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Shutter

Thu, 06 Aug 2009 11:15:28 +0100

Shutter

From Wikipedia, the free encyclopedia

The 1911 Cyclopedia of Photography divides shutters into "roller-blind" and "diaphragm" types, corresponding roughly to the modern focal-plane and leaf types.

In photography, a shutter is a device that allows light to pass for a determined period of time, for the purpose of exposing photographic film or a light-sensitive electronic sensor to light to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as in a movie projector or signal lamp.

Camera shutters

Camera shutters can be fitted in two positions:

Central shutters are mounted within a lens assembly, or more rarely behind or even in front of a lens, and shut off the beam of light where it is narrow. A leaf mechanism is usually used.

Focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor.

Shutters immediately behind the lens were used in some cameras with limited lens interchangeability. Shutters in front of the lens were used in the early days of photography.

Other mechanisms than the dilating aperture and the sliding curtains have been used; anything which exposes the film to light (for a specified time) will suffice.

The time for which a shutter remains open (exposure time) is determined by a timing mechanism. These were originally mechanical, but since the late twentieth century are mostly electronic.

The exposure time and the effective aperture of the lens must together be such as to allow the right amount of light to reach the film or sensor. Additionally, the exposure time must be suitable to handle any motion of the subject. Usually it must be fast enough to "freeze" rapid motion; sometimes a controlled degree of blur is desired, to give a sensation of movement.

Most shutters generate a flash synchronization switch to trigger a flash, if connected. This was quite a complicated matter with mechanical shutters and flashbulbs which took an appreciable time to reach full brightness, focal-plane shutters making this even more difficult. Special flashbulbs were designed in a slow-burn style where the light would reach full intensity, and then remain at that intensity to wait for the slow focal-plane shutter to expose the full film frame. Many of these problems have been alleviated with modern electronic timers and electronic flash units which fire virtually instantaneously. When using a focal-plane shutter with a flash, a photographer will typically operate the shutter at its X-sync speed or slower; however, some electronic flashes can produce a steady pulse compatible with a focal-plane shutter operated at much faster shutter speeds. Keeping in mind that the focal-plane shutter is still going to impart focal-plane shutter distortions to anything that is moving.

Cinematography uses a rotary disc shutter in movie cameras, a continuously spinning disc which conceals the image with a reflex mirror during the intermittent motion between frame exposure. The disc then spins to an open section that exposes the next frame of film while it is held by the registration pin.

Focal-plane shutters

A focal-plane shutter. The plastic curtains travel vertically.

Main article: Focal-plane shutter

Focal-plane shutters are usually implemented as a pair of cloth, metal, or plastic curtains which shield the film from light. For shutter speeds slower than a certain point (known as the X-sync speed of the shutter), which depends on the camera, one curtain of the shutter opens, and the other closes after the correct exposure time. At shutter speeds faster than the X-sync speed, the top curtain of the shutter travels across the focal plane, with the second curtain following behind, so that each section of the film or sensor is exposed for the correct amount of time. The effective exposure time can be much shorter than for central shutters.

Focal plane shutters have the advantages of allowing the use of interchangeable lenses without requiring the expense of a separate shutter for each lens.

They have several disadvantages as well:

Distortion of fast-moving objects: although no part of the film is exposed for longer than the time set on the dial, one edge of the film is exposed an appreciable time after the other, so that a horizontally moving shutter will, for example, elongate or shorten the image of a car speeding in the same or the opposite direction to the shutter movement. For an example of such distortions see this image taken with a vertically traveling focal-plane shutter, showing extreme distortion of fast-moving helicopter rotor blades.

Their louder noise which is a detriment to candid photography and nature photography.

Their more complex mechanical structure causes a shorter life-span than other shutter designs.

If a focal-plane shutter camera is left with the mirror up and sunlight falls on the face of the lens it is possible to burn holes in the closed curtain of the shutter because its surface lies very near the focal-point of the lens.

Camera shake due to the impact of the larger curtains starting and stopping rapidly. Camera designers have learned to partially overcome this problem by including a mirror-lock-up feature in some cameras. This will reduce the camera-shake from the large slapping mirror inside the camera but it still does nothing to prevent camera-shake by the shutter mechanism itself. This method introduces yet another problem, with the mirror locked-up out of the way then you can no longer use the optical viewfinder for focusing, framing, or exposure metering. Newer DSLR cameras are now including a "live-view" where the image from the sensor is displayed directly on an LCD display, so you can still focus (by contrast detection) and frame, but this still does not prevent camera shake from the focal-plane shutter.

Leaf shutters

Simple leaf shutter
1. Shutter plate
2. Aperture covered by leaf shutter
3. Aperture during exposure
4. Leaf blade
5. Catch mechanism
6. Butterfly spring

A leaf shutter is a type of camera shutter consisting of a mechanism with one or more pivoting metal leaves which normally does not allow light through the lens onto the film, but which when triggered opens the shutter by moving the leaves to uncover the lens for the required time to make an exposure, then shuts.

Simple leaf shutters have a single leaf, or two leaves, which pivot so as to allow light through to the lens when triggered. If two leaves are used they have curved edges to create a roughly circular aperture. Simple leaf shutters typically have only one shutter speed and are commonly found in disposable cameras. Some have more than one speed. Some of the most expensive and accurate cameras in the world also employ leaf-shutter mechanisms of one design or another. In modern point and shoot cameras the leaf-shutter is now allowing shutter speeds as fast as 1/40,000 second exposures along with perfect flash-sync at those shutter speeds, with flash speed durations as short as 1/224,000th of a second. Shutters for newer digital cameras are a combination of electronic and mechanical timings. Some cameras employ a 100% electronic shutter, created by turning on and off the imaging sensor's signals. Digital cameras that can also take video implement this method for their video modes. For single-frame photography then either mechanical or mechanical+electronic methods are used.

Diaphragm shutter

One diaphragm shutter opening over another in an Akarex camera

Entries in Cassell's Cyclopedia of Photography, 1911. The terminology diaphragm shutter has since fallen from common use.

A diaphragm shutter is a type of leaf shutter consisting of a number of thin blades which briefly uncover the camera aperture to make the exposure. The blades slide over each other in a way which creates a circular aperture which enlarges as quickly as possible to uncover the whole lens, stays open for the required time, then closes in the same way.^[1] The larger the number of blades, the more accurately circular is the aperture. An odd number of blades is usually used: 3, 5, or more.

The term diaphragm shutter has also been used to describe an optical stop with a slit, near the focal plane of a moving-film high-speed camera.^[2]

Central shutters

A central shutter is a camera shutter normally located within the lens assembly where a relatively small opening allows light to cover the entire image. The term is also used for shutters behind, but near to, the lens. The alternative to a central shutter is a focal-plane shutter.

Interchangeable lens cameras with a central shutter within the lens body require that each lens has a shutter built into it. In practice most cameras with interchangeable lenses use a single focal plane shutter in the camera body for all lenses, while cameras with a fixed lens use a central shutter.

Film cameras, but not digital cameras, with a central shutter and interchangeable lenses often have a secondary shutter or darkslide to cover the film and allow changing lens in mid-roll without fogging the film.

Central shutters usually use either the simple leaf mechanism or the diaphragm mechanism.

The main advantages of the central shutter compared to a focal-plane shutter are:

Relatively simple construction is possible.
Less expensive to produce than a focal-plane shutter^{[citation needed]}.
Flash synchronization is possible at all speeds because the shutter opens fully.
Ultra-fast exposures with speeds up to and possibly above 1/40,000 second^{[citation needed]}, with perfect full-frame flash-sync at all speeds.
Small size is achieved by placing the shutter where the bundle of rays is smaller, either inside the lens or inside the camera body.
Many versions have no connection between the cocking mechanism and the film advance mechanism, making multiple exposures possible.
Generally much quieter operation because of fewer and less bulky moving parts
More realistic photographs in high speed follow-through—lateral focal plane shutters compress or elongate the image in such cases.
Longer shutter life.

Some disadvantages of the central shutter are:

For an interchangeable lens system, each lens has to have a shutter built into it.
Leaf shutter speeds are limited by the speed at which the leaves can move: normally 1/500th of a second for a diaphragm shutter and 1/125th of a second for a simple leaf shutter.
Some versions may have no connection between the cocking mechanism and the film advance mechanism, making accidental multiple exposures a common problem, although this is a feature of camera manufacture rather than the shutter itself.

Shutter lag

Shutter lag is the time between pressing the shutter release and the camera responding by taking the picture. While this delay was insignificant on most film cameras and some digital cameras, it may be a problem when trying to capture subjects which are moving quickly such as in sports or other action photography.

Shutter cycle

A shutter cycle is the process of the shutter opening, closing, and resetting to where it is ready to open again. The life-expectancy of a mechanical shutter is often expressed as a number of shutter cycles.

Projector shutters

In movie projection, the shutter admits light from the lamphouse to illuminate the film across to the projection screen. To avoid flicker, a double-bladed rotary disc shutter admits light two times per frame of film. There are also some models which are triple-bladed, and thus admit light three times per frame (see Persistence of vision).

Shutters are also used simply to regulate pulses of light, with no film being used, as in a signal lamp.

Nature photography

Thu, 06 Aug 2009 11:10:10 +0100

Nature photography

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The Tetons - Snake River (1942) by Ansel Adams

Nature photography refers to a wide range of photography taken outdoors and devoted to displaying natural elements such as landscapes (See Landscape Photography), wildlife, plants, and close-ups of natural scenes and textures. Nature photography tends to put a stronger emphasis on the aesthetic value of the photo than other photography genres, such as photojournalism and documentary photography.

Nature photographs are published in scientific, travel and cultural magazines such as National Geographic Magazine and Audubon Magazine or other more specific magazines such as Outdoor Photographer and Nature's Best Photography. Well known nature photographers include Frans Lanting, Galen Rowell, and Art Wolfe.

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Wildlife Photography

Giraffe in Kenya

Wildlife photography, such as this midflight shot of a male mallard duck, can be very challenging and require a high power telephoto lens

Wildlife photography is devoted to capturing interesting animals in action, such as eating, fighting, or in flight. Although usually shot in the wild, game farms are also a frequent location for wildlife photography.

The techniques of wildlife photography differ greatly from those used in landscape photography. For example, in wildlife photography wide apertures are used to achieve a fast shutter speed, freeze the subject's motion, and blur the backgrounds, while landscape photographers prefer small apertures. Wildlife is also usually shot with long telephoto lenses from a great distance; the use of such telephoto lenses frequently necessitates the use of a tripod (since the longer the lens, the harder it is to handhold). Many wildlife photographers use blinds or camouflage.

Macro / Texture

An example of a macro shot - this one showing two Hoverflies

The macro photography article explains close-up photography in general; however, this is also a type of nature photography. While common macro subjects - bees, dragonflies, and so on - could be described as wildlife, their world also makes for good photography.

Many photographers record images of the texture in a stone, tree bark, leaf, or any of other small scenes. Many of these images are abstract. Tiny plants and mushrooms are also popular subjects. Close-up nature photography doesn't always need a true macro lens; however, the scenes here are small enough that they're generally considered different from regular landscapes.

Use of Color

Valley of Fire State Park, Nevada

The presence (or absence) of color is not a requirement of nature photography. More black and white photos are being produced by digital means today than on film in the 1930s.^{[citation needed]}

Ansel Adams is famous for his black and white depictions of nature, which are still held in high regard today. Galen Rowell praised Fuji Velvia film for its bright, saturated colors, asking "Who wants to take dull pictures that will last a hundred years?" ^[1] Both men distinguish between photography as an expressive art form and sensitometry; an accurate reproduction is not necessary.

For further reading, see: Black and white, Sepia tone, Cyanotype, Color, Saturation

Ethics

A number of ethical concerns and debates surround the creation of nature photography. Common issues involve the potential of stress or harm to wildlife, the potential of photographers overrunning and destroying natural areas, the use of game farms, and veracity and manipulation in photography.

Macro photography

Thu, 06 Aug 2009 11:09:04 +0100

Macro photography

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Macro photograph of a Common Yellow Dung fly (Scathophaga stercoraria)

Macro photography is close-up photography. The classical definition is that the image projected on the "film plane" (i.e., film or a digital sensor) is close to the same size as the subject. On 35 mm film (for example), the lens is typically optimized to focus sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, that is to say, the image on the film is 1/2 the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances.

In recent years, the term macro has been used in marketing material to mean being able to focus on a subject close enough so that when a regular 6×4 inch (15×10 cm) print is made, the image is life-size or larger. With 35mm film this requires a magnification ratio of only approximately 1:4, which demands less of lens quality than 1:1. With digital cameras the actual image size is rarely stated, so that the magnification ratio is largely irrelevant; cameras instead advertise their closest focussing distance.

Equipment

Vivitar Series 1 macro lens

Extension tubes for SLRs

Bellows fitted between an SLR and reversed lens

Techniques for making a well-lit image of the required size include:

Using a lens specifically designed for close work and with a long barrel for close focusing, called a macro lens. Some manufacturers call it a micro, which might actually be scientifically more accurate, but can be confusing, since it goes against the established convention. A macro lens might be optimized to provide its best performance at a magnification of 1:1. Some macro lenses, such as the Canon MP-E 65 mm f/2.8, can achieve higher magnification – up to 5:1 macro, enabling photography of the structure of small insect eyes, snowflakes, and other minuscule but detailed objects. However, "standard" (1:1) macro lenses are more common. There are different categories of macro lenses, depending on the focal length:
- 50–60mm range typically used for product photography and small objects
- 90–105mm range the standard focal range used for insects, flowers, small objects
- 150–200mm range gives more working distance — typically used for insects and other small animals
- a few zooms provide a macro option, but they generally do not allow a 1:1 magnification
Extending the distance between the lens and the film or sensor by inserting either extension tubes or a continuously adjustable bellows, with no optical components; between the camera body and the lens. The further the lens is from the film or sensor, the closer the focusing distance, the greater the magnification, and the darker the image for the same aperture. Tubes of various lengths can be stacked, decreasing lens-to-subject distance and increasing magnification. Bellows or tubes must be removed for normal working at longer distances. They can be used in conjunction with some other techniques (e.g., reversing the lens).

typical close-up lens

Placing an auxiliary close-up lens in front of the camera's taking lens. Inexpensive screw-in or slip-on attachments provide close focusing at very low cost. The quality is variable, with some two-element versions being excellent while many inexpensive single element lenses exhibit chromatic aberration and reduced sharpness of the resulting image. This method works with cameras that have fixed lenses, and is commonly used with bridge cameras. These lenses add diopters to the optical power of the lens, decreasing the minimum focusing distance, and allowing the camera to get closer to the subject.
Attaching a telephoto extender between the camera body and the lens. A 1.4× or 2× teleconverter gives a larger image, adding macro capabilities. As with an extension tube, less light will reach the film or sensor, and a longer exposure time will be needed. However, working distance remains the same as without the teleconverter.
Reversing the lens using a "reversing ring". This special adapter attaches to the filter thread on the front of a lens and makes it possible to attach the lens in reverse. Excellent quality results up to 4x lifesize magnification using fairly cheap, "standard" (not specially designed for macro) lenses can be produced. For cameras with all-electronic communications between the lens and the camera body, such as Canon EOS, reversing rings are available which allow all camera functions, including open aperture metering, to be used. When used with extension tubes or bellows a relatively cheap but highly versatile macro system can be assembled.
Reversing a lens of lesser focal length in front of a normally mounted lens using an inexpensive macro coupler, which screws into the filter threads on the front of the two lenses to join them mechanically. This method allows most cameras to maintain the full function of electronic communication with the normally mounted lens for features such as open-aperture metering. Magnification ratio is calculated by dividing the focal length of the normally mounted lens by the focal length of the reversed lens (e.g., when an 18 mm lens is reverse mounted on a 300 mm lens the magnification ratio is 16:1). The use of automatic focus is not advisable as the extra weight of the reverse-mounted lens could damage the autofocus mechanism. Working distance is significantly less than the original lens.
Depth of field is extremely small when focusing on close objects; a small stop is often required to ensure sufficient depth of field. This requires either a slow shutter speed or bright lighting for correct exposure; in all but the brightest natural lighting if a prolonged exposure is not advisable, auxiliary lighting (such as from a flash unit) is required. Uniform lighting can be difficult with subjects very close to the lens; a ring flash mounted on the front of the lens can provide even illumination. Good results can also be obtained by using a flash diffuser, which can be made of inexpensive Styrofoam.

Technical considerations

Depth of field

Shallow depth of field

Limited depth of field is an important consideration in macro photography. This makes it essential to focus critically on the most important part of the subject, as elements that are even a millimetre closer or farther from the focal plane might be noticeably blurry. Due to this, the use of a microscope stage is highly recommended for precise focus with large magnification such as photographing skin cells. Alternatively, more shots of the same subject can be made with slightly different focusing lengths and joined afterwards with specialized image editing software which picks out the sharpest parts of every image, artificially increasing depth of field.

Compact digital cameras and small-sensor bridge cameras have an incidental advantage in macro photography due to their inherently further working distance. For instance, some popular bridge cameras produce the equivalent magnification of a 420 mm lens on 35 mm format but only use a lens of actual focal length 89 mm (1/1.8″-type CCD) or 72 mm (1/2.5″-type CCD). (See crop factor.) Since depth of field appears to decrease with the actual focal length of the lens, not the equivalent focal length, these bridge cameras can achieve the magnification of a 420 mm lens with the greater depth of field of a much shorter lens. High-quality inexpensive auxiliary close-up lenses can be used to achieve the needed close focus; they function identically to reading glasses. This effect makes it possible to achieve very high quality macrophotographs with relatively inexpensive equipment, since auxiliary closeup lenses are far cheaper than dedicated SLR macro lenses.

Lighting

The problem of sufficiently and evenly lighting the subject can be difficult to overcome. Some cameras can focus on subjects so close that they touch the front of the lens. It is impossible to place a light between the camera and a subject that close, making this extreme close-up photography impractical. A normal-focal-length macro lens (50 mm on a 35 mm camera) can focus so close that lighting remains difficult. To avoid this problem, many photographers use telephoto macro lenses, typically with focal lengths from about 100 to 200 mm. These are popular as they permit sufficient distance for lighting between the camera and the subject.

Ring flashes, with flash tubes arranged in a circle around the front of the lens, can be helpful in lighting at close distances. Ring lights have emerged, using white LEDs to provide a continuous light source for macrophotography.

Homemade flash diffusers made out of white Styrofoam or plastic attached to a camera's built-in flash can also yield surprisingly good results by diffusing and softening the light, eliminating specular reflections and providing more even lighting.

Examples

Close up of the head of a Housefly, taken with a SMC Pentax f/1.4 reversed on a Fujifilm s6500fd. Focus stacking has been used to create a larger Depth of Field	The skin of a North American Cantaloupe, taken with a Canon MP-E 65mm f/2.8 1–5× Macro lens and Macro Twin Lite MT-24EX	Hibiscus petal, taken through Canon PowerShot A95	Colony of aphids on a stem, using an inverse mounted lens on a Canon G3
Thumbnail on the Macro photography page, taken with a Pentax *ist DS and macro lens	Lily Flower taken with Canon PowerShot A550	head of Tipulidae (150mm Sigma and Nikon D80)	Magnification of 1:1 (Coin 21mm CCD 23.6mm)
Magnification of 2:1 (Photographed zone 11.8mm CCD 23.8mm)	Close-up macro photograph of a Bumblebee inside a red flower. Taken with Canon Powershot A430	Magnification 11:1 macro photo of a mustard seed, taken with a reversed Canon EF 14mm lens on a 400D at f/11	A macro of a rusty chain, showing cracks and grooves

Landscape photography

Thu, 06 Aug 2009 11:07:32 +0100

Landscape photography

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Tanzania

Landscape photography is a genre intended to show different spaces within the world, sometimes vast and unending, but other times microscopic.

Many landscape photographers show little or no human activity in their photos, striving to attain pure, unsullied landscapes^[1] that are devoid of human influence, using instead subjects such as strongly defined landforms, weather, and ambient light. Despite this, there is no pure or absolute definition of what makes a landscape in photography, as such it has become a very broad term, encompassing urban, industrial, macro and nature photography. A beach full of parasols and sunbathers can be a landscape photo, but so can the view through an electron microscope, which shows a different type of landscape. Waterfalls, and mountains are especially popular in classic landscape photography, often calling for Large Format cameras^[2] and neutral density or polarizing filters. Though many photographs are inspired by traditional landscape painting, the term in photography is very broad, most places and things can be photographed as a landscape, a kitchen, a lamp, a wall, or even the human body^[3] can be turned into a rolling vista by a skilled photographer.

Landscapes are often created with such tools as a pinhole camera, or a large format camera and tripod, usually with a wide angle lenses (24 mm and 35 mm are especially popular). Many serious photographers use medium or large format systems to record as much detail as possible, although the vast majority of landscapes shot today are from digital SLRs and compact cameras.

Landscape photography has become a valuable tool to inspire environmental stewardship. Capturing the beauty of unspoiled places serves to bring dwindling wilderness areas into the public eye. Many noted landscape photographers provide images to environmental protection organizations. Noted organizations use professional and amateur photographers' work to further the preservation cause. Notable landscape photographers include Ansel Adams, Bill Brandt, and Edward Weston.[

Portrait photography

Thu, 06 Aug 2009 11:06:06 +0100

Portrait photography

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An example of a photographic portrait.

Portrait photography is the capture by means of photography of the likeness of a person or a small group of people (a group portrait), in which the face and expression is predominant. The objective is to display the likeness, personality, and even the mood of the subject. Like other types of portraiture, the focus of the photograph is the person's face, although the entire body and the background may be included. A portrait is generally not a snapshot, but a composed image of a person in a still position. A portrait often shows a person looking directly at the camera.

Unlike many other styles of photography, the subjects of portrait photography are often non-professional models. Family portraits commemorating special occasions, such as graduations or weddings, may be professionally produced or may be vernacular and are most often intended for private viewing rather than for public exhibition.

However, many portraits are created for public display ranging from fine art portraiture, to commercial portraiture such as might be used to illustrate a company's annual report, to promotional portraiture such a might be found on a book jacket showing the author of the book.

History

An example of a late 19th century family portrait. Note the custom of mourning the dead in a family photo during that era. A shrine to a deceased child is visible in the background. Also, two of the female members are dressed in black; a contemporary mourning tradition. (c. 1894)

Portrait photography has been around since the invention and popularization of the camera. It is a cheaper and often more accessible method than portrait painting, which has been used by distinguished figures before the popularity of the camera.

The relatively low cost of the daguerreotype in the middle of the 19th century lead to its popularity for portraiture. Studios sprang up in cities around the world, some producing more than 500 plates a day. The style of these early works reflected the technical challenges associated with 30-second exposure times and the painterly aesthetic of the time. Subjects were generally seated against plain backgrounds and lit with the soft light of an overhead window and whatever else could be reflected with mirrors. As the equipment became more advanced, the ability to capture images with short exposure times gave photographer more creative freedom and thus created new styles of portrait photography.

As photographic techniques developed, photographers took their talents out of the studio and onto battlefields, across oceans and into remote wilderness. William Shew's Daguerreotype Saloon, Roger Fenton's Photographic Van and Mathew Brady's What-is-it? wagon set the standards for making portraits and other photographs in the field.

Lighting for portraiture

Portrait of Romanian writer Mircea Cărtărescu. This is an example of "butterfly" lighting, though the placement of the key light is somewhat higher than is common, resulting in deeper than normal shadows under the eyes and nose. Note also, the background light creating a halo around the subject's head, the lack of a rim light, and use of a fill card, located below the subject's chin, which can be seen as catch lights in the subject's eyes.

When portrait photographs are composed and captured in a studio, the professional photographer has control over the lighting of the composition of the subject and can adjust direction and intensity. There are many ways to light a subject's face, but there are several common lighting plans which are easy enough to describe. Of course making them work in a studio or on location is a matter of experimentation and practice.

Three-Point Lighting

One of the most basic lighting plans is called three-point lighting. This plan uses three (and sometimes four) lights to fully model (bring out details and the three-dimensionality of) the subject's features. The three main lights used in this light plan are as follows:

The Key light

Also called a main light, the key light is usually placed to one side of the subject's face, between 30 and 60 degrees off centre and a bit higher than eye level. The key light is the brightest light in the lighting plan.

The Fill light

Placed opposite the key light, the fill light fills in or softens the shadows on the opposite side of the face. The brightness of the fill light is usually between 1/3 and 1/4 that of the key light. This is expressed as a ratio as in 3:1 or 4:1. When the ratio is 3:1 this is sometimes called Kodak lighting since this was the ratio suggested by Kodak in the instructional booklets accompanying the company's early cameras.

The purpose of these two lights is to mimic the natural light created by placing a subject in a room near a window. The daylight falling on the subject through the window is the Key light and the Fill light is reflected light coming from the walls of the room. This type of lighting can be found in the works of hundreds of classical painters and early photographers and is often called Rembrandt lighting.

Modern portraitists have chosen to add one or two lights to this lighting plan.

The Rim light

Also called a backlight or hair light, the rim light (the third main light in the three-point lighting plan) is placed behind the subject, out of the picture frame, and often rather higher than the Key light or Fill. The point of the rim light is to provide separation from the background by highlighting the subject's shoulders and hair. The rim light should be just bright enough to provide separation from the background, but not as bright as the key light.

Butterfly lighting

Butterfly lighting is another common lighting plan and has been very popular over the past decade or so. In this case, only two lights are common. The Key light is placed directly in front of the subject, often above the camera or slightly to one side, and a bit higher than is common for a three-point lighting plan. The second light is a rim light. Often a reflector is placed below the subject's face to provide fill light and soften shadows.

This lighting can be recognised by the strong light falling on the forehead, the bridge of the nose and the upper cheeks, and by the distinct shadow below the nose which often looks rather like a butterfly and thus provides the name for this lighting plan. Butterfly lighting was a favourite of famed Hollywood portraitist George Hurrell which is why this style of lighting is often called Paramount lighting, after the movie studio of the same name.

Accessory lights

These lights can be added to basic lighting plans to provide additional highlights or add background definition.

The Kicker

A kicker is a small light, often made directional through the use of a snoot, umbrella, or softbox. The kicker is designed to add highlights to the off side of the subject's face, usually just enough to establish the jaw line or edge of an ear. The kicker should thus be a bit brighter than the fill light, but not so bright it over fills the off side of the face. Many portraitists choose not to use a kicker and settle for the three main lights of the standard plans.

Background lights

Not so much a part of the portrait lighting plan, but rather designed to provide illumination for the background behind the subject, background lights can pick out details in the background, provide a halo effect by illuminating a portion of a backdrop behind the subject's head, or turn the background pure white by filling it with light.

Other lighting equipment

Most lights used in modern photography are a flash of some sort. The lighting for portraiture is typically diffused by bouncing it from the inside of an umbrella, or by using a soft box. A soft box is a fabric box, encasing a photo strobe head, one side of which is made of translucent fabric. This provides a softer lighting for portrait work and is often considered more appealing than the harsh light often cast by open strobes. Hair and background lights are usually not diffused. It is more important to control light spillage to other areas of the subject. Snoots, barn doors and flags or gobos help focus the lights exactly where the photographer wants them. Background lights are sometimes used with color gels placed in front of the light to create coloured backgrounds.

Styles of portraiture

There are many different techniques for portrait photography. Often it is desirable to capture the subject's eyes and face in sharp focus while allowing other less important elements to be rendered in a soft focus. At other times, portraits of individual features might be the focus of a composition such as the hands, eyes or part of the subject's torso.

Digital photography

Thu, 06 Aug 2009 11:03:21 +0100

Digital photography

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10 MP Nikon D200 and a Nikon film scanner

Nikon D700 — a 12.1 megapixel full-frame DSLR

The Canon EOS 350D

The Canon PowerShot A95

Digital photography is a form of photography that uses digital technology to make images of subjects. Until the advent of such technology, photography used photographic film to create images which could be made visible by photographic processing. By contrast, digital photographs can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing.

Digital photography is one of several forms of digital imaging. Digital images are also created by non-photographic equipment such as computer tomography scanners and radio telescopes. Digital images can also be made by scanning conventional photographic images.

History

Main article: Digital camera#History

This section requires expansion.

Sensors and storage

Sensors read the intensity of light as filtered through different color filters, and digital memory devices store the digital image information, either as RGB color space or as raw data.

There are two main types of sensors:

charge-coupled device (CCD) – photocharge is shifted to a central charge-to-voltage converter
CMOS sensors ("Active pixel sensor")

Nearly all digital cameras now use built in and/or removable solid state flash memory. Digital camcorders that double as a digital still camera use flash memory, discs and internal hard disks. For a time floppy disks and mini-CDs were used in early digital cameras such as the Sony Mavica range.

Multifunctionality and connectivity

Except for some linear array type of cameras at the highest-end and simple web cams at the lowest-end, a digital memory device (usually flash memory; floppy disks and CD-RWs are less common) is usually used for storing images, which may then be transferred to a computer later.

Digital cameras can take pictures, and may also record sound and video. Some can be used as webcams, some can use the PictBridge standard to connect to a printer without using a computer, and some can display pictures directly on a television set. Similarly, many camcorders can take still photographs, and store them on videotape or on flash memorycards with the same functionality as Digital Cameras.

Performance metrics

The quality of a digital image is the sum of various factors, many of which are similar to film cameras. Pixel count (typically listed in megapixels, millions of pixels) is only one of the major factors, though it is the most heavily marketed. Pixel count metrics were created by the marketing organizations of digital camera manufacturers because consumers can use it to easily compare camera capabilities. It is not, however, the major factor in evaluating a digital camera. The processing system inside the camera that turns the raw data into a color-balanced and pleasing photograph is the most critical, which is why some 4+ megapixel cameras perform better than higher-end cameras.

Lens quality: resolution, distortion, dispersion (see Lens (optics))
Capture medium: CMOS, CCD, negative film, reversal film etc.
Capture format: pixel count, digital file type (RAW, TIFF, JPEG), film format (135 film, 120 film, 5x4, 10x8).
Processing: digital and / or chemical processing of 'negative' and 'print'.

Pixel counts

The number of pixels n for a given maximum resolution (w horizontal pixels by h vertical pixels) is the product n = w × h. This yields e. g. 1.92 megapixels (1,920,000 pixels) for an image of 1600 × 1200. The majority of compact as well as some DSLR digital cameras have a 4:3 aspect ratio, i.e. w/h = 4/3. ^[1]. According to Digital Photography Review, the 4:3 ratio is because "computer monitors are 4:3 ratio, old CCD's always had a 4:3 ratio, and thus digital cameras inherited this aspect ratio."^[1]

The pixel count quoted by manufacturers can be misleading as it may not be the number of full-colour pixels. For cameras using single-chip image sensors the number claimed is the total number of single-colour-sensitive photosensors, whether they have different locations in the plane, as with the Bayer sensor, or in stacks of three co-located photosensors as in the Foveon X3 sensor. However, the images will have different numbers of RGB pixels: the Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing (interpolation), while the cameras with Foveon sensors produce uninterpolated image files with one-third as many RGB pixels as photosensors. It is difficult to compare the resolutions based on the megapixel ratings of these two types of sensors, and therefore sometimes subject of dispute.

Resolution

Resolution provides an indication of the amount of detail that is captured, but, like the other metrics, resolution is just another factor out of many in determining the quality of an image. Furthermore, different methods of creating an image make it impossible to compare the resolutions of cameras simply based on the number of pixels produced by the image sensor. For example, the Sigma SD14 camera uses Foveon technology, which is quite different from most other digital cameras. It claims to be a 14 megapixel camera, but is generally considered to have detail-capturing capabilities roughly equivalent to 9 megapixels in terms of Bayer sensors. ^[2]

The relative increase in detail resulting from an increase in resolution is better compared by looking at the number of pixels across (or down) the picture, rather than the total number of pixels in the picture area. For example, a sensor of 2560 × 1600 sensor elements is described as "4 megapixels" (2560 × 1600 = 4,096,000). Increasing to 3200 × 2048 increases the pixels in the picture to 6,553,600 (6.5 megapixels), a factor of 1.6, but the pixels per cm in the picture (at the same image size) increases by only 1.25 times. A measure of the comparative increase in linear resolution is the square root of the increase in area resolution, i.e., megapixels in the entire image.

Resolution in pixels is not the only measure of image quality; a larger sensor with the same number of pixels will generally produce a better image than a smaller one. One of the most important differences is an improvement in image noise. This is one of the advantages of digital SLR cameras, which have larger sensors than simpler cameras of the same resolution.

Dynamic range

Practical imaging systems, digital and film, have a limited "dynamic range": the range of luminosity which can be reproduced accurately. Highlights of the subject which are too bright will be rendered as white, with no detail; shadows which are too dark will be rendered as black. The loss of detail is not abrupt with film, or in dark shadows with digital sensors: some detail is retained as brightness moves out of the dynamic range. "Highlight burn-out" of digital sensors, however, can be abrupt, and highlight detail may be lost. And as the sensor elements for different colors saturate in turn, there can be gross hue or saturation shift in burnt-out highlights.

Some digital cameras can show these blown highlights in the image review, allowing the photographer to re-shoot the picture with a modified exposure. Others compensate for the total contrast of a scene by selectively exposing darker pixels longer. A third technique is used by Fujifilm in its FinePix S3 Pro digital SLR. The image sensor contains additional photodiodes of lower sensitivity than the main ones; these retain detail in parts of the image too bright for the main sensor.

High dynamic range imaging (HDR) addresses this issue by increasing the dynamic range of images by either

increasing the dynamic range of the image sensor or
by using exposure bracketing and post-processing the separate images to create a single image with a higher dynamic range.

HDR images curtail burn-outs and black-outs.

Applications and considerations

The Presidential Portrait of Barack Obama was the first official U.S. Presidential Portrait to be taken with a digital camera.

With the acceptable image quality and the other advantages of digital photography (particularly the time pressures of vital importance to daily newspapers) the majority of professional news photographers have begun capturing their images with digital cameras.

Digital photography has also been adopted by many amateur snapshot photographers, who take advantage of the convenience of the form when sending images by email, placing them on the World Wide Web, or displaying them in digital picture frames. Digital cameras have also been integrated into many cell phones, although, because of the small, poor quality lenses and sensors in most of these phones, the quality of these pictures makes them unsuitable for making even moderate size prints.

Some commercial photographers, and some amateurs interested in artistic photography, have been resistant to using digital rather than film cameras because they believe that the image quality available from a digital camera is still inferior to that available from a film camera, and the quality of images taken on medium format film was thought to be impossible to match with a digital camera. Some have expressed a concern that changing computer technology may make digital photographs inaccessible in the future. A related concern in a specialized application is the use of digital photographs in court proceedings, with the added difficulty of demonstrating an image's authenticity. Some high-end film can also still be projected for viewing at a much higher optical resolution than even the best digital projectors.

Other commercial photographers, and many amateurs, have enthusiastically embraced digital photography because they believe that its flexibility and lower long-term costs outweigh its initial price disadvantages. Almost all of the cost of digital photography is capital cost, meaning that the cost is for the equipment needed to store and copy the images, and once purchased requires virtually no further expense outlay. Film photography requires continuous expenditure of funds for supplies and developing, although the equipment itself does not outdate so quickly and has a longer service life. Some commercial photographers have also begun moving to digital technology because of the tremendous editing capabilities now offered on computers. The photographer is able to color-balance and manipulate the image in ways that traditional darkroom techniques cannot offer, although film users can utilize the same technology with a film scanner. With fully color-balanced systems from the camera to the monitor to the printer, the photographer can now print what is actually seen on the screen.

However, digital cameras require batteries that need to be recharged or replaced frequently, and this means that a photographer needs access to electrical outlets. Digital cameras also tend to be much more sensitive to moisture and extreme cold. For this reason, photographers who work in remote areas may favour film SLR cameras, though many higher-end DSLRs are now equipped with weather-resistant bodies. Medium- and large-format film cameras are also still preferred by publications insisting on the very highest detail and resolution.

Digital photography was used in astronomy long before its use by the general public and had almost completely displaced photographic plates by the early 1980s. Not only are CCDs more sensitive to light than plates, but they have a much more uniform and predictable response. The CCDs used in astronomy are similar to those used by the general public, but are generally monochrome and cooled with liquid nitrogen so as to reduce the noise caused by heat. Many astronomical instruments have arrays of many CCDs, sometimes totaling almost a billion pixels. Nowadays amateur astronomers also commonly use digital cameras, including the use of webcams for speckle imaging or "video astronomy".

Sensor size and angle of view

Cameras with digital sensors that are smaller than the typical 35mm film size will have a smaller field or angle of view when used with a lens of the same focal length. This is because angle of view is a function of both focal length and the sensor or film size used.

If a sensor smaller than the full-frame 35mm film format is used, such as the use of APS-C-sized digital sensors in DSLRs, then the field of view is cropped by the sensor to smaller than the 35mm full-frame format's field of view. This narrowing of the field of view is often described in terms of a focal length multiplier or crop factor, a factor by which a longer focal length lens would be needed to get the same field of view on a full-frame camera.

If the digital sensor has approximately the same resolution (effective pixels per unit area) as the 35mm film surface (24 x 36 mm), then the result is similar to taking the image from the film camera and cutting it down (cropping) to the size of the sensor. For an APS-C size sensor, this would be a reduction to approximately the center 50% of the image. The cheaper, non-SLR models of digital cameras typically use much smaller sensor sizes and the reduction would be greater.

If the digital sensor has a higher or lower density of pixels per unit area than the film equivalent, then the amount of information captured will differ correspondingly. While resolution can be estimated in pixels per unit area, the comparison is complex since most types of digital sensor record only a single colour at each pixel location, and different types of film will have different effective resolutions. There are various trade-offs involved, since larger sensors are more expensive to manufacture and require larger lenses, while sensors with higher numbers of pixels per unit area are likely to suffer higher noise levels.

For these reasons, it is possible to obtain cheap digital cameras with sensor sizes much smaller than 35mm film, but with high pixel counts, that can still produce high-resolution images. Such cameras are usually supplied with lenses that would be classed as extremely wide angle on a 35mm camera, and which can also be smaller size and less expensive, since there is a smaller sensor to illuminate. For example, a camera with a 1/1.8" sensor has a 5.0x field of view crop, and so a hypothetical 5-50mm zoom lens will produce images that look similar (again the differences mentioned above are important) to those produced by a 35mm film camera with a 25–250mm lens, while being much more compact than such a lens for a 35mm camera since the imaging circle is much smaller.

This can be useful if extra telephoto reach is desired, as a certain lens on an APS sensor will produce an equivalent image to a significantly longer lens on a 35mm film camera shot at the same distance from the subject, the equivalent length of which depends on the camera's field of view crop. This is sometimes referred to as the focal length multiplier, but the focal length is a physical attribute of the lens and not the camera system itself. The downside to this is that wide angle photography is made somewhat more difficult, as the smaller sensor effectively and undesirably reduces the captured field of view. Some methods of compensating for this or otherwise producing much wider digital photographs involve using a fisheye lens and "defishing" the image in post processing to simulate a rectilinear wide angle lens.

Full-frame digital SLRs, that is, those with sensor size matching a frame of 35mm film, include Canon 1DS, 1DS II, and 5D, Kodak Pro DCS-14n, Nikon D3X (with a 24.5 megapixel sensor) and Contax N Digital. There are very few digital cameras with sensors that can approach the resolution of larger-format film cameras, with the possible exception of the Mamiya ZD (22MP) and the Hasselblad H3D series of DSLRs (22 to 39 MP).

Common values for field of view crop in DSLRs include 1.3x for some Canon sensors, 1.5x for Sony APS-C sensors used by Nikon, Pentax and Konica Minolta and for Fujifilm sensors, 1.6 (APS-C) for most Canon sensors, ~1.7x for Sigma's Foveon sensors and 2x for Kodak and Panasonic 4/3" sensors currently used by Olympus and Panasonic. Crop factors for non-SLR consumer compact and bridge cameras are larger, frequently 4x or more.

Drawing showing the relative sizes of sensors used in most current digital cameras.

Table of sensor sizes ^[3]
Type	Width (mm)	Height (mm)	Size (mm²)
1/3.6"	4.00	3.00	12.0
1/3.2"	4.54	3.42	15.5
1/3"	4.80	3.60	17.3
1/2.7"	5.37	4.04	21.7
1/2.5"	5.76	4.29	24.7
1/2"	6.40	4.80	30.7
1/1.8"	7.18	5.32	38.2
1/1.7"	7.60	5.70	43.3
2/3"	8.80	6.60	58.1
1"	12.8	9.6	123
4/3"	18.0	13.5	243
APS-C	25.1	16.7	419
35 mm	36	24	864
Back	48	36	1728

Storage

Main article: Digital camera#Storage

Storage for digital cameras have increased in size and technology with the time. From magnetic tape (Steven Sasson's 1975 prototype) to floppy disks to flash memory.

Digital camera backs

Main article: digital camera back

Most digital cameras are built to operate as a self-contained unit. This is especially so at the lower-end, for these cameras usually include zoom lens and flashes that cannot be changed. However, at the highest-end, some digital cameras are nothing but a sophisticated light-sensing unit. Experienced photographers attach these digital "camera backs" to their professional medium format SLR cameras, such as a Mamiya.

Area array
- CCD
- CMOS
Linear array
- CCD (monochrome)
- 3-strip CCD with color filters

Linear array cameras are also called scan backs.

Single-shot
Multi-shot (three-shot, usually)

Scanning and multi-shot camera backs are usually used only in studios to take pictures of still objects. Most earlier digital camera backs used linear array sensors which could take seconds or even minutes for a complete high-resolution scan. The linear array sensor acts like its counterpart in a flatbed image scanner by moving vertically to digitize the image.

Many early such cameras could only capture grayscale images. To take a color picture, it required three separate scans done with a rotating colored filter. These are called multi-shot backs. Some other camera backs use CCD arrays similar to typical cameras. These are called single-shot backs.

Since it is much easier to manufacture a high-quality linear CCD array with only thousands of pixels than a CCD matrix with millions, very high resolution linear CCD camera backs were available much earlier than their CCD matrix counterparts. For example, you could buy an (albeit expensive) camera back with over 7,000 pixel horizontal resolution in the mid-1990s. However, as of 2004^[update], it is still difficult to buy a comparable CCD matrix camera of the same resolution. Rotating line cameras, with about 10,000 color pixels in its sensor line, are able, as of 2005^[update], to capture about 120,000 lines during one full 360 degree rotation, thereby creating a single digital image of 1,200 Megapixels.

Most modern digital camera backs use very large CCD matrices. This eliminates the need for scanning. For example, Phase One produces a 39 million pixel digital camera back with a 49.1 x 36.8 mm CCD in 2008. This CCD array is a little smaller than a frame of 120 film and much larger than a 35 mm frame (36 x 24 mm). In comparison, a consumer digital camera usually uses a much smaller 1/2.5 inch or 7.176 x 5.329 mm (~ 1/1.8 inch) CCD sensor. Further, the 1/2.5 or 1/1.8 inch diagonal measurement is the size of the entire CCD chip- the actual photo-sensitive area is much smaller.

At present, there are relatively few complete digital SLR cameras with sensors large enough to compete with medium to large format film cameras. Phase One and Mamiya manufacture medium format digital devices that can capture 16MP up to 39MP^[4]. The units tend to be quite large and expensive. Additionally, because of their high build quality and lack of moving parts tend to be quite long lasting and are prominent on the used market ^[5].

[edit] Comparison with film photography

Main article: Digital versus film photography

Advantages of consumer digital cameras

The advantages of digital photography over traditional film include:

Instant review of pictures, with no wait for the film to be developed: if there's a problem with a picture, the photographer can immediately correct the problem and take another picture
Minimal ongoing costs for those wishing to capture hundreds of photographs for digital uses, such as computer storage and e-mailing, but not printing
If one already owns a newer computer, permanent storage on digital media is considerably cheaper than film
Photos may be copied from one digital medium to another without any degradation
Pictures do not need to be scanned before viewing them on a computer
Ability to print photos using a computer and consumer-grade printer
Ability to embed metadata within the image file, such as the time and date of the photograph, model of the camera, shutter speed, flash use, and other similar items, to aid in the reviewing and sorting of photographs. Film cameras have limited ability to handle metadata, though many film cameras can "imprint" a date over a picture by exposing the film to an internal LED array (or other device) which displays the date.
Ability to capture and store hundreds of photographs on the same media device within the digital camera; by contrast, a film camera would require regular changing of film (typically after every 24 or 36 shots)
Many digital cameras now include an AV-out connector (and cable) to allow the reviewing of photographs to an audience using a television
Anti-shake functionality (increasingly common in inexpensive cameras) allow taking sharper hand-held pictures where previously a tripod was required
Ability to change ISO speed settings more conveniently in the middle of shooting, for example when the weather changes from bright sunlight to cloudy. In film photography, film must be unloaded and new film with desired ISO speed loaded.
Smaller sensor format, compared to 35mm film frame, allows for smaller lenses, wider zoom ranges, and greater depth of field.
Ability to use the same device to capture video as well as still images.
Ability to convert the same photo from color to sepia to black & white

Advantages of professional digital cameras

The Golden Gate Bridge retouched for painterly light effects

Immediate image review and deletion is possible; lighting and composition can be assessed immediately, which ultimately conserves storage space.
Faster workflow: Management (colour and file), manipulation and printing tools are more versatile than conventional film processes. However, batch processing of RAW files can be time consuming, even on a fast computer.
Digital manipulation: A digital image can be modified and manipulated much easier and faster than with traditional negative and print methods. The digital image to the right was captured in RAW format, processed and output in 3 different ways from the source RAW file, then merged and further processed for color saturation and other special effects to produce a more dramatic result than was originally captured with the RAW image.

Recent manufacturers such as Nikon and Canon have promoted the adoption of digital single-lens reflex cameras (DSLRs) by photojournalists. Images captured at 2+ megapixels are deemed to be of sufficient quality for small images in newspaper or magazine reproduction. Eight to 24 megapixel images, found in modern digital SLRs, when combined with high-end lenses, can approximate the detail of film prints taken with 35 mm film based SLRs, and the latest 16 megapixel models can produce astoundingly detailed images which are believed to be better than 35mm film images and the majority of medium format cameras.^[6]

Disadvantages of digital cameras

Whereas film cameras can have manual backups for electronic and electrical features, digital cameras are entirely dependent on an electrical supply (usually batteries but sometimes power cord when in 'tethered' mode).
Many digital sensors have less dynamic range than color print film. However, some newer CCDs such as Fuji's Super CCD, which combines diodes of different sensitivity, have improved this issue.
When highlights burn out, they burn to white without details, while film cameras retain a reduced level of detail, as discussed above.
High ISO image noise may manifest as multicolored speckles in digital images, rather than the less-objectionable "grain" of high-ISO film. While this speckling can be removed by noise-reduction software, either in-camera or on a computer, this can have a detrimental effect on image quality as fine detail may be lost in the process.
Aliasing may add patterns to images which do not exist and would not appear in film.
The possibility that in the future certain digital file formats (for example, JPEG) may become obsolete/replaced.
Whereas a traditional film camera uses a fresh piece of film for each shot, dust particles, known as "bunnies", can adhere to the camera sensor (film equivalent) that, for a novice, requires the sensor to be professionally cleaned.

For most consumers in prosperous countries such as the United States and Western Europe, the advantages of digital cameras outweigh their disadvantages. However, some professional photographers still prefer film. Much of the post-shooting work done by a photo lab for film is done by the photographer himself for digital images. Concerns that have been raised by professional photographers include: editing and post-processing of RAW files can take longer than 35mm film, downloading a large number of images to a computer can be time-consuming, shooting in remote sites requires the photographer to carry a number of batteries and add to the load to carry, equipment failure—while all cameras may fail, some film camera problems (e.g., meter or rangefinder problems, failure of only some shutter speeds) can be worked around. As time passes, it is expected that more professional photographers will switch to digital.

In some cases where very high-resolution digital images of good quality are needed it may be advantageous to take large-format film photographs and digitise them. This allows the creation of very large computer files without speed or capacity disadvantages at picture-taking time.^[7]

Equivalent features

Image noise / grain

Noise in a digital camera's image is remarkably similar to film grain in a film camera. At high ISO levels (film speed) the grain/noise becomes more apparent in the final image. Although film ISO levels can be lower than digital ISO levels (25 and 50 respectively), digital settings can be changed quickly according to requirements, while film must be physically replaced and protected from all light during such replacement. Additionally, image noise reduction techniques can be used to remove noise from digital images and film grain is fixed. From an artistic point of view, film grain and image noise may be desirable when creating a specific mood for an image. Modern digital cameras have comparable noise/grain at the same ISO as film cameras. Some digital cameras though, do exhibit a pattern in the digital noise which is not found on film.

Speed of use

Previously digital cameras had a longer start-up delay compared to film cameras, i.e., the delay from when they are turned on until they are ready to take the first shot, but this is no longer the case for modern digital cameras.^{[citation needed]} Similarly, the amount of time needed to write the data for a digital picture to the memory card is now comparable to the amount of time it takes to wind the film on a film camera, at least with modern digital cameras and modern fast memory cards.^{[citation needed]} Both digital cameras and film cameras have a small delay between when the shutter button is pressed and when the picture is taken – this is the time necessary to autofocus the lens and compute and set the exposure. (This shutter delay is practically zero for SLR and the best DSLR cameras.)

Frame rate

The Nikon D3 can take still photographs at 11 frames per second; the fastest film SLR could shoot 10 frames per second. The Nikon F5 is limited to 36 continuous frames (the length of the film) while the Canon EOS-1D Mark III is able to take about 110 high definition JPEG images before its buffer must be cleared and the remaining space on the storage media can be used.

Image longevity

Although digital image data does not degrade (film stock can fade), the media on which the digital images are stored can decay or become corrupt, leading to a loss of image integrity. Film should be stored under archival conditions for maximum longevity; this should not be a problem for digital images as perfect copies can be made and stored elsewhere. Without backup it is easier to lose huge amounts of digital data, for example by accidental deletion of folders, or by failure of a mass storage device. In comparison, each generation of copies of film negatives and transparencies is degraded compared to its parent. Film images can easily be converted to digital (by using a digital film scanner for example) with some possible loss of quality.

Colour reproduction

Colour reproduction (gamut) is dependent on the type and quality of film or sensor used and the quality of the optical system and film processing. Different films and sensors have different color sensitivity; the photographer needs to understand his equipment, the light conditions, and the media used to ensure accurate colour reproduction. Many digital cameras offer RAW format (sensor data) which makes it possible to choose color space in the development stage regardless of camera settings; in effect the scene itself is stored as far as the sensor allows, and can to some extent be "rephotographed" with different color balance, exposure, etc.

A comparison of frame aspect ratios

A typical digital camera's aspect ratio is 1.33 (4:3), the same as today's NTSC or PAL/SECAM TVs or earliest movies. However, a 35 mm picture's aspect ratio is 1.5 (3:2). Several new digital cameras will take photos in either ratio and nearly all digital SLRs take pictures in a 3:2 ratio as they usually use lenses designed for 35 mm film (Olympus and Panasonic digital SLRs are notable exceptions). Some photo labs also offer the option of printing photos on 4:3 ratio paper, as well as the existing 3:2. In 2005 Panasonic launched the first consumer camera with a native aspect ratio of 16:9, matching HDTV. This is similar to a 7:4 aspect ratio, which was a common size for APS film. Different aspect ratios are one of the main reasons consumers have cropping issues when printing digital photos, or film photos as well. Moreover, the majority of digital cameras take an aspect ratio of 4:3 which translates to a size of 4.5" x 6.0". This translates into losing a half an inch when printing on the "standard" size of 4" x 6", an aspect ratio of 3:2. Similar cropping occurs when printing on other sizes as well, i.e., 5"x7", 8"x10",

Digital single-lens reflex camera

Thu, 06 Aug 2009 10:58:16 +0100

Digital single-lens reflex camera

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For more detail, see below.

For timelines of DSLR models, see Canon DSLR cameras, Konica Minolta/Sony DSLR cameras, Nikon DSLR cameras, Olympus DSLR cameras, and Pentax DSLR cameras.

A digital single-lens reflex camera (digital SLR or DSLR) is a digital camera that uses a mechanical mirror system and pentaprism to direct light from the lens to an optical viewfinder on the back of the camera.

The basic operation of a DSLR is as follows: for viewing purposes, the mirror reflects the light coming through the attached lens upwards at a 90 degree angle. It is then reflected twice by the pentaprism, rectifying it for the photographer's eye. During exposure, the mirror assembly swings upward, the aperture narrows (if stopped down, or set smaller than wide open), and a shutter opens, allowing the lens to project light onto the image sensor. A second shutter then covers the sensor, ending the exposure, and the mirror lowers while the shutter resets. The period that the mirror is flipped up is referred to as "viewfinder blackout". A fast-acting mirror and shutter is preferred so as to not delay an action photo.

All of this happens automatically over a period of milliseconds, with cameras designed to do this 3~10 times a second.

DSLRs are often preferred by professional still photographers because they allow an accurate preview of framing close to the moment of exposure, and because DSLRs allow the user to choose from a variety of interchangeable lenses. Most DSLRs also have a function that allows accurate preview of depth of field.

Many professionals also prefer DSLRs for their larger sensors compared to most compact digitals. DSLRs have sensors which are generally closer in size to the traditional film formats that many current professionals started out using. These large sensors allow for similar depths of field and picture angle to film formats.

The term DSLR generally refers to cameras that resemble 35 mm format cameras, although some medium format cameras are technically DSLRs.

[hide]

Brief difference between a DSLR and a digital point and shoot camera

The reflex design scheme is a major difference between a DSLR and an ordinary digital point and shoot camera, which typically exposes the sensor constantly to the light projected by the lens, allowing the camera's screen to be used as an electronic viewfinder.

In contrast, the mirror arrangement in a DSLR usually precludes the ability to view the scene on the liquid crystal display (LCD) before the photograph is taken. However, many newer DSLR models feature live preview, allowing the LCD to be used as a viewfinder in the same way as a normal digicam, although with certain limitations and with the optical viewfinder disabled.

DSLR design principles

Cross-section view of SLR system.
1 - 4-element lens
2 - Reflex mirror
3 - Focal-plane shutter
4 - Sensor
5 - Matte focusing screen
6 - Condenser lens
7 - Pentaprism
8 - Eyepiece

A camera based on the single-lens reflex (SLR) principle uses a mirror to show in a viewfinder the image that will be captured. The cross-section (side-view) of the optical components of an SLR shows how the light passes through the lens assembly (1), is reflected into the pentaprism by the reflex mirror (which must be at an exact 45 degree angle) (2) and is projected on the matte focusing screen (5). Via a condensing lens (6) and internal reflections in the roof pentaprism (7) the image is projected through the eyepiece (8) to the photographer's eye. Focusing is either automatic, activated by pressing half-way on the shutter release or a dedicated AF button, as is mainly the case with an autofocusing film SLR; or manual, where the photographer manually focuses the lens by turning a lens ring on the lens barrel. When an image is photographed, the mirror swings upwards in the direction of the arrow, the focal-plane shutter (3) opens, and the image is projected and captured on the sensor (4), after which actions, the shutter closes, the mirror returns to a critical 45 degree angle, and the diaphragm reopens and the built in drive mechanism retensions the shutter for the next exposure. There is often a ring of soft material around the focusing screen, which helps to both cushion the impact of the mirror slapping up and help seal the mirror box from light entering through the eye piece.^[1] Some high end cameras incorporate a shutter into the eyepiece to further eliminate light that may enter there during long exposures.

Fast phase-detection autofocus

The diagram shown here is an over-simplification in that it omits the sensors used to activate the drive for the autofocus system. Those sensors reside at the bottom of the mirror box. In such a system, the main mirror is slightly translucent in the center, which allows light to pass through it to a secondary mirror which reflects light to the sensors below.

DSLRs typically use a phase detection autofocus system. This method of focus is very fast, and results in less focus "searching", but requires the incorporation of a special sensor into the optical path, so it is usually only used in SLR designs. Digicams that use the main sensor to create a live preview on the LCD or electronic viewfinder must use contrast-detect autofocus instead, which is slower in some implementations.

[edit] DSLR optical viewfinder vs. digital point and shoot camera LCD

Nikon D700 full-frame (FX) digital SLR camera

Depending on the viewing position of the reflex mirror (down or up), the light from the scene can only reach either the viewfinder or the sensor. Therefore, many DSLRs do not currently provide "live preview" (allowing focusing, framing, and depth-of-field preview using the display), a facility that is always available on digicams.

The advantages of an optical viewfinder are that it alleviates eye-strain sometimes caused by electronic view finders (EVF), and that it constantly shows (except during the time for the sensor to be exposed) the exact image that will be exposed because its light is routed directly from the lens itself. Compared to ordinary digital cameras with their LCDs and/or electronic viewfinders the advantage is that there is no time lag in the image; it is always correct as it is being "updated" at the speed of light. This is important for action and/or sports photography, or any other situation where the subject or the camera is moving too quickly. Furthermore, the "resolution" of the viewed image is much better than that provided by an LCD or an electronic viewfinder, which can be important if manual focusing is desired for precise focusing, as would be the case in macro photography and "micro-photography" (with a microscope).

Compared to some low cost cameras that provide an optical viewfinder that uses a small auxiliary lens, the DSLR design has the advantage of being parallax-free; that is, it never provides an off-axis view.

A disadvantage of the DSLR optical viewfinder system is that while it is used it prevents the possibility of using the LCD for viewing and composing the picture before taking it. Some people prefer to compose pictures on the display – for them this has become the de-facto way to use a camera. Electronic viewfinders may also provide a brighter display in low light situations, as the picture can be electronically amplified; conversely, LCDs can be difficult to see in very bright sunlight.

DSLRs with live preview

A fairly recent development in DSLRs is the increased availability of live preview options, which make it possible to use either the optical viewfinder or the LCD when composing the picture (but not both at the same time). This can be an advantage because some people simply prefer to use the display and because in some situations it is not convenient or possible to hold the camera up to one's face to look through the viewfinder. Underwater photography, where the camera is enclosed in a plastic waterproof case, is an example of a situation where composing on the display is preferred. On most DSLRs, a disadvantage when using live preview is that the phase detection autofocus system does not work and the slower contrast system used in non DSLRs must be used.

Olympus introduced the first DSLR with live preview – albeit an atypical design with a fixed lens – the Olympus E-10, in the summer of 2000. Since then other manufacturers have launched DSLR models with live preview.

In late 2008^[update], some DSLRs from Canon, Nikon, Olympus, Panasonic, Leica, Pentax, Samsung and Sony all provide continuous live preview as an option. Additionally, the Fujifilm FinePix S5 Pro^[2] offers 30 seconds of live preview.

Some live preview systems make use of the primary sensor to provide the image on the LCD (which is the way all non-DSLR digicams work), and some systems use a secondary sensor. Possible advantages of using a secondary sensor for live preview is to avoid additional noise that might result from the primary sensor heating up from continuous use, and allowing faster auto-focus.^[3]

A new feature via a separate software package introduced from Breeze Systems in October, 2007, features live view from a distance. The software package is named "DSLR Remote Pro v1.5" and enables support for the Canon EOS 40D and 1D Mark III.^[4]

High Definition DSLRs (HDSLRs)

Introduced in 2008, HDSLRs are DSLRs which, in addition to taking still-photographs, offer a movie-mode capable of recording high definition motion-video. This feature parallels the evolution of compact digital cameras, many of which also offer HD-movie mode. The term HDSLR (High Definition Single Lens Reflex) first came into popular usage in April 2009 about the time of the debut of the ebook entitled HDSLR Nikon D90 by Peter iNova and Uwe Steinmueller.

The first HDSLR, the Nikon D90, captures video at 720p24 (1280x720 resolution at 24 fps) using an APS-sized imager. The more expensive Canon EOS 5D Mark II captures video at 1080p30 using a (35mm) full-size imager. Less than a year after the first HDSLR introduction, HD-movie mode has reached the entry-level models with the Canon EOS 500D (Rebel T1i) and Nikon D5000. The 500D supports both 720p30 and a limited 1080p mode which captures 20 fps. The D5000's movie-mode is comparable to the D90, with a maximum capture-mode of 720p24.

At PMA 2009 (Photo Marketing Association Trade Show) Panasonic gave the first public debut of a new combo-camera offering called the Lumix DMC-GH1, a new generation HDSLR offering greater video flexibility than previous competitors, while using a smaller Four Thirds-sized imager. The GH1 is the first HDSLR to offer full resolution HD (1920x1080) 1080p captured at the 24fps, the standard Academy frame-rate used by the motion picture industry. Also worth noting is that the Panasonic Lumix DMC-GH1 can autofocus while in shooting in movie-mode, a first for an HDSLR, and is currently the only HDSLR to support video-capture at 720p60 (or 720p50, for European models.) The GH1 became available for purchase in Japan in April 2009, and as of June 2009 is available worldwide in limited quantities.

On 05/20/2009, Pentax announced its K-7 HDSLR. It supports video-capture at 30 fps, in both 720p resolution, and an unusual high-resolution video mode of 1536×1024 which matches the 3:2 aspect ratio of the image sensor.

In July 2009, Olympus released the E-P1, which is the smallest and lightest HDSLR currently on the market. The E-P1 records video in 720p30 format.

DSLR lenses

Main articles: Photographic lens and Lenses for SLR and DSLR cameras

The ability to exchange lenses, to select the best lens for the current photographic need, and to allow the attachment of specialized lenses, is a key to the popularity of DSLR cameras.

Nikon Nikkor 18-70mm DX (APS-C) Lens

Lens mounts and lens manufacturers

Interchangeable lenses for SLRs and DSLRs are built to operate correctly with a specific lens mount that is generally unique to each brand. A photographer will often use lenses made by the same manufacturer as the camera body (for example, Canon lenses on a Canon body) although there are also many independent lens manufacturers, such as Sigma,^[5] Tamron,^[6] Tokina,^[7] and Vivitar,^[8] to name a few, that make lenses for a variety of different lens mounts. There are also lens adapters that allow a lens for one lens mount to be used on a camera body with a different lens mount, but with often reduced functionality.

Many lenses are mountable, "diaphragm-and-meter-compatible", on modern DSLRs and on older film SLRs that use the same lens mount. For more information see Mount compatibility across camera generations.

Most DSLR manufacturers have introduced lines of lenses with image circles and focal lengths optimized for the smaller sensors generally offered for existing 35 mm mount DSLRs, mostly in the wide angle range. These lenses tend not to be completely compatible with full frame sensors or 35 mm film.

Several manufacturers produce full-frame digital SLR cameras that allow lenses designed for the 35 mm film frame to operate at their intended angle of view. For more information about the dependence of angle of view on format size, see the article on crop factor.

DSLR design considerations

Pentaprism vs. penta-mirror

Most of the entry level DSLRs use a pentamirror instead of the traditional pentaprism. The pentamirror design is composed mostly of plastic and is lighter and cheaper to produce however the image in the viewfinder is usually darker.

Drawing showing the relative sizes of sensors used in current digital cameras.

Sensor size and image quality

Main article: Image sensor format

Image sensors used in DSLRs come in a range of sizes. The very largest are the ones used in "medium format" cameras, typically via a "digital back" which can be used as an alternative to a film back. Because of the manufacturing costs of these large sensors the price of these cameras is typically over $20,000 as of December 2007^[update].

With the exception of medium format DSLRs, the largest sensors are referred to as "full-frame", and are the same size as 35 mm film (135 film, standard image format 24x36 mm); these sensors are used in quite expensive DSLRs such as the Canon EOS-1Ds Mark III, the Canon EOS 5D Mark II, the Nikon D700, the Nikon D3, the Nikon D3X, and the Sony Alpha 900. Most modern DSLRs use a smaller sensor commonly referred to as APS-C sized, that is, approximately 22 mm × 15 mm, a little smaller than the size of an APS-C film frame, or about 40% of the area of a full-frame sensor. Other sensor sizes found in DSLRs include the Four Thirds System sensor at 26% of full frame, APS-H sensors (used, for example, in the Canon EOS-1D Mark III) at around 61% of full frame, and the Foveon X3 sensor at 33% of full frame.

The sensors used in current DSLRs are much larger than the sensors found in digicam-style cameras, most of which use sensors known as 1/2.5", whose area is only 3% of a full frame sensor. Even high-end digicams such as the Canon PowerShot G9 or the Nikon CoolPix P5000 use sensors that are approximately 5% and 4% of the area of a full frame sensor, respectively. The one current exception is the Sigma DP1, which uses a Foveon X3 sensor.

Leica offers an "S-System" DSLR with a 30x45mm sensor containing 37-million pixels.^[9] This sensor is 56% larger than a full-frame sensor.

There is a connection between sensor size and image quality; in general, a larger sensor provides lower noise, higher sensitivity, and increased latitude and dynamic range. There is also a connection between sensor size and depth of field, with the larger sensor resulting in shallower depth of field.

Table of sensor sizes

The table lists dimensions of typical DSLR sensors.^[10]

Type	Four Thirds	Canon APS-C	Nikon DX	Canon APS-H	35mm / Canon APS-F / Nikon FX	Leica S2	Phase One P 65+
Diagonal (mm)	21.6	26.7	28.4	34.5	43.3	54	67.3
Width (mm)	17.3	22.2	23.6-.7	28.7	36	45	53.9
Height (mm)	13.0	14.8	15.5-.8	19.1	24	30	40.4
Area (mm²)	225	329	366-374	548	864	1350	1773
Crop factor^[11]	2.00	1.62	1.52	1.26	1.0	0.8	0.64

Depth-of-field control

The lenses typically used on DSLRs have a wider range of apertures available to them, ranging from as large as f/1.0 to about f/32. Lenses for digicams rarely have true available aperture sizes much larger than f/2.8 or much smaller than f/5.6.

The f/5.6 limitation is because lens designs of typical small sensor digicams already produce diffraction blur bigger than a few pixels at f/5.6.^[12] Because of digicams' smaller sensors there are a limited number of apertures available that will produce an acceptably sharp image. Many digicams only have a two-stop range of apertures because at settings outside of these the image will become too soft because of limits of lens design at large apertures, or diffraction at smaller apertures. To help extend the exposure range, some digicams will also incorporate an ND filter pack into the aperture mechanism.^[13]

The apertures that digicams have available give much more depth of field than equivalent angles of view on a DSLR. For example a 6 mm lens on a 2/3" sensor digicam has a field of view similar to a 24 mm lens on a 35 mm camera. At an aperture of f/2.8 the digicam (assuming a crop factor of 4) has a similar depth of field to that 35 mm camera set to f/11 – that's a four-stop difference. Put another way, with both cameras at f/2.8 and focused on a subject 1 meter from the camera, and both cameras zoomed to produce the same angle of view (35 mm camera will need to use larger focal length to produce same angle of view from same distance), the digicam might have a depth of field of 2 meters and the larger camera would have a depth of field of 0.3 meters.^[14]^[15]

Angle of view

An APS-C format SLR (left) and a full-frame DSLR (right) show the difference in the size of the image sensors.

The angle of view of a lens depends upon its focal length and the camera's image sensor size; a sensor smaller than 35 mm film format (36 mm × 24 mm frame) gives a narrower angle of view for a lens of a given focal length than a camera equipped with a full-frame (35 mm) sensor. As of 2008, only a few current DSLRs have full-frame sensors, including the Sony α 900, Canon EOS-1Ds Mark III, 5D Mark II, Nikon D3 and Nikon D700. The scarcity of full-frame DSLRs is partly a result of the cost of such large sensors. Medium format size sensors, such as those used in the Mamiya ZD among others, are even larger than full-frame (35 mm) sensors, and capable of even greater resolution, and are correspondingly more expensive.

The impact of sensor size on field of view is referred to as the "crop factor" or "focal length multiplier", which is a factor by which a lens focal length can be multiplied to give the full-frame-equivalent focal length for a lens. Typical APS-C sensors have crop factors of 1.5 to 1.7, so a lens with a focal length of 50 mm will give a field of view equal to that of a 75 mm to 85 mm lens on a 35 mm camera. The smaller sensors of Four Thirds System cameras have a crop factor of 2.0.

While the crop factor of APS-C cameras effectively narrows the angle of view of long-focus (telephoto) lenses, making it easier to take close-up images of distant objects, wide-angle lenses suffer a reduction in their angle of view by the same factor.

DSLRs with "crop" sensor size have slightly more depth-of-field than cameras with 35 mm sized sensors for a given angle of view. The amount of added depth of field for a given focal length can be roughly calculated by multiplying the depth of field by the crop factor. Shallower depth of field is often preferred by professionals for portrait work and to isolate a subject from its background.

Mode dial

Digital SLR cameras, along with most other digital cameras, generally have a mode dial to access standard camera settings or automatic scene-mode settings. Sometimes called a "PASM" dial, they typically provide as minimum Program, Aperture-priority, Shutter-priority, and full Manual modes. Scene modes vary and are inherently less customizable. They often include full-auto, landscape, portrait, action, macro, and night modes, among others. Professional DSLRs seldom contain automatic scene modes because professionals understand their equipment and can quickly adjust the settings to take the image that they want.

Dust reduction systems

Main article: Dust reduction system

The fact that it is possible to change lenses on a DSLR results in the possibility of dust entering the camera body and adhering to the image sensor. This can reduce image quality, and make it necessary to clean the sensor. Various techniques exist including using a cotton swab with various fluids or blowing with compressed air. Some people prefer to clean the sensor themselves and some send the camera in for service.^[16]

A method to prevent dust entering the chamber, by using a "dust cover" filter right behind the lens mount, was pioneered by Sigma in their first DSLR, the Sigma SD9, in 2002.

Olympus pioneered a built-in sensor cleaning facility in their first DSLR that had a sensor exposed to air, the Olympus E-1, in 2003. Other DSLR manufacturers followed suit, and dust reduction systems are becoming common in DSLRs. There is some controversy as to how effective these systems are; see dust reduction system for more information.

Medium format digital

Many medium format roll-film SLRs can accept a digital camera back to turn the camera into a DSLR with very high image resolution and quality (typically 21–60 megapixels as of July 2009). However, the combination is very expensive and bulky, and more suited to still life than to action photography. Another potential disadvantage of medium format digital backs is that there are none currently available (as of early 2008) that incorporate a low-pass (aka optical anti-aliasing filter) except for the Mamiya ZD, which has a removable one. This is done to allow the maximum resolution to be extracted from a given image, but at the cost of moiré.^[17]^[18]

As of 2007 integrated medium formats like the Phase One 645 system^[19], Hasselblad H System^[20] and Leaf AFi^[21] have started to appear.

Unusual features – infrared and ultraviolet photography

On July 13, 2007, FujiFilm announced the FinePix IS Pro, which uses Nikon F-mount lenses. This camera, in addition to having live preview, has the ability to record in the infrared and ultraviolet spectra of light.^[22]

History

On August 25, 1981 Sony unveiled a prototype of the first still video camera, the Sony Mavica. This camera was an analog electronic camera that featured interchangeable lenses and a SLR viewfinder.

At Photokina in 1986, Nikon revealed a prototype analog electronic still SLR camera, the Nikon SVC, a precursor to the digital SLR.^[23] The prototype body shared many features with the N8008.^[23]

In 1991, Kodak released the first commercially available digital SLR, the Kodak DCS-100. It consisted of a modified Nikon F3 SLR body, modified drive unit, and an external storage unit connected via cable. The 1.3 megapixel camera cost approximately US$30,000. This was followed by the Kodak DCS-200 with integrated storage.^[24]

Over the next decade, DSLRs have been released by various companies, including Canon, Nikon, Kodak, Pentax, Olympus, Panasonic, Samsung, Minolta (later Konica Minolta, and whose camera assets were then acquired by Sony), Fujifilm, and Sigma, with higher resolutions and lower prices.

In 1999, Nikon announced the Nikon D1, the first DSLR to truly compete with, and begin to replace, film cameras in the professional photojournalism and sports photography fields. This camera was able to use current autofocus Nikkor lenses available at that time for the Nikon film series cameras, and was also able to utilize the older Nikon and similar, independent mount lenses designed for those cameras. A combination of price, speed, and image quality was the beginning of the end of 35 mm film for these markets.

In January 2000, Fujifilm announced the FinePix S1 Pro, the first DSLR marketed to non-professionals.

In November 2001, Canon released its 4.1 megapixel EOS-1D, the brand's first professional digital body.

In 2003, Canon introduced the 6.3 megapixel EOS 300D SLR camera (known in the United States as the Digital Rebel and in Japan as the Kiss Digital) with an MSRP of US$999, directed at the consumer market. Its popularity encouraged other manufacturers to produce affordable digital SLR cameras, lowering entry costs and allowing more amateur photographers to purchase DSLRs.

Since 2003, the number of megapixels in imaging sensors have increased steadily, with most companies focusing on build quality, high ISO performance, speed of focus, higher frame rates, the elimination of digital 'noise' produced by the imaging sensor, and price reductions to lure new customers.

Market share

As of 2008^[update], DSLR sales are dominated by Canon's and Nikon's offerings. For 2007, Canon edged out Nikon with 41% of worldwide sales to the latter's 40%, followed by Sony and Olympus each with approximately 6% market share.^[25] In the Japanese domestic market, Nikon captured 43.3% to Canon's 39.9%, with Pentax a distant third at 6.3%.^[26]

The duopoly of Canon and Nikon is sometimes referred to as "Canikon" or "Nikanon" in online forums in skeptical challenge to the presumptive acceptance of these manufacturer's cameras as always "the best". Canon and Nikon have used their professional market presence especially persuasively in the sale of entry level offerings to the uninitiated general public who presume that everything from Canon or Nikon is superlative.^{[citation needed]} Online contributors often challenge the "Canikon/Nikanon" supposed superiority when they believe there are superior innovations from the smaller DSLR manufacturers.

The DSLR market is dominated by Japanese companies, including all of the top five manufacturers (Canon, Nikon, Olympus, Pentax, and Sony), as well as Fujifilm, Mamiya, and Sigma. Leica is German, Hasselblad is Swedish, and Samsung is Korean, while the American company Kodak formerly produced DSLRs as well.

Present-day models

Mainstream DSLRs (full-frame or smaller image sensor format) are currently produced by Canon, Fujifilm, Leica, Nikon, Olympus, Panasonic, Pentax, Samsung, Sigma, and Sony. Hasselblad and Mamiya also produce expensive, high-end medium-format DSLRs.

Canon's current EOS digital line includes the

index

Shutter

Shutter

From Wikipedia, the free encyclopedia

Contents

Camera shutters

Focal-plane shutters

Leaf shutters

Diaphragm shutter

Central shutters

Shutter lag

Shutter cycle

Projector shutters

Nature photography

Nature photography

From Wikipedia, the free encyclopedia

Contents

Wildlife Photography

Macro / Texture

Use of Color

Ethics

Macro photography

Macro photography

From Wikipedia, the free encyclopedia

Contents

Equipment

Technical considerations

Depth of field

Lighting

Examples

Landscape photography

Landscape photography

From Wikipedia, the free encyclopedia

Portrait photography

Portrait photography

From Wikipedia, the free encyclopedia

Contents

History

Lighting for portraiture

Three-Point Lighting

The Key light

The Fill light

The Rim light

Butterfly lighting

Accessory lights

The Kicker

Background lights

Other lighting equipment

Styles of portraiture

Digital photography

Digital photography

From Wikipedia, the free encyclopedia

Contents

History

Sensors and storage

Multifunctionality and connectivity

Performance metrics

Pixel counts

Resolution

Dynamic range

Applications and considerations

Sensor size and angle of view

Storage

Digital camera backs

[edit] Comparison with film photography

Advantages of consumer digital cameras

Advantages of professional digital cameras

Disadvantages of digital cameras

Equivalent features

A comparison of frame aspect ratios

Digital single-lens reflex camera

Digital single-lens reflex camera

From Wikipedia, the free encyclopedia

Contents

Brief difference between a DSLR and a digital point and shoot camera

DSLR design principles

Fast phase-detection autofocus

[edit] DSLR optical viewfinder vs. digital point and shoot camera LCD

DSLRs with live preview

High Definition DSLRs (HDSLRs)