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A key light of 800 footcandles and a fill light of 200 footcandles has a ratio of 5:1 according to the lighting ratio formula — (800 + 200):200 = 1000 / 200 = 5 : 1. The ratio can be determined in relation to F stops since each increase in f-stop is equal to double the amount of light: 2 to the power of the difference in f stops is equal to ...
[1] [2] [3] The f-number is also known as the focal ratio, f-ratio, or f-stop, and it is key in determining the depth of field, diffraction, and exposure of a photograph. [4] The f-number is dimensionless and is usually expressed using a lower-case hooked f with the format f / N , where N is the f-number.
Artificial light sources are usually evaluated in terms of luminous efficacy of the source, also sometimes called wall-plug efficacy. This is the ratio between the total luminous flux emitted by a device and the total amount of input power (electrical, etc.) it consumes.
In some cases, ambient light may be used as a fill, in which case additional lighting provides the stronger light source, for example in bounce flash photography. The relative intensity of ambient light and fill light is known as the lighting ratio, an important factor in calculating contrast in the finished image.
Light scattering from many common surfaces can be modelled by reflectance. Light scattering depends on the wavelength of the light being scattered. Thus, limits to spatial scales of visibility arise, depending on the frequency of the incident lightwave and the physical dimension (or spatial scale) of the scattering center, which is typically in ...
The CU is the ratio of luminous flux from a luminaire incident upon a work plane to that emitted by the lamps within the luminaire. As a ratio, the coefficient of utilization is unitless. For example, some of the light emitted by a luminaire may exit away from the desired plane and is therefore wasted.
LLD = (mean lumens/rated lumens) Those values can be found from the lamp manufacturer data; Ballast Factor (BF): Compares the ratio of light output of a lamp working by a specific ballast to the light output of the same lamp working by a standard reference ballast. The BF is given in the ballast manufacturer data.
Shader Model 3.0's lighting precision has a minimum of 32 bits as opposed to 2.0's 8-bit minimum. Also all lighting-precision calculations are now floating-point based. NVIDIA states that contrast ratios using Shader Model 3.0 can be as high as 65535:1 using 32-bit lighting precision. At first, HDRR was only possible on video cards capable of ...