Describes width of a picture to the height. The NTSC standard is 4:3. The current HDTV standard is 16:9. Modern movies range from 1.66:1 to 2.4:1. By far the most common are 1.85:1 and 2.35:1.
The contrast ratio is a figure used to measure the luminance difference between the brightest white and the darkest black.
A foot-lambert or footlambert (fL, sometimes fl or ft-L) is a unit of luminance in U.S. customary units and some other unit systems. A foot-lambert equals 1/π candela per square foot, or 3.426 candela per square meter (the corresponding SI unit). The foot-lambert is named after Johann Heinrich Lambert (1728–1777), a Swiss-German mathematician, physicist and astronomer. It is rarely used by electrical and lighting engineers, in favor of the candela per square foot or candela per square meter.
We often use fL to measure cinema screen brightness. It is particularly useful to measure screen brightness before and after cinema screen cleaning to better understand how much improvement in brightness and consequently, patron experience, results from the cinema screen cleaning process.
A measurement made to determined the screen reflectance. The higher the number, the greater light is transmitted to the audience.
The ability of a lens to pass light. Expressed in a ratio, it is the focal length of the lens divided by the effective diameter of the lens. A fast lens passes more light and gets a lower rating.
The quantity of visible light falling on a 1 square foot surface of a sphere 1 foot in radius as radiated by a source of 1 standard candle. This specification is often used to rate the light output of video projectors. Look for ANSI lumen ratings, it is a standardized measurement.
Term used to characterize emission or reflection of light from flat, diffuse surfaces. The luminance indicates how much luminous power will be detected by an eye looking at the surface from a particular angle of view. Luminance is thus an indicator of how bright the surface will appear.
Smaller perforation holes allowing sound to pass directly through the screen. Hole diameter typically 0.8mm. Mainy used in small theatres where the audience is near the screen.
The limit of a display’s ability to present fine detail. “Optical resolution” is usually the number of lines seen, “video resolution” is usually the number of “line pairs” seen.
What the picture is projected onto. The screen is more important when it comes to front projectors, when the screen must be bought separately.
The distance from the screen surface to a video display device. This is an important number used in the installation of a video display.
The angle at which a person is able to stand in regard to an image and still be able to see the entire image without distortion.
Term used to describe a picture in which the aspect ratio is wider than the NTSC standard of 4:3/1.33:1. Almost all movies made nowadays are shot in some widescreen format. To solve the problem of different aspect ratios, several different techniques can be used. Among them are anamorphic squeezing, letterboxing, and Pan and Scanning.