Wednesday, April 9, 2014

Special Lighting Guide: Lights!

By William Sawalich Published in Photography Lighting
Special Lighting Guide: Lights!

Continuous Hot Lights

In a still and motion world, these traditional movie lights have emerged as powerful options for hybrid shooters. Many photographers like the soft, warm look hot lights can give to a portrait. They aren't suitable for all situations, but hot lights have some definite advantages.

The broad appeal of continuous lights is that, unlike strobes, they can also be used for video, as well. In this age of convergence, continuous lights are practically a necessity for the well-heeled professional.

See The Light

Continuous lights offer WYSIWYG convenience—what you see is what you get—and hot lights are perhaps the most economical lighting available. In their simplest form, they resemble hardware store work lights: a parabolic dish reflector, a socket and an incandescent bulb. Higher-end models incorporate high-output quartz tungsten lamps or daylight-balanced HMI lamps and often Fresnel lenses that focus the light from flood to spot. This style of hot light defined 20th-century movie and television production, partly because the Fresnel lens focuses the pinpoint source into a beam that more closely emulates the characteristics of sunlight better than any other type of artificial source. Some hot lights are known as PARs because, instead of a Fresnel lens, they utilize a parabolic reflector.

Hot lights are so named because not only do the units themselves get incredibly hot (too hot to touch, in fact, requiring the use of leather gloves), they send heat toward the subject. That's an important distinction because hot lights can be uncomfortable for talent and heat up a set quickly, particularly in close quarters. This can be a challenge when working with food or other subjects that will wilt or melt. When used improperly or with low-grade accessories, hot lights become downright dangerous. As such, there's a robust offering of heat-resistant accessories and light modifiers, as well as barndoors and scrims to cut and shape the output. With tungsten hot lights, simple dimmer switches can be employed to provide stepless dimming from full power down to nothing.

1. You have to work carefully with hot lights to avoid motion blur in the subject. You can select a high shutter speed, obviously, but you'll need larger, hotter, more powerful lights. Modern DSLRs with broad ISO ranges are a good fit for hot lights.
2. Because the lights themselves get hot, some subjects and some modifiers can't be used. Of course, they're excellent for hybrid shooters when you have access to power.
3. Hot lights tend to give a scene a warm, soft look that can be particularly pleasing with skin tones.

Power & Price

HMI hot lights are more expensive than their tungsten counterparts, but they also put out considerably more light. Measured in lumens, or the actual amount of visible light emitted, a 400-watt HMI delivers an amount of light roughly equivalent to a 1200-watt tungsten lamp, and because the HMI lights use ballasts, they can be plugged into regular 110 outlets. (Old-style magnetic ballasts for HMIs are less expensive, but much bulkier and quirkier. For instance, once they're turned off, they require a cool-down period of several minutes before they can be lit up again. Tungsten hot lights don't have this issue.) If you're trying to match daylight, gelling a tungsten light reduces its output even further, widening the gulf between tungsten and HMI.

Many tungsten kits include lights in the 150-watt to 650-watt range. For serious lighting power, though, and a source that delivers a lot of light (and heat), there are 1000-watt, 2000-watt and even 5000-watt (and higher) options. These are known as 1K, 2K and 5K, respectively, and whether they employ quartz tungsten bulbs or HMIs, they typically require very heavy-duty stands and accessories, and even could require a generator for power. These are the kind of lights used on movie sets to stand in for the sun.
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