|
Pentaprism
A pentaprism is a five-sided reflecting prism (optics), prism used to deviate a beam of light by a constant 90°, even if the entry beam is not at 90° to the prism. The beam reflects inside the prism ''twice'', allowing the transmission of an image through a right angle without inverting it (that is, without changing the image's Chirality (electromagnetism), handedness) as an ordinary right-angle prism or mirror would. The reflections inside the prism are not caused by total internal reflection, since the beams are incident at an angle less than the critical angle (optics), critical angle (the minimum angle for total internal reflection). Instead, the two faces are coated to provide mirror surfaces. The two opposite transmitting faces are often coated with an anti-reflective coating, antireflection coating to reduce spurious reflections. The fifth face of the prism is not used optically but truncates what would otherwise be an awkward angle joining the two mirrored faces. In c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-lens Reflex Camera
In photography, a single-lens reflex camera (SLR) is a type of camera that uses a mirror and prism system to allow photographers to view through the lens and see exactly what will be captured. SLRs became the dominant design for professional and consumer-level cameras throughout the late 20th century, offering interchangeable lenses, through-the-lens (TTL) metering, and precise framing. Originating in the 1930s and popularized in the 1960s and 70s, SLR technology played a crucial role in the evolution of modern photography. Although digital single-lens reflex (DSLR) cameras succeeded film-based models, the rise of Mirrorless camera, mirrorless cameras in the 2010s has led to a decline in SLR use and production. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on most SLRs, the mirror flips out of the light path and allows light to pass through to the light receptor and the im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nikon F
The Nikon F camera, introduced in April 1959, was Nikon Corporation, Nikon's first Single-lens reflex camera, SLR camera. It was one of the most advanced cameras of its day. Although many of the concepts had already been introduced elsewhere, it was revolutionary in that it was the first to combine them all in one camera. It was produced until October 1973 and was replaced by the Nikon F2. Aspects of its design remain in all of Nikon's subsequent SLR cameras, through the current Nikon F6 film and Nikon D6 digital models (which still share its Nikon F-mount for lenses). The "F" in Nikon F was selected from the term "re-f-lex", since the pronunciation of the first letter "R" is not available in many Asian languages. That tradition was carried all the way through their top line of Nikon cameras until the introduction of the Nikon D1 (digital) cameras decades later. Specially modified Nikon F cameras were used in space in the early 1970s aboard the Skylab space station. History The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contax
Contax (stylised as CONTAX in the Yashica/Kyocera era) began as a German camera model in the Zeiss Ikon line in 1932, and later became a brand name. The early cameras were among the finest in the world, typically featuring high quality Carl Zeiss AG, Zeiss interchangeable Photographic lens, lenses. The final products under the Contax name were a line of 135 film, 35 mm, medium format, and digital cameras engineered and manufactured by Japanese multinational Kyocera, and featuring modern Zeiss optics. In 2005, Kyocera announced that it would no longer produce Contax cameras. The rights to the brand are currently part of Carl Zeiss AG, but no Contax cameras are currently in production, and the brand is considered dormant. Historical overview While the firm of Ernst Leitz of Wetzlar established the 24 mm × 36 mm negative format on perforated 35 mm movie film as a viable photographic system, Zeiss Ikon of Dresden decided to produce a competitor designed to b ... [...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] |
Prism (optics)
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled—elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides. Not all optical prisms are geometric prisms, and not all geometric prisms would count as an optical prism. Prisms can be made from any material that is transparent to the wavelengths for which they are designed. Typical materials include glass, acrylic and fluorite. A dispersive prism can be used to break white light up into its constituent spectral colors (the colors of the rainbow) to form a spectrum as described in the following section. Other types of prisms noted below can be used to reflect light, or to split light into components with different polarizations. Types Dispersive ''Dispersive prisms'' are used to break up light into its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Total Internal Reflection
In physics, total internal reflection (TIR) is the phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected back into the first ("internal") medium. It occurs when the second medium has a higher wave speed (i.e., lower refractive index) than the first, and the waves are incident at a sufficiently oblique angle on the interface. For example, the water-to-air surface in a typical fish tank, when viewed obliquely from below, reflects the underwater scene like a mirror with no loss of brightness (Fig.1). TIR occurs not only with electromagnetic waves such as light and microwaves, but also with other types of waves, including sound and water waves. If the waves are capable of forming a narrow beam (Fig.2), the reflection tends to be described in terms of " rays" rather than waves; in a medium whose properties are independent of direction, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light
Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequency, frequencies of 750–420 terahertz (unit), terahertz. The visible band sits adjacent to the infrared (with longer wavelengths and lower frequencies) and the ultraviolet (with shorter wavelengths and higher frequencies), called collectively ''optical radiation''. In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity (physics), intensity, propagation direction, frequency or wavelength spectrum, and polarization (waves), polarization. Its speed of light, speed in vacuum, , is one of the fundamental physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construction
Construction are processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the asset is built and ready for use. Construction also covers repairs and maintenance work, any works to expand, extend and improve the asset, and its eventual demolition, dismantling or wikt:decommission, decommissioning. The construction industry contributes significantly to many countries' gross domestic products (Gross domestic product, GDP). Global expenditure on construction activities was about $4 trillion in 2012. In 2022, expenditure on the construction industry exceeded $11 trillion a year, equivalent to about 13 percent of global Gross domestic product, GDP. This spending was forecasted to rise to around $14.8 trillion in 2030. The construction industry promotes economic development and brings many non-monetary benefits to many cou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Right Angle
In geometry and trigonometry, a right angle is an angle of exactly 90 Degree (angle), degrees or radians corresponding to a quarter turn (geometry), turn. If a Line (mathematics)#Ray, ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles. The term is a calque of Latin ''angulus rectus''; here ''rectus'' means "upright", referring to the vertical perpendicular to a horizontal base line. Closely related and important geometrical concepts are perpendicular lines, meaning lines that form right angles at their point of intersection, and orthogonality, which is the property of forming right angles, usually applied to Euclidean vector, vectors. The presence of a right angle in a triangle is the defining factor for right triangles, making the right angle basic to trigonometry. Etymology The meaning of ''right'' in ''right angle'' possibly refers to the Classical Latin, Latin adjective ''rectus'' 'erect, straight, upright, perp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plumb-bob
A plumb bob, plumb bob level, or plummet, is a weight, usually with a pointed tip on the bottom, suspended from a string and used as a vertical direction as a reference line, or plumb-line. It is a precursor to the spirit level and used to establish a vertical datum reference, datum. It is typically made of stone, wood, or lead, but can also be made of other metals. If it is used for decoration, it may be made of bone or ivory. The measuring instrument, instrument has been used since at least the time of ancient EgyptDenys A. Stocks. Experiments in Egyptian archaeology: stoneworking technology in Ancient Egypt'. Routledge; 2003. . p. 180. to ensure that constructions are "wikt:plumb, plumb", or vertical. It is also used in surveying, to establish the nadir (opposite of zenith) with respect to Gravity of Earth, gravity of a point in space. It is used with a variety of instruments (including Level (instrument), levels, theodolites, and tape measure, steel tapes) to set the in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
