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Hurter And Driffield
Ferdinand Hurter (1844–1898) and Vero Charles Driffield (1848–1915) were nineteenth-century photographic scientists who brought quantitative scientific practice to photography through the methods of sensitometry and densitometry. Among their other innovations was a photographic exposure estimation device known as an actinograph. See also * H&D speed numbers, originally described in 1890, for film speed Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relations ... measurements References External links A brief history of Hurter and Driffield by Ron Callender in ''Encyclopedia of Nineteenth-century Photography'' 2008 pp.732-4 History of photography {{photo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H&D Curve
H&D (), is a South Korean duo formed by Pocketdol Studio in 2020. The duo debuted on April 21, 2020, with ''Soulmate''. Members *Lee Han-gyul (이한결) *Nam Do-hyon (남도현) History Pre-debut Prior to their debut as a duo, both members had participated as contestants on multiple shows. Hangyul had previously debuted as a member of Yama and Hotchicks Entertainment's ballad group IM and in 2017 and 2018, competed in the show ''The Unit'' alongside his members. The group is considered to be disbanded as they've been inactive since. Dohyon previously competed in the show ''Under Nineteen'' in 2018 and 2019. Later in 2019, both Hangyul and Dohyon competed in ''Produce X 101'', representing MBK Entertainment, alongside fellow MBK trainee Kim Yeongsang. In the show's finale, Hangyul and Dohyon placed 7th and 8th respectively, making them part of the show's debut line-up and members of the group X1. They promoted with the group until their disbandment on January 6, 2020. After ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferdinand Hurter
Ferdinand Hurter (15 March 1844 – 12 March 1898) was a Swiss industrial chemist who settled in England. He also carried out research into photography. Early life Ferdinand Hurter was born in Schaffhausen, Switzerland, the only son of Tobias Hurter, a bookbinder, and his wife Anna Oechslein.N. J. Travis (2004) ‘Hurter, Ferdinand (1844–1898)’, rev., ''Oxford Dictionary of National Biography'', Oxford University PressRetrieved on 10 July 2007 His father died when Ferdinand was aged only two and his mother worked as a nurse to support him and his sister Elizabeth. She later married her late husband's half-brother, David, and Ferdinand developed a strong relationship with his stepfather. After education at the local Gymnasium (school), Gymnasium he became an apprentice to a dyer in Winterthur before moving to Zürich to work in a silk firm. He then attended Zürich Polytechnic before going to Heidelberg University. Here he studied chemistry under Robert Bunsen and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vero Charles Driffield
Vero Charles Driffield (7 May 1848 – 14 November 1915) was an English chemical engineer who also became involved in photographic research. Driffield was educated at Liverpool Collegiate and Sandbach Grammar School. He also attended a private school in Southport where he came into contact with a Swiss master called Dr Knecht. Leaving school he became an apprentice to a photographer in Southport but then decided to study engineering. In 1871 he became an engineer at the Gaskell–Deacon Works in Widnes, Lancashire where the chief chemist was the Swiss Ferdinand Hurter. Through a common interest in music they became friends and around 1876 Driffield persuaded Hurter to take up photography as a hobby. Hurter applied his scientific mind to photography and together they carried out important research into the subject. They published eight papers and in 1898 they were jointly awarded the Progress Medal of the Royal Photographic Society.Royal Photographic Society. ''Pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photography
Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing. The result with photographic emulsion is an invisible latent image, which is later chemically "developed" into a visible image, either negative or positive, depending on the purp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensitometry
Sensitometry is the scientific study of light-sensitive materials, especially photographic film. The study has its origins in the work by Ferdinand Hurter and Vero Charles Driffield (circa 1876) with early black-and-white emulsions. They determined how the density of silver produced varied with the amount of light received, and the method and time of development. Details Plots of film density (log of opacity) versus the log of exposure are called characteristic curves, Hurter–Driffield curves, H–D curves, HD curves, H & D curves, D–logE curves, or D–logH curves. At moderate exposures, the overall shape is typically a bit like an "S" slanted so that its base and top are horizontal. There is usually a central region of the HD curve which approximates to a straight line, called the "linear" or "straight-line" portion; the slope of this region is called the gamma. The low end is called the "toe", and at the top, the curve rounds over to form the "shoulder". At extremely hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Densitometry
Densitometry is the quantitative measurement of optical density in light-sensitive materials, such as photographic paper or photographic film, due to exposure to light. Overview Optical density is a result of the darkness of a developed picture and can be expressed absolutely as the number of dark spots (i.e., silver grains in developed films) in a given area, but usually it is a relative value, expressed in a scale. Since density is usually measured by the decrease in the amount of light which shines through a transparent film, it is also called ''absorptiometry'', the measure of light absorption through the medium. The corresponding measuring device is called a densitometer (''absorptiometer''). The decadic (base-10) logarithm of the reciprocal of the transmittance is called the absorbance or ''density''. ''DMax'' and ''DMin'' refer to the maximum and minimum density that can be produced by the material. The difference between the two is the ''density range''. The density ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure (photography)
In photography, exposure is the amount of light per unit area (the image plane's illuminance times the exposure time) reaching a frame of photographic film or the surface of an electronic image sensor, as determined by shutter speed, lens F-number, and scene luminance. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region. An "exposure" is a single shutter cycle. For example, a long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated ''photometric exposure'' (''H''v) is the same so long as the total exposure time is the same. Definitions Radiant exposure Radiant exposure of a ''surface'', denoted ''H''e ("e" for "energetic", to avoid confusion with photometric quantities) and measured in , is given by :H_\mathrm = E_\mathrmt, where *''E'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinograph
An actinograph is an instrument for measuring or estimating the amount of light available, in terms of its ability to expose photographic film. That is, it measures the ''actinic'' or ''chemical'' intensity of light, as opposed to radiometric or photometric amount of light. The earliest actinographs were 24-hour recording devices, using a rotating cylinder of photographic paper exposed through a wedged-shaped slit to record a graph of actinic light during the period of a day; hence the ''graph'' suffix in ''actinograph''. Such devices were developed and described by Robert Hunt, secretary of the Royal Cornwall Polytechnic Society in 1845, as an improvement on T. B. Jordan's 1839 ''Heliograph''. In 1888, Ferdinand Hurter and Vero Charles Driffield patented a device for estimating the actinic power of sunlight and for computing exposure times and apertures for cameras, based on the plate speed, time of day, time of year, and latitude. These were slide rules, not measuring in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Film Speed
Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relationship between exposure and output image lightness in digital cameras. Relatively insensitive film, with a correspondingly lower speed index, requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a ''slow film''. Highly sensitive films are correspondingly termed ''fast films''. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality (via coarser film grain or higher image noise of other types). In short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the quantum efficiency of the film or sensor. Film speed measurement systems His ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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