. Some instant cameras can take flash picturesand focus automatically.Electronic cameras, including digital cameras, create pictures that can be viewed on atelevision screen or transferred to a computer. The lens in most electronic camerasfocuses light on a light-sensitive mechanism called a charge-coupled device, or CCD.The CCD changes the light into electronic signals. The electronic pictures can then bestored on floppy disks used in computers, on electronic storage devices called memorycards, or on a hard disk. With additional equipment, electronic images can also be sentover telephone lines or printed on paper.Motion-picture cameras take pictures that re-create the motion of a subject when theyare viewed. Professional moviemakers generally use large cameras that take 70-, 35-, or16-millimeter film. Most amateurs record on 8-millimeter film that is called super-8.Today, many amateur moviemakers use portable video cameras called camcorders.These cameras convert light reflected by the subject into electronic signals that are
  7. 7. recorded on magnetic tape. Most movie cameras and camcorders can record sound atthe same time as they record images. Most of them also have a zoom lens.Stereo cameras produce images that seem to have depth. One kind of stereo camerahas two identical picture-taking lens systems with matched shutters. This camera takestwo pictures of the same subject at the same time--one picture through each lenssystem--but from slightly different angles. When viewed through special glasses or adevice called a stereoscope the two pictures blend into one image that seems to havedepth.PhotographyPhotography is the process of making pictures by means of the action of light. Lightreflected from an object forms a picture on a material sensitive to light. This picture isthen chemically processed into a photograph. The word photography comes fromGreek words meaning to write or draw with light. A photograph is basically a picturedrawn with rays of light.Nearly all photographs are made with cameras. A camera works in much the same wayas the human eye. Like the eye, a camera takes in rays of light that are reflected froman object and focuses the rays into an image. But the camera records the image on film.As a result, the image not only can be made permanent but also can be seen by anunlimited number of people.Photography enriches our lives in many ways. From photographs, we can learn aboutpeople in other parts of the world. Photographs show us scenes from such historicevents as the American Civil War and the first landing on the moon by human beings.Photos also remind us of special people and important events in our own lives. Millionsof people throughout the world take pictures of their family, friends, vacations, andcelebrations.In addition to recording things and people we can see, photographs capture manyimages outside our range of vision. Cameras can travel where human beings cannot go--beyond the moon, to the bottom of the ocean, and inside the human body.Photographs taken through telescopes reveal distant objects that are too faint for thehuman eye to see. By using a camera in combination with a powerful microscope andhighly concentrated light, physicists photograph collisions of subatomic particles.Pictures made on film sensitive to heat radiation help physicians detect certain forms ofcancer and other diseases.Cameras can also "see" events in a way that the eye cannot. High-speed camerasrecord action that occurs so rapidly we see it only as a blur. Through this type ofphotography, scientists examine moving parts of machinery and study hummingbirdsin flight. Other kinds of cameras "speed up" processes, such as the growth of a plant orthe opening of a cocoon, that take place too slowly to observe.
  8. 8. Scientific research is only one of the many fields in which photography plays animportant role. In advertising, photographs are the most widely used means ofpublicizing products and services. Photography is such an essential part of newsreporting that photojournalism has become a specialized field. Mug shots and picturestaken with hidden cameras help the police track down criminals. Military leaders useaerial photographs to learn about enemy troop movements and plan battle strategy.Anthropologists and sociologists study photos of various groups of people for clues topatterns of human behavior.Some photographs, like great paintings, have lasting value as works of art. Suchpictures, through the photographers imagination and technical skill, are exceptionallybeautiful or express significant ideas.A crude type of camera was developed by about 1500. However, the first truephotograph was not made until 1826. Early photographers needed much equipmentand a knowledge of chemistry. Gradually, as a result of the scientific and technicaldiscoveries of the 1800s and 1900s, cameras became more efficient and easier tooperate. Today, a person can take a picture simply by aiming the camera and pressinga button. An instant camera can produce a photo in about 15 seconds.Photography can be divided into two general areas--still photography and motionpictures.The photographic processThe process of making a photograph begins and ends with light. Rays of light enter acamera and are focused into an image. The light exposes the film in the camera,causing chemical changes on the films surface. The exposed film is then treated withcertain chemicals in a procedure called developing. Finally, light is used to make aprint by transferring the image from the film to a sheet of special paper.There are five principal steps in the photographic process: (1) capturing light rays, (2)focusing the image, (3) exposing the film, (4) developing the film, and (5) making aprint. This section describes the process of making a black-and-white photograph. Theprocedures used for making color photographs and instant prints are discussed in theDeveloping and printing section.Capturing light raysA camera is basically a box with a small aperture (opening) at one end and film at theother end. The inside of a camera must be completely dark so that rays of light reachthe film only through the aperture. A device called a shutter opens when the camera isbeing used to take a picture. The shutter remains closed at all other times in order tokeep light away from the film.
  9. 9. In nearly all cameras, the aperture is part of a lens system. The lens systemconcentrates incoming rays of light on the film. In this way, the lens gathers enoughlight to expose the film in only a fraction of a second. Without a lens, the exposuremight have to last as long as several minutes.When the shutter opens, light from an object passes through the aperture and forms animage of the object on the film. Rays of light from the top of the object go through theaperture and strike the lower part of the film. Light rays from the bottom of the objectform the upper part of the image. Thus, the image on the film is upside down.Focusing the imageIn addition to concentrating the incoming rays of light, the camera lens serves to focusthem on the film. As the light rays pass through the aperture into the camera, the lensbends them so that they form a sharp image. The sharpness of the image depends onthe distance between the object and the lens, and between the lens and the film. Manycameras have a focusing mechanism that moves the lens forward and backward. Inother cameras, the lens is fixed. Such cameras automatically focus on objects at acertain distance from the lens.Exposing the filmBlack-and-white film is a thin sheet of paper or plastic with a coating called anemulsion. The emulsion consists of tiny grains of silver salts held together by gelatin, ajellylike substance. Silver salts are highly sensitive to light and undergo chemicalchanges when exposed to it. The degree of change in the salts depends on the amount oflight that reaches them. A large amount of light causes a greater change than does asmall amount.The light that reaches the film varies in intensity. Light-colored objects reflect muchlight, and dark colors reflect little or no light. Therefore, the silver salts on the filmreact differently to different colors. Light from a white or yellow object changes thesalts greatly. Light from a gray or tan object changes them only slightly. Black objectsdo not reflect any light and thus have no effect on the salts. The chemical changes inthe silver salts produce a latent image on the film. This image cannot be seen, but itcontains all the details that will appear in the photograph.Developing the filmAfter the film has been exposed, it can be removed from the camera. However, it mustthen be kept away from light because further exposure would destroy the latent image.The film is taken to a darkroom or a photographic laboratory. There, it is treated withchemical developers that convert the silver salts on the emulsion into metallic silver.The image on the film then becomes visible.
  10. 10. During development, the silver salts that received much light form a thick deposit ofsilver and appear dark on the film. The salts that received little or no light form a thinmetallic layer or no layer at all. They appear light or clear on the film. Thus, the lightcolors and dark colors of the subjects photographed are reversed on the film. Forexample, a piece of coal would appear white on the film, and a snowball would lookblack. The developed film is called a negative. Before further processing, negatives aretreated with a chemical solution that makes the image on the film permanent.Making a print is similar to exposing and developing film. Like film, printing paper iscoated with a light-sensitive emulsion. Light passes through the negative and exposesthe paper, forming a latent image. After development and chemical treatment, theimage on the printing paper is visible and permanent.During exposure, the dark areas of the negative hold back much light. These darkareas show up as light areas on the print. The light and clear areas of the negative let alarge amount of light pass through to the printing paper. They appear as dark areas onthe print. Thus, the tones of the print reproduce those of the objects photographed.Taking photographsNearly anyone can take an ordinary photograph. All you need is a camera, film, light,and a subject. First, you look through the viewfinder of the camera to make sure thatall of the subject will appear in the picture. Next, you press the shutter release buttonto let light from the subject enter the camera and expose the film. Then you use thefilm advance, which moves the film forward through the camera to put unexposed filmin position for the next picture.To take a truly good photograph, you must follow certain principles of photography.You should try to "see" as the camera does--that is, be aware of the elements thatcompose a picture. You also should know the effects of different types of light on film.Many cameras have controls that adjust the focus of the image and the amount ofincoming light. In using such adjustable cameras, you need to know how the lens worksand how exposure can be controlled. These aspects of good photography can begrouped as (1) composition, (2) light, (3) focusing, and (4) exposure.CompositionComposition is the arrangement of elements in a photograph. These elements includeline, shape, space, and tone or color. Composition has no fixed rules because it isbasically a matter of individual taste. However, some guidelines for the use of thevarious elements of composition may help you create the kind of photograph desired.LineThere are two principal kinds of lines in photography, real lines and implied lines. Reallines are physically visible. For example, telephone poles and the edges of buildings
  11. 11. form real lines. Implied lines are created by nonphysical factors, such as a pointinggesture or a persons gaze.Both real lines and implied lines can be used to direct a viewers eye to various parts ofa picture. In most effective photographs, the lines draw attention to the main subject.The direction of these lines can also be used to reinforce the mood of a picture. Verticallines, such as those of a tower or a tall tree, may convey a sense of dignity and grandeur.Horizontal lines tend to suggest peace and stillness, and diagonal ones may emphasizeenergy and tension.Shape is the chief structural element in the composition of most photographs. Itenables the viewer to immediately recognize the objects in a picture. Shape also addsinterest to composition. The shape of such objects as rocks and seashells is interestingin itself. A combination of different shapes provides variety. For example, an outdoorscene can be made more interesting by contrasting the jagged shape of a fence with thesoft curves of hills and clouds.Space is the area between and surrounding the objects in a photograph. Space can beused to draw attention to the main subject and to isolate details in the picture.However, large amounts of space tend to detract from a pictures interest. A generalprinciple for the use of space is that it should not occupy more than a third of the photo.Tone or color adds depth to the composition of a photograph. Without this element, theshapes and spaces in a picture would appear flat. In black-and-white photography, thecolors of objects are translated into tones of black, gray, and white. These tones helpestablish the mood of a picture. If light tones dominate the photo, the mood may seemhappy and playful. A picture with many dark tones may convey a sense of sadness ormystery.Color, like tone, carries an emotional message. In a color photograph, such brightcolors as red and orange create an impression of action and energy. Blue, green, andother softer colors are more restful to the eye and may suggest a feeling of peace.According to many professional photographers, a color picture should have onedominant color and a balance between bright colors and softer shades.LightThere are two basic types of light in photography, natural light and artificial light.Natural light, which is also called available light or existing light, is normally present inoutdoor and indoor locations. Such light comes chiefly from the sun and electric lights.Artificial light is produced by various types of lighting equipment, such as flashbulbsand electronic flash devices. Lighting equipment is discussed in the Photographicequipment section.Natural light and artificial light have certain characteristics that greatly affect thequality of photographs. These characteristics include (1) intensity, (2) color, and (3)direction.
  12. 12. Intensity is the quantity or brightness of light. Photographers measure the intensity oflight to determine the lighting ratio of a scene. The lighting ratio is the difference inintensity between the areas that receive the most light and those that receive the least.On a sunny day or in a room with bright lights, the lighting ratio is likely to be high.On a cloudy day or in dim indoor light, the ratio is probably low.The lighting ratio affects the degree of contrast in a photograph. A high lighting ratiomay produce sharp images with strongly contrasting light and dark tones. A low ratiocreates softer images with a wide range of medium tones. Thus, a high lighting ratiocan increase the sense of drama and tension in a picture. A low ratio makes portraitsand still-life photographs look more natural.Most lighting ratios can be used with black-and-white film. In taking colorphotographs, however, a high lighting ratio may make some colors appear either faintor excessively dark.ColorThe color of light varies according to its source, though most of these variations areinvisible to the human eye. For example, ordinary light bulbs produce reddish light,and fluorescent light is basically blue-green. The color of sunlight changes during theday. It tends to be blue in the morning, white at about noon, and pink just beforesunset.Variations in the color of light make little difference in a black-and-white photograph.However, they produce a wide variety of effects in color pictures. To control theseeffects, you can use color filters on your camera, or you can use color film that isdesigned for different types of indoor and outdoor lighting. Such accessories arediscussed in the Photographic equipment section of this article.Direction refers to the direction from which light strikes a subject. Light may reach asubject from the front, the back, the side, or the top. Light may also strike a subjectfrom several directions at once. The direction of light greatly affects how the subjectlooks in the picture.Front lighting comes from a source near or behind the camera. This type of lightingshows surface details clearly. However, it should be avoided for pictures of peoplebecause the light makes them squint and casts harsh shadows under their features.Back lighting comes from a source behind the subject. Light from this direction casts ashadow across the front of the subject. To fill in the shadow, additional light from aflashbulb or electronic flash can be used. This technique is called flash fill-in. If theback lighting is extremely bright, the picture may show only the outline of the subject.Back lighting can be used in this way to create silhouettes.
  13. 13. Side lighting shines on one side of the subject. Shadows fall on the side opposite thesource of the light. Flash fill-in can be used to lighten these shadowed areas. Sidelighting does not show surface detail as clearly as front lighting does, but it creates astrong impression of depth and shape.Top lighting comes from a source directly above the subject. It is used most frequentlyin situations where other types of lighting would cause a glare or reflection in a picture.For example, top lighting may be used to photograph fish in an aquarium or objects ina display case or behind a window because the light will not be reflected by the glass.FocusingFocusing controls the sharpness of the image in a photograph. The degree of sharpnessis determined by (1) the distance between the camera lens and the subject and (2) thedistance between the lens and the film inside the camera. To form a sharp image of asubject that is close to the camera, the lens must be relatively far from the film. Forsubjects far from the camera, the lens must be close to the film.In nonadjustable cameras--that is, cameras without a control to adjust the focus--focusing depends on taking pictures at a certain distance from the subject. Most suchcameras are designed to focus on subjects more than 6 feet (1.8 meters) away. If thesubject is closer than 6 feet, the picture will be blurred.Adjustable cameras have a focusing mechanism that changes the distance between thelens and the film. Many of these cameras contain a built-in viewing screen thatprovides an image of the subject while the photographer focuses. Various devices onthe viewing screen indicate the proper focus. In some cameras, the viewing screenshows two identical images or one image split into two halves. To focus, thephotographer turns the focusing control until the double image becomes one sharpimage or until the two halves come together. In other cameras, tiny dots appear on thescreen until the image has been focused.ExposureExposure is the total amount of light that reaches the film in a camera. Exposureaffects the quality of a photograph more than any other factor. If too much light entersthe camera, the film will be overexposed, and the picture will be too bright. If there isinsufficient light, the film will be underexposed, resulting in a dark, uninterestingpicture.In nonadjustable cameras, the exposure is set automatically. Most adjustable camerashave controls that regulate the incoming light. To set the exposure, the photographeradjusts the settings on these controls.
  14. 14. Controlling exposureAdjustable cameras have two controls that regulate exposure. One of these controlschanges the speed of the shutter, and the other changes the size of the aperture.Shutter speed is the amount of time the shutter remains open to let light expose the film.A slow shutter speed lets in a large amount of light, and a fast shutter speed admits onlya little.Many adjustable cameras have a range of shutter speeds that vary from 30 seconds to1/8,000 of a second. These speeds are represented by whole numbers on the standardscale of shutter speeds. The number 500 on the scale stands for 1/500 of a second, 250means 1/250 of a second, and so on. Each number on the scale represents twice thespeed of the preceding number or half the speed of the next number. At a setting of250, for example, the shutter works twice as fast as at a setting of 125 and half as fast asat a setting of 500.Fast shutter speeds enable photographers to take sharp pictures of moving subjects.Any movement of the subject will be recorded as a blur while the shutter remains open.At a setting of 1/1,000 of a second or faster, the shutter is open for such a short timethat even the motion of a speeding race car appears to be "stopped." Most ordinarymovement can be stopped at shutter-speed settings of 1/60 or 1/125.Aperture size is changed by a device called a diaphragm, which consists of a circle ofoverlapping metal leaves. The diaphragm expands to make the aperture larger andcontracts to make it smaller. A large aperture admits more light than a small one.The various sizes of an aperture are called f-stops or f-numbers. On most adjustablecameras, the f-stops range from 1.4 or 1.8 to 22 or 32 and include 2, 2.8, 4, 5.6, 8, 11,and 16. The smaller the number, the larger the size of the aperture. Like the shutterspeeds, each f-stop lets in either twice as much light as the preceding setting or half asmuch light as the next higher setting. For example, if you open up the setting from f/11to f/8, the aperture admits twice as much light into the camera. If you stop down thesetting from f/11 to f/16, the aperture lets half as much light into the camera.Changes in the size of the aperture affect the overall sharpness of the picture. As theaperture becomes smaller, the area of sharpness in front of and behind the subjectbecomes larger. This area of sharpness is called depth of field. It extends from thenearest part of the subject area in focus to the farthest part in focus. A small aperture,such as f/11 or f/16, creates great depth of field. As you open up the aperture, the areain focus becomes shallower. At f/4 or f/2, the subject will be in focus, but objects in theforeground and background may be blurred.
  15. 15. Setting the exposureThe proper exposure for a picture depends chiefly on (1) the lighting, (2) the subject,and (3) the desired depth of field. Each of these factors may require an adjustment inshutter speed or aperture size. You must choose a combination of settings that willmeet all the requirements.The amount of light in a scene affects both shutter speed and aperture size. On acloudy day, you should reduce the shutter speed and increase the f-stop. On a sunnyday, you should use settings for a fast shutter and a small aperture. Certain types ofartificial lighting have special requirements for exposure.The type of subject to be photographed may require an adjustment in the shutter speed,and depth of field may determine the aperture size. If the subject is moving, you mustincrease the shutter speed to prevent blurring. If you want a large area of the picture tobe in sharp focus, you should choose a small aperture to provide greater depth of field.If you adjust either the shutter speed or the aperture size, you must also adjust theother. A fast shutter speed stops the action, but it also reduces the amount of lightreaching the film. To make up for this reduction in light, you should increase the f-stop. Similarly, a small aperture increases depth of field but reduces the amount ofincoming light. Therefore, you should change to a slower shutter speed.Suppose you want to photograph some squirrels on a sunny day. A suitable exposurefor this type of lighting might be a shutter speed of 1/60 and an aperture of f/11. If thesquirrels are moving, you might decide to increase the shutter speed to 1/125. Thisspeed is twice as fast as 1/60, and so half as much light will reach the film. You shouldmake the aperture twice as large by setting it at f/8. In the same way, if you change theshutter speed to 1/250--four times as fast--you should change the f-stop to f/5.6--fourtimes as large.You may want the photograph to include some acorns on the ground in front of thesquirrels, and also the trees in the background. You can increase depth of field byreducing the size of the aperture. At a setting of f/16, the film will receive half as muchlight as it did at f/11. You should also change the shutter to the next slowest speed, sothat the film will be exposed for twice as long.Photographic equipmentThere are four main types of photographic equipment. They are (1) cameras, (2) film,(3) lighting equipment, and (4) filters.CamerasNearly all cameras have the same basic design, which includes an aperture, a shutter, aviewfinder, and a film advance. However, cameras vary widely in such features as
  16. 16. adjustability and the type of film used. The simplest cameras, called fixed-focuscameras, have a nonadjustable lens and only one or two shutter speeds. The majorityof these cameras use cartridges of 110-sized film. Professional cameras, including viewcameras and studio cameras, have many adjustable parts. Most such cameras use largesheets of film.Cameras can be classified in several ways. One widely used classification is based onthe viewing system. The principal types of viewing systems are the (1) range finder, (2)single-lens reflex, and (3) twin-lens reflex.Range finder cameras have a viewing system that is separate from the lens. On most ofthese cameras, the viewfinder is a small window to the left of the lens. An angledmirror behind the lens reflects a second image of the subject into the viewfinder. Tofocus, a person looks through the viewfinder and adjusts the focusing mechanism untilthe two images come together.The focused image in the viewfinder differs from the image on the film. This differenceis called parallax error. To help correct for parallax error, the viewfinder on mostrange finder cameras has lines that frame the subject area "seen" by the lens.The majority of range finder cameras are lightweight and relatively inexpensive. Theyuse film that measures 35 millimeters (about 13/8 inches) wide.Single-lens reflex cameras enable a photographer to look at a subject directly throughthe lens. A mirror mechanism between the lens and the film reflects the image onto aviewing screen. When the shutter release button is pressed, the mirror rises out of theway so that the light exposes the film. Thus, the photographer sees the image almostexactly as it is recorded on the film, and parallax error is avoided.Most single-lens reflex cameras use 35-millimeter film and are heavier and moreexpensive than range finder models. These cameras have the advantage of a widevariety of interchangeable lenses. Their standard lens can be replaced by lenses thatchange the size and depth relationships of objects in a scene. Such lenses include wide-angle lenses, telephoto lenses, macro lenses, and zoom lenses.A wide-angle lens provides a wider view of a scene than a standard lens does. It is usedfor large scenes and in locations where the photographer cannot move back far enoughto photograph the entire scene. A telephoto lens makes objects appear larger andcloser. It enables photographers to take detailed pictures of distant subjects. A macrolens, which is used in extreme close-up photography, focuses on subjects from a shortdistance. A zoom lens combines many features of standard, wide-angle, and telephotolenses.Twin-lens reflex cameras have their viewing lens directly above the picture-taking lens.The image in the viewing lens is reflected onto a screen at the top of the camera. Aperson holds the camera at waist- or chest-level and looks down at the viewing screen.
  17. 17. A twin-lens reflex camera has several advantages. Its viewing screen is much largerand clearer than those of eye-level cameras. Most twin-lens reflex models use film thatproduces negatives measuring 21/4 by 21/4 inches (5.7 by 5.7 centimeters). However,these cameras are subject to parallax error and are heavier than the majority of single-lens reflex cameras. Also, most twin-lens reflex cameras do not have interchangeablelenses.FilmThere are three main kinds of photographic film, based on the type of picturesproduced. Black-and-white prints are made from black-and-white negative film, colorprints from color negative film, and color slides from color reversal film. Film of eachtype varies in a number of characteristics that affect the overall quality of photographs.The most important of these characteristics include (1) speed, (2) graininess, (3) colorsensitivity, and (4) color balance.Speed is the amount of time required for film to react to light. The speed of a filmdetermines how much exposure is needed to record an image of the subject. A fast filmreacts quickly to light and needs little exposure. This type of film is useful for scenesthat have dim light or involve fast action. A medium-speed film requires moderateexposure and is suitable for average conditions of light and movement. A slow filmneeds much exposure and should be used for stationary subjects in a brightly lightedscene.The principal systems of measuring film speed are the DIN system, used chiefly inWestern Europe, and the international ASA and ISO systems. ASA stands for theAmerican Standards Association, and ISO stands for the International StandardsOrganization. The higher the ASA or ISO number, the faster the film. Films that havenumbers of 200 or higher are generally considered fast. Medium-speed films havenumbers ranging from 80 to 125, and slow films are numbered lower than 80.Graininess is the speckled or hazy appearance of some photographs. It is caused byclumps of silver grains on the film. The degree of graininess depends on the speed ofthe film. A fast film is more sensitive to light than other films are because its emulsioncontains larger grains of silver salts. The fastest films produce the grainiest pictures.Medium-speed films and slow films produce little or no graininess in standard-sizedprints, though some graininess may appear in enlargements.Color sensitivity refers to a black-and-white films ability to record differences in color.On the basis of color sensitivity, black-and-white films are classified into several types,including panchromatic film and orthochromatic film. Panchromatic film, the mostwidely used type, is sensitive to all visible colors. Orthochromatic film records all colorsexcept red. It is used chiefly by commercial artists to copy designs that have few colors.Color balance applies only to color film. Such film is sensitive to all colors, includingthose of different kinds of light. The human eye sees light from most sources as white.
  18. 18. But color film records light from light bulbs as reddish, light from fluorescent bulbs asblue-green, and daylight as slightly blue. Variations in the emulsions of different typesof color film make the film less sensitive to certain colors. These variations balance thecolor of light recorded on the film so colors in the photograph appear natural. Mostcolor film is balanced either for daylight or for specific types of artificial light.Lighting equipmentLighting equipment can be divided into two basic categories according to function.Exposure meters, the first category, measure the light available for photography.Artificial lighting devices, the second category, provide any additional light needed totake a picture.Exposure meters, also called light meters, help determine the correct exposure.Exposure meters are held in the hand or are built into a camera. Handheld metersrecord the light in a scene and indicate the camera settings for the proper exposure.Built-in meters measure the light that strikes the lens of the camera. Light readingsappear on a scale on the viewing screen. Some cameras with exposure metersautomatically adjust the shutter speed and aperture size to the amount of lightavailable. Exposure meters are classified according to the way they measure light.They include (1) reflected light meters and (2) incident light meters. Many handheldinstruments can be used as both types of meters. Most built-in meters are reflectedlight meters.Reflected light meters measure the light reflected from a scene toward the camera.Various areas in the scene reflect different amounts of light. Most built-in meters showthe average amount of light reflected from all the areas. To measure reflected lightwith a handheld meter, the meter should be aimed at the main part of the scene. Ifthere are strong contrasts in light and shadow, separate readings of the brightest anddarkest areas should be taken and then averaged.Incident light meters measure the light falling on a subject. When measuring this kindof light, the photographer should stand near the subject and point the meter toward thespot where the photo will be taken.Artificial lighting devicesThe most widely used sources of artificial lighting are (1) flashbulbs and (2) electronicflash. Both flash systems provide a short burst of light. Many professionalphotographers use lighting devices called photoflood lamps, which can providecontinuous light for several hours.Most cameras have a built-in device called a flash synchronizer. A flash synchronizercoordinates the flash system with the shutter, so that the greatest brightness of the flashoccurs at the instant the shutter reaches its full opening. On many cameras, the flash
  19. 19. synchronizer works for flashbulbs at a shutter setting of M and for electronic flash at asetting of X.Flashbulbs are powered by batteries or are activated by a device on the camera. Aflashbulb contains fine wire filament that spans two metal prongs called the primer.The filament ignites and creates the flash when an electric current passes through theprimer. Each flashbulb supplies one burst of light. Flashbulbs vary widely in size andintensity. Most camera manuals specify the type to use.The most widely used flash bulb units are flashcubes and flash bars. A flashcubeconsists of four small flashbulbs set in the sides of a cube that plugs into a rotatingfixture on the top of certain cameras. After each flash, the cube rotates so that a freshbulb is pointed at the subject. A flash bar is a set of five or more flashbulbs that fitsonto the top of most instant cameras. In other flashbulb units, individual bulbs fit intoa firing device called a flash gun. A flash gun may be attached to the camera orconnected to it by means of a cable.In fixed-focus cameras, flash pictures will be correctly exposed if taken at a certaindistance from the subject. This distance is listed in the camera manual. In adjustablecameras, the flash exposure is controlled by changing the size of the aperture. Todetermine the proper f-stop, find the guide number in the instructions that come withthe flashbulbs. Then divide the guide number by the number of feet between theflashbulb and the subject. For example, if the guide number is 80 and the distance is 10feet, the correct f-stop would be f/8.Electronic flash units operate on batteries or on electricity from an outlet. They containan ionized (electrically charged) gas inside a sealed tube. The gas emits a burst ofbright light when an electric current is passed through it. Electronic flash units can firethousands of flashes. Each flash provides as much light as a flashbulb but lasts a muchshorter time. Electronic flash equipment ranges from small flash guns that fit onto thetop of a camera to large studio units. Some flash devices are small enough to be builtinto cameras. Electronic flash units are more expensive than most flash bulb units butcost less per flash.FiltersA photographic filter is a disk of colored, plastic like gelatin or colored glass in a holder.The holder fits over the lens of specific types of cameras. Filters screen out haze andglare or increase the contrast among tones in a picture. Nearly all filters hold backsome light from the film. Therefore, when using a filter on most cameras, you mustincrease the exposure by the filter factor listed in the instructions provided with thefilm.The most widely used filters include ultraviolet filters, polarizing filters, and colorfilters. An ultraviolet filter reduces haze. It is useful for photographing distant subjectsand for taking pictures at high altitudes. A polarizing filter screens out glare from
  20. 20. shiny surfaces, such as water and glass. A color filter increases contrast in black-and-white photographs. It lets light of its own color pass through the lens to the film butholds back certain other colors. As a result, objects that are the same color as the filterappear light in the picture, and the blocked colors are dark. Suppose you use a redfilter when taking a black-and-white photograph of an apple tree. The apples will looklight gray, and the leaves and the sky will be dark gray or black.Developing and printingAfter the picture has been taken, the latent image on the film cannot be seen. Theimage becomes visible through the process of developing the film into a negative. Thenegative shows the reverse of the subjects light and dark areas. During printing, theimage on the film is transferred onto paper, and the original colors or tones of thesubject are restored.Most amateur photographers have their film processed in commercial laboratories.However, an increasing number of photographers develop and print their own pictures.By processing the film themselves, they can change the size, composition, contrast, andother features of the photographs.Black-and-white film and color film are developed and printed in much the same way.However, the processing of color film requires a few extra steps and some additionalmaterials. Most types of film are removed from the camera and processed in adarkroom or a photographic laboratory. Instant film produces photographs directlyfrom the camera.Developing black-and-white film requires two or more chemical solutions, severalpieces of equipment, and running water. The chemical solutions should be stored inamber-colored bottles made of polyethylene plastic. Such bottles are highly resistant tochemicals and keep light from harming the solutions. Each bottle should be clearlylabeled with the name of its contents. Undeveloped film must not be exposed to light,and so a completely dark room or a light proof changing bag are also needed.The developing process has five basic steps. First, a chemical called a developerconverts the exposed silver salts on the films emulsion into metallic silver. The actionof the developer is then stopped either by water or by a chemical solution known as astop bath. In the third step, a chemical called a fixer, or hypo, dissolves the unexposedsilver salts so they can be washed away. The fixer also contains a special hardeningagent that makes the emulsion resistant to scratches. Next, the film is washed toremove the unexposed salts and the remaining chemicals. In the final step, the film isdried. The developed film is now a negative on which a visible, permanent image hasbeen recorded.If you wish to process film yourself, first darken the room or use a changing bag andremove the film from its spool. Then wind the film onto a reel that fits inside alightproof developing tank. This tank is designed so that liquids can be poured into or
  21. 21. out of it without removing the lid. After the film is in the developing tank, you canwork on it in the light.Different types of developers and fixers are used for various kinds of film. Theinstructions provided with the film specify the type of solutions to use and the correcttemperatures for the best results. Temperature is particularly important for thedeveloper. Negatives will be overdeveloped if the developer is too warm, orunderdeveloped if it is too cold. The instructions also tell you how long to treat the filmwith the various solutions. To ensure proper development, each operation should betimed exactly.After the developer has been heated or cooled to the correct temperature, pour thechemical into the developing tank. Then agitate the tank for 30 seconds by repeatedlyturning it upside down and back again in a steady movement. Agitation keeps a freshsupply of the developer in contact with the film so the image on the films surfacedevelops evenly. Next, rap the tank on a hard surface to dislodge any air bubbles. Airbubbles can leave spots on the film. While the developer is in the tank, the film shouldbe agitated at half-minute or one-minute intervals after the first 30 seconds.When the developer has been in the developing tank for the specified time, pour it outand fill the tank with either running water or a stop-bath solution. Agitate the tankvigorously for about 10 seconds, and then drain it and pour in the fixer. After thefixing bath, which may last from 2 to 10 minutes, rinse the film with water or a specialwashing agent. Such an agent reduces the washing time from about 20 minutes toabout 5 minutes. The film should then be treated with a wetting agent to remove anywater spots.To dry the film, unwind it from the reel in the developing tank and hang it in a dust-free area. A clip or a clothespin should be attached to the lower end of the film toprevent the film from curling. As soon as the film has dried completely, cut it intostrips of from four to six negatives. Store the strips of negatives in film envelopes in aclean, dry place. Negatives can easily be scratched or bent, and so you should handlethem by the edges.Printing black-and-white photographs is a process similar to making negatives.Printing paper is coated with an emulsion containing silver salts. During the printingprocess, light exposes the salts and forms a latent image on the printing paper. Thepaper must be developed before it can produce the visible image that will appear in thefinished print.To develop the printing paper, repeat the steps used in developing film. However, thepaper is generally placed in open printing trays rather than in a developing tank, anddifferent chemicals are used. To protect the latent image, you should work under asafelight. This kind of light illuminates the work area but does not expose the printingpaper.
  22. 22. There are two principal methods of printing black-and-white photographs, contactprinting and projection printing. Each process requires special equipment andproduces a different type of print.Contact printing is the simplest method. To make a contact print, place the strips ofnegatives on a sheet of printing paper and cover them with a piece of glass. Use aprinting frame, a printing box, or some similar device to hold the negatives and paperin place. Shine a light through the glass for a few seconds, and then remove the paperand develop it. If the print is too dark, repeat the process with a shorter exposure time.If the print is too light, use a longer exposure.Contact printing is a quick, inexpensive way to preview photographs before making thefinal prints. Contact prints are the same size as the negatives, and so you can print anentire roll of film in one operation. For example, a 36-exposure roll of 35-millimeterfilm can be contact printed on a sheet of paper that measures 8-by-10 inches (20-by-25centimeters).Projection printing, or enlarging, produces photographs that are larger than theirnegatives. In projection printing, the negative is placed in a device called an enlarger.The enlarger projects the negative image onto printing paper in much the same way asa slide projector throws an image onto a screen. The image on the printing paper islarger than that on the negative. The size of this projected image depends on thedistance between the negative and the paper. The greater the distance, the larger theimage.Enlargers have three basic parts, the head, the baseboard, and a rigid column thatsupports the head and is connected to the baseboard. The head contains a lens, acarrier for the negative, and a source of light. Like many cameras, the enlarger headalso has a focusing control and an adjustable aperture. An easel on the baseboardholds the printing paper. During the enlarging process, the lens focuses the negativeimage on the printing paper, and light from the light source passes through the negativeand exposes the paper.The head of an enlarger can be raised or lowered to change the size of the image on theprinting paper. This flexibility in size enables you to change the composition of thepicture as well as enlarge the size of prints. By making the image larger than theintended print, you can crop undesirable areas along the edges and reposition theelements of the picture.Before using an enlarger, you should clean the negative carefully with a camels-hairbrush or an aerosol device. Particles of dust on a negative may show up as white spotson the finished prints. Place the negative in the carrier, turn on the enlarger light, andfocus the image on a piece of plain white paper or cardboard in the easel. Next, adjustthe aperture. For most prints, you should at first set the aperture at a medium f-stop,such as f/8. After the image has been focused and framed, turn off the enlarger light
  23. 23. and the light in the work area, and turn on the safelight. Then insert a sheet of printingpaper into the easel.The next step in the enlarging process is to determine the proper exposure time for theprint by making test strips. Test strips are portions of a print that have been exposedfor different amounts of time, generally ranging from 10 seconds to 50 seconds. Afterthe test strips have been developed, you can decide which of the exposure timesproduced the best result. If all the test strips appear too light, open up the enlarger lensby two f-stops and make another set of strips. If the test strips are all too dark, closedown the lens by two f-stops and repeat the procedure.If only one area of the print turns out too light, you can darken the area by burning inthe print. In this technique, a piece of cardboard with a small hole in it is held over thearea to be darkened. Light passes through the hole in the cardboard and exposes thearea, which then becomes darker. If an area of the print is too dark, it can be lightenedby means of dodging. This procedure involves covering the dark area with a specialdodging tool or a cardboard disk during part of the exposure time. The covered areawill appear lighter in relation to the fully exposed parts of the print.Overall contrast in prints is determined largely by the type of printing paper used.Printing papers are graded by number from 0 to 6 according to the degree of contrastproduced in the prints. The higher the number, the greater the degree of contrast. Ahigh-contrast paper, such as No. 4, is generally used to print a normal range of tonesfrom a negative that has little contrast. Paper No. 1, a low-contrast paper, may be usedto reduce the contrast in a negative that has extreme light and dark tones.Some papers contain different grades of contrast. These multi contrast papers requiredifferent colors of light to produce each grade. You can change the color of theenlarger light by placing a colored printing filter over the lens.In addition to contrast, printing papers vary in several characteristics that affect theappearance of prints. One of these characteristics is tone. In a photograph printed onwarm-toned paper, the color black is reproduced as brown. On cold-toned paper, blackappears blue. Another feature of printing papers is surface, which ranges from matte(dull) to glossy.Developing color film involves the same basic procedures as black-and-whitedeveloping. However, the chemical processes in color developing are much morecomplicated. To understand these processes, you need to know some of the basicprinciples of color.Color depends chiefly on lightAlthough most light looks white to the eye, it is actually a mixture of three primarycolors--blue, green, and red. Any color can be produced by blending these three colorsof light.
  24. 24. Color film contains three layers of emulsions. These emulsions are similar to theemulsion on black-and-white film. But in color film, each of the emulsions is sensitiveto only one of the primary colors of light. During exposure, the first emulsion reactsonly to blue light, the second emulsion only to green light, and the third only to redlight.When color film is exposed, light strikes the first emulsion and forms an image on theblue areas of the scene. The light then passes through the second emulsion, forming animage of the green areas. Finally, the light goes through the third emulsion and recordsan image of the red areas. Three latent images are thus recorded on the film.The developing process changes color film in two main ways. First, the developerconverts the exposed silver salts on the emulsions into metallic silver. The silver imageproduced on each layer of emulsion represents the color of light--blue, green, or red--that exposed the emulsion.Second, the developer activates a substance called a coupler in each emulsion. Couplersunite with chemicals in the developer to produce colored dyes. The colors of the dyesare the complements (opposite colors) of the light that exposed the emulsions. Yellow isthe complement of blue, and so a yellow dye forms in the first layer. In the secondlayer, the dye is magenta (purplish-red) because magenta is the complement of green.The dye in the third layer is cyan (bluish-green), the complement of red.Complementary colors are used as dyes because they reproduce the original colors ofthe subject when the film is processed into photographs.Both color reversal film, which produces slides, and color negative film, which makesprints, record colored images in the same way. However, different materials andslightly different procedures are used to develop each type of film.Color reversal film requires two different developers. The first developer changes theexposed silver salts on the film into metallic silver. The film is then re-exposed ortreated with a chemical agent so that the remaining silver salts can be developed. Thesecond developer activates the couplers in the emulsions, causing colored dyes to formaround the silver image in each emulsion layer. After the silver has been bleached outof the images, the images remain as transparent areas on the film. The developed film,called a positive, can be cut into separate pictures and mounted as slides.On a slide, each area of the subject is transparent in one of the emulsion layers. In eachof the other two layers, the area has a complementary color different from that of itsoriginal color. For example, the image of a blue sky would be transparent in the firstemulsion layer. The image would be magenta (the complement of green) in the secondlayer and cyan (the complement of red) in the third layer. When light passes throughthe slide, each dye acts as a filter on a primary color. The magenta layer holds backgreen light, and the cyan layer holds back red light. As a result, only blue light passesthrough the transparent area of the slide, and the sky appears blue.
  25. 25. Color negative film is treated with only one developer. The developer converts theexposed silver salts into metallic silver and activates the dye couplers at the same time.After the developing procedure, each area of the subject appears on a layer of emulsionin a color complementary to the original color. For example, a blue object would berecorded as a yellow image on the first emulsion layer, and a green one would appear asa magenta image on the second layer. The colors of the images are reversed to theiroriginal shades during the printing process.Printing color photographs involves the same chemical processes as those in thedevelopment of color film. Like color film, color printing paper has three layers ofemulsions, each of which is sensitive to one of the primary colors of light. Duringprinting, the yellow, magenta, and cyan dyes on the negative hold back light of theircomplementary colors--that is, each dye filters out one of the primary colors. Thus, thecolors of light that expose the printing paper are the opposite of those that exposed thefilm. When the paper is developed, couplers in the emulsion layers form dyes thatreproduce the colors of the subject.Certain features of color prints can be changed by some of the same techniques used inblack-and-white printing--adjusting the exposure, cropping, burning in, and dodging.In addition, the color balance of the prints can be adjusted by placing color filters overthe enlarger lens. These filters, which are tinted in various shades of yellow, magenta,and cyan, reduce the intensity of the corresponding primary colors in the print. If theblue tones in the print are too strong, for example, you should put a yellow filter on theenlarger lens and repeat the printing procedure.Color prints can be made from color slides as well as from color negatives. The samebasic printing procedures are used in making slides and negatives. However, the effectsof exposure are reversed with slides, which contain positive images. In printing fromnegatives, for example, a longer exposure makes a print darker. But in printing fromslides, the same exposure time makes a print lighter. The effects of color filters are alsoreversed in making prints from slides. Strong colors in such prints are balanced byusing filters of the same colors rather than of complementary colors.Instant processingInstant film produces prints in from 15 seconds to 8 minutes, depending on the type offilm that is used. When the exposed film is taken out of an instant camera, it is coveredby a lightproof sheath. This sheath can be either a sheet of paper or an opaque(nontransparent) layer of chemicals. The sheath serves as a kind of darkroom for theprocessing of the film. If the film has a paper sheath, the sheet of paper is peeled fromthe print after the specified developing time. If the film has a chemical sheath, the printis finished when the opaque layer turns completely transparent.Instant prints are processed in much the same way as contact prints. The chiefdifference between the two procedures is that the negative and the positive of an instantprint are developed at the same time rather than in separate stages.
  26. 26. Instant black-and-white film contains layers of negative and positive emulsions, with apacket of jellylike developing chemicals between the layers. After exposure, the filmpasses through a pair of steel rollers in the camera. The pressure of the rollers causesthe packet to burst, releasing the developing chemicals. The chemicals immediatelyconvert the exposed silver salts on the negative layer into metallic silver. Within a fewseconds, the unexposed salts move to the positive layer. There, they are changed intosilver, forming a positive image on the print.Instant color film has layers of colored dyes in addition to negative and positiveemulsions and a packet of developing chemicals. When the chemicals are released, theydevelop the silver salts and activate the colored dyes at the same time. An image incolors complementary to those of the subject forms on the negative layer of emulsion.Then the image is transferred onto the positive emulsion layer, where the colors arereversed to the original ones.HistoryEarly developmentsThe ancient Greek philosopher Aristotle observed that light passing through a smallhole in the wall of a room formed an upside-down image of an object. However, thischaracteristic of light was not used to construct a camera until about A.D. 1500, inItaly. The first crude camera, called a camera obscura (dark chamber), consisted of ahuge box with a tiny opening in one side that admitted light. On the opposite side of thebox, the light formed an inverted image of the scene outside. The camera obscura waslarge enough for a person to enter, and it was used chiefly by artists as a sketching aid.They traced the outline of the image formed inside the box and then colored the picture.A camera obscura could only project images onto a screen or a piece of paper.Scientists sought a way to make the images permanent. In 1727, a German physicistnamed Johann H. Schulze discovered that silver salts turn dark when exposed to light.About 50 years later, Carl Scheele, a Swedish chemist, showed that the changes causedin the salts by light could be made permanent by chemical treatment. However, thesediscoveries were not used for photography until the 1830s.Meanwhile, a French inventor named Joseph Nicephore Niepce found a way to producea permanent image in a camera obscura. In 1826, he coated a metal plate with a light-sensitive chemical and then exposed the plate in the camera for about eight hours. Theresulting picture, showing the view from Niepces window, was the worlds firstphotograph.Niepces technique was perfected during the 1830s by the French inventor LouisDaguerre. Daguerre exposed a sheet of silver-coated copper, developed the image withmercury vapor, and then "fixed" it with table salt. His pictures, called daguerreotypes,
  27. 27. required a relatively short exposure of 15 to 30 seconds and produced sharp, detailedimages.In 1839, the same year Daguerre patented his process, a British inventor namedWilliam H. Fox Talbot announced his invention of light-sensitive paper. This paperproduced a negative from which positive prints could be made. Fox Talbots friend, theastronomer Sir John Herschel, called the invention photography. Herschel suggestedthe use of sodium thiosulfate (hypo) as a fixing agent. Both Daguerre and Fox Talbotthen began using this chemical in their processes.Fox Talbots paper prints, which were called talbotypes or calotypes, did not containimages as sharp as those of daguerreotypes. But the negative-to-positive process ofmaking photographs had two important advantages. It produced many prints from oneexposure, and the pictures could be included in books, newspapers, and other printedmaterials.In addition to the new developing and printing processes, photography was greatlyimproved during the 1840s by the introduction of specialized lenses. A Hungarianmathematician named Josef M. Petzval designed two types of lenses, one for makingportraits and the other for landscape pictures. The portrait lens admitted much morelight than previous lenses had and so reduced the exposure time to a few minutes. Thelandscape lens produced sharper pictures of large areas than previously had beenpossible.The beginnings of modern photographyDuring the second half of the 1800s, scientists further improved photographicprocesses and the design of cameras. These advances enabled photographers toexperiment with the artistic possibilities of photography.Technical improvementsIn 1851, a British photographer named Frederick S. Archer introduced a photographicprocess that greatly reduced exposure time and improved the quality of prints. InArchers process, a glass plate was coated with a mixture of silver salts and an emulsionmade of a wet, sticky substance called collodion. After being exposed for a few seconds,the plate was developed into a negative and then treated with a fixing agent. Thecollodion had to remain moist during exposure and developing, and so a photographerhad to process pictures immediately after taking them. Many photographers traveledin wagons that served as a darkroom and a developing laboratory.The invention of the dry-plate process overcame the inconvenience of the collodionmethod. In 1871, Richard L. Maddox, a British physician, used an emulsion of gelatinto coat photographic plates. Unlike collodion, gelatin dried on a plate without harmingthe silver salts. By using dry plates, photographers did not have to process a pictureimmediately.
  28. 28. The use of gelatin also eliminated the necessity of keeping a camera motionless on atripod during exposure. By the late 1870s, improvements in the gelatin emulsion hadreduced exposure time to 1/25 of a second or even less. Photographers could now takepictures while holding the camera in their hands.In addition to giving photographers greater mobility and freedom, the introduction ofthe gelatin emulsion revolutionized the design of cameras. Earlier types of printingpaper could only be contact printed, and, therefore, negatives had to be as large as theintended print. But photos on paper coated with gelatin could be made by projectionprinting. Photographers could enlarge such pictures during the printing process, andso the size of negatives could be reduced. Smaller negatives meant smaller cameras.In 1888, George Eastman, an American dry-plate manufacturer, introduced the Kodakbox camera. The Kodak was the first camera designed specifically for mass productionand amateur use. It was lightweight, inexpensive, and easy to operate.The Kodak system also eliminated the need for photographers to process their ownpictures. The Kodak used a roll of gelatin-coated film that could record 100 roundphotographs. After a roll had been used, a person sent the camera with the film insideto one of Eastmans processing plants. The plant developed the film, made prints, andthen returned the camera loaded with a new roll of film. The Kodak slogan declared:"You Press the Button, We Do the Rest."Artistic advancesDuring the 1850s and 1860s, many people began to experiment with the artisticpossibilities of photography. One of the first to use a camera creatively was GaspardFelix Tournachon, a French photographer who called himself Nadar. Nadar added anew element to portrait photography by emphasizing the pose and gesturescharacteristic of his subjects. However, his most famous achievement was the firstaerial photograph, a view of Paris taken from a balloon.Another pioneer in portrait photography was the British photographer Julia M.Cameron. She emphasized expressiveness over technical quality, and so many of herpictures were blurred or out of focus. But Cameron captured the personalities of hersubjects, who included such famous persons as Sir John Herschel and the Britishnaturalist Charles Darwin.Landscapes and architecture were also popular subjects for early art photographers.During the 1850s and 1860s, a number of governments commissioned photographersto make visual records of important buildings and natural features in various countries.Photographs were taken of historical sites in Europe and the Middle East, the sceneryof the American West, and many other major landmarks. Some of these pictures wereremarkable not only for their technical excellence but also for the effort involved intaking them. In 1861, for example, two French photographers named Auguste andLouis Bisson withstood intense cold and avalanches to take pictures from the top of
  29. 29. Mont Blanc in France. The brothers needed so much equipment that they took 25porters up the mountain with them.Some of the most dramatic photographs of the mid-1800s are battlefield scenes. Theearliest surviving pictures of this type were taken by Roger Fenton, a British journalistcovering the Crimean War (1853-1856). The photos of the American Civil War (1861-1865) made by Mathew Brady and his assistants rank among the finest war pictures ofall time.During the late 1800s, some photographers used their pictures to dramatize issues,rather than simply record events or create artistic effects. One such photographer wasWilliam H. Jackson, an American, who specialized in photographing the Far West.Jacksons photographs of the Yellowstone area helped persuade Congress to establishthe worlds first national park there.Two other American photographers, Jacob A. Riis and Lewis W. Hine, took picturesthat exposed social evils. In 1888, Riiss photographs of the slums of New York Cityshocked the public and helped bring about the abolition of one of the citys worstdistricts (see RIIS, JACOB A.). Hine, who was a sociologist, documented the miserableworking conditions of the poor. His pictures of children working in coal mines anddimly lighted factories helped bring about the passage of child-labor laws.The photographic revolution.By the late 1800s, the development of photography was moving in two directions. Theappearance of the Kodak camera and other inexpensive box cameras had led to atremendous rise in the number of amateur photographers. Previously, photographyhad been limited to people who knew how to use complicated photographic equipmentand could afford to buy this equipment. Now, almost anyone could take a picture.On the other hand, some photographers wanted photography to be considered acreative art in the tradition of drawing and painting. Many of these pictorialphotographers tried to make their prints look like paintings. They used special printingtechniques and paper to give their photographs a texture similar to that of paintedcanvases. Some photographers even colored the images with paint. In 1902, AlfredStieglitz, Edward Steichen, and a number of other American photographers formed agroup to promote photography as an independent art form. This group, which wascalled the Photo-Secession, organized photographic exhibitions in the United States andloaned collections of photos to exhibitors in many other countries.The idea that photographers should imitate painters was soon challenged. After about1910, many photographers believed that un-retouched photographs had a beauty andelegance unmatched by other works of art. Their ideal of "pure" photographyinfluenced such later photographers as Edward Weston and Paul Strand of the UnitedStates.
  30. 30. During the 1920s and early 1930s, photography underwent dramatic changes as theresult of two major developments. First, photographic equipment was revolutionizedby the miniature 35-millimeter camera and artificial lighting. The Leica camera,introduced in 1924 in Germany, was small enough to fit in a pocket, but it producedclear, detailed photographs. Many photographers used the Leica to take candidpictures, in which people did not know they were being photographed. The electricflashbulb, introduced in 1929, and electronic flash, invented in 1931, greatly expandedthe range of photographic subjects.The second major development involved experimentation with new ways of composingpictures and viewing subjects. Laszlo Moholy-Nagy, a Hungarian, and Man Ray, anAmerican, produced photographs without using a camera. They placed objects on apiece of printing paper and exposed the paper with a flashlight. Other photographerscreated abstract compositions with X-ray photographs and multiple exposures. TheFrench photographer Henri Cartier-Bresson was one of the first to utilize the creativepossibilities of the miniature camera. He tried to capture peoples gestures and feelingsat "decisive moments" of their lives.A technique called documentary photography developed in the 1930s. During theGreat Depression, the Department of Agriculture hired photographers to surveyconditions in rural areas of the United States. The outstanding photographers involvedin this project included Walker Evans and Dorothea Lange. Their pictures portray thecourage and suffering of poverty-stricken farm families. At the same time, theappearance of illustrated news magazines in Europe and the United States created ademand for news photographs. Such photojournalists as Margaret Bourke-White andRobert Capa, both of the United States, vividly recorded some of the most importantpeople and dramatic events of the period.Other photographers of the 1930s and 1940s concentrated on ordinary subjects ornatural scenery. Many pictures taken by Edward Weston and Paul Strand emphasizethe textures and geometric shapes of everyday objects. Weston and Strand helpeddevelop the technique of straight photography, which features sharply focused, detailedimages. Another American photographer, Ansel Adams, specialized in landscapes,especially the mountains and deserts of the West.During the 1950s and 1960s, photographic styles became increasingly varied,particularly in the United States. The "street photography" of such photographers asRobert Frank and Garry Winogrand followed the tradition of documentary realism.Other photographers experimented with various printing techniques to achieve unusualeffects. For example, Robert Heinecken produced some of the most imaginativephotographs by making contact prints directly from the illustrated pages of magazines.Other photographers, including Minor White and Aaron Siskind, tried to convey ahighly personal, almost spiritual view of the world in their work.The artistic possibilities of color photography were not fully explored until the 1970s.Color film had been popular among amateur photographers since it was first
  31. 31. commercially produced in 1935. However, most professional photographers continuedto work almost entirely with black-and-white film. The American photographers ErnstHaas and Marie Cosindas were among the first professionals to concentrate on colorphotography. Haass work includes both realistic landscapes and abstract compositions.Cosindas, who chiefly uses instant color film, specializes in still lifes and portraits.Photography today is firmly established as both an art form and an essential tool incommunication and research. Nearly all major art museums hold exhibitions ofphotographs, and a number of museums specialize in photographic art. A picture by awell-known photographer, such as Paul Strand, may cost as much as a fine painting. Atthe same time, the practical value of photography has steadily risen in many fields,ranging from advertising to zoology.Professional photography includes a greater variety of styles and themes than everbefore. But much of the work can be broadly classified as either realistic or fanciful.Among the outstanding realistic photographers are Donald McCullin of Britain andLee Friedlander of the United States. Many of their photographs vividly document the"social landscape" of their countries. Another realistic photographer is HarryCallahan of the United States, whose work includes detailed, sharply focused picturesthat follow the principles of straight photography.Fanciful photographers may distort the appearance of objects in their pictures to createan illusion or convey a mood. The American photographer Jerry Uelsmann producesdreamlike images by combining several negatives into a single print. AnotherAmerican photographer, Eileen Cowin, poses herself and her family in settings thatsuggest images from television soap operas.Amateur photographers use a wide variety of equipment and techniques. Camerasrange from simple fixed-focus models to adjustable ones that have interchangeablelenses and many built-in features. Home processing of both black-and-white and colorfilm has been simplified by easy-to-use equipment and fast-acting chemicals. Amateursalso shoot color home movies with available light, and they make videotape movies thatcan be shown on a television set.One of the greatest technical advances in both amateur and professional photographyhas been the instant processing of film. Ever since the instant camera was introduced in1947, manufacturers have steadily improved the efficiency and ease of instantprocessing. The original model was bulky and expensive. But some of todays instantcameras are about the size of a paperback book and cost no more than a good standardcamera. Many studio cameras can be adapted for instant photography by means ofspecial attachments.
  32. 32. CareersPhotography offers a wide variety of challenging career opportunities. A personinterested in a career in photography should have a general academic background andtechnical knowledge of photography.Commercial photographyMost commercial photographers take pictures for advertisements or for illustrationsthat appear in books, magazines, and other publications. These photographers workwith subjects as varied as farm equipment and high-fashion clothing, and they may beassigned to take photographs at a variety of locations. Commercial photographersmust be skilled and imaginative in a wide range of photographic techniques.PortraitureA portrait photographer takes pictures of people and of special events in the lives ofthese individuals. Some photographers in this field specialize in one type of portraiture,such as children, families, or weddings. Portrait photographers must know how to posetheir subjects and how to create pleasing effects.PhotojournalismMost photojournalists take pictures for news papers or news magazines. They must beskilled in seeking out and recording dramatic action in such fields as politics and sports.A photojournalist must also be able to take pictures rapidly and process them quickly.Scientific photography includes an increasing number of specialized areas. Major fieldsof scientific photography include medical photography and engineering photography.Medical photographers provide much of the information used by physicians to diagnoseand treat illnesses. These photographers may work with such medical equipment asmicroscopes,X-ray machines, and infrared scanning systems. Engineeringphotographers help engineers improve the design of equipment and structuralmaterials. These photographers sometimes use special cameras to "stop" the action ofmachines and to make visible the flaws in metal, plastic, and other materials.Other fields in photography include research, manufacturing, and film processing aswell as business management and sales. Careers are also open to people who can teachphotography or write about it.