Common Lighting Terminology
|
Ambient Light |
The light already present in a scene, before any additional lighting is added. |
| Incident Light | Light seen directly from a light source (lamp, sun, etc). |
| Reflected Light | Light seen after having bounced off a surface. |
| Colour Temperature | A standard of measuring the characteristics of light, measured in degrees Kelvin. More Info: Colour Temperature Chart |
| Contrast Ratio | The difference in brightness between the brightest white and the darkest black within an image. More Info: Contrast Ratio |
| Key Light | The main light on the subject, providing most of the illumination and contrast. More Info: 3 Point Lighting |
| Fill Light | A light placed to the side of the subject to fill out shadows and balance the key light. More Info: 3 Point Lighting |
| Back Light | A light placed at the rear of a subject to light from behind. More Info: 3 Point Lighting |
| Hard Light |
Light directly from a source such as the sun, traveling undisturbed onto the subject being lit. |
| Soft Light | Light which appears to "wrap around" the subject to some degree. Produces less shadows or softer shadows. |
| Spot | A controlled, narrowly-focused beam of light. |
| Flood | A broad beam of light, less directional and intense than a spot. |
| Tungsten | Light from an ordinary light bulb containing a thin coiled tungsten wire that becomes incandescent (emits light) when an electric current is passed along it. Tungsten colour temperature is around 2800K to 3400K. Also known as incandescent light. |
| Halogen | Type of lamp in which a tungsten filament is sealed in a clear capsule filled with a halogen gas. |
| Fresnel | A light which has a lens with raised circular ridges on its outer surface. The fresnel lens is used to focus the light beam. |
| Incandescent | Incandescent lamps produce heat by heating a wire filament until it glows. The glow is caused by the filament's resistance to the current and is called incandescence. |
Measuring Light
There are many different units for measuring light and it can get very complicated. Here are a few common measurement terms:
Candela (cd)
Unit of luminous intensity of a light source in a specific direction. Also called candle.
Technically, the radiation intensity in a perpendicular direction of a surface of 1/600000 square metre of a black body at the temperature of solidification platinum under a pressure of 101,325 newtons per square metre.
Footcandle (fc or ftc)
Unit of light intensity, measured in lumens per square foot. The brightness of one candle at a distance of one foot. Approximately 10.7639 lux.
Lumen (lm)
Unit of light flow or luminous flux. The output of artificial lights can be measured in lumens.
Lux (lx)
Unit of illumination equal to one lumen per square metre. The metric equivalent of foot-candles (one lux equals 0.0929 footcandles). Also called metre-candle.