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Digital Photography
Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is stored as a computer file ready for further digital processing, viewing, electronic publishing, or digital printing. It is a form of digital imaging based on gathering visible light (or for scientific instruments, light in various ranges of the electromagnetic spectrum). Until the advent of such technology, photographs were made by exposing light-sensitive photographic film and paper, which was processed in liquid chemical solutions to develop and stabilize the image. Digital photographs are typically created solely by computer-based photoelectric and mechanical techniques, without wet bath chemical processing. In consumer markets, apart from enthusiast digital single-lens reflex cameras (DSLR), most digital cameras now come wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars Observer - MOC2 Cb
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of Mars surface color, its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () Atmosphere of Mars, atmosphere. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from and cosmic radiation is high. Mars retains some water, Groundwater on Mars, in the ground as well as thinly in the atmosphere, forming cirrus clouds, frost, larger polar regions of permafrost and Martian polar ice caps, ice caps (with seasonal snow), but no liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. It is half List of Solar System objects by size, as wide as Earth or twice the Moon, with a diameter of , and has a surface area the size of all the dry land of Earth. Martian regolith#Atmospheric dust, Fine dust is prevalent across the surface and the atmosphere, bein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photograph
A photograph (also known as a photo, or more generically referred to as an ''image'' or ''picture'') is an image created by light falling on a photosensitivity, photosensitive surface, usually photographic film or an electronic image sensor. The process and practice of creating such images is called photography. Most photographs are now created using a smartphone or camera, which uses a photographic lens, lens to focus the scene's visible spectrum, visible wavelengths of light into a reproduction of what the human eye would perceive. Etymology The word ''photograph'' was coined in 1839 by Sir John Herschel and is based on the Greek language, Greek φῶς ('':el:phos, phos''), meaning "light", and γραφή (''graphê''), meaning "drawing, writing", together meaning "drawing with light". History The first permanent photograph, a contact-exposed copy of an engraving, was made in 1822 using the Bitumen of Judea, bitumen-based "heliography" process developed by Nicéphore Niép ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focus Ring
In the field of photography, a manual focus camera is one in which the user has to adjust the focus of the lens by hand. Before the advent of autofocus, all cameras had manually adjusted focusing; thus, the term is a retronym. The focus itself may be adjusted in a variety of ways. Larger view camera A view camera is a large format, large-format camera in which the large format lens, lens forms an erect image, inverted image on a ground glass, ground-glass screen directly at the film plane. The image is viewed, composed, and focused, then the ...s and the like slide the lens closer or further from the film plane on rails; on smaller cameras, a focus ring on the lens is often rotated to move the lens elements by means of a helical screw. Other systems include levers on the lens or on the camera body. There are a number of ways in which focus may be determined. Simplest is using a distance scale and measuring or estimating distance to the subject. Other methods include th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure (photography)
In photography, exposure is the amount of light per unit area reaching a frame (photography), frame of photographic film or the surface of an electronic image sensor. It is determined by shutter speed, lens f-number, and scene luminance. Exposure is measured in unit of measurement, units of lux-seconds (symbol lxs), and can be computed from exposure value (EV) and scene luminance in a specified region. An "exposure" is a single shutter cycle. For example, a long-exposure photography, long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated ''photometric exposure'' (''H''v) is the same so long as the total exposure time is the same. Definitions Radiant exposure Radiant exposure of a ''surface'', denoted ''H''e ("e" for "energetic", to avoid confusion with Photometry (optics), photometric quantities) and measured in , i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Servomotor
A servomotor (or servo motor or simply servo) is a rotary or linear actuator that allows for precise control of angular or linear position, velocity, and acceleration in a mechanical system. It constitutes part of a servomechanism, and consists of a suitable motor coupled to a sensor for position feedback and a controller (often a dedicated module designed specifically for servomotors). Servomotors are not a specific class of motor, although the term ''servomotor'' is often used to refer to a motor suitable for use in a closed-loop control system. Servomotors are used in applications such as robotics, CNC machinery, and automated manufacturing. Mechanism A servomotor is a closed-loop servomechanism that uses position feedback (either linear or rotational position) to control its motion and final position. The input to its control is a signal (either analog or digital) representing the desired position of the output shaft. The motor is paired with some type of positio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focus (optics)
In geometrical optics, a focus, also called an image point, is a point where ray (optics), light rays originating from a point on the object vergence (optics), converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the circle of confusion, blur circle. This non-ideal focusing may be caused by optical aberration, aberrations of the imaging optics. Even in the absence of aberrations, the smallest possible blur circle is the Airy disc caused by diffraction from the optical system's aperture; diffraction is the ultimate limit to the light focusing ability of any optical system. Aberrations tend to worsen as the aperture diameter increases, while the Airy circle is smallest for large apertures. An image, or image point or region, is in focus if light from object points is converged almost as much as possible in the image, and defocus aberration, out of focus if light is not well converged. The border between these is sometimes define ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aperture
In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image of the aperture and focal length of an optical system determine the cone angle of a bundle of rays that comes to a focus in the image plane. An optical system typically has many structures that limit ray bundles (ray bundles are also known as ''pencils'' of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that primarily determines the cone of rays that an optical system accepts (see entrance pupil). As a result, it also determines the ray cone angle and brightne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instant Camera
An instant camera is a camera which uses instant film, self-developing film to create a chemically Photographic processing, developed print shortly after taking the picture. Polaroid Corporation pioneered (and Patent, patented) consumer-friendly instant cameras and film, and were followed by various other manufacturers. The invention of commercially viable instant cameras which were easy to use is generally credited to Edwin Land, the inventor of the model 95 Land Camera, widely considered the first commercial instant camera, in 1948, a year after he unveiled instant film in New York City. In February 2008, Polaroid filed for Chapter 11, Title 11, United States Code, Chapter 11 bankruptcy protection for the second time and announced it would discontinue production of its instant films and cameras, shut down three manufacturing facilities, and lay off 450 workers. Sales of analog film by all makers dropped by at least 25% per year in the first decade of the 21st century. In 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photograph Manipulation
Photograph manipulation involves the transformation or alteration of a photograph. Some photograph manipulations are considered to be skillful artwork, while others are considered to be unethical practices, especially when used to deceive. Motives for manipulating photographs include political propaganda, altering the appearance of a subject (both for better and for worse), entertainment and humor. Depending on the application and intent, some photograph manipulations are considered an art form because they involve creation of unique images and in some instances, signature expressions of art by photographic artists. For example, Ansel Adams used darkroom exposure techniques to darken and lighten photographs. Other techniques include retouching using ink or paint, airbrushing, double exposure, piecing photos or negatives together in the darkroom, and scratching instant films. Software for digital image manipulation ranges from casual to professional skillsets. One of these, Ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Real-time Computing
Real-time computing (RTC) is the computer science term for Computer hardware, hardware and software systems subject to a "real-time constraint", for example from Event (synchronization primitive), event to Event (computing), system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines".Mordechai Ben-Ari, Ben-Ari, Mordechai; "Principles of Concurrent and Distributed Programming", ch. 16, Prentice Hall, 1990, , p. 164 The term "real-time" is also used in Computer simulation, simulation to mean that the simulation's clock runs at the same speed as a real clock. Real-time responses are often understood to be in the order of milliseconds, and sometimes microseconds. A system not specified as operating in real time cannot usually ''guarantee'' a response within any timeframe, although ''typical'' or ''expected'' response times may be given. Real-time processing ''fails'' if not completed within a specified deadline rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Viewfinder
An electronic viewfinder (EVF) is a camera viewfinder where the image captured by the lens is displayed on a small screen (usually LCD or OLED) which the photographer can look through when composing their shot. It differs from a live preview screen in being smaller and shaded from ambient light, and may also use less power. The sensor records the view through the lens, the view is processed, and finally projected on a miniature display which is viewable through the eyepiece. Digital viewfinders are used in digital still cameras and in video cameras. Some cameras (such as Panasonic, Sony, Fujifilm) have an automatic eye sensor which switches the display from screen to EVF when the viewfinder is near the eye. More modest cameras use a button to switch the display. Some have no button at all. While many cameras come with a built-in EVF, this is fixed in place and can only be used while holding the camera to the user's eye, which may not be convenient. Other cameras don't come with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Single-lens Reflex Camera
A digital single-lens reflex camera (digital SLR or DSLR) is a digital camera that combines the optics and mechanisms of a single-lens reflex camera with a solid-state image sensor and digitally records the images from the sensor. The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design, light travels through the lens and then to a mirror that alternates to send the image to either a prism, which shows the image in the optical viewfinder, or the image sensor when the shutter release button is pressed. The viewfinder of a DSLR presents an image that will not differ substantially from what is captured by the Image sensor, camera's sensor, as it presents it as a direct optical view through the main camera lens rather than showing an image through a separate secondary lens. DSLRs largely replaced film-based SLRs during the 2000s. Major camera manufacturers began to transition their product lines away from DSLR cameras to mirror ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
