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An optical power meter (OPM) is a device used to measure the power in an optical signal. The term usually refers to a device for testing average power in fiber optic systems. Other general purpose light power measuring devices are usually called radiometers , photometers , laser power meters (can be photodiode sensors or thermopile laser ...
In modern photometry, the radiant power at each wavelength is weighted by a luminosity function that models human brightness sensitivity. Typically, this weighting function is the photopic sensitivity function, although the scotopic function or other functions may also be applied in the same way.
Wattmeter measures the electrical power circulating in any electric circuit; Microwave power meter measures power in a microwave signal; Optical power meter measures power in an optical signal; Google PowerMeter is a tool to track a household's energy usage; A cycling power meter measures the power output of a bicycle rider; Health meter, a ...
Historically, a photometer was separate from the camera and known as an exposure meter. The advanced photometers then could be used either to measure the light from the potential picture as a whole, to measure from elements of the picture to ascertain that the most important parts of the picture are optimally exposed, or to measure the incident ...
Use of a light meter for portrait cinematography in a Turkish music video set. A light meter (or illuminometer) is a device used to measure the amount of light.In photography, an exposure meter is a light meter coupled to either a digital or analog calculator which displays the correct shutter speed and f-number for optimum exposure, given a certain lighting situation and film speed.
The meter was uncoupled – the photographer would need to wait until the meter stabilized and manually set the shutter speed and lens aperture to match the indicated exposure reading. [145] The first camera with a built-in meter (also uncoupled) was the Zeiss Ikon Contaflex (Germany) 35 mm twin-lens reflex (TLR) camera of 1935. [93] [145] [146 ...
Other names for etendue include acceptance, throughput, light grasp, light-gathering power, optical extent, [1] and the AΩ product. Throughput and AΩ product are especially used in radiometry and radiative transfer where it is related to the view factor (or shape factor). It is a central concept in nonimaging optics.
The Zone System is a photographic technique for determining optimal film exposure and development, formulated by Ansel Adams and Fred Archer. [1] Adams described the Zone System as "[...] not an invention of mine; it is a codification of the principles of sensitometry, worked out by Fred Archer and myself at the Art Center School in Los Angeles, around 1939–40."