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Pellicle Mirror
A pellicle mirror is an ultra-thin, ultra-lightweight semi-transparent mirror employed in the light path of an optical instrument, splitting the light beam into two separate beams, both of reduced light intensity. Splitting the beam allows its use for multiple purposes simultaneously. The thinness of the mirror practically eliminates beam or image doubling due to a non-coincident weak second reflection from the nominally non-reflecting surface, a problem with mirror-type beam splitters. The name ''pellicle'' is a diminutive of ''pellis'', a skin or film. In photography In photography, the pellicle mirror has been employed in single-lens reflex (SLR) cameras, at first to enable through-the-lens exposure measurement and possibly to reduce camera shake, but later most successfully to enable fast series photography, which otherwise would be slowed down by the movement of the reflex mirror, while maintaining constant finder vision. The first use of pellicle mirrors for consumer pho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EOS 630
In ancient Greek mythology and religion, Eos (; Ionic and Homeric Greek ''Ēṓs'', Attic ''Héōs'', "dawn", or ; Aeolic ''Aúōs'', Doric ''Āṓs'') is the goddess and personification of the dawn, who rose each morning from her home at the edge of the river Oceanus to deliver light and disperse the night. In Greek tradition and poetry she is characterized as a goddess with a great sexual appetite, who took numerous lovers for her own satisfaction and bore them several children. Like her Roman counterpart Aurora and Rigvedic Ushas, Eos continues the name of an earlier Indo-European dawn goddess, Hausos. Eos, or her earlier Proto-Indo-European (PIE) ancestor, also shares several elements with the love goddess Aphrodite, perhaps signifying Eos's influence on her or otherwise a common origin for the two goddesses. In surviving tradition, Aphrodite is the culprit behind Eos' numerous love affairs, having cursed the goddess with insatiable lust for mortal men. In Greek li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1984 Summer Olympics
The 1984 Summer Olympics (officially the Games of the XXIII Olympiad and also known as Los Angeles 1984) were an international multi-sport event held from July 28 to August 12, 1984, in Los Angeles, California, United States. It marked the second time that Los Angeles had hosted the Games, the first being in 1932. California was the home state of the incumbent U.S. President Ronald Reagan, who officially opened the Games. These were the first Summer Olympic Games under the IOC presidency of Juan Antonio Samaranch. The 1984 Games were boycotted by a total of fourteen Eastern Bloc countries, including the Soviet Union and East Germany, in response to the American-led boycott of the 1980 Summer Olympics in Moscow in protest of the Soviet invasion of Afghanistan; Romania and Yugoslavia were the only Socialist European states that opted to attend the Games. Albania, Iran and Libya also chose to boycott the Games for unrelated reasons. Despite the field being depleted in certain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1972 Winter Olympics
The 1972 Winter Olympics, officially the and commonly known as Sapporo 1972 ( ja, 札幌1972), was a winter multi-sport event held from February 3 to 13, 1972, in Sapporo, Japan. It was the first Winter Olympic Games to take place outside Europe and North America. Host city selection Sapporo first won the rights to host the 1940 Winter Olympics, but Japan resigned as the Games' host after its Second Sino-Japanese War, 1937 invasion of China. The 1940 Games were later cancelled. All the cities awarded Games that were cancelled due to war have since hosted the Games (London, Tokyo, Helsinki, Sapporo and Cortina d'Ampezzo). Sapporo competed with Banff, Lahti, and Salt Lake City. The Games were awarded at the 64th IOC Session in Rome, Italy, on April 26, 1966. In preparation, the Japanese constructed new largescale facilities at Sapporo and conducted a trial run a full year in advance of the Games. An international sport week was held in February, 1971, to assess the city's prepa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viewfinder
In photography, a viewfinder is what the photographer looks through to compose, and, in many cases, to focus the picture. Most viewfinders are separate, and suffer parallax, while the single-lens reflex camera lets the viewfinder use the main optical system. Viewfinders are used in many cameras of different types: still and movie, film, analog and digital. A zoom camera usually zooms its finder in sync with its lens, one exception being rangefinder cameras. History Before the development of microelectronics and electronic display devices, only optical viewfinders existed. Direct optical viewfinders Direct viewfinders are essentially miniature Galilean telescopes; the viewer's eye was placed at the back, and the scene viewed through the viewfinder optics. A declining minority of point and shoot cameras use them. Parallax error results from the viewfinder being offset from the lens axis, to point above and usually to one side of the lens. The error varies with distance, being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-number
In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill Professional, p. 183. It is also known as the focal ratio, f-ratio, or f-stop, and is very important in photography. It is a dimensionless number that is a quantitative measure of lens speed; increasing the f-number is referred to as ''stopping down''. The f-number is commonly indicated using a lower-case hooked f with the format ''N'', where ''N'' is the f-number. The f-number is the reciprocal of the relative aperture (the aperture diameter divided by focal length). Notation The f-number is given by: N = \frac \ where f is the focal length, and D is the diameter of the entrance pupil (''effective aperture''). It is customary to write f-numbers preceded by "", which forms a mathematical expression of the entrance pupil diameter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirror Lock-up
Mirror lock-up (often abbreviated to MLU) is a feature employed in many Single Lens Reflex (SLR) cameras. It allows the operator to reduce vibration-induced motion blur during exposure. It also allows the mounting of lenses which extend into the SLR's mirror box when mounted. Reducing vibration Normal operation in an SLR camera involves flipping the mirror up out of the light-path just before the shutter opens, and then returning it when the shutter closes (although very early SLR's required the shutter to be cocked for the mirror to return). This causes vibration of the camera, particularly when the mirror slaps into the top of the mirror box. This vibration quickly dies away so the most motion blur is actually seen with short shutter times that capture multiple 'swings' of the vibration (shutter speeds of 1/2 to 1/60 second are often affected by this). While longer exposures will capture all of the vibrations, the exposure will be dominated by light captured when the camera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Range
Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base-10 ( decibel) or base-2 (doublings, bits or stops) logarithmic value of the difference between the smallest and largest signal values. Electronically reproduced audio and video is often processed to fit the original material with a wide dynamic range into a narrower recorded dynamic range that can more easily be stored and reproduced; this processing is called dynamic range compression. Human perception The human senses of sight and hearing have a relatively high dynamic range. However, a human cannot perform these feats of perception at both extremes of the scale at the same time. The human eye takes time to adjust to different light levels, and its dynamic range in a given scene is actually quite limited due to optical glare. The ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Balance
In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors like white or grey – correctly. Hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to deliberately change them for effect. White balance is one of the most common kinds of balancing, and is when colors are adjusted to make a white object (such as a piece of paper or a wall) appear white and not a shade of any other colour. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate for color reproduct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure Value
In photography, exposure value (EV) is a number that represents a combination of a camera's shutter speed and f-number, such that all combinations that yield the same exposure have the same EV (for any fixed scene luminance). Exposure value is also used to indicate an interval on the photographic exposure scale, with a difference of 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a stop. The EV concept was developed by the German shutter manufacturer in the 1950s ( Gebele 1958; Ray 2000, 318). Its intent was to simplify choosing among equivalent camera exposure settings by replacing combinations of shutter speed and ''f''-number (e.g., 1/125 s at ''f''/16) with a single number (e.g., 15). On some lenses with leaf shutters, the process was further simplified by allowing the shutter and aperture controls to be linked such that, when one was changed, the other was automatically adjusted to maintain the same exposure. This was especially he ... [...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] |
Image Sensor
An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, camera phones, optical mouse devices, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others. As technology changes, electronic and digital imaging tends to replace chemical and analog imaging. The two main types of electronic image sensors are the charge-coupled device (CCD) and the active-pixel sensor (CMOS sensor). Both CCD and CMOS sensors are based on metal–oxide–semiconductor (MOS) technology, with CCDs based on MOS capacitors and CMOS sensors based on M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
