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Afocal Photography
Afocal photography, also called afocal imaging or afocal projection is a method of photography where the camera with its lens attached is mounted over the eyepiece of another image forming system such as an optical telescope or optical microscope, with the camera lens taking the place of the human eye. Overview Afocal photography works with any system that can produce a virtual image of parallel light, for example telescopes and microscopes. Afocal photographic setups work because the imaging device's eyepiece produces collimated light and with the camera's lens focused at infinity, creating an afocal system with no net convergence or divergence in the light path between the two devices. In this system the device is focused on the object and the camera is placed above the eyepiece as close as possible. The drawback is the system will have a high focal ratio, with a correspondingly dim image, and some vignetting. A high focal ratio also means the field of view will be narrow. Field ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afocal Photography
Afocal photography, also called afocal imaging or afocal projection is a method of photography where the camera with its lens attached is mounted over the eyepiece of another image forming system such as an optical telescope or optical microscope, with the camera lens taking the place of the human eye. Overview Afocal photography works with any system that can produce a virtual image of parallel light, for example telescopes and microscopes. Afocal photographic setups work because the imaging device's eyepiece produces collimated light and with the camera's lens focused at infinity, creating an afocal system with no net convergence or divergence in the light path between the two devices. In this system the device is focused on the object and the camera is placed above the eyepiece as close as possible. The drawback is the system will have a high focal ratio, with a correspondingly dim image, and some vignetting. A high focal ratio also means the field of view will be narrow. Field ... [...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 the mechanisms of a single-lens reflex camera with a digital imaging 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 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 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 mirrorless interchangeable-lens cameras (MILC) beginning in the 2010s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleconverter
A teleconverter (sometimes called tele extender) is a secondary lens mounted between a camera and a photographic lens which enlarges the central part of an image obtained by the lens. For example, a 2× teleconverter for a 35 mm camera enlarges the central 12×18 mm part of an image to the size of 24×36 mm in the standard 35 mm film format. Teleconverters are typically made in 1.4×, 1.7×, 2× and 3× variants, with 1.4× and 2× being the most common. A 2× teleconverter doubles the apparent focal length of a given lens. Teleconverters also decrease the intensity of the light that reaches the film plane (or sensor) by the square of its magnification. A 2× teleconverter reduces the light to 1/4, doubles the focal ratio and halves the resolution of the master lens it is connected to. This, however, does not necessarily halve the resolution of the digital image. A closely related device reduces the focal length. It is generally marketed under the name speed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Lens
In photography, a secondary lens or accessory lens is a lens designed to be used in conjunction with another lens, called the ''primary lens''. A secondary lens may be designed to be used either in front of the primary lens, between it and the subject, or behind the primary lens, between it and the film. Secondary lenses are typically simpler in mechanical design than other photographic lenses. Normally but not always there is no provision for control of focus or aperture, as these are achieved by the controls on the primary lens. Lenses used in front of the primary lens Examples of secondary lenses designed to be used in front of the primary lens are: * Fisheye adaptors * Corrected wide angle adaptors * Telephoto adaptors such as teleside converters * Close-up lenses All of these lens typically mount on the filter ring of the primary lens. Front-mounting secondary lenses are commonly used to provide wide-angle and telephoto lenses for cameras which lack the facility to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Long Focus Lens
In photography, a long-focus lens is a camera lens which has a focal length that is longer than the diagonal measure of the film or sensor that receives its image. It is used to make distant objects appear magnified with magnification increasing as longer focal length lenses are used. A long-focus lens is one of three basic photographic lens types classified by relative focal length, the other two being a normal lens and a wide-angle lens. As with other types of camera lenses, the focal length is usually expressed in a millimeter value written on the lens, for example: a 500 mm lens. The most common type of long-focus lens is the telephoto lens, which incorporate a special lens group known as a ''telephoto group'' to make the physical length of the lens shorter than the focal length. Effects Long-focus lenses are best known for making distant objects appear magnified. This effect is similar to moving closer to the object, but is not the same, since perspective i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spotting Scope
A spotting scope is a compact high-power telescope optimized for detailed observation of distant objects. They are used as portable optical enhancement devices for various outdoor activities such as birdwatching, skygazing and other naturalist activities, for hunting and target shooting to verify a marksman's shot placements, for tactical ranging and surveillance, and for any other application that requires higher magnification than ordinary binoculars (typically 20× to 60×). The light-gathering power and resolution of a spotting scope is determined by the diameter of the objective lens, typically between . The larger the objective, the more massive and expensive the telescope. The optical assembly has a small refracting objective lens, an internal image-erecting system, and an eyepiece that is usually removable. The image-erecting system may use relay lenses, prisms such as Porro or roof prisms, or a catadioptric system of the Schmidt or Maksutov design. Spotting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digiscoping
Digiscoping is a neologism for afocal photography, using a ( digital) camera to record distant images through the eyepiece of an optical telescope. Digiscoping usually refers to using either a digital single-lens reflex camera with lens attached or, more often, a fixed lens point and shoot digital camera to obtain photos through the eyepiece of a birdwatcher's spotting scope. The term has also been associated with the use of a digital camera and spotting scope equipped for prime focus photography. Origins The portmanteau term "''digiscoping''" (= digital camera + telescoping) was coined in 1999 by French birdwatcher Alain Fossé. Less notable neologisms for this activity are ''digiscope birding'', ''digiscopy birding'', ''digi-birding'', ''digibinning'' (using digital camera with binoculars), and ''phonescoping'' (using a digital camera phone with a spotting scope or binoculars). The origins of the activity called ''Digiscoping'' has been attributed to the photographic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birdwatching
Birdwatching, or birding, is the observing of birds, either as a recreational activity or as a form of citizen science. A birdwatcher may observe by using their naked eye, by using a visual enhancement device like binoculars or a telescope, by listening for bird sounds, or by watching public webcams. Most birdwatchers pursue this activity for recreational or social reasons, unlike ornithologists, who engage in the study of birds using formal scientific methods. Birding, birdwatching, and twitching The first recorded use of the term ''birdwatcher'' was in 1901 by Edmund Selous; ''bird'' was introduced as a verb in 1918. The term ''birding'' was also used for the practice of ''fowling'' or hunting with firearms as in Shakespeare's '' The Merry Wives of Windsor'' (1602): "She laments sir... her husband goes this morning a-birding." The terms ''birding'' and ''birdwatching'' are today used by some interchangeably, although some participants prefer ''birding'', partly because it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mergus Merganser M
''Mergus'' is the genus of the typical mergansers , fish-eating ducks in the subfamily Anatinae. The genus name is a Latin word used by Pliny the Elder and other Roman authors to refer to an unspecified waterbird. The common merganser (''Mergus merganser'') and red-breasted merganser (''M. serrator'') have broad ranges in the northern hemisphere. The Brazilian merganser (''M. octosetaceus'') is a South American duck, and one of the six most threatened waterfowl in the world, with possibly fewer than 250 birds in the wild. The scaly-sided merganser or "Chinese merganser" (''M. squamatus'') is an endangered species. It lives in temperate East Asia, breeding in the north and wintering in the south. The hooded merganser (''Lophodytes cucullatus'', formerly known as ''Mergus cucullatus'') is not of this genus but is closely related. The other "aberrant" merganser, the smew (''Mergellus albellus''), is phylogenetically closer to goldeneyes (''Bucephala''). Although they are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smallest element that can be manipulated through software. Each pixel is a sample of an original image; more samples typically provide more accurate representations of the original. The intensity of each pixel is variable. In color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black. In some contexts (such as descriptions of camera sensors), ''pixel'' refers to a single scalar element of a multi-component representation (called a ''photosite'' in the camera sensor context, although ''sensel'' is sometimes used), while in yet other contexts (like MRI) it may refer to a set of component intensities for a spatial position. Etymology The w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charge-coupled Device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging. In a CCD image sensor, pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors. These MOS capacitors, the basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and professional digital cameras, act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
