![]() You might think the atrium of a movie theater is bright until you step outside into the sunlight. When asked how “bright” a light is, the answer is rather subjective. Understanding Measurements (Units) of Brightness How to Get the Best Visibility for Warning Lights.The candela per square metre is sometimes called the nit. Luminous flux per unit solid angle per unit projected source area. The lumen second is sometimes called the talbot. ![]() Lighting requirements for commercial spaces range from 5 fc for storage spaces to 200 fc for visually intensive work. Indoor lighting for residences seeks to provide 5-40 fc for general spaces and 70-90 fc for work spaces. The intensity of light near a window can range from 100 to 5,000 fc, depending on the orientation of the window, time of year and latitude. An overcast day will produce an intensity of around 100 fc. Since light intensity is the primary factor in the photosynthesis of plants, US horticulturalists often measure and discuss optimum intensity for various plants in foot-candles.įull, unobstructed sunlight has an intensity of approximately 10,000 fc. In the motion picture cinematography field in the US, incident light meters are used to measure the number of foot-candles present, which are used to calculate the intensity of motion picture lights, allowing cinematographers to set up proper lighting-contrast ratios when filming. Foot-candles are also commonly used in the museum and gallery fields in the US, where lighting levels must be carefully controlled to conserve light-sensitive objects such as prints, photographs, and paintings, the colors of which fade when exposed to bright light for a lengthy period. In the US lighting industry, foot-candles are a common unit of measurement used by architects to calculate adequate lighting levels. In many practical applications, as when measuring room illumination, it is often not needed to measure illuminance more accurately than ☑0% in these situations it is sufficient to think of one foot-candle as about ten lux. ![]() ![]() One foot-candle is equal to approximately 10.76 lux. Given the relation between candela and lumen, the two definitions listed are identical, with the second one potentially being easier to relate to in some everyday situations. Alternatively, it can be defined as the illuminance of one lumen on a one- square foot surface with a uniform distribution. The foot-candle is defined as the illuminance of the inside surface of a one-foot-radius sphere with a point source of one candela at its center. Nearly all of the world uses the corresponding SI derived unit lux, defined as one lumen per square meter. This unit is commonly used in lighting layouts in parts of the world where United States customary units are used, mainly the United States. The foot-candle is defined as one lumen per square foot. General Electric Light Meter used in photography to measure light values in foot-candles.Ī foot-candle (sometimes foot candle abbreviated fc, lm/ft 2, or sometimes ft-c) is a non- SI unit of illuminance or light intensity.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |