For applications where continuous lighting is needed, many photographers have used what are commonly referred to as “Hot Lights”. Hot Light is slang for continuous lighting due to the amount of heat generated when used. These traditional lights are being replaced by lighting technology which is more energy efficient and does not get nearly as hot.
Legacy Hot Lights
Traditional (legacy) lights use incandescent (tungsten), quartz or halogen bulbs. Besides the high electrical consumption and heat generated, another challenge of these lights was the color temperature variations. It was not uncommon for color gels (plastic filters) to be used to modify the color temperature.
Besides being relatively inexpensive for bulbs and fixtures, the legacy hot lights had reasonably consistent color temperature throughout most of the bulbs life. The lights were are dimmable, allowing the photographer to control how much light was produced.
These legacy hot lights consume a lot of electricity and require large batteries or a generator to use when photographing on location.
Modern Hot Lights
Compact Fluorescent fixtures started being used in place of legacy lights to reduce the amount of heat generated and energy use of hot lights, but color temperature control was still an issue – that varied with the age of the bulb and how long it has been energized.
Many fluorescent bulbs take a few minutes to warm up and reach full brightness. they are usually not dimmable and those that are dimmable tend to flicker at lower brightness and have a different color temperature.
Although fluorescent hot lights consume about 50-65% less energy than the legacy hot lights, they still require large batteries or a generator to be used shooting on location.
Solid-state LED (Light Emitting Diode) technology was introduced more than a half-century ago, but never took its place in mainstream lighting until recently when better development allowed LEDs to be brighter and more reliable.
LED-based hot lights generate a cleaner, white light and are usually dimmable without flicker or color variation. Some units are dual-colored to allow introduction of warm or cool colored light.
LED fixtures consume 70-85% less energy than equivalent tungsten, halogen or quartz based hot lights, making them ideal for location shooting where continuous light is needed. A number of reliable battery-powered units are available on the market giving lighting capacity measured in hours.
A major flaw in LED technology is that it is more of a directional light, depending on the way it is molded. Typically when looking directly straight into an LED it is the brightest, but when shifting the point of view by just 10-degrees the light is not as intense.
When looking for a bright and clean, white continuous light that uses very little energy, runs touchable warm and has a long life – LED-based hot lights are a solid investment; no pun intended. It comes at a cost though; up to five times the cost of tungsten and twice as much as fluorescent.
Pay now or pay later … if the up front cost is a factor, then using inexpensive traditional hot lights will be sufficient, but be prepared for higher energy use and frequent bulb replacement. The latter point being a particular issue as replacement bulbs become scarce. Government restrictions worldwide are causing the phase-out of incandescent and similar light bulbs.