35 mm film

35 mm film is the film gauge most commonly used for motion pictures and chemical still photography (see 135 film). The name of the gauge refers to the width of the photographic film, which consists of strips 34.98 ±0.03 mm (1.377 ±0.001 inches) wide. The standard negative pulldown for movies ("single-frame" format) is four perforations per frame along both edges, which results in 16 frames per foot of film. For still photography, the standard frame has eight perforations on each side.

A variety of largely proprietary gauges were devised for the numerous camera and projection systems being developed independently in the late 19th century and early 20th century, ranging from 13 mm to 75 mm (0.51–2.95 in), as well as a variety of film feeding systems. This resulted in cameras, projectors, and other equipment having to be calibrated to each gauge. The 35 mm width, originally specified as 1.375 inches, was introduced in 1892 by William Dickson and Thomas Edison, using film stock supplied by George Eastman. Film 35 mm wide with four perforations per frame became accepted as the international standard gauge in 1909, and remained by far the dominant film gauge for image origination and projection until the advent of digital photography and cinematography, despite challenges from smaller and larger gauges, because its size allowed for a relatively good trade-off between the cost of the film stock and the quality of the images captured.

Prime lens

In film and photography, a prime lens is either a photographic lens whose focal length is fixed, as opposed to a zoom lens, or it is the primary lens in a combination lens system.

Confusion can sometimes result due to the two meanings of the term if the context does not make the interpretation clear. Alternative terms primary focal length, fixed focal length, and FFL are sometimes used to avoid ambiguity.

As alternative to zoom lens

The term prime has come to be used as the opposite of zoom; that is, a prime lens is a fixed-focal-length, or unifocal lens, while a zoom lens has a variable focal length.

While a prime lens of a given focal length is less versatile than a zoom, it is often of superior optical quality, wider maximum aperture, lighter weight, smaller size. These advantages stem from having fewer moving parts, optical elements optimized for one particular focal length, and a less complicated lens formula which means that they suffer from fewer problems of optical aberration. The larger maximum aperture (smaller f-number) allows photography in lower light, and a shallower depth of field.

Canon

Canon may refer to:

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Lens

Lens may refer to:

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Online shopping

Online shopping (sometimes known as e-tail from "electronic retail" or e-shopping) is a form of electronic commerce which allows consumers to directly buy goods or services from a seller over the Internet using a web browser. Alternative names are: e-web-store, e-shop, e-store, Internet shop, web-shop, web-store, online store, online storefront and virtual store. Mobile commerce (or m-commerce) describes purchasing from an online retailer's mobile optimized online site or app.

An online shop evokes the physical analogy of buying products or services at a bricks-and-mortar retailer or shopping center; the process is called business-to-consumer (B2C) online shopping. In the case where a business buys from another business, the process is called business-to-business (B2B) online shopping. The largest of these online retailing corporations are Alibaba, Amazon.com, and eBay.

History

English entrepreneur Michael Aldrich invented online shopping in 1979. His system connected a modified domestic TV to a real-time transaction processing computer via a domestic telephone line. He believed that videotex, the modified domestic TV technology with a simple menu-driven human–computer interface, was a 'new, universally applicable, participative communication medium — the first since the invention of the telephone.' This enabled 'closed' corporate information systems to be opened to 'outside' correspondents not just for transaction processing but also for e-messaging and information retrieval and dissemination, later known as e-business. His definition of the new mass communications medium as 'participative' [interactive, many-to-many] was fundamentally different from the traditional definitions of mass communication and mass media and a precursor to the social networking on the Internet 25 years later.