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61-620: The Ballon Generali is a tethered helium balloon , used as tourist attraction and as an air quality awareness tool. Installed in Paris since 1999 in the Parc André-Citroën , it was created and developed by the French company Aerophile SAS for the celebration of the year 2000. The balloon has lofted more than 500,000 passengers into the sky since its opening. The balloon, filled with 6,000 m (210,000 cu ft) of helium ,

122-488: A helicopter . Tethered balloons are frequently used as a recreational attraction. Tethered balloons can be used as temporary transmitters, instead of a radio mast, either by using the tether which holds the balloon as the antenna, or by carrying antennas on the balloon fed by a fiber optic or radio frequency cable contained inside the tether. The advantage of tethered balloons is that great antenna heights are easily attainable and they are significantly cheaper than erecting

183-452: 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

244-676: A balloon with advertisements written on, or attached to it. Often both methods are combined. It is not uncommon to use specially designed balloons. Blimp -shaped balloons are especially popular for advertising use. By suspending a light source within the envelope, the balloon can be illuminated at night, drawing attention to its message. The United States Geological Survey uses tethered balloons to carry equipment to places where conventional aircraft cannot go, such as above an erupting volcano . Tethered balloons are ideal as they can easily remain more or less in one place, are less likely to be damaged by volcanic ash, and are less expensive to operate than

305-417: 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. Focus involves adjusting the lens elements to sharpen the image of the subject at various distances. The focus

366-454: 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. Most cameras capture light from the visible spectrum , while specialized cameras capture other portions of the electromagnetic spectrum , such as infrared . All cameras use

427-521: 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. Two primary types of lenses include zoom and prime lenses. A zoom lens allows for changing its focal length within

488-535: A high-tech optics system to detect and observe enemies from miles away. They have been used to over watch foot patrols and convoys in Baghdad , Afghanistan , and are permanently installed above US military bases in Kabul and Bagram . The US Drug Enforcement Administration has contracted with Lockheed Martin to operate a series of radar -equipped tethered balloons to detect low-flying aircraft attempting to enter

549-472: A larger coverage area and better line of sight, would be more economical and would have better latency than satellite systems . During the 1990 Invasion of Kuwait , the first indication of the Iraqi ground advance was from a radar -equipped tethered balloon that detected Iraqi armor and air assets moving south. Tethered surveillance balloons were used in the 2004 American occupation of Iraq . They utilized

610-400: 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. In photography, the single-lens reflex camera (SLR) is provided with a mirror to redirect light from the lens to

671-399: 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). In movie cameras, a rotary shutter opens and closes in sync with the advancement of each frame of film. The duration for which the shutter

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732-499: A partnership was signed with Banque populaire and Airparif . Renamed ballon Air de Paris , the balloon's internal illumination system changes its outer colour in real-time according to the ambient air pollution in Paris, as measured by Airparif . Colors range from green (good), through orange (poor), to red (bad). This system was completed by an independent lighting (panels light-emitting diode , visible especially at night on

793-484: A payload hung beneath. The round shape uses the minimum material to accommodate a given volume of lifting gas, making it the lightest construction. However, in any significant wind the round shape is aerodynamically unstable and will bob about, risking damage or the balloon breaking free. To avoid this problem, the kite balloon was developed. This form has an elongated shape to reduce wind resistance and some form of tail surface to stabilize it so that it always points into

854-409: 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). Many flash units measure the light reflected from the flash to help determine the appropriate duration of the flash. When

915-429: 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. Specialized viewfinder systems exist for specific applications, like subminiature cameras for spying or underwater photography . Parallax error , resulting from misalignment between the viewfinder and lens axes, can cause inaccurate representations of

976-405: 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

1037-563: A surge in camera ownership. 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

1098-401: A temporary mast. This allows for more localized coverage with a high capacity within a 80-kilometer (50 mi) radius of the balloon at an altitude between 450 and 600 m (1,500 and 2,000 feet) above ground level. Tethered balloons or blimps have been studied to overcome the limitations of terrestrial cell towers for telecommunications. Because of their higher elevation they can provide

1159-475: 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. Advanced lenses may include mechanical image stabilization systems that move lens elements or

1220-416: Is adjusted, the opening expands and contracts in increments called f-stops . 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 in standard increments: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, and 32. The light entering the camera is halved with each increasing increment. The wider opening at lower f-stops narrows

1281-462: Is an assembly of multiple optical elements, typically made from high-quality glass. Its primary function is to focus light onto a camera's film or digital sensor, thereby producing an image. This process significantly influences image quality, the overall appearance of the photo, and which parts of the scene are brought into focus. A camera lens is constructed from a series of lens elements, small pieces of glass arranged to form an image accurately on

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1342-409: Is attached to the ground with a cable, controlled by an hydroelectric winch . This tourist attraction can board up to 30 passengers (this amounts to around 2,500 kg (5,500 lb)) at 150 m (490 ft) above Paris. It is 32 m (105 ft) high, and has a diameter of 22 m (72 ft). It has been used as advertising billboard for Fortis , then from 2002 for Eutelsat . In 2008,

1403-433: 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. The film must be advanced after each shot to prevent double exposure — where

1464-464: Is dictated by the sensor's size and properties, necessitating storage media such as Compact Flash , Memory Sticks , and SD (Secure Digital) cards . Modern digital cameras typically feature a built-in monitor for immediate image review and adjustments. 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. A flash provides

1525-461: Is in use from 2022. Camera 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

1586-487: Is measured using a built-in light meter or exposure meter. Taken through the lens (called TTL metering ), these readings are taken using a panel of light-sensitive semiconductors . 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

1647-400: 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

1708-465: 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. A digital camera may use

1769-547: Is replaced by the film to make the exposure; they are suitable for static subjects only and are slow to use. 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

1830-526: The Canon Pellix and others with a small periscope such as in the Corfield Periflex series. 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

1891-412: 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

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1952-673: 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. 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

2013-669: The United States. A total of twelve tethered balloons, called Tethered Aerostat Radar System (TARS), are positioned approximately 350 miles (550 km) apart, from California to Florida to Puerto Rico , providing unbroken radar coverage along the entire southern border of the US. The U.S. Army has developed a tethered aerostat to perform operational testing at Aberdeen Proving Ground beginning in 2015. The system, called JLENS , uses two moored balloons designed to provide over-the-horizon missile defense capability. Israeli missile detection system called Sky Dew , similar to TARS and JLENS,

2074-413: 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

2135-410: The camera through an aperture, an opening adjusted by overlapping plates called the aperture ring. Typically located in the lens, this opening can be widened or narrowed to alter the amount of light that strikes the film or sensor. 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. As the aperture

2196-533: The composition, lighting, and exposure of their shots, enhancing the accuracy of the final image. 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

2257-422: The degree of magnification expected of the final image. 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. There are two types of mechanical shutters:

2318-536: The drum of a winch , which may be fixed or mounted on a vehicle, and is used to raise and lower the balloon. A balloon is a form of aerostat , along with the powered free-flying airship , although the American GAO has used the term "aerostat" to describe a tethered balloon in contrast to the powered airship. Tethered balloons have been used for advertising, recreation, observation , and civil or military uses. Early balloons were simple round spheres , with

2379-410: 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. 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

2440-528: 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

2501-408: 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. In most modern cameras, the amount of light entering the camera

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2562-543: The finger pressure was released. The Asahiflex II , released by Japanese company Asahi (Pentax) in 1954, was the world's first SLR camera with an instant return mirror. 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

2623-556: 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. Additional flash equipment can include a light diffuser , mount and stand, reflector, soft box , trigger and cord. Accessories for cameras are mainly used for care, protection, special effects, and functions. Large format cameras use special equipment that includes

2684-438: The image sensor itself to counteract camera shake, especially beneficial in low-light conditions or at slow shutter speeds. Lens hoods, filters, and caps are accessories used alongside a lens to enhance image quality, protect the lens, or achieve specific effects. 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

2745-498: 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

2806-426: 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, profoundly influencing how society creates, shares, and consumes visual content. Beginning with the use of the camera obscura and transitioning to complex photographic cameras,

2867-467: 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. More commonly, a focal-plane shutter is used. 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

2928-437: 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. The focal length of the lens, measured in millimeters, plays

2989-529: The lower part of the shell) stating the air quality near traffic with the same colour code. On April 18, 2013, a brand new tethered helium balloon was introduced, renamed the "Ballon Generali" (the Italian insurance company Generali has entered partnership agreements to more than 14 years with the Mairie de Paris ). Since that day, every year it lifts around 50,000 visitors. The trip lasts around 10 minutes. In

3050-531: The morning, with optimal weather conditions, the Ballon Generali can reach the altitude of 300 m (980 ft), making it the second highest point in Paris after the Eiffel Tower . Moored balloon A tethered , moored or captive balloon is a balloon that is restrained by one or more tethers attached to the ground so it cannot float freely. The base of the tether is wound around

3111-429: The optimal exposure. 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). A camera lens

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3172-407: 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. What is acceptably in focus is determined by the circle of confusion , the photographic technique, the equipment in use and

3233-408: 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. A shutter mechanism controls the length of time that light enters the camera. 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 . Light enters

3294-429: 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

3355-873: 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. 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. 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

3416-404: The shutter is briefly opened to allow light to pass during the exposure. 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

3477-402: 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. Image capture in a camera occurs when light strikes a light-sensitive surface: photographic film or a digital sensor . Housed within the camera body, the film or sensor records the light's pattern when

3538-734: The user to preview the scene; and the film or sensor, which captures the image. Several types of cameras 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

3599-428: 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

3660-960: The wind. Like the powered airship, such balloons are often called blimps. A hybrid tethered balloon or kytoon is shaped to provide aerodynamic lift similar to a kite , as well as to reduce drag. Designed by Albert Caquot, a French engineer, in 1914, the barrage balloons of World War I and World War II were early examples of tethered balloons. Military observation balloons were also used extensively in World War I. These early types used hydrogen as their lifting gas. Tethered balloons are used for lifting cameras , radio antennas, electro-optical sensors, radio-relay equipment and advertising banners – often for long durations. Tethered balloons are also used for position marking and bird control work. Typically, they use non-flammable helium gas to provide lift. Tethered balloons are often used for advertising , either by lifting advertisement signs, or by using

3721-455: 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

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