The key tool we use to create and shape our images is light itself, in all its many forms and textures. Indeed, it’s said that Sir John Herschel coined the term “photography” from the Greek words for “writing with light” in a paper read before the Royal Society in March 1839. Our dependence on the qualities of the light we use to produce our images is absolute. An adept photographer knows how to compensate for too much or too little illumination, how to soften harsh lighting to mask defects, or increase its contrast to evoke shape and detail. Sometimes, we must adjust our cameras for the apparent “color” of light, use a brief burst of it to freeze action, or filter it to reduce glare.
The many ways we can work with light deserve three full chapters in this book. This chapter introduces using continuous lighting (such as daylight, incandescent, LED, or fluorescent sources). I’ll cover the brilliant snippets of light we call electronic flash, in Chapters 9 and 10.
You’ll often hear the term available light, meaning the ambient light at a scene, including whatever illumination is present outdoors during the day or at night, and that provided by lighting fixtures, windows, and other sources. In practice, available light includes any sort of illumination that’s available, and can include supplementary lighting added by the photographer in the form of additional lamps, reflectors, or studio continuous light sources.
For our purposes, available light is exactly what you might think: uninterrupted illumination that is available all the time during a shooting session. Daylight, moonlight, and the artificial lighting encountered both indoors and outdoors count as continuous light sources (although all of them can be “interrupted” by passing clouds, solar eclipses, a blown fuse, or simply by switching a lamp off). Indoor continuous illumination includes both the lights that are there already (such as incandescent lamps or overhead fluorescent lights indoors) and fixtures you supply yourself, including photoflood lamps or reflectors used to bounce existing light onto your subject.
Continuous lighting differs from electronic flash, which illuminates our photographs only in brief bursts. Flash, or “strobe” light is notable because it can be much more intense than continuous lighting, lasts only a moment, and can be much more portable than supplementary incandescent sources. It’s a light source you can carry with you and use anywhere. There are advantages and disadvantages to each type of illumination.
Here’s a quick checklist of pros and cons:
While continuous lighting and its effects are generally much easier to visualize and use than electronic flash, there are some factors you need to take into account, particularly the color temperature of the light, how accurately a given form of illumination reproduces colors (we’ve all seen the ghastly looks human faces assume under mercury-vapor lamps outdoors), and other considerations.
One important aspect is color temperature. Of course, color temperature concerns aren’t exclusive to continuous light sources, but the variations tend to be more extreme and less predictable than those of electronic flash, which output relatively consistent daylight-like illumination.
In practical terms, color temperature is how “bluish” or how “reddish” the light appears to be to the digital camera’s sensor. Indoor illumination is quite warm, comparatively, and appears reddish to the sensor. Daylight, in contrast, seems much bluer to the sensor. Our eyes (our brains, actually) are quite adaptable to these variations, so white objects don’t appear to have an orange tinge when viewed indoors, nor do they seem excessively blue outdoors in full daylight. Yet, these color temperature variations are real, and the sensor is not fooled. To capture the most accurate colors, we need to take the color temperature into account in setting the color balance (or white balance)—either automatically using the camera’s intelligence or manually using our own knowledge and experience.
While Canon has been valiant in its efforts to smarten up the camera’s ability to adjust for color balance automatically, an entire cottage industry has developed to provide us additional help, including gadgets like the ExpoDisc filter/caps (see Figure 8.3) and their ilk (www.expoimaging.com), which allow the camera’s add-on external custom white balance measuring feature to evaluate the illumination that passes through the disc/cap/filter/Pringle’s can lid, or whatever neutral-color substitute you employ. (A white or gray card also works.) Unfortunately, to help us tangle with the many different types of non-incandescent/non-daylight sources, Canon has provided only a single White Fluorescent setting (some competing models offer more than a half-dozen different presets for fluorescents, sodium-vapor, and mercury vapor illumination). When it comes to zeroing in on the exact color temperature for a scene, your main tools will be custom white balances set using neutral targets like the ExpoDisc, and adjustment of RAW files when you import photos into your image editor.
The only time you need to think in terms of actual color temperature is when you’re making adjustments using the Color Temp. setting in the White Balance entry of the Shooting 3 menu, as I’ll describe in Chapter 11. It allows you to dial in exact color temperatures, if known. You can also shift and bias color balance along the blue/amber and magenta/green axes, and bracket white balance.
In most cases, however, the Auto setting in the Shooting menu’s White Balance entry will do a good job of calculating white balance for you. Auto can be used as your choice most of the time. Use the preset values or set a custom white balance that matches the current shooting conditions when you need to.
Remember that if you shoot RAW, you can specify the white balance of your image when you import it into Photoshop, Photoshop Elements, or another image editor using Adobe Camera Raw, or your preferred RAW converter. While color-balancing filters that fit on the front of the lens exist, they are primarily useful for film cameras, because film’s color balance can’t be tweaked as extensively as that of a sensor.
When using WB bracketing, the camera takes a single shot, and then saves multiple JPEG copies, each with a different color balance. It’s not necessary to capture multiple shots, as the raw information retrieved from the sensor for the single exposure is used to generate the multiple different versions. Rotate the Main Dial or QCD to the right to bracket one, two, or three increments in the blue/amber direction (see Figure 8.4, left), or to the left to bracket one, two, or three increments in the magenta/green direction. Once you have set blue/amber or magenta/green bias orientations, you can use the Multi-controller joystick to shift the bracket to provide greater bias in any of the two orientations. Figure 8.4, right shows a bracketing sequence along that blue/amber axis that is shifted in the blue and green directions. It’s unlikely you’ll need such fine-tuning; making images bluer/yellower or more green/magenta will usually suffice.
Making these adjustments are the only times you’re likely to be confused by a seeming contradiction in how color temperatures are named: warmer (more reddish) color temperatures (measured in degrees Kelvin) are the lower numbers, while cooler (bluer) color temperatures are higher numbers. It might not make sense to say that 3,400K is warmer than 6,000K, but that’s the way it is. If it helps, think of a glowing red ember contrasted with a white-hot welder’s torch, rather than fire and ice.
The confusion comes from physics. Scientists calculate color temperature from the light emitted by a mythical object called a black body radiator, which absorbs all the radiant energy that strikes it, and reflects none at all. Such a black body not only absorbs light perfectly, but it emits it perfectly when heated (and since nothing in the universe is perfect, that makes it mythical).
At a particular physical temperature, this imaginary object always emits light of the same wavelength or color. That makes it possible to define color temperature in terms of actual temperature in degrees on the Kelvin scale that scientists use. Incandescent light, for example, typically has a color temperature of 3,200K to 3,400K. Daylight might range from 5,500K to 6,000K. Each type of illumination we use for photography has its own color temperature range—with some cautions.
Daylight is produced by the sun, and so is moonlight (which is just reflected sunlight). Daylight is present, of course, even when you can’t see the sun. When sunlight is direct, it can be bright and harsh. If daylight is diffused by clouds, softened by bouncing off objects such as walls or your photo reflectors, or filtered by shade, it can be much dimmer and less contrasty.
Daylight’s color temperature can vary quite widely. It is highest in temperature (most blue) at noon when the sun is directly overhead, because the light is traveling through a minimum amount of the filtering layer we call the atmosphere. The color temperature at high noon may be 6,000K. At other times of day, the sun is lower in the sky and the particles in the air provide a filtering effect that warms the illumination to about 5,500K for most of the day. Starting an hour before dusk and for an hour after sunrise, the warm appearance of the sunlight is even visible to our eyes when the color temperature may dip to 5,000K–4,500K, as shown in Figure 8.5.
Because you’ll be taking so many photos in daylight, you’ll want to learn how to use or compensate for the brightness and contrast of sunlight, as well as how to deal with its color temperature. I’ll provide some hints later in this chapter.
The term incandescent or tungsten/halogen illumination is usually applied to the direct descendents of Thomas Edison’s original electric lamp. Such lights consist of a glass bulb that contains a vacuum, or is filled with a halogen gas, and contains a tungsten filament that is heated by an electrical current, producing photons and heat. Tungsten-halogen lamps are a variation on the basic light bulb, using a more rugged (and longer-lasting) filament that can be heated to a higher temperature, housed in a thicker glass or quartz envelope, and filled with iodine or bromine (“halogen”) gases. The higher temperature allows tungsten-halogen (or quartz-halogen/quartz-iodine, depending on their construction) lamps to burn “hotter” and whiter. Although popular for automobile headlamps today, they’ve also been used for photographic illumination.
Although incandescent illumination isn’t a perfect black body radiator, it’s close enough that the color temperature of such lamps can be precisely calculated and used for photography without concerns about color variation (at least, until the very end of the lamp’s life). As I noted earlier, the color rendering index of such lamps tends to be very high, so you need to account only for the color temperature.
Of course, old-style tungsten lamps are on the way out, at first replaced either by compact fluorescent lights (CFL) or newer, more energy-efficient (and expensive) tungsten and halogen lights, and, eventually, by LED illumination. It appears that LED illumination is on track to supplant all of these for most applications in the near future. The other qualities of this type of lighting, such as contrast, are dependent on the distance of the lamp from the subject, type of reflectors used, and other factors that I’ll explain later in this chapter.
Fluorescent light has some advantages in terms of illumination, but some disadvantages from a photographic standpoint. This type of lamp generates light through an electro-chemical reaction that emits most of its energy as visible light, rather than heat, which is why the bulbs don’t get as hot. The type of light produced varies depending on the phosphor coatings and type of gas in the tube. So, the illumination fluorescent bulbs produce can vary widely in its characteristics.
That’s not great news for photographers. Different types of lamps have different “color temperatures” that can’t be precisely measured in degrees Kelvin, because the light isn’t produced by heating. Worse, fluorescent lamps have a discontinuous spectrum of light that can have some colors missing entirely. A particular type of tube can lack certain shades of red or other colors (see Figure 8.6), which is why fluorescent lamps and other alternative technologies such as sodium-vapor illumination can produce ghastly looking human skin tones. Their spectra can lack the reddish tones we associate with healthy skin and emphasize the blues and greens popular in horror movies.
Faithful color rendition goes beyond color temperature. So-called “white” light is produced by a spectrum of colors that, when added together, provide the neutral color needed for accuracy. Artificial light sources don’t necessarily offer the same balanced spectrum found in sunlight. Some portions of the spectrum may be deficient or truncated or include gaps with certain wavelengths missing entirely. Astronomers use their knowledge of which elements absorb which colors of light to calculate the makeup of distant stars using spectrographs. In photography, the analysis of spectra is used to calculate the color rendering index, which measures how accurately colors are presented.
All artificial light sources have a color rendering index (CRI). That figure is calculated by rating eight different colors on a scale of 0 to 100, based on how natural the color looks compared to a perfect or “reference” light source at a particular color temperature. A CRI of 80-plus is considered acceptable; for critical applications like photography, a CRI higher than 93 is best. Incandescent and halogen bulbs typically have a CRI of 100 compared to a reference light source at the same color temperature. Standard LED lamps are rated at 83, although some can have CRIs as high as 98. Many types of fluorescent lights fall into the CRI 50–75 range.
Vendors, such as GE and Sylvania, may actually provide a figure known as the color rendering index on the packaging using a scale of 0 (some sodium-vapor lamps) to 100 (daylight and most incandescent lamps). Daylight fluorescents and deluxe cool white fluorescents suitable for photography might have a CRI of about 79 to 95, which is perfectly acceptable for most photographic applications. Less desirable are warm white fluorescents, which may have a CRI of 55. White deluxe mercury-vapor lights are even less suitable with a CRI of 45, while low-pressure sodium lamps can vary from CRI 0–18. If you’re using such a source not intended for photography, it may be worth your while to determine its color rendering index before you shoot. Fluorescent lights, discussed next, are an excellent example.
As I mentioned earlier, their color rendering indexes are far from ideal.
Compact fluorescent lights (CFLs) are those spiraling bulbs that became popular as old-school tungsten bulbs were phased out. However, CFLs don’t work in all fixtures and for all applications, such as dimmers (even if you purchase special “dimmable” CFLs), electronic timer or “dusk-to-dawn” light controllers, some illuminated wall switches, or with motion sensors. Only certain types of CFLs (cold cathode models) operate outside in cold weather; they emit IR signals that can confuse the remote control of your TV, air conditioner, etc.
Gaining in popularity are LED light sources, particularly for movies, in the form of compact units that clip onto the camera and provide a continuous beam of light to fill in shadows indoors or out, and/or to provide the main illumination when shooting video inside. Several vendors have introduced LED studio lights that are bright enough for general-purpose shooting. It’s become obvious that LED illumination will soon become the most widely used continuous light source. They’ve already made dramatic inroads in the automotive industry for taillights, headlights, and interior illumination. Innovations like the Lume Cube 2, a brilliant $90 waterproof variable-brightness LED lamp that can be triggered wirelessly, will find broader use. (See Figure 8.7.)
Once you start working with light, you’ll find there are plenty of useful accessories that can help you. Here are some of the most popular that you might want to consider. These all work well with both continuous lighting, discussed in this chapter, as well as with electronic flash, which will be our focus in the chapter that follows this one.
The cool thing about continuous lighting is that anything that lights up can be used as a lighting tool for your Flashlights (for “painting with light” techniques), shop work lights, or even desktop high-intensity lamps, like the one seen in Figure 8.8, top, can be pressed into service at little or no cost (if you already happen to own something that will work). I used that desk lamp to shoot the image seen in Figure 8.8, bottom, simply because the lamp was bright enough to let me use a small f/stop to maximize depth-of-field, and it was really easy to see the lighting effect and move the lamp an inch or two to get different effects.
Umbrellas are just what you might think, a variation on those trusty shields-on-a-stick that protect us from the ravages of sun, rain, snow, or other elements of nature. Whether we know them as parasols (for the sun) or paraguas (for the water) on the Costa del Sol, as parapluies/ombrelles on the Riviera, or Sonnenschirme/Regenschirme (gotta love those Germans!), these inexpensive accessories are just as versatile for reflecting light as blocking it.
Indeed, you can use umbrellas in multiple roles:
Tents, like the one seen in at right Figure 8.9, are useful for photographing shiny objects or any subject where you want to reduce the shadows and reflections to a minimum. The fabric of the tent is translucent, so you place the light sources around the sides or above, and a soft glow filters through to illuminate the image. You can still maintain subtle lighting effects by choosing to light up—or not light up—individual sides of the cube.
The lens protrudes through a hole or slit in the tent, so you can photograph the shiniest subject without having you or your camera show up in the final picture.
Soft boxes are also handy for photographing shiny objects. They not only provide a soft light, but if the box itself happens to reflect in the subject (say you’re photographing a chromium toaster), the box will provide an interesting highlight that’s indistinct and not distracting.
You can buy soft boxes or make your own. Some lengths of friction-fit plastic pipe and a lot of muslin cut and sewed just so may be all that you need. Soft boxes are large square, rectangular, or round or octagonal devices that may resemble an umbrella with a front cover and produce a similar lighting effect. They can extend from a few feet square to massive boxes that stand five or six feet tall—virtually a wall of light. With a light source or two inside a soft box, you have a very large, semi-directional light source that’s very diffuse and very flattering for portraiture and other people photography.
Both electronic flash and incandescent lamps can benefit from light stands. These are lightweight, tripod-like devices (but without a swiveling or tilting head) that can be set on the floor, tabletops, or other elevated surfaces and positioned as needed. Light stands should be strong enough to support an external lighting unit, up to and including a relatively heavy flash with soft box or umbrella reflectors. You want the supports to be capable of raising the lights high enough to be effective. Look for light stands capable of extending six to seven feet high. The nine-foot units usually have larger, steadier bases, and extend high enough that you can use them as background supports. You’ll be using these stands for a lifetime, so invest in good ones. I bought my light stands when I was in college, and I have been using them for decades.
Backgrounds can be backdrops of cloth, sheets of muslin you’ve painted yourself using a sponge dipped in paint, rolls of seamless paper, or any other suitable surface your mind can dream up. Backgrounds provide a complementary and non-distracting area behind subjects (especially portraits) and can be lit separately to provide contrast and separation that outlines the subject, or which helps set a mood.
I like to use plain-colored backgrounds for portraits, and white or gray seamless paper backgrounds for product photography. You can usually construct these yourself from cheap materials and tape them up on the wall behind your subject or mount them on a pole stretched between a pair of light stands.
These fit over the flash unit and direct the light at your subject. Snoots are excellent for converting a light source into a hair light, while barn doors give you enough control over the illumination by opening and closing their flaps that you can use another flash as a background light, with the capability of feathering the light exactly where you want it on the background.