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  2. Luminous efficacy - Wikipedia

    en.wikipedia.org/wiki/Luminous_efficacy

    Not all wavelengths of light are equally visible, or equally effective at stimulating human vision, due to the spectral sensitivity of the human eye; radiation in the infrared and ultraviolet parts of the spectrum is useless for illumination. The luminous efficacy of a source is the product of how well it converts energy to electromagnetic ...

  3. Exposure value - Wikipedia

    en.wikipedia.org/wiki/Exposure_value

    E is the image-plane illuminance (lux or lumens/m²) t is the exposure time ("shutter speed") (seconds) The illuminance E is controlled by the f-number but also depends on the scene luminance. To avoid confusion, some authors (Ray 2000, 310) have used camera exposure to refer to combinations of camera settings.

  4. Flash (photography) - Wikipedia

    en.wikipedia.org/wiki/Flash_(photography)

    A flash is a device used in photography that produces a brief burst of light (lasting around 1 ⁄ 200 of a second) at a color temperature of about 5500 K [1] [citation needed] to help illuminate a scene. The main purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light.

  5. Light meter - Wikipedia

    en.wikipedia.org/wiki/Light_meter

    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.

  6. Photometry (optics) - Wikipedia

    en.wikipedia.org/wiki/Photometry_(optics)

    The lumen is defined as amount of light given into one steradian by a point source of one candela strength; while the candela, a base SI unit, is defined as the luminous intensity of a source of monochromatic radiation, of frequency 540 terahertz, and a radiant intensity of 1/683 watts per steradian.

  7. During her interview on First We Feast's "Hot Ones," Sydney Sweeney dished about Cassie's hot tub scene in "Euphoria" season 2.

  8. LED lamp - Wikipedia

    en.wikipedia.org/wiki/LED_lamp

    A 230-volt LED filament lamp, with an E27 base. The filaments are visible as the eight yellow vertical lines. An assortment of LED lamps commercially available in 2010: floodlight fixtures (left), reading light (center), household lamps (center right and bottom), and low-power accent light (right) applications An 80W Chips on board (COB) LED module from an industrial light luminaire, thermally ...

  9. Effective temperature - Wikipedia

    en.wikipedia.org/wiki/Effective_temperature

    The effective temperature of the Sun (5778 kelvins) is the temperature a black body of the same size must have to yield the same total emissive power.. The effective temperature of a star is the temperature of a black body with the same luminosity per surface area (F Bol) as the star and is defined according to the Stefan–Boltzmann law F Bol = σT eff 4.