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Lens Hood
In photography, a lens hood or lens shade is a device used on the front end of a photographic lens, lens to block the Sun or other light source(s) to prevent glare (vision), glare and lens flare. Lens hoods may also be used to protect the lens from scratches and the elements without having to put on a lens cover. The geometry of a lens hood is dependent on three parameters: the focal length of the lens, the size of the front lens element and the dimensions of the image sensor or film in the camera. Cause of lens flare Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the Sun, bright studio lights, or a bright white background. If a light source is in the lens' angle of view, a lens hood will hardly have any effect, but the light does not have to cause lens flare. It is sufficient that stray light from a bright light source enters the lens. Multi-layer Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Five Lens Hoods
5 (five) is a number, numeral (linguistics), numeral and numerical digit, digit. It is the natural number, and cardinal number, following 4 and preceding 6, and is a prime number. Humans, and many other animals, have 5 Digit (anatomy), digits on their Limb (anatomy), limbs. Mathematics 5 is a Fermat prime, a Mersenne prime exponent, as well as a Fibonacci number. 5 is the first congruent number, as well as the length of the hypotenuse of the smallest integer-sided right triangle, making part of the smallest Pythagorean triple (3, 4, 5). 5 is the first safe prime and the first good prime. 11 forms the first pair of sexy primes with 5. 5 is the second Fermat number, Fermat prime, of a total of five known Fermat primes. 5 is also the first of three known Wilson primes (5, 13, 563). Geometry A shape with five sides is called a pentagon. The pentagon is the first regular polygon that does not Tessellation, tile the Plane (geometry), plane with copies of itself. It is the ... [...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 magnification, 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 magnification, magnified. This effect is similar to moving closer to the object, but is not the same, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens Cover
A lens cover or lens cap provides protection from scratches and minor collisions for camera and camcorder lenses. Lens covers come standard with most cameras and lenses. Some mobile camera phones include lens covers, such as the Sony Ericsson W800, the Sony Ericsson K750 and the Sony Ericsson K550. A more secure lens cap is the metal screw-in lens cap which cannot pop off a lens accidentally. Although a screw-in cap takes more time to remove in order to take a photograph than a standard lens cap, it is stronger than plastic and therefore more protective. Some cameras (mostly compact cameras) feature an automatic lens cap that opens when the camera is powered on, they often use plastic blades and thus do not offer much protection against damage. Friction fit lens caps exist but are quite rare. Lens caps or covers are often lost, they are not a high value item among photographers, especially professionals, photographers at large events or in large crowds may drop their lens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barn Doors
Stage lighting accessories are components manufactured for conventional (non- automated) stage lighting instruments. Most conventional fixtures are designed to accept a number of different accessories designed to assist in the modification of the output. These accessories are intended to either provide relatively common functionality not originally provided in a fixture (such as beam shaping through barn doors), or to extend the versatility of a lighting instrument by introducing features. Other accessories have been designed to overcome limitations or difficulties some fixtures present in specific applications. All stage lighting accessories fall into one of three distinct categories: components installed inside the fixture, components affixed to the front of the fixture (in front of the lens), or components mounted elsewhere on the exterior of a fixture (to the side, top or bottom). External Barn doors Barn doors, or occasionally a set of barn doors, are an attachment fitte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellows (photography)
In photography, a bellows is the accordion-like, pleated expandable part of a camera, usually a large or medium format camera, to allow the lens to be moved with respect to the focal plane for focusing. Bellows are also used on enlargers. The bellows provides a flexible, dark extension between the film plane and the lens. Classification Two kinds of bellows are commonly used on cameras; bag bellows are normally used with a lens of short focal length, and accordion bellows with a much longer range of extension. For large format cameras, “double extension” refers to bellows that extend to a length equal to about twice the focal length of a standard lens, e.g. 300 mm for the 4×5 inch format. “Triple extension” for the same format indicates bellows extension of 450 to 500 mm. Flexibility Bellows allow movements that can be used to correct distortion in a photograph and to avoid converging or diverging verticals. Use of a bellows-based camera can ensure that paralle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon EF 70–200mm Lens
The EF 70–200mm lenses are a group of telephoto zoom lens, zoom Full-frame digital SLR, full-frame lenses made by Canon Inc., Canon. The lenses have an Canon EF lens mount, EF mount to work with the Canon EOS, EOS line of cameras. The lens comes in seven different versions, all of which have fixed maximum Apertures, aperture at all focal lengths, and are Canon EF lens mount#L-series lenses, L-series lenses. * f/4L USM * f/4L IS USM * f/4L IS II USM * f/2.8L USM * f/2.8L image stabilization, IS Ultrasonic motor, USM * f/2.8L IS II USM * f/2.8L IS III USM The latest iterations of both the f/4 and the f/2.8 variants were announced on 7 June 2018. The f/4 is currently under production and the original Suggested retail price, MSRP was increased from US$1,299 to US$1,499. In March 2021, it was reported that Canon had decided to discontinue the lens. Common fields of application The f/4 USM is popular among weight-sensitive landscape photographers and hobbyists who want L lens qu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentax DA 21mm Limited Lens
The Pentax smc DA 21mm F3.2 AL Limited is a moderate wide angle lens announced by Pentax on February 13, 2006. It is one of the five very compact "Limited" prime lenses for APS-C Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System film negative in its C ("Classic") format, of 25.1×16.7 mm, an aspect ratio of 3:2 and Ø 30.15 mm field d ... format cameras. Like its siblings, it was replaced in 2013 with a version that is HD-coated and has rounded aperture blades. Referenceswww.dpreview.com External links * {{Pentax K-mount lenses 21 Pancake lenses Camera lenses introduced in 2006 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canon EF 70-300mm Lens
The EF 70–300mm lenses are a series of telephoto zoom lenses made by Canon Inc. They have a Canon EF lens mount to work with the EOS line of cameras. Four Canon EF telephoto zoom lenses carry the 70–300mm designation. *EF 70–300mm 4.5–5.6 DO IS USM *EF 70–300mm 4–5.6L IS USM *EF 70–300mm 4–5.6 IS USM *EF 70–300mm 4–5.6 IS II USM All versions offer image stabilization (IS) and ultrasonic motor drive (USM) and have nearly the same maximum aperture of 4/4.5 to 5.6 over their entire focal range. EF 70–300mm 4.5–5.6 DO IS USM This lens makes use of Canon's Diffractive optics rather than a traditional lens of wholly refractive design. This allows the lens to be more compact, albeit heavier and much more expensive than a lens of conventional design. The lens contains Image Stabilization and a ring USM, which allows full-time manual focusing of the lens while using the camera in single shot mode. This lens offers good optical quality with the caveat that the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focal Length
The focal length of an Optics, optical system is a measure of how strongly the system converges or diverges light; it is the Multiplicative inverse, inverse of the system's optical power. A positive focal length indicates that a system Convergence (optics), converges light, while a negative focal length indicates that the system Divergence (optics), diverges light. A system with a shorter focal length bends the Ray (optics), rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. For the special case of a thin lens in air, a positive focal length is the distance over which initially Collimated beam, collimated (parallel) rays are brought to a Focus (optics), focus, or alternatively a negative focal length indicates how far in front of the lens a point source must be located to form a collimated beam. For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power. In mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wide-angle Lens
In photography and cinematography, a wide-angle lens is a Photographic lens, lens covering a large angle of view. Conversely, its focal length is substantially smaller than that of a normal lens for a given film plane. This type of lens allows more of the Scene (perception), scene to be included in the photograph, which is useful in architectural, interior, and landscape photography where the photographer may not be able to move farther from the scene to photograph it. Another use is where the photographer wishes to emphasize the difference in size or distance between objects in the foreground and the background; nearby objects appear very large and objects at a moderate distance appear small and far away. This exaggeration of relative size can be used to make foreground objects more prominent and striking, while capturing expansive backgrounds. A wide-angle lens is also one that projects a substantially larger image circle than would be typical for a standard design lens of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Of View
In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term '' field of view''. It is important to distinguish the angle of view from the angle of coverage, which describes the angle range that a lens can image on a given image sensor or film location (the image plane). In other words, the angle of coverage is determined by the lens and the image plane while the angle of view (AOV) is decided by not only them but also the film or image sensor size. The image circle (giving the angle of coverage) produced by a lens on a given image plane is typically large enough to completely cover a film or sensor at the plane, possibly including some vignetting toward the edge. If the angle of coverage of the lens does not fill the sensor, the image circle will be visible, typically with strong vignetting toward the edge, and the effective angle of view will be limited to the angle of cov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vignetting
In photography and optics, vignetting ( ) is a reduction of an image's brightness or saturation toward the periphery compared to the image center. The word '' vignette'', from the same root as ''vine'', originally referred to a decorative border in a book. Later, the word came to be used for a photographic portrait that is clear at the center and fades off toward the edges. A similar effect is visible in photographs of projected images or videos off a projection screen, resulting in a so-called "hotspot" effect. Vignetting is often an unintended and undesired effect caused by camera settings or lens limitations. However, it is sometimes deliberately introduced for creative effect, such as to draw attention to the center of the frame. A photographer may deliberately choose a lens that is known to produce vignetting to obtain the effect, or it may be introduced with the use of special filters or post-processing procedures. When using zoom lenses, vignetting may occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
