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  2. Fluorescent-lamp formats - Wikipedia

    en.wikipedia.org/wiki/Fluorescent-lamp_formats

    High-lumen retrofit lamps for 40W T12 lamps in North America. Popular tube diameter in Japan; Circular 32W and 40W T10 lamps (Older versions of the 32W and 40W T9 lamps) T12 T38 1 + 1 ⁄ 2: 38.1 G13 bi-pin; Fa8 single-pin; R17d recessed double contact; One of the first diameters of fluorescent lamps, with the 15W T12 and 20W T12 having been ...

  3. Exposure (photography) - Wikipedia

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

    lux (= lumen per square metre) lx (= lm/m 2) L −2 ⋅J: Luminous flux incident on a surface Luminous exitance, luminous emittance M v: lumen per square metre lm/m 2: L −2 ⋅J: Luminous flux emitted from a surface Luminous exposure: H v: lux second: lx⋅s L −2 ⋅T⋅J: Time-integrated illuminance Luminous energy density ω v: lumen ...

  4. Fluorescent lamp - Wikipedia

    en.wikipedia.org/wiki/Fluorescent_lamp

    The efficacy of fluorescent tubes ranges from about 16 lumens per watt for a 4 watt tube with an ordinary ballast to over 100 lumens per watt [51] with a modern electronic ballast, commonly averaging 50 to 67 lm/W overall. [52] Ballast loss can be about 25% of the lamp power with magnetic ballasts, and around 10% with electronic ballasts.

  5. 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.

  6. Guide number - Wikipedia

    en.wikipedia.org/wiki/Guide_number

    Cameras with focal-plane shutters—even if they had PC connectors with X, F, M, or S-sync delays ("xenon sync" with zero delay and flashbulbs with peak delays of 5, 20, and 30 ms)—could not be used at speeds that attenuated guide numbers with most types of flashbulbs because their light curves were characterized by rapid rise and fall rates; the second shutter curtain would begin wiping ...

  7. Illuminance - Wikipedia

    en.wikipedia.org/wiki/Illuminance

    Illuminance diagram with units and terminology. In photometry, illuminance is the total luminous flux incident on a surface, per unit area. [1] It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. [2]