What the pros use.

I’m going to cover some continuous lighting equipment that is designed from the ground up for photography and cinematography here, these devices are readily available, but expensive due to their specialized nature.

HMI: Hydrargyrum medium-arc iodide lamps are arguably the best light for photography and film work, they are available in high CRIs and their intensity is practically unmatched. Their extreme intensity as well as their point source allow them to be used as spotlights, illuminating areas from significant distances. Their main problem is their cost, starting with an initial investment in the fixture, ballast, and bulb of around $10K, and with bulb costing upwards of $500 and lasting ~1000 hours, maintenance costs are prohibitive as well. These lights have been the status quo for large productions for years, despite their cost.

Pros: Bright, can be used for fill in direct sun. Intense, point source, useful for spot and long-throw applications. Good CRI, renders colors accurately.

Cons: Expensive, initial investment of ~$10,000 makes them a little out of range of most photographers. Color Temperature Drift, color temperature changes as the lamp wears, ~1000K change over the life of the lamp. New lamps must be “burned in” new lamps start at about 10,000K, settling into their design temperature after about 2 hours of burning. Heavy, even electronic ballast units are still very heavy, and the magnetic previous generation ballasts are extremely heavy.

Halogen: Halogen lighting is better than regular incandescent, typically having a higher color temperature. Small, lightweight and very portable, halogen lights are great for on-location high intensity, or wide flood applications. Halogen’s main downside is the immense amount of heat generated, due to the fact that they are a black body type emission. They typically require a lot of power as well, with many pro lights being at least a kilowatt. At one time the de facto standard for continuous portrait lighting, they are quickly losing ground in the studio to our next subject.

Pros: Lightweight, since they run off mains voltages, they require no heavy or bulky ballasts, making them ideal for on-location shooting. Less expensive, cheaper than HMI both in initial cost and maintenance, bulb life is typically between 2,000 and 10,000 hours. Universal, because they’ve been around a while, there are a multitude of diffusers, umbrellas and other accessories available.

Cons: Heat, HOT HOT HOT, despite being 150-200% more efficient than tungsten incandescent, more than 95% of the energy used is released as heat. Color Temperature, typical color temperature of halogen photographic lamps is 3200K, looking distinctly warm if used with either daylight or strobe. Efficiency, with typical lamps ranging from 500 to 1500 watts, you’ll need a substantial power source to run a set of these lamps.

Fluorescent: Cool, daylight balanced fluorescent is quickly becoming the main continuous lighting product in the pro’s toolkit. Products range from large dimmable arrays of 48″ tubes to simple clusters of high wattage CFLs. With 5500K daylight and strobe balanced lamps available, the ability to mix continuous, sunlight, and strobe is unparalleled. Fluorescent light is naturally diffuse, emitting from the internal surface of the bulb rather than a filament in the center, this is great for most photographic work, but is a shortcoming when you need to throw light any distance. A few of the CFL cluster fixtures are capable of some spot or throw capabilities, but it is limited.

Pros: Diffuse, naturally soft, it takes minimal accessories to make the perfect portrait light. CRI, available with CRIs of over 95, colors render well with the pop of full spectrum. Color Temperature, available with virtually any color temperature, they can be balanced with either daylight/strobe, or tungsten. Efficiency, a 45 Watt lamp puts out as much light as an 150 watt incandescent, meaning fewer heavy cords to haul around the site.

Cons: Diffuse, light is not directionally biased in emission, making it hard to throw any meaningful distance. Size, due to the relatively low intensity of fluorescent, fixtures tend to be pretty bulky, when working with tube based fixtures, minimum length is 48”. Fragile, Bulk also increases due to the protection needed for the lamps made from thin glass.

This gives a pretty good overview of what’s available on the market today, the only source I did not cover is LED, and it is becoming viable. I will probably add it later, but I’m not quite as informed on those as I am on the other types. My next post will deal with how to “re-purpose” some inexpensive non-photographic lighting equipment for creating your own continuous lighting kit.

Andrew Rodgers

What makes good light?

There are several parameters one must look at to determine the quality of a light source, we’re going to spend a little time talking about them here.

Temperature/White Balance

The color temperature of the light, measured in Kelvin Degrees, indicates the spectrum distribution as related to a black-body emission. I will not attempt to cover this fully, but a few common numbers are: Direct Sunlight 5500K, Shade 6500K, Tungsten/Incandescent 3500K, and Strobe/flash 5500K.  Fluorescent lamps can have color temperatures as low as 3000K and as high as 8000K, making it difficult to prepare to shoot under fluorescent lamps you haven’t seen before.

CRI Color Rendering Index is a measurement of how well a given light source matches the spectrum distribution of a black body emission. Light that comes from black body sources: daylight, tungsten, and halogen, has a CRI of 100, or a 100% match to the expected black body spectrum distribution. Metal Halide and Sodium Vapor lamps can have CRIs as low as 45, hardly suitable for a work environment, much less photography. Most modern fluorescents will have a CRI of over 70, making them OK, but not great light sources. Fluorescents are however, available with CRIs as high as 98, making them indistinguishable from natural light. A fluorescent with a CRI of at least 90 is suitable for most all photography, giving you full rich colors that jump with vibrancy.

Efficiency You may think efficiency in photographic lights is an after thought, and it is one of the lower priorities, but the thing to remember is that all of that energy wasted to inefficiency is still emitted as heat. Thus, any increase in efficiency is a decrease in the heat produced. Cooler lights equals more comfortable, patient, and less irritable clients, happy clients equals repeat customers equals more money Another case for efficiency is that the less power you use the fewer cables you have to drag around during setup, and the lighter and easier to carry your equipment is. So efficiency is important, just for different reasons than maybe you thought.

So the thing to remember, in choosing your continuous light sources, is the closer the temperature to daylight (5500K) and the higher the CRI, the better, some efficiency thrown in doesn’t hurt. Next post we’ll discuss the products available to pro photographers and their associated pros and cons.

See you then,
Andrew Rodgers