svtelnosti

Svetelnosti, often written svetelnost or svetelnosti in Czech, is a term describing the property of a system or surface related to the emission, reflection, or transmission of light. It is used to convey the general idea of brightness or perceived lightness. In texts without diacritics, the form svetelnosti may be used.

In optics and photography, svetelnost commonly denotes a system’s light-gathering ability, most often expressed by the maximum aperture of a lens. A lens with a smaller f-number (for example, f/1.4) has greater svetelnost than one with a larger f-number (for example, f/4), enabling brighter images under the same exposure.

In photometry, luminance (the quantity often referred to as brightness) is a measured parameter that quantifies how bright a surface appears to the eye, expressed in candela per square meter (cd/m²). Svetelnost is thus a design or perceptual trait, while luminance is a specific measurable quantity; the terms are related but not interchangeable in precise contexts.

Etymology: from světlo “light” plus the noun-forming suffix -nost. The term is common in Czech and Slovak engineering, photography, and physics literature. See also brightness, luminance, photometry, radiometry, optics.