Foot-lambert

Foot-lambert (fL) is a unit of luminance used in the field of photometry. It is defined as the luminance of a surface that emits or reflects one lumen per square foot. The foot-lambert is named after the German physicist Johann Heinrich Lambert, who made significant contributions to the study of light and optics.

Definition

A foot-lambert is equal to 1/π candela per square foot. This unit is commonly used in the United States and other countries that use the imperial system of measurement. The SI unit equivalent of the foot-lambert is the candela per square meter, also known as the nit.

Applications

Foot-lamberts are primarily used in the fields of cinematography, theater, and display technology to measure the brightness of screens and projected images. For example, in the context of movie theaters, the brightness of the screen is often specified in foot-lamberts to ensure a consistent viewing experience.

Conversion

To convert foot-lamberts to candelas per square meter (nits), the following formula is used:

1 fL = 3.426 nits

Related Units

• Candela
• Lumen
• Nit (unit)
• Lux

See Also

• Photometry (optics)
• Luminance
• Illuminance
• Brightness