What is tungsten lighting?

Answer 1

Tungsten lighting is a term used by photographers to distinguish from fluorescent lighting or strobe lighting. Tungsten is a type of incandescent lighting using a bulb with a filament made of the metal tungsten, as opposed to, say, carbon or platinum. Unless you have switched to compact fluorescents, most of the lighting in your home is tungsten. In still Photography, tungsten lighting gave studio photographers greater flexibility than the classic north sky light. Tungsten lights reigned supreme for many years in commercial studios until the introduction of strobes (or speed lights) and some workers still prefer tungsten for its controllability (what you see is what you get). For television and cinematography tungsten is essential.

Tungsten lamps specifically for photographic purposes are made to very tight tolerances since most photography or cinematography today is done in color. For photography, tungsten lamps are produced in two types, having very specific "color temperatures:" type B lamps, the most common, have a color temperature of 3200 degrees Kelvin (3200°K); type A lamps had a color temperature of 3400°K and were matched to Kodachrome Type A (ASA/ISO 40). This material is now discontinued and so far as I know there are no other Type A still stocks on the market.

Without getting too tediously technical we should try briefly to explain "color temperature:" The higher the color temperature, the bluer the light. The lower the color temperature, the more yellow to red the light. Noon daylight (sun shining, no cloud cover) in the area of the globe between the tropics is considered for practical purposes to have a color temperature of 5000 degrees Kelvin (5000°K). "Daylight" color films, or your default setting on your digital camera, are balanced for ±5000°K. Electronic flashes ("strobes" or "speed lights" or the little strobe on your camera) have a nominal color temperature equal to noon daylight. All other light sources have different color temperatures and theoretically require some sort of compensation to render "true" color, either by filtering the film or the light or by changing the film or settings on the camera. If you are using studio quality tungsten lighting, you should also use a type-B incandescent balanced film, or set your digital camera for either AUTO or incandescent. In practice, plain household tungsten lighting (color temperature around 2800°K) will yield a perfectly acceptable photograph with a type-B film or with your digital camera set on auto or incandescent.

Most 3200°K studio lamps used today are tungsten halogen. Halogen lamps have quartz envelopes and are filled with a halogen gas such as iodine or bromine. The gas combines with the evaporated tungsten from the filament during use and helps some of the tungsten plate back onto the filament when it cools, lengthening the life of the lamp. The quartz envelope does not darken over the life of the lamp, so the color temperature does not significantly change, nor does its brilliance.