Camera
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A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.
Cameras function through a combination of multiple mechanical components and principles. These include exposure control, which regulates the amount of light reaching the sensor or film; the lens, which focuses the light; the viewfinder, which allows the user to preview the scene; and the film or sensor, which captures the image.
Several types of camera exist, each suited to specific uses and offering unique capabilities. Single-lens reflex (SLR) cameras provide real-time, exact imaging through the lens. Large-format and medium-format cameras offer higher image resolution and are often used in professional and artistic photography. Compact cameras, known for their portability and simplicity, are popular in consumer photography. Rangefinder cameras, with separate viewing and imaging systems, were historically widely used in photojournalism. Motion picture cameras are specialized for filming cinematic content, while digital cameras, which became prevalent in the late 20th and early 21st century, use electronic sensors to capture and store images.
The rapid development of smartphone camera technology in the 21st century has blurred the lines between dedicated cameras and multifunctional devices, as the smartphone camera is easier to use, profoundly influencing how society creates, shares, and consumes visual content.
History
[edit]19th century
[edit]Beginning with the use of the camera obscura and transitioning to complex photographic cameras, the evolution of the technology in the 19th century was driven by pioneers like Thomas Wedgwood, Nicéphore Niépce, and Henry Fox Talbot. First using the camera obscura for chemical experiments, they ultimately created cameras specifically for chemical photography, and later reduced the camera's size and optimized lens configurations.
The introduction of the daguerreotype process in 1839 facilitated commercial camera manufacturing, with various producers contributing diverse designs. As camera manufacturing became a specialized trade in the 1850s, designs and sizes were standardized.
The latter half of the century witnessed the advent of dry plates and roll-film, prompting a shift towards smaller and more cost-effective cameras, epitomized by the original Kodak camera, first produced in 1888. This period also saw significant advancements in lens technology and the emergence of color photography, leading to a surge in camera ownership.[1][2][3]
20th century
[edit]The first half of the 20th century saw continued miniaturization and the integration of new manufacturing materials. After World War I, Germany took the lead in camera development, spearheading industry consolidation and producing precision-made cameras. The industry saw significant product launches such as the Leica camera and the Contax, which were enabled by advancements in film and lens designs. Additionally, there was a marked increase in accessibility to cinematography for amateurs with Eastman Kodak's production of the first 16-mm and 8-mm reversal safety films. The World War II era saw a focus on the development of specialized aerial reconnaissance and instrument-recording equipment, even as the overall pace of non-military camera innovation slowed.
In the second half of the century, Japanese manufacturers in particular advanced camera technology. From the introduction of the affordable Ricohflex III TLR in 1952 to the first 35mm SLR with automatic exposure, the Olympus AutoEye in 1960, new designs and features continuously emerged. Electronics became integral to camera design in the 1970s, evident in models like Polaroid's SX-70 and Canon's AE-1.
Transition to digital photography marked the late 20th century, culminating in digital camera sales surpassing film cameras in the United States by 2003. In contrast, the film camera industry in the UK, Western Europe, and the USA declined during this period, while manufacturing continued in the USSR, German Democratic Republic, and China, often mimicking Western designs.[1][2][3]
21st century
[edit]The 21st century witnessed the mass adoption of digital cameras and significant improvements in sensor technology. A major revolution came with the incorporation of cameras into smartphones, making photography a commonplace activity. The century also marked the rise of computational photography, using algorithms and AI to enhance image quality. Features like low-light and HDR photography, optical image stabilization, and depth-sensing became common in smartphone cameras.[4][5][6]
Mechanics
[edit]
Most cameras capture light from the visible light spectrum, while specialized cameras capture other portions of the electromagnetic spectrum, such as infrared.[7]: vii
All cameras use the same basic design: light enters an enclosed box through a converging or convex lens and an image is recorded on a light-sensitive medium.[8] A shutter mechanism controls the length of time that light enters the camera.[9]: 1182–1183
Most cameras also have a viewfinder, which shows the scene to be recorded, along with means to adjust various combinations of focus, aperture and shutter speed.[10]: 4
Exposure control
[edit]Aperture
[edit]
Light enters the camera through an aperture, an opening adjusted by overlapping plates called the aperture ring.[11][12][13] Typically located in the lens,[14] this opening can be widened or narrowed to alter the amount of light that strikes the film or sensor.[11] The size of the aperture can be set manually, by rotating the lens or adjusting a dial or automatically based on readings from an internal light meter.[11]
As the aperture is adjusted, the opening expands and contracts in increments called f-stops.[a][11] The smaller the f-stop, the more light is allowed to enter the lens, increasing the exposure. Typically, f-stops range from f/1.4 to f/32[b] in standard increments: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, and 32.[15] The light entering the camera is halved with each increasing increment.[14]

The wider opening at lower f-stops narrows the range of focus so the background is blurry while the foreground is in focus. This depth of field increases as the aperture closes. A narrow aperture results in a high depth of field, meaning that objects at many different distances from the camera will appear to be in focus.[16] What is acceptably in focus is determined by the circle of confusion, the photographic technique, the equipment in use and the degree of magnification expected of the final image.[17]
Shutter
[edit]The shutter, along with the aperture, is one of two ways to control the amount of light entering the camera. The shutter determines the duration that the light-sensitive surface is exposed to light. The shutter opens, light enters the camera and exposes the film or sensor to light, and then the shutter closes.[14][18]
There are two types of mechanical shutters: the leaf-type shutter and the focal-plane shutter. The leaf-type uses a circular iris diaphragm maintained under spring tension inside or just behind the lens that rapidly opens and closes when the shutter is released.[15]

More commonly, a focal-plane shutter is used.[14] This shutter operates close to the film plane and employs metal plates or cloth curtains with an opening that passes across the light-sensitive surface. The curtains or plates have an opening that is pulled across the film plane during exposure. The focal-plane shutter is typically used in single-lens reflex (SLR) cameras, since covering the film (rather than blocking the light passing through the lens) allows the photographer to view the image through the lens at all times, except during the exposure itself. Covering the film also facilitates removing the lens from a loaded camera, as many SLRs have interchangeable lenses.[11][15]
A digital camera may use a mechanical or electronic shutter, the latter of which is common in smartphone cameras. Electronic shutters either record data from the entire sensor simultaneously (a global shutter) or record the data line by line across the sensor (a rolling shutter).[11] In movie cameras, a rotary shutter opens and closes in sync with the advancement of each frame of film.[11][19]
The duration for which the shutter is open is called the shutter speed or exposure time. Typical exposure times can range from one second to 1/1,000 of a second, though longer and shorter durations are not uncommon. In the early stages of photography, exposures were often several minutes long. These long exposure times often resulted in blurry images, as a single object is recorded in multiple places across a single image for the duration of the exposure. To prevent this, shorter exposure times can be used. Very short exposure times can capture fast-moving action and eliminate motion blur.[20][15][11][14] However, shorter exposure times require more light to produce a properly exposed image, so shortening the exposure time is not always possible.
Like aperture settings, exposure times increment in powers of two. The two settings determine the exposure value (EV), a measure of how much light is recorded during the exposure. There is a direct relationship between the exposure times and aperture settings so that if the exposure time is lengthened one step, but the aperture opening is also narrowed one step, then the amount of light that contacts the film or sensor is the same.[14]
Light meter
[edit]
In most modern cameras, the amount of light entering the camera is measured using a built-in light meter or exposure meter.[c] Taken through the lens (called TTL metering), these readings are taken using a panel of light-sensitive semiconductors.[12] They are used to calculate optimal exposure settings. These settings are typically determined automatically as the reading is used by the camera's microprocessor. The reading from the light meter is incorporated with aperture settings, exposure times, and film or sensor sensitivity to calculate the optimal exposure.[d]
Light meters typically average the light in a scene to 18% middle gray. More advanced cameras are more nuanced in their metering—weighing the center of the frame more heavily (center-weighted metering), considering the differences in light across the image (matrix metering), or allowing the photographer to take a light reading at a specific point within the image (spot metering).[16][20][21][11]
Lens
[edit]A camera lens is an assembly of multiple optical elements, typically made from high-quality glass.[22] Its primary function is to focus light onto a camera's film or digital sensor, thereby producing an image.[12] This process significantly influences image quality, the overall appearance of the photo, and which parts of the scene are brought into focus.[22]
A camera lens is constructed from a series of lens elements, small pieces of glass arranged to form an image accurately on the light-sensitive surface. Each element is designed to reduce optical aberrations, or distortions, such as chromatic aberration (a failure of the lens to focus all colors at the same point), vignetting (darkening of image corners), and distortion (bending or warping of the image). The degree of these distortions can vary depending on the subject of the photo.[22]
The focal length of the lens, measured in millimeters, plays a critical role as it determines how much of the scene the camera can capture and how large the objects appear. Wide-angle lenses provide a broad view of the scene, while telephoto lenses capture a narrower view but magnify the objects. The focal length also influences the ease of taking clear pictures handheld, with longer lengths making it more challenging to avoid blur from small camera movements.[22]
Two primary types of lenses include zoom and prime lenses. A zoom lens allows for changing its focal length within a certain range, providing the convenience of adjusting the scene capture without moving the camera or changing the lens. A prime lens, in contrast, has a fixed focal length. While less flexible, prime lenses often provide superior image quality, are typically lighter, and perform better in low light.[22]
Focus involves adjusting the lens elements to sharpen the image of the subject at various distances.[23] The focus is adjusted through the focus ring on the lens, which moves the lens elements closer or further from the sensor. Autofocus is a feature included in many lenses, which uses a motor within the lens to adjust the focus quickly and precisely based on the lens's detection of contrast or phase differences. This feature can be enabled or disabled using switches on the lens body.[12]
Advanced lenses may include mechanical image stabilization systems that move lens elements or the image sensor itself to counteract camera shake, especially beneficial in low-light conditions or at slow shutter speeds.[22] Lens hoods, filters, and caps are accessories used alongside a lens to enhance image quality, protect the lens, or achieve specific effects.[12]
Viewfinder
[edit]The camera's viewfinder provides a real-time approximation of what will be captured by the sensor or film. It assists photographers in aligning, focusing, and adjusting the composition, lighting, and exposure of their shots, enhancing the accuracy of the final image.[14]
Viewfinders fall into two primary categories: optical and electronic. Optical viewfinders, commonly found in Single-Lens Reflex (SLR) cameras, use a system of mirrors or prisms to reflect light from the lens to the viewfinder, providing a clear, real-time view of the scene. Electronic viewfinders, typical in mirrorless cameras, project an electronic image onto a small display, offering a wider range of information such as live exposure previews and histograms, albeit at the cost of potential lag and higher battery consumption.[11] Specialized viewfinder systems exist for specific applications, like subminiature cameras for spying or underwater photography.[18]
Parallax error, resulting from misalignment between the viewfinder and lens axes, can cause inaccurate representations of the subject's position. While negligible with distant subjects, this error becomes prominent with closer ones. Some viewfinders incorporate parallax-compensating devices to mitigate that issue.[15]
Film and sensor
[edit]Image capture in a camera occurs when light strikes a light-sensitive surface: photographic film or a digital sensor.[18] Housed within the camera body, the film or sensor records the light's pattern when the shutter is briefly opened to allow light to pass during the exposure.[16]
Loading film into a film camera is a manual process. The film, typically housed in a cartridge, is loaded into a designated slot in the camera. One end of the film strip, the film leader, is manually threaded onto a take-up spool. Once the back of the camera is closed, the film advance lever or knob is used to ensure the film is correctly placed. The photographer then winds the film, either manually or automatically depending on the camera, to position a blank portion of the film in the path of the light. Each time a photo is taken, the film advance mechanism moves the exposed film out of the way, bringing a new, unexposed section of film into position for the next shot.[16]
The film must be advanced after each shot to prevent double exposure — where the same section of film is exposed to light twice, resulting in overlapped images. Once all frames on the film roll have been exposed, the film is rewound back into the cartridge, ready to be removed from the camera for developing.[18]
In digital cameras, sensors typically comprise Charge-Coupled Devices (CCDs) or Complementary Metal-Oxide-Semiconductor (CMOS) chips, both of which convert incoming light into electrical charges to form digital images.[11] CCD sensors, though power-intensive, are recognized for their excellent light sensitivity and image quality. Conversely, CMOS sensors offer individual pixel readouts, leading to less power consumption and faster frame rates, with their image quality having improved significantly over time.
Digital cameras convert light into electronic data that can be directly processed and stored. The volume of data generated is dictated by the sensor's size and properties, necessitating storage media such as Compact Flash, Memory Sticks, and SD (Secure Digital) cards.[18] Modern digital cameras typically feature a built-in monitor for immediate image review and adjustments.[11] Digital images are also more readily handled and manipulated by computers, offering a significant advantage in terms of flexibility and post-processing potential over traditional film.[18]
Camera accessories
[edit]Flash
[edit]A flash provides a short burst of bright light during exposure and is a commonly used artificial light source in photography. Most modern flash systems use a battery-powered high-voltage discharge through a gas-filled tube to generate bright light for a very short time (1/1,000 of a second or less).[e][21]
Many flash units measure the light reflected from the flash to help determine the appropriate duration of the flash. When the flash is attached directly to the camera—typically in a slot at the top of the camera (the flash shoe or hot shoe) or through a cable—activating the shutter on the camera triggers the flash, and the camera's internal light meter can help determine the duration of the flash.[21][16]
Additional flash equipment can include a light diffuser, mount and stand, reflector, soft box, trigger and cord.
Other accessories
[edit]Accessories for cameras are mainly used for care, protection, special effects, and functions.
- Lens hood: used on the end of a lens to block the sun or other light source to prevent glare and lens flare (see also matte box).
- Lens cap: covers and protects the camera lens when not in use.
- Lens adapter: allows the use of lenses other than those for which the camera was designed.
- Filter: allows artificial colors or changes light density.
- Lens extension tube: allows close focus in macro photography.
- Care and protection: including camera case and cover, maintenance tools, and screen protector.
- Camera monitor: provides an off-camera view of the composition with a brighter and more colorful screen, and typically exposes more advanced tools such as framing guides, focus peaking, zebra stripes, waveform monitors (oftentimes as an "RGB parade"), vectorscopes and false color to highlight areas of the image critical to the photographer.
- Tripod: primarily used for keeping the camera steady while recording video, doing a long exposure, and time-lapse photography.
- Microscope adapter: used to connect a camera to a microscope to photograph what the microscope is examining.
- Cable release: used to remotely control the shutter using a remote shutter button that can be connected to the camera via a cable. It can be used to lock the shutter open for the desired period, and it is also commonly used to prevent the camera shake from pressing the built-in camera shutter button.
- Dew shield: prevents moisture build-up on the lens.
- UV filter: can protect the front element of a lens from scratches, cracks, smudges, dirt, dust, and moisture while keeping a minimum impact on image quality.
- Battery and sometimes a charger.
Large format cameras use special equipment that includes a magnifier loupe, view finder, angle finder, and focusing rail/truck. Some professional SLRs can be provided with interchangeable finders for eye-level or waist-level focusing, focusing screens, eyecup, data backs, motor-drives for film transportation or external battery packs.
Primary types
[edit]Single-lens reflex (SLR) camera
[edit]
In photography, the single-lens reflex camera (SLR) is provided with a mirror to redirect light from the lens to the viewfinder prior to releasing the shutter for composing and focusing an image. When the shutter is released, the mirror swings up and away, allowing the exposure of the photographic medium, and instantly returns after the exposure is finished. No SLR camera before 1954 had this feature, although the mirror on some early SLR cameras was entirely operated by the force exerted on the shutter release and only returned when the finger pressure was released.[24][25] The Asahiflex II, released by Japanese company Asahi (Pentax) in 1954, was the world's first SLR camera with an instant return mirror.[26]
In the single-lens reflex camera, the photographer sees the scene through the camera lens. This avoids the problem of parallax which occurs when the viewfinder or viewing lens is separated from the taking lens. Single-lens reflex cameras have been made in several formats including sheet film 5x7" and 4x5", roll film 220/120 taking 8,10, 12, or 16 photographs on a 120 roll, and twice that number of a 220 film. These correspond to 6x9, 6x7, 6x6, and 6x4.5 respectively (all dimensions in cm). Notable manufacturers of large format and roll film SLR cameras include Bronica, Graflex, Hasselblad, Seagull, Mamiya and Pentax. However, the most common format of SLR cameras has been 35 mm and subsequently the migration to digital SLR cameras, using almost identical sized bodies and sometimes using the same lens systems.
Almost all SLR cameras use a front-surfaced mirror in the optical path to direct the light from the lens via a viewing screen and pentaprism to the eyepiece. At the time of exposure, the mirror is flipped up out of the light path before the shutter opens. Some early cameras experimented with other methods of providing through-the-lens viewing, including the use of a semi-transparent pellicle as in the Canon Pellix[27] and others with a small periscope such as in the Corfield Periflex series.[28]
Large-format camera
[edit]The large-format camera, taking sheet film, is a direct successor of the early plate cameras and remained in use for high-quality photography and technical, architectural, and industrial photography. There are three common types: the view camera, with its monorail and field camera variants, and the press camera. They have extensible bellows with the lens and shutter mounted on a lens plate at the front. Backs taking roll film and later digital backs are available in addition to the standard dark slide back. These cameras have a wide range of movements allowing very close control of focus and perspective. Composition and focusing are done on view cameras by viewing a ground-glass screen which is replaced by the film to make the exposure; they are suitable for static subjects only and are slow to use.
Plate camera
[edit]The earliest cameras produced in significant numbers were plate cameras, using sensitized glass plates. Light entered a lens mounted on a lens board which was separated from the plate by extendible bellows. There were simple box cameras for glass plates but also single-lens reflex cameras with interchangeable lenses and even for color photography (Autochrome Lumière). Many of these cameras had controls to raise, lower, and tilt the lens forwards or backward to control perspective.
Focusing of these plate cameras was by the use of a ground glass screen at the point of focus. Because lens design only allowed rather small aperture lenses, the image on the ground glass screen was faint and most photographers had a dark cloth to cover their heads to allow focusing and composition to be carried out more quickly. When focus and composition were satisfactory, the ground glass screen was removed, and a sensitized plate was put in its place protected by a dark slide. To make the exposure, the dark decline was carefully slid out and the shutter opened, and then closed and the dark fall replaced.
Glass plates were later replaced by sheet film in a dark slide for sheet film; adapter sleeves were made to allow sheet film to be used in plate holders. In addition to the ground glass, a simple optical viewfinder was often fitted.
Medium-format camera
[edit]Medium-format cameras have a film size between the large-format cameras and smaller 35 mm cameras.[29] Typically these systems use 120 or 220 roll film.[30] The most common image sizes are 6×4.5 cm, 6×6 cm and 6×7 cm; the older 6×9 cm is rarely used. The designs of this kind of camera show greater variation than their larger brethren, ranging from monorail systems through the classic Hasselblad model with separate backs, to smaller rangefinder cameras. There are even compact amateur cameras available in this format.
Twin-lens reflex camera
[edit]
Twin-lens reflex cameras used a pair of nearly identical lenses: one to form the image and one as a viewfinder.[31] The lenses were arranged with the viewing lens immediately above the taking lens. The viewing lens projects an image onto a viewing screen which can be seen from above. Some manufacturers such as Mamiya also provided a reflex head to attach to the viewing screen to allow the camera to be held to the eye when in use. The advantage of a TLR was that it could be easily focused using the viewing screen and that under most circumstances the view seen on the viewing screen was identical to that recorded on film. At close distances, however, parallax errors were encountered, and some cameras also included an indicator to show what part of the composition would be excluded.
Some TLRs had interchangeable lenses, but as these had to be paired lenses, they were relatively heavy and did not provide the range of focal lengths that the SLR could support. Most TLRs used 120 or 220 films; some used the smaller 127 films.
Compact cameras
[edit]Instant camera
[edit]
After exposure, every photograph is taken through pinch rollers inside the instant camera. Thereby the developer paste contained in the paper 'sandwich' is distributed on the image. After a minute, the cover sheet just needs to be removed and one gets a single original positive image with a fixed format. With some systems, it was also possible to create an instant image negative, from which then could be made copies in the photo lab. The ultimate development was the SX-70 system of Polaroid, in which a row of ten shots – engine driven – could be made without having to remove any cover sheets from the picture. There were instant cameras for a variety of formats, as well as adapters for instant film use in medium- and large-format cameras.
Subminiature camera
[edit]
Subminiature cameras were first produced in the twentieth century and use film significantly smaller than 35mm. The expensive 8×11mm Minox, the only type of camera produced by the company from 1937 to 1976, became very widely known and was often used for espionage (the Minox company later also produced larger cameras). Later inexpensive subminiatures were made for general use, some using rewound 16 mm cine film. Image quality with these small film sizes was limited.
Folding camera
[edit]The introduction of films enabled the existing designs for plate cameras to be made much smaller and for the baseplate to be hinged so that it could be folded up, compressing the bellows. These designs were very compact and small models were dubbed vest pocket cameras. One of the smallest and best-selling cameras was the Vest Pocket Kodak, sold in two generations between 1912 and 1934. Folding roll film cameras were preceded by folding plate cameras, more compact than other designs.
Box camera
[edit]Box cameras were introduced as budget-level cameras and had few if any controls. The original box Brownie models had a small reflex viewfinder mounted on the top of the camera and had no aperture or focusing controls and just a simple shutter. Later models such as the Brownie 127 had larger direct view optical viewfinders together with a curved film path to reduce the impact of deficiencies in the lens.
Rangefinder camera
[edit]
As camera lens technology developed and wide aperture lenses became more common, rangefinder cameras were introduced to make focusing more precise. Early rangefinders had two separate viewfinder windows, one of which is linked to the focusing mechanisms and moved right or left as the focusing ring is turned. The two separate images are brought together on a ground glass viewing screen. When vertical lines in the object being photographed meet exactly in the combined image, the object is in focus. A normal composition viewfinder is also provided. Later the viewfinder and rangefinder were combined. Many rangefinder cameras had interchangeable lenses, each lens requiring its range- and viewfinder linkages.
Rangefinder cameras were produced in half- and full-frame 35 mm and roll film (medium format).
Motion picture cameras
[edit]A movie camera or a video camera operates similarly to a still camera, except it records a series of static images in rapid succession, commonly at a rate of 24 frames per second. When the images are combined and displayed in order, the illusion of motion is achieved.[32]: 4
Cameras that capture many images in sequence are known as movie cameras or as cine cameras in Europe; those designed for single images are still cameras. However, these categories overlap as still cameras are often used to capture moving images in special effects work and many modern cameras can quickly switch between still and motion recording modes.
A ciné camera or movie camera takes a rapid sequence of photographs on an image sensor or strips of film. In contrast to a still camera, which captures a single snapshot at a time, the ciné camera takes a series of images, each called a frame, through the use of an intermittent mechanism.
The frames are later played back in a ciné projector at a specific speed, called the frame rate (number of frames per second). While viewing, a person's visual system merges the separate pictures to create the illusion of motion. The first ciné camera was built around 1888 and by 1890 several types were being manufactured. The standard film size for ciné cameras was quickly established as 35mm film and this remained in use until the transition to digital cinematography. Other professional standard formats include 70 mm film and 16 mm film whilst amateur filmmakers used 9.5 mm film, 8 mm film, or Standard 8 and Super 8 before the move into digital format.
The size and complexity of ciné cameras vary greatly depending on the uses required of the camera. Some professional equipment is very large and too heavy to be handheld whilst some amateur cameras were designed to be very small and light for single-handed operation.
Professional video camera
[edit]
A professional video camera (often called a television camera even though the use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). Originally developed for use in television studios, they are now also used for music videos, direct-to-video movies, corporate and educational videos, marriage videos, etc.
These cameras earlier used vacuum tubes and later electronic image sensors.
Camcorders
[edit]
A camcorder is an electronic device combining a video camera and a video recorder. Although marketing materials may use the colloquial term "camcorder", the name on the package and manual is often "video camera recorder". Most devices capable of recording video are camera phones and digital cameras primarily intended for still pictures; the term "camcorder" is used to describe a portable, self-contained device, with video capture and recording its primary function.
Digital camera
[edit]
A digital camera (or digicam) is a camera that encodes digital images and videos and stores them for later reproduction.[33] They typically use semiconductor image sensors.[34] Most cameras sold today are digital,[35] and they are incorporated into many devices ranging from mobile phones (called camera phones) to vehicles.
Digital and film cameras share an optical system, typically using a lens of variable aperture to focus light onto an image pickup device.[36] The aperture and shutter admit the correct amount of light to the imager, just as with film but the image pickup device is electronic rather than chemical. However, unlike film cameras, digital cameras can display images on a screen immediately after being captured or recorded, and store and delete images from memory. Most digital cameras can also record moving videos with sound. Some digital cameras can crop and stitch pictures & perform other elementary image editing.
Consumers adopted digital cameras in the 1990s. Professional video cameras transitioned to digital around the 2000s–2010s. Finally, movie cameras transitioned to digital in the 2010s.
The first camera using digital electronics to capture and store images was developed by Kodak engineer Steven Sasson in 1975. He used a charge-coupled device (CCD) provided by Fairchild Semiconductor, which provided only 0.01 megapixels to capture images. Sasson combined the CCD device with movie camera parts to create a digital camera that saved black and white images onto a cassette tape.[37]: 442 The images were then read from the cassette and viewed on a TV monitor.[38]: 225 Later, cassette tapes were replaced by flash memory.
In 1986, Japanese company Nikon introduced an analog-recording electronic single-lens reflex camera, the Nikon SVC.[39]

The first full-frame digital SLR cameras were developed in Japan from around 2000 to 2002: the MZ-D by Pentax,[40] the N Digital by Contax's Japanese R6D team,[41] and the EOS-1Ds by Canon.[42] Gradually in the 2000s, the full-frame DSLR became the dominant camera type for professional photography.[citation needed]
On most digital cameras a display, often a liquid crystal display (LCD), permits the user to view the scene to be recorded and settings such as ISO speed, exposure, and shutter speed.[10]: 6–7 [43]: 12
Camera phone
[edit]
In 2000, Sharp introduced the world's first digital camera phone, the J-SH04 J-Phone, in Japan.[44] By the mid-2000s, higher-end cell phones had an integrated digital camera, and by the beginning of the 2010s, almost all smartphones had an integrated digital camera.
See also
[edit]Footnotes
[edit]- ^ These f-stops are also referred to as f-numbers, stop numbers, steps or stops. The f-number is the focal length of the lens divided by the diameter of the effective aperture.
- ^ Theoretically, they can extend to f/64 or higher.[13]
- ^ Some photographers use handheld exposure meters independent of the camera and use the readings to manually set the exposure settings on the camera.[21]
- ^ Film canisters typically contain a DX code that can be read by modern cameras so that the camera's computer knows the sensitivity of the film, the ISO.[14]]
- ^ The older type of disposable flashbulb uses an aluminum or zirconium wire in a glass tube filled with oxygen. During the exposure, the wire is burned away, producing a bright flash.[21]
References
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- ^ a b Lagasse, Paul, ed. (2018). "camera". The Columbia Encyclopedia (8 ed.). Columbia University Press.
- ^ a b The Focal encyclopedia of photography: digital imaging, theory and applications history and science. Michael R. Peres (ed.) (4th ed.). Amsterdam: Elsevier. 2007. ISBN 978-0-240-80740-9.
{{cite book}}: CS1 maint: others (link) - ^ "A snapshot history of digital camera technology". VentureBeat. 26 June 2014. Archived from the original on 10 November 2023. Retrieved 5 July 2023.
- ^ "Timeline: The history of digital cameras". Digital Spy. 19 August 2014. Archived from the original on 5 July 2023. Retrieved 5 July 2023.
- ^ "History of digital cameras: From '70s prototypes to iPhone and Galaxy's everyday wonders". CNET. Archived from the original on 8 April 2023. Retrieved 5 July 2023.
- ^ Gustavson, Todd (2009). Camera: a history of photography from daguerreotype to digital. New York: Sterling Publishing Co., Inc. ISBN 978-1-4027-5656-6.
- ^ "camera design | designboom.com". designboom | architecture & design magazine. Archived from the original on 18 September 2021. Retrieved 18 September 2021.
- ^ Young, Hugh D.; Freedman, Roger A.; Ford, A. Lewis (2008). Sears and Zemansky's University Physics (12 ed.). San Francisco, California: Pearson Addison-Wesley. ISBN 978-0-321-50147-9.
- ^ a b London, Barbara; Upton, John; Kobré, Kenneth; Brill, Betsy (2002). Photography (7 ed.). Upper Saddle River, New Jersey: Prentice Hall. ISBN 978-0-13-028271-2.
- ^ a b c d e f g h i j k l Columbia University (2018). "camera". In Paul Lagasse (ed.). The Columbia Encyclopedia (8 ed.). Columbia University Press.
- ^ a b c d e "How Cameras Work". How Stuff Works. 21 March 2001. Archived from the original on 14 December 2019. Retrieved 13 December 2019.
- ^ a b Laney, Dawn A. ..BA, MS, CGC, CCRC. “Camera Technologies.” Salem Press Encyclopedia of Science, June 2020. Accessed 6 February 2022.
- ^ a b c d e f g h Lynne Warren, ed. (2006). "Camera: An Overview". Encyclopedia of twentieth-century photography. New York: Routledge. ISBN 978-1-57958-393-4.
- ^ a b c d e "technology of photography". Britannica Academic. Archived from the original on 10 November 2023. Retrieved 13 December 2019.
- ^ a b c d e Lynne Warren, ed. (2006). "Camera: 35 mm". Encyclopedia of twentieth-century photography. New York: Routledge. ISBN 978-1-57958-393-4.
- ^ The British Journal Photographic Almanac. Henry Greenwood and Co. Ltd. 1956. pp. 468–471.
- ^ a b c d e f Rose, B (2007). "The Camera Defined". The Focal Encyclopedia of Photography. Elsevier. pp. 770–771. doi:10.1016/B978-0-240-80740-9.50152-5. ISBN 978-0-240-80740-9. Archived from the original on 14 December 2019. Retrieved 12 December 2019.
- ^ "Motion-picture camera". Encyclopedia Britannica. Retrieved 12 December 2019.[dead link]
- ^ a b "Camera". World Encyclopedia. Philip's. 2004. ISBN 978-0-19-954609-1. Retrieved 12 December 2019.
- ^ a b c d e "camera". Britannica Academic. Archived from the original on 10 November 2023. Retrieved 12 December 2019.
- ^ a b c d e f "Understanding Camera Lenses". Cambridge in Color. Archived from the original on 19 June 2023. Retrieved 13 December 2019.
- ^ Adams, Ansel; Baker, Robert (1980). The camera. Boston: Little, Brown. ISBN 978-0-8212-1092-5.
- ^ Roger Hicks (1984). A History of the 35 mm Still Camera. Focal Press, London & Boston. p. 137. ISBN 978-0-240-51233-4.
- ^ Rudolph Lea (1993). Register of 35 mm SLR cameras. Wittig Books, Hückelhoven. p. 23. ISBN 978-3-88984-130-8.
- ^ Michael R. Peres (2013), The Focal Encyclopedia of Photography, p. 779, Taylor & Francis
- ^ "Canon Pellix Camera". Photography in Malaysia. Archived from the original on 16 October 2013.
- ^ Parker, Bev. "Corfield Cameras – The Periflex Era". Wolverhampton Museum of Industry. Archived from the original on 22 October 2013. Retrieved 22 October 2013.
- ^ Wildi, Ernst (2001). The medium format advantage (2nd ed.). Boston: Focal Press. ISBN 978-1-4294-8344-5. OCLC 499049825.
- ^ The manual of photography. Elizabeth Allen, Sophie Triantaphillidou (10th ed.). Oxford: Elsevier/Focal Press. 2011. ISBN 978-0-240-52037-7. OCLC 706802878.
{{cite book}}: CS1 maint: others (link) - ^ Burrows, Paul (13 September 2021). "The rise and fall of the TLR: why the twin-lens reflex camera is a real classic". Digital Camera World. Future US Inc. Archived from the original on 27 December 2021. Retrieved 27 December 2021.
- ^ Ascher, Steven; Pincus, Edward (2007). The Filmmaker's Handbook: A Comprehensive Guide for the Digital Age (3 ed.). New York: Penguin Group. ISBN 978-0-452-28678-8.
- ^ Farlex Inc: definition of digital camera at the Free Dictionary Archived 9 December 2014 at the Wayback Machine; retrieved 7 September 2013
- ^ Williams, J. B. (2017). The Electronics Revolution: Inventing the Future. Springer. pp. 245–8. ISBN 978-3-319-49088-5. Archived from the original on 10 November 2023. Retrieved 26 November 2019.
- ^ Musgrove, Mike (12 January 2006). "Nikon Says It's Leaving Film-Camera Business". Washington Post. Archived from the original on 13 October 2008. Retrieved 23 February 2007.
- ^ MakeUseOf: How does a Digital Camera Work Archived 4 December 2017 at the Wayback Machine; retrieved 7 September 2013
- ^ Gustavson, Todd (1 November 2011). 500 Cameras: 170 Years of Photographic Innovation. Toronto, Ontario: Sterling Publishing, Inc. ISBN 978-1-4027-8086-8.
- ^ Hitchcock, Susan (20 September 2011). Hitchcock, Susan Tyler (ed.). National Geographic complete photography. Washington, D.C.: National Geographic Society. ISBN 978-1-4351-3968-8.
- ^ Nikon SLR-type digital cameras Archived 9 August 2011 at the Wayback Machine, Pierre Jarleton
- ^ The long, difficult road to Pentax full-frame The long, difficult road to Pentax full-frame Archived 4 July 2017 at the Wayback Machine, Digital Photography Review
- ^ British Journal of Photography, Issues 7410-7422, 2003, p. 2
- ^ Canon EOS-1Ds, 11 megapixel full-frame CMOS Archived 26 January 2021 at the Wayback Machine, Digital Photography Review
- ^ Burian, Peter; Caputo, Robert (2003). National Geographic photography field guide (2 ed.). Washington, D.C.: National Geographic Society. ISBN 978-0-7922-5676-2.
- ^ "Evolution of the Camera phone: From Sharp J-SH04 to Nokia 808 Pureview". Hoista.net. 28 February 2012. Archived from the original on 31 July 2013. Retrieved 21 June 2013.
Further reading
[edit]- Ascher, Steven; Pincus, Edward (2007). The Filmmaker's Handbook: A Comprehensive Guide for the Digital Age (3 ed.). New York: Penguin Group. ISBN 978-0-452-28678-8.
- Frizot, Michel (January 1998). "Light machines: On the threshold of invention". In Michel Frizot (ed.). A New History of Photography. Koln, Germany: Konemann. ISBN 978-3-8290-1328-4.
- Gernsheim, Helmut (1986). A Concise History of Photography (3 ed.). Mineola, New York: Dover Publications, Inc. ISBN 978-0-486-25128-8.
- Hirsch, Robert (2000). Seizing the Light: A History of Photography. New York: McGraw-Hill Companies, Inc. ISBN 978-0-697-14361-7.
- Hitchcock, Susan Tyler (20 September 2011). Hitchcock, Susan Tyler (ed.). National Geographic complete photography. Washington, D.C.: National Geographic Society. ISBN 978-1-4351-3968-8.
- Johnson, William S.; Rice, Mark; Williams, Carla (2005). Therese Mulligan; David Wooters (eds.). A History of Photography. Los Angeles, California: Taschen America. ISBN 978-3-8228-4777-0.
- Spira, S.F.; Lothrop, Easton S. Jr.; Spira, Jonathan B. (2001). The History of Photography as Seen Through the Spira Collection. New York: Aperture. ISBN 978-0-89381-953-8.
- Starl, Timm (January 1998). "A New World of Pictures: The Daguerreotype". In Michel Frizot (ed.). A New History of Photography. Koln, Germany: Konemann. ISBN 978-3-8290-1328-4.
- Wenczel, Norma (2007). "Part I – Introducing an Instrument" (PDF). In Wolfgang Lefèvre (ed.). The Optical Camera Obscura II Images and Texts. Max Planck Institute for the History of Science. pp. 13–30. Archived from the original (PDF) on 2 April 2012.
{{cite book}}:|work=ignored (help)
External links
[edit]Camera
View on GrokipediaFundamentals
Definition and Purpose
A camera is an optical instrument designed to capture and record permanent images by focusing light from a scene onto a light-sensitive surface, such as photographic film or an electronic sensor.[11] This process creates a visual representation of the subject, allowing for the preservation and reproduction of moments or phenomena that would otherwise be transient.[12] The term "camera" derives from the Latin phrase camera obscura, meaning "dark chamber" or "dark room," referring to an early optical device that projected images through a small aperture into a darkened enclosure.[13] Over time, this etymological root evolved to encompass modern devices that perform a similar light-capturing function in a compact, portable form.[14] Cameras serve diverse primary purposes, including still photography for artistic expression and documentation, motion picture recording to capture sequential images for video and film, scientific imaging to analyze natural and experimental phenomena, and surveillance for monitoring and security applications.[15][16][17][18] In essence, these applications enable the recording of visual information across personal, professional, and analytical contexts. At its core, a camera operates on the principle of directing light through an aperture or lens to form an image on the recording medium; this can be achieved via a simple pinhole for basic projection or a converging lens for sharper focus.[19] The focused light then exposes the medium, chemically developing an image in analog systems or generating digital signals in electronic ones, thereby converting optical input into a durable record.[20]Image Formation Principles
The fundamental principle of image formation in cameras is exemplified by the camera obscura, where light from an external scene passes through a small aperture into a darkened enclosure, projecting an inverted image onto the opposite surface due to the straight-line propagation of light rays.[21] This pinhole effect creates a real, though dim and somewhat blurred, image by restricting light to single rays from each point in the scene, avoiding the need for focusing elements while inherently inverting the image top-to-bottom and left-to-right.[21] To improve brightness and sharpness, modern cameras employ lenses, which use refraction to bend incoming light rays and converge them to form a focused real image on the sensor or film plane.[22] The refraction occurs at the curved glass-air interfaces of the lens, following Snell's law, where the lens's shape—typically convex for converging lenses—directs parallel rays from distant objects to intersect at a common focal point.[22] This focused image is also inverted, similar to the camera obscura, but with greater light collection efficiency. The relationship between object distance , image distance , and focal length is governed by the thin lens formula:Historical Development
Pre-19th Century Origins
The earliest conceptual foundations of the camera trace back to ancient observations of optical phenomena that prefigured the camera obscura, a darkened enclosure where light passing through a small aperture projects an inverted image of the external scene onto an opposite surface. In the 4th century BCE, the Greek philosopher Aristotle noted the projection of crescent-shaped images of a partially eclipsed sun onto the ground through gaps in foliage, demonstrating an intuitive grasp of pinhole imaging principles without a constructed device. This natural occurrence served as an early precursor to controlled optical projections, highlighting how light rays converge to form images.[27][28] Advancing into the Islamic Golden Age, the polymath Ibn al-Haytham, also known as Alhazen (c. 965–1040 CE), provided the first systematic description of pinhole imaging in his influential treatise Kitāb al-Manāẓir (Book of Optics), completed around 1021 CE. Through experiments in a darkened room, he observed how light rays from an illuminated object pass through a small aperture to form a clear, inverted image on the opposite wall, refuting earlier emission theories of vision and establishing the rectilinear propagation of light. Ibn al-Haytham's work emphasized the camera obscura's utility for studying lunar and solar eclipses safely, laying groundwork for later optical theories by detailing how aperture size affects image sharpness—smaller holes yield clearer projections, though too small a hole blurs the image due to diffraction.[3][29] During the Renaissance in the 15th century, the camera obscura evolved from a scientific tool into a practical aid for artists, as evidenced by the sketches and notes of Leonardo da Vinci (1452–1519). In his Codex Atlanticus (c. 1490–1515), da Vinci illustrated various camera obscura configurations, including tent-like structures and box devices with lenses, recommending their use to capture accurate perspective and proportions in drawings by tracing the projected image. He described how the device could project landscapes or architectural scenes onto paper, enabling precise replication that enhanced artistic realism without relying solely on freehand skill. Da Vinci's adaptations, such as incorporating convex lenses for brighter images, bridged theoretical optics with creative application, influencing subsequent European artists.[30][28] By the 17th and 18th centuries, the camera obscura became increasingly portable, transforming into compact drawing aids that democratized accurate depiction for traveling artists and surveyors. German astronomer Johannes Kepler (1571–1630) coined the term "camera obscura" in his 1604 work Ad Vitellionem Paralipomena and pioneered a tent-based portable version, using it to sketch landscapes and astronomical events by projecting images onto paper within the enclosure. These devices, often wooden boxes or collapsible tents fitted with lenses and adjustable apertures, allowed users to trace inverted projections directly, achieving lifelike proportions; examples include the "lucterna magica" variants and refined models by instrument makers like Johann Zahn in 1685. Widely adopted across Europe, such portables facilitated en plein air sketching, as seen in the works of artists like Canaletto, though their reliance on manual tracing limited them to preparatory tools rather than permanent image capture.[31][32][33]19th and 20th Centuries
The invention of photography in the 19th century marked a pivotal shift from optical concepts to practical image capture, beginning with chemical processes that produced permanent images. In 1826 or 1827, Joseph Nicéphore Niépce created the world's oldest surviving photograph, "View from the Window at Le Gras," using his heliograph process, which involved coating a pewter plate with bitumen of Judea and exposing it for about eight hours in a camera obscura to harden the light-sensitive material and form a positive image.[5] This breakthrough laid the groundwork for further advancements, though Niépce's images were faint and difficult to replicate consistently. Building on Niépce's collaboration, Louis Daguerre refined the technique and announced the daguerreotype process in 1839 before the French Academy of Sciences; it used a silver-plated copper sheet sensitized with iodine vapor, exposed in a camera for several minutes, and developed over heated mercury to produce a highly detailed, one-of-a-kind positive image on a mirrored surface.[34] The French government purchased the rights and made the process public domain, spurring widespread adoption across Europe and the United States for portraits and landscapes until the 1850s.[35] Advancements in the 1870s and 1880s addressed the limitations of wet collodion plates, which required on-site preparation and immediate development, by introducing more convenient alternatives. In 1871, Richard Leach Maddox invented the gelatin dry plate process, emulsifying silver bromide in gelatin on glass plates that could be pre-sensitized and stored, allowing exposures of fractions of a second and enabling studio and field photography without darkroom urgency; commercial production began around 1878.[36] This innovation democratized photography by reducing technical barriers. Concurrently, in the 1880s, George Eastman developed flexible roll film as a substitute for rigid glass plates, patenting a nitrocellulose-based strip in 1885 that could be wound through a camera to capture multiple images sequentially.[37] Eastman's Kodak No. 1 camera, introduced in 1888, embodied this with its pre-loaded 100-exposure roll film in a simple box design, marketed under the slogan "You press the button, we do the rest," which outsourced processing to the company and made snapshot photography accessible to amateurs.[38] The 20th century saw mechanical refinements that enhanced portability, precision, and immediacy in camera design. In 1925, Oskar Barnack's Leica I introduced the 35mm rangefinder camera, adapting cinema film stock into a compact, handheld format with a coupled rangefinder for accurate focusing, revolutionizing photojournalism and street photography by enabling discreet, high-speed shooting with 36 exposures per roll.[39] Single-lens reflex (SLR) cameras, featuring a mirror that allowed viewing through the taking lens, had prototypes dating to the 1880s, such as early designs by Ottomar Anschütz, but remained niche until the mid-20th century; the format gained popularity in the 1950s with affordable models like the East German Praktica and Japanese Asahiflex, offering interchangeable lenses and through-the-lens composition for professional versatility.[40] In 1948, Edwin Land's Polaroid Land Camera debuted instant film, where a pod of reagents processed the exposed negative in situ to yield a peel-apart positive print within 60 seconds, transforming casual and scientific imaging by eliminating darkroom waits.[41] The World Wars accelerated camera evolution through military demands, fostering innovations in portability and aerial applications. During World War I, the need for battlefield reconnaissance spurred compact, hand-held cameras like the German Goerz Tengor for soldiers and synchronized aerial cameras mounted on aircraft, such as the British Williamson L-type camera, which captured detailed images for mapping trenches from altitudes up to 10,000 feet.[42] World War II further advanced these, with lightweight rangefinders and SLRs adapted for troops—exemplified by the American Argus A camera's use in combat documentation—and high-resolution aerial systems like the K-17 with 6x9-inch film for strategic bombing intelligence, influencing postwar civilian designs for durability and speed.[43]Digital Revolution and Beyond
The digital revolution in photography began in 1975 when Steven Sasson, an engineer at Eastman Kodak, developed the first prototype digital camera using a charge-coupled device (CCD) sensor to capture black-and-white images at 0.01 megapixels, stored on a cassette tape.[44] This invention, weighing about 8 pounds and requiring 23 seconds to record a single frame, demonstrated the feasibility of electronic image capture but was not commercialized due to Kodak's focus on film.[44] By the early 1990s, digital cameras entered the consumer market, with the Dycam Model 1 (1990) becoming one of the first commercially available models, offering 376x240 pixel resolution and direct computer connectivity via serial port.[45] The Casio QV-10, released in 1995, marked a significant advancement as the first digital camera with a built-in LCD preview screen, enabling immediate image review and spurring broader adoption among hobbyists.[46] During this decade, CCD sensors rose to prominence in digital imaging, providing high-quality light sensitivity and forming the backbone of early consumer and professional cameras due to their superior signal-to-noise ratio compared to emerging alternatives.[47] The 2000s saw digital single-lens reflex (DSLR) cameras achieve market dominance, capturing over 80% of interchangeable-lens camera sales by mid-decade as prices fell and image quality rivaled film.[48] This era's growth was fueled by accessible models like the Canon EOS Digital Rebel (2003), which democratized high-resolution digital photography for enthusiasts.[48] Concurrently, smartphone integration of cameras accelerated the shift, with the original iPhone (2007) featuring a 2-megapixel sensor that embedded photography into mobile communication, rapidly expanding casual image capture beyond dedicated devices.[49] By the late 2000s, smartphones accounted for a growing share of everyday photography, challenging traditional camera sales while inspiring innovations in compact digital models. Entering the 2010s, mirrorless cameras gained traction, with Sony launching its NEX-3 and NEX-5 in 2010 as the company's first interchangeable-lens mirrorless systems, eliminating the mirror mechanism for more compact designs without optical viewfinders.[50] A post-2010 boom followed, driven by full-frame models like the Sony Alpha 7 (2013), which combined DSLR-like performance with portability and electronic viewfinders, leading to mirrorless systems comprising over 50% of the interchangeable-lens market by 2020.[50] Computational photography emerged as a transformative force, exemplified by Google’s HDR+ pipeline introduced in the Pixel smartphone (2016), which merged multiple underexposed raw frames using burst capture and alignment algorithms to enhance dynamic range and reduce noise in low-light conditions.[51] By 2025, AI integration has redefined autofocus capabilities, with phase-detection systems enabling real-time subject tracking across humans, animals, and vehicles in cameras like the Sony Alpha 1 II through machine learning-based prediction.[52] Sustainable manufacturing trends are also prominent, as major producers such as Canon, Sony, and Nikon incorporate recycled materials in their chassis and energy-efficient assembly processes to reduce carbon footprints, aligning with global regulations like the EU's Ecodesign Directive.[53] These advancements, including modular designs for easier repairs, reflect the industry's pivot toward circular economies while maintaining high-performance imaging standards.Core Components
Lenses and Optics
Camera lenses are optical systems composed of multiple glass elements arranged to bend and focus incoming light rays onto the image plane, enabling sharp image formation across various distances and fields of view. These elements, typically made from high-quality optical glass such as flint or crown glass, are precision-ground into curved shapes to manipulate light paths according to the principles of refraction. Modern lenses often incorporate 5 to 20 or more elements grouped into assemblies to minimize distortions and enhance performance.[54] To reduce unwanted reflections and flare that can degrade image contrast, lenses feature anti-reflective coatings applied to their surfaces. These coatings, first developed in the 1930s by researchers at Carl Zeiss, involve thin layers of materials like magnesium fluoride that interfere with reflected light waves, transmitting up to 99% of incident light instead of the typical 4-5% loss per uncoated surface. Multi-layer coatings, introduced in the mid-20th century, further optimize performance across a broader spectrum of wavelengths, becoming standard in professional lenses by the 1970s.[55][56] Lenses are categorized by their focal length and design versatility, with prime lenses offering a fixed focal length for superior sharpness and wider maximum apertures, while zoom lenses provide a variable focal length range through internal moving elements, trading some optical quality for convenience. Prime lenses, such as a 50mm f/1.8, excel in low-light conditions and shallow depth-of-field portraits due to their simpler construction. Zoom lenses, like a 24-70mm f/2.8, allow photographers to adjust framing without changing position, making them ideal for versatile shooting scenarios.[57][58] Within these categories, specialized types address specific photographic needs: wide-angle lenses (typically 14-35mm) capture expansive scenes with a broad field of view, often used in landscapes to emphasize depth and scale; telephoto lenses (70mm and longer) compress perspective and magnify distant subjects, essential for wildlife and sports photography; and macro lenses enable extreme close-up reproduction ratios up to 1:1, revealing fine details in subjects like insects or jewelry.[59] Optical imperfections known as aberrations can blur or color-fringe images, with chromatic aberration causing different wavelengths of light to focus at varying points due to varying refractive indices in glass, and spherical aberration resulting from the failure of peripheral light rays to converge precisely with central rays in spherical surfaces. These are corrected using aspherical lens elements, which deviate from perfect spherical curvature to equalize focus across the aperture, reducing aberrations without adding excessive elements. Low-dispersion glass further mitigates chromatic issues by minimizing color separation.[60][61][62] The aperture, controlled by an iris diaphragm within the lens, regulates light intake and depth of field, specified by the f-number (e.g., f/2.8), which is the ratio of the lens's focal length to the effective aperture diameter. A lower f-number indicates a larger relative opening, enhancing light-gathering capability—doubling the aperture area quadruples the light transmitted—thus allowing faster shutter speeds or lower ISO in dim conditions. This metric directly influences exposure settings and bokeh quality in images.[63][64] Lens mount systems standardize attachment to camera bodies, with the Nikon F-mount, introduced in 1959, featuring a bayonet design that supports manual aperture control via a mechanical linkage. The Canon EF-mount, launched in 1987, pioneered fully electronic communication through multiple contacts, enabling autofocus, aperture control, and image stabilization data exchange between lens and body. Modern mounts incorporate additional pins for advanced features like lens calibration and firmware updates.[65][66][67]Exposure Mechanisms
Exposure mechanisms in cameras regulate the amount of light reaching the image sensor or film to achieve proper exposure, balancing intensity and duration through interconnected components. These systems evolved from mechanical designs to electronic controls, enabling precise adjustments for varying lighting conditions. The primary elements include the aperture for light intensity, the shutter for exposure duration, and metering for light assessment, which together form the foundation of the exposure triangle alongside ISO sensitivity. The aperture, implemented as an iris diaphragm within the lens, consists of overlapping blades that form a circular opening to control the quantity of light entering the camera. This adjustable stop is quantified by f-stops, where the f-number is the ratio of the lens focal length to the aperture diameter; for instance, an f/2.8 setting allows more light than f/8, with each full stop change halving or doubling the light transmission. A smaller aperture (higher f-number) increases depth of field, sharpening a greater range from foreground to background, while a larger one creates a shallower focus ideal for isolating subjects.[68] Shutter mechanisms determine the duration light exposes the image plane, typically ranging from 1/8000 second for freezing fast action to bulb (B) mode for extended exposures beyond 30 seconds. Focal-plane shutters, located near the film or sensor, use two curtains that create a traveling slit across the frame; horizontal-travel cloth designs predominated until the 1980s, when vertical-travel metal blades became standard in 35mm SLRs for their shorter 24mm path, enabling faster speeds and reduced vibration. Leaf shutters, integrated into the lens barrel with multiple blades, offer quieter operation and flash synchronization at all speeds but are limited to maximums around 1/500 second in most designs.[69] Light metering systems measure scene illuminance to recommend exposure settings, with the Minolta SR-T 101 (1966) introducing contrast light compensation (CLC) to through-the-lens (TTL) metering, evaluating the entire frame for balanced readings across highlights and shadows. Evaluative (or matrix) metering divides the scene into zones for algorithmic analysis, prioritizing the focused area while considering overall contrast. Center-weighted metering emphasizes the central 60-80% of the frame, suitable for subjects positioned in the middle, whereas spot metering assesses only a 1-5% area around the focus point for precise control in high-contrast scenes.[70][71] The exposure triangle describes the reciprocal relationship among aperture, shutter speed, and ISO sensitivity, where adjustments to one require compensation in others to maintain correct exposure; for example, widening the aperture to f/2.8 might necessitate halving the shutter speed from 1/125 to 1/60 second or lowering ISO from 400 to 200. ISO standards, formalized in 1974 under ISO 6 for black-and-white negative materials, merged the American ASA arithmetic scale and German DIN logarithmic scale into a unified system (e.g., ISO 100/21°), standardizing film and sensor sensitivity measurements.[72][73] Automatic exposure modes, enabled by 1970s electronic advancements, automate these adjustments for user convenience. Aperture priority allows manual f-stop selection with the camera choosing shutter speed, as in the Nikon Nikomat EL introduced in 1972. Program mode, debuting in the Canon A-1 in 1978, automatically sets both aperture and shutter speed based on metering while permitting shifts for creative control. These modes simplified photography for amateurs without sacrificing precision in professional workflows.[74]Viewfinders and Focusing Systems
Viewfinders serve as essential tools for composing images in cameras, allowing photographers to frame shots and assess composition before capture. Traditional optical viewfinders, prevalent in single-lens reflex (SLR) cameras, utilize a system of mirrors and prisms to provide a direct, real-time view through the lens. The pentaprism, a five-sided optical element that reflects light by 90 degrees while maintaining image orientation, became a standard feature in eye-level optical viewfinders for SLRs starting in the late 1940s. The Rectaflex 1000, introduced in 1948, was among the earliest 35mm SLRs to incorporate a pentaprism for upright, non-reversed viewing at eye level.[75] Similarly, the Contax S of 1949 marked a significant adoption of this technology by Zeiss Ikon, enhancing usability over waist-level finders.[76] Electronic viewfinders (EVFs), which display a digital representation of the scene on a small LCD or OLED screen viewed through an eyepiece, emerged in the mid-1990s through prototypes and early digital cameras, offering advantages like exposure preview and magnification for precise focusing. These systems gained prominence in mirrorless cameras from the late 2000s, eliminating the need for a reflex mirror and enabling compact designs. For instance, the Panasonic Lumix DMC-G1 in 2008 was an early mirrorless model featuring an integrated EVF for live composition. EVFs also support exposure simulation, allowing photographers to preview the final image brightness directly in the viewfinder, a feature tied to the camera's metering system.[50] Focusing systems determine how photographers achieve sharp images by aligning the lens plane with the subject distance. Manual focusing aids, such as split-image rangefinders, appeared in the 1930s to assist with precise alignment in rangefinder cameras, where a divided viewfinder image coalesces when in focus. These aids, often using prisms to create a split or microprism effect, were integrated into models like the Leica II introduced in 1932, improving accuracy over scale focusing.[77] Depth of field preview mechanisms, allowing stop-down to the selected aperture for assessing sharpness range, were pioneered in the 1930s with Leica rangefinders equipped with aperture levers on lenses like the Summar, enabling manual verification of focus and depth.[78] Autofocus revolutionized focusing by automating detection and adjustment, with phase-detection systems emerging in the 1980s through dedicated sensors that compare light phases from off-axis points to calculate focus direction and distance. Canon pioneered commercial phase-detection autofocus in its SLR lineup during this period, integrating it into models like the EOS series by the late 1980s for faster, through-the-lens operation.[79] In contrast, compact cameras predominantly employed contrast-detection autofocus, which analyzes image contrast via the sensor to maximize edge sharpness, a method suited to their simpler optics and first widely adopted in point-and-shoot models from the 1970s onward. The Konica C35 AF of 1977 was an early example using a precursor to contrast detection for reliable close-range focusing.[80] Live view systems, utilizing rear LCD screens for real-time composition and focusing, were introduced in DSLRs during the 2000s to bridge optical and electronic viewing. The Olympus E-330 in 2006 was the first interchangeable-lens DSLR to offer live view on its LCD, allowing handheld composition without the viewfinder and supporting contrast-detection autofocus on the sensor.[81] Modern cameras often feature hybrid focusing systems combining phase- and contrast-detection for versatile performance across scenarios, paired with advanced eye-level EVFs boasting high resolutions like 5.76 million dots as a 2020s standard. This resolution, seen in models such as the Canon EOS R5 (2020) and Sony Alpha 7R IV (2019), provides near-optical clarity with 120 fps refresh rates for smooth tracking.[82][83]Image Capture Technologies
Analog Film Systems
Analog film systems rely on photographic film, a light-sensitive medium consisting of emulsion layers coated onto a flexible base, typically acetate or polyester. The emulsion is primarily composed of silver halide crystals—such as silver bromide, silver chloride, or silver iodide—suspended in a gelatin matrix, which capture light exposure through a photochemical reaction.[84] These crystals are sensitized to specific wavelengths of light using spectral dyes, enabling selective response to blue, green, or red light in multilayered structures for color reproduction.[85] In black-and-white film, a single or multilayer emulsion produces metallic silver densities upon development, while color film incorporates dye couplers within the emulsion layers to form cyan, magenta, and yellow dyes during processing.[86] Common film formats dictate the physical dimensions of the exposed image area and influence resolution and aspect ratio. The 35mm format, widely used in small-format cameras, features a standard frame size of 24 × 36 mm, allowing for 24 or 36 exposures per roll.[87] Medium-format 120 film, with a 61.5 mm width, supports larger frames such as 6 × 4.5 cm (up to 16 exposures), 6 × 6 cm (12 exposures), or 6 × 7 cm (10 exposures), providing enhanced detail for professional applications.[88] Large-format sheet film, cut into individual sheets, enables even greater image sizes like 4 × 5 inches or 8 × 10 inches, favored for studio and landscape work due to minimal grain and maximum sharpness.[89] Color film development employs chromogenic processes that integrate dye formation with silver halide reduction, contrasting with black-and-white film's simpler silver-based imaging. The C-41 process, introduced by Kodak in 1972, is the standard for color negative films; it involves color development in a p-phenylenediamine-based solution where oxidized developer reacts with incorporated dye couplers in the red-, green-, and blue-sensitive layers to produce subtractive dyes, followed by bleaching to remove silver and stabilizing.[90] Black-and-white film, lacking dye couplers, uses a single developer to reduce exposed silver halides to metallic silver, then fixes unexposed halides in a thiosulfate bath, all conducted in darkroom conditions with controlled temperature and agitation.[91] For color reversal (slide) films, the E-6 process yields positive transparencies through a first developer to form the negative silver image, a reversal bath to fog unexposed areas, color development for dye formation, and subsequent bleaching and fixing, as detailed in Kodak's official guidelines requiring six chemical baths for precise control.[92] Analog film's advantages include exceptional dynamic range and long-term stability when properly stored. Certain emulsions, such as Kodak Portra or Tri-X, can capture over 14 stops of latitude, accommodating extreme highlights and shadows without clipping, which exceeds many early digital sensors and supports creative exposure flexibility.[93] Archival stability is notable for polyester-based films, which, stored at 35–50% relative humidity and below 5°C in inert environments, can preserve images for 200–500 years with minimal degradation, outperforming acetate bases prone to vinegar syndrome.[94]| Format | Base Width | Common Frame Sizes | Typical Exposures per Roll |
|---|---|---|---|
| 35mm (135) | 35 mm | 24 × 36 mm | 24 or 36 |
| 120 (Medium) | 61.5 mm | 6 × 4.5 cm, 6 × 6 cm, 6 × 7 cm | 10–16 |
| Sheet (Large) | Varies | 4 × 5 in, 8 × 10 in | 1 per sheet |