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Fluorescent lamps using conventional magnetic ballasts flicker at twice the supply frequency. Electronic ballasts do not produce light flicker since the phosphor persistence is longer than a half cycle of the higher operation frequency of 20 kHz. The 100–120 Hz flicker produced by magnetic ballasts is associated with headaches and eyestrain. [8]
The short-term flicker indicator P st LM is implemented in a light flickermeter which processes the light measured by means of a light sensor. The light flickermeter [ 14 ] [ 15 ] consists of four processing blocks which include weighting filters to account for frequency dependency of the visibility of TLMs as well as statistical processing to ...
Photographic lighting refers to how a light source, artificial or natural, illuminates the scene or subject that is photographed; put simply, it is lighting in regards to photography. Photographers can manipulate the positioning and the quality of a light source to create visual effects , potentially changing aspects of the photograph such as ...
Video demonstration of high-speed 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.
Light painting inside an abandoned limestone quarry in France. Light painting, painting with light, light drawing, light art performance photography, or sometimes also freezelight are terms that describe photographic techniques of moving a light source while taking a long-exposure photograph, either to illuminate a subject or space, or to shine light at the camera to 'draw', or by moving the ...
The fluorescent chemicals in fluorescent paint absorb the invisible UV radiation, then emit the energy as longer wavelength visible light of a particular color. Human eyes perceive this light as the unusual 'glow' of fluorescence. The painted surface also reflects any ordinary visible light striking it, which tends to wash out the dim ...
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New York Daily News (1880–2007), online photo archive DailyNewsPix, with photographs dating back to 1880 New York Public Library: ≈ 30% Public domain: 922,400+ (May 2024) [3] No No Yes English Pexels: Pexels license: Yes No Yes Pixabay: Pixabay license: 950,000+ (May 2017) Yes No Yes English (Default) + 25 other languages Pond5: Royalty-free