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Hologon
The Zeiss Hologon is an ultra wide-angle f=15mm 8 triplet lens, providing a 110° angle of view for 35mm format cameras. The Hologon was originally fitted to a dedicated camera, the Zeiss Ikon Contarex Hologon in the late 1960s; as sales of that camera were poor and the Zeiss Ikon company itself was going bankrupt, an additional 225 lenses were made in Leica M mount and released for sale in 1972 as the only Zeiss-branded lenses for Leica rangefinders until the ZM line was released in 2005. The Hologon name was revived in 1994 for a recomputed f=16mm 8 lens fitted to the Contax G series of rangefinder cameras. Design The Hologon was designed by and others at Zeiss in 1966 and patented in 1972. It is a largely symmetric triplet with a fixed aperture; the original German patent application describes a lens with 120° angle of coverage and a 8 maximum aperture, while the US patent expands this to three related designs with different coverage angles and apertures (120° 8, 110° 5.6 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contax G
The Contax G camera line consists of two cameras, the G1 and G2, interchangeable-lens cameras sold by Kyocera under the Contax brand in competition with the Leica M7, Cosina Voigtländer Bessa-R, and Konica Hexar RF. The G1 was introduced in 1994 with the G2 joining it in 1996. In 2005, Kyocera retreated from the camera business and announced it would cease all activity related to the manufacture of Contax cameras at the end of the year, effectively spelling the end of the G system. Design The two G-series cameras have titanium-clad bodies and use the Contax G-mount, an electronic autofocus mount. When tested in 1995, the Contax G1 cost with the 45 mm Planar lens; the 28 mm Biogon and 90 mm Sonnar lenses were each , and the list price for the 16 mm Hologon was . The 45 mm Planar was listed separately at . The Contax G2 listed for with the 45 mm Planar lens in 1999. Critics were quick to accuse the G1 of not being a "true" (mechanical) rangefinder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeiss Biogon
Biogon is the brand name of Carl Zeiss for a series of photographic camera lenses, first introduced in 1934. Biogons are typically wide-angle lenses. History The first lens branded Biogon (2.8 / 3.5 cm, unbalanced) was designed in 1934 by Ludwig Bertele, then assigned to Zeiss Ikon Dresden, the Contax created as a modification of the then Sonnar. It was developed by Carl Zeiss in approximately 1937 and manufactured in Jena, then a redesign in Oberkochen. In 1951, a new Biogon with a 90° angle of view (Super Wide Angle) was designed, also by Ludwig Bertele. The advent of the Biogon opened the way to extreme wide-angle lenses. The first examples were produced from 1954 as the 4.5 / 21 mm for Contax, in 1954, 4.5 / 38 mm for Hasselblad Super Wide, and from 1955 to 1956 as the 4.5 / 53 mm and 4.5 / 75 mm for the Linhof. The original patent spanned three different variants, each with a different maximum aperture: 6.3, 4.5, and 3.4 lenses. Examples Since t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Zeiss AG
Carl Zeiss AG (), branded as ZEISS, is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe (joined 1866) and Otto Schott (joined 1884) he laid the foundation for today's multi-national company. The current company emerged from a reunification of Carl Zeiss companies in East and West Germany with a consolidation phase in the 1990s. ZEISS is active in four business segments with approximately equal revenue (Industrial Quality and Research, Medical Technology, Consumer Markets and Semiconductor Manufacturing Technology) in almost 50 countries, has 30 production sites and around 25 development sites worldwide. Carl Zeiss AG is the holding of all subsidiaries within Zeiss Group, of which Carl Zeiss Meditec AG is the only one that is traded at the stock market. Carl Zeiss AG is owned by the foundation Carl-Zeiss-Stiftung. The Zeiss Group has its headquarters in southern Germany, in the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeiss Ikon
Carl Zeiss AG (), branded as ZEISS, is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe (joined 1866) and Otto Schott (joined 1884) he laid the foundation for today's multi-national company. The current company emerged from a reunification of Carl Zeiss companies in East and West Germany with a consolidation phase in the 1990s. ZEISS is active in four business segments with approximately equal revenue (Industrial Quality and Research, Medical Technology, Consumer Markets and Semiconductor Manufacturing Technology) in almost 50 countries, has 30 production sites and around 25 development sites worldwide. Carl Zeiss AG is the holding of all subsidiaries within Zeiss Group, of which Carl Zeiss Meditec AG is the only one that is traded at the stock market. Carl Zeiss AG is owned by the foundation Carl-Zeiss-Stiftung. The Zeiss Group has its headquarters in southern Germany, in the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G Hologon-16 (1996)
G, or g, is the seventh letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''gee'' (pronounced ), plural ''gees''. History The letter 'G' was introduced in the Old Latin period as a variant of ' C' to distinguish voiced from voiceless . The recorded originator of 'G' is freedman Spurius Carvilius Ruga, who added letter G to the teaching of the Roman alphabet during the 3rd century BC: he was the first Roman to open a fee-paying school, around 230 BCE. At this time, ' K' had fallen out of favor, and 'C', which had formerly represented both and before open vowels, had come to express in all environments. Ruga's positioning of 'G' shows that alphabetic order related to the letters' values as Greek numerals was a concern even in the 3rd century BC. According to some records, the original seventh letter, 'Z', had been purged from the Latin alphabet somewhat ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depth Of Field
The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object distance at a time, depth of field is the distance between the nearest and the farthest objects that are in acceptably sharp focus. "Acceptably sharp focus" is defined using a property called the " circle of confusion". The depth of field can be determined by focal length, distance to subject, the acceptable circle of confusion size, and aperture. Limitations of depth of field can sometimes be overcome with various techniques and equipment. The approximate depth of field can be given by: : \text \approx \frac for a given circle of confusion (c), focal length (f), f-number (N), and distance to subject (u). As distance or the size of the acceptable circle of confusion increases, the depth of field increases; however, increasing the size ... [...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 superzoom lenses, vignetting may occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petzval Field Curvature
Petzval field curvature, named for Joseph Petzval, describes the optical aberration in which a flat object normal to the optical axis (or a non-flat object past the hyperfocal distance) cannot be brought properly into focus on a flat image plane. Field curvature can be corrected with the use of a field flattener, designs can also incorporate a curved focal plane like in the case of the human eye in order to improve image quality at the focal surface. It is not to be confused with flat-field correction, which refers to brightness uniformity. Analysis Consider an "ideal" single-element lens system for which all planar wave fronts are focused to a point at distance ''f'' from the lens. Placing this lens the distance ''f'' from a flat image sensor, image points near the optical axis will be in perfect focus, but rays off axis will come into focus before the image sensor, dropping off by the cosine of the angle they make with the optical axis. This is less of a problem when the im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astigmatism (optical Systems)
An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. The term comes from the Greek α- (''a-'') meaning "without" and στίγμα (''stigma''), "a mark, spot, puncture". Forms of astigmatism There are two distinct forms of astigmatism. The first is a third-order aberration, which occurs for objects (or parts of objects) away from the optical axis. This form of aberration occurs even when the optical system is perfectly symmetrical. This is often referred to as a "monochromatic aberration", because it occurs even for light of a single wavelength. This terminology may be misleading, however, as the ''amount'' of aberration can vary strongly with wavelength in an optical system. The second form of astigmatism occurs when the optical system is not symmetric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatic Aberration
In optics, chromatic aberration (CA), also called chromatic distortion and spherochromatism, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the wavelength of light. The refractive index of most transparent materials decreases with increasing wavelength. Since the focal length of a lens depends on the refractive index, this variation in refractive index affects focusing. Chromatic aberration manifests itself as "fringes" of color along boundaries that separate dark and bright parts of the image. Types There are two types of chromatic aberration: ''axial'' (''longitudinal''), and ''transverse'' (''lateral''). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens (focus ''shift''). Longitudinal aberration is typical at long focal lengths. Transverse aberration occurs when different wavelengths are focused at different position ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spherical Aberration
In optics, spherical aberration (SA) is a type of aberration found in optical systems that have elements with spherical surfaces. Lenses and curved mirrors are prime examples, because this shape is easier to manufacture. Light rays that strike a spherical surface off-centre are refracted or reflected more or less than those that strike close to the centre. This deviation reduces the quality of images produced by optical systems. Overview A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a radius that equals the radius of the sphere divided by the index of refraction of the lens material. A typical value of refractive index for crown glass is 1.5 (see list), which indicates that only about 43% of the area (67% of diameter) of a spherical lens is useful. It is often considered to be an imperfection of telescopes and other instruments which makes their focusing less than ideal due to the spherical shape of lenses and mirrors. This is an imp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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