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Luminous efficacy can be normalized by the maximum possible luminous efficacy to a dimensionless quantity called luminous efficiency.The distinction between efficacy and efficiency is not always carefully maintained in published sources, so it is not uncommon to see "efficiencies" expressed in lumens per watt, or "efficacies" expressed as a percentage.
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 ...
To help compare different orders of magnitude, the following list describes various source in lux, which is a lumen per square metre. Factor Multiple 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.
Google on Monday removed derogatory reviews about McDonald's after the suspect in the killing of UnitedHealth executive Brian Thompson was arrested at its restaurant in Altoona, Pennsylvania ...
By early Wednesday, Jabbar was walking the streets of New Orleans’ French Quarter between 1 a.m. and 2 a.m. and planting at least two improvised explosive devices, or IEDs, authorities have said ...
Pipes exposed to "severe cold" including outdoor hose bibs, swimming pool supply lines, and water sprinkler lines. (If you have swimming pool or sprinkler supply lines, they needed drained too.)
A typical problem with cameras using built-in flash units is the low intensity of the flash; the level of light produced will often not suffice for good pictures at distances of over 3 metres (10 ft) or so. Dark, murky pictures with excessive image noise or "grain" will result. In order to get good flash pictures with simple cameras, it is ...