Chapter 3: Flash Photography Basics

Flash photography can be intimidating. Many photographers only shoot with available light and confine their outdoor shooting to when the light is just right. This is very limiting! Available light is just that — it’s the light that you have available. If that happens to be a Canon 600EX or 600EX-RT Speedlite, great. If it happens to be the sun, that’s great too. And if it’s a combination of both a Speedlite and the sun, that’s also great. The goal is to take creative control and not be held captive by the existing lighting conditions. It’s valuable to develop the skills and confidence necessary to create the light you need when you need it.

This chapter helps demystify flash photography and encourages you to experiment. Invest time to develop the skills to effectively incorporate Speedlites into your photography. Learning how to use Speedlites and strobes is a tremendous asset both creatively and financially.

Studio Strobes or Speedlites?

Studio lighting systems fall into two main categories — continuous lighting and flash lighting. Here I concentrate primarily on flash lighting. Whether you’re using Speedlites or studio strobes, lighting with flash is convenient because the light output can be adjusted in specific increments and shaped with numerous modifiers. Furthermore, flashes can freeze action, can be triggered wirelessly, and can sometimes deliver the watt-seconds necessary to overpower the sun.

Continuous lights, such as fluorescents, HMI’s (Hydrargyrum medium-arc iodide lamps), and hot lights, are a great addition to any studio’s equipment list and worth mentioning briefly. Keep in mind that the quality of light produced by continuous lights differs from that produced by Speedlites and strobes. Continuous light can, in some situations, cause the pupils of a subject’s eyes to become small when they adjust to the light. This can easily be remedied in post-processing but is something to keep in mind, as larger pupils are considered more flattering. Don’t get me wrong — I love continuous lights for many, many things. F.J. Westcott’s fluorescent Spiderlites produce gorgeous, soft, glowing light. Incandescent hot lights and HMI’s can be used to great effect producing dramatic portraits reminiscent of the 1940s Hollywood style made famous by George Hurrell. They’re great in situations when you want a “what you see is what you get” lighting setup. They’re also terrific because they never make you wait like strobes or Speedlites do while they recycle, and they never flash, which can make some subjects self-conscious.

There are three main types of flash lighting systems that you should consider before you start to outfit your studio and purchase equipment. The first and most powerful is the pack-and-head system, which includes individual flash heads connected by cables to a single power pack. For this type of flash, I use a 1200 watt-second Profoto Pro-7b pack with two air-cooled heads. It can be used in the studio with an AC power adapter or in the field with its DC battery. Profoto and other systems have a large number of light modifiers, such as softboxes, grids, and snoots, available and are well suited to everyday studio or location use. However, when compared with Speedlites, they tend to be rather large. Even those packs that can operate on battery power can be cumbersome when working alone. One new entry in this category worth mentioning is Elinchrom’s Ranger Quadra. At 400 watt-seconds, battery powered, and extremely portable, this setup is a versatile hybrid between Speedlites and higher powered strobes.

NOTE A watt-second is a unit of energy, equal to a watt of power expended for 1 second. It’s precisely equal to a newton meter or a joule. The name joule is used with devices other than photographic strobes. All other things being equal, twice the number of watt-seconds delivers twice the light output. In other words, it gives you a 1-stop increase in exposure value.

The second type of flash lighting equipment is the monolight. Monolights combine the power supply and flash head into one lightweight, easy-to-transport unit. They allow a full range of output adjustments independent of one another and accept the same modifiers as their pack cousins. However, they still require AC power or a portable battery to operate. Many pack-and-head systems have symmetric/asymmetric power distribution between their light heads, meaning that the output of the lights is always divided into a variable power ratio set by the user, such as 1:1 or 2:1. The independent power control over each light head with monolights provides more fine-tuning control on a head-by-head basis and is appealing to many for this reason.

The last type is, of course, small handheld flashes, or in this case, Speedlites. Although lower in power output than the previously discussed systems, their portability, E-TTL capabilities, and ease of use make them great solutions for travel, location, and entry-level studio work.

Each system is meant for different purposes and, therefore, has different strengths and weaknesses. No one size fits all. To make an informed decision concerning what type of flash system to purchase, you should consider your needs. Ideally, as a working photographer, you have a few different systems at your disposal for the different situations that arise. Keep in mind that you don’t have to purchase everything all at once. Pros often rent equipment from photographic supply houses, such as Calumet and others. The following list looks at some of the pros and cons of the three different lighting systems:

▶ Cost. Without a doubt, Speedlites and monolights are the most economical of the three systems mentioned. Many times, the cost of pack-and-head systems is beyond the reach of a casual photographer’s budget. Speedlites are more financially feasible in the short run and can last for years of regular use.

▶ Portability. Speedlites win in this category. You still need stands and light modifiers for many types of shooting, but the Speedlites themselves are small and very portable, and offer a good range of power output. You can also use gorilla pods or small clamps to easily mount Speedlites, which is not something you can do with monolights or studio flash heads.

▶ Power supply. Speedlites run on AA batteries. You don’t have to rely on AC current and long extension cords to power these small flashes. For location work, you can power studio flashes with auxiliary batteries, but the battery can sometimes weigh more than the actual flash heads. That’s one more piece of equipment that you have to purchase, carry, and maintain.

TIP The night before a photo shoot, I always put a freshly charged set of rechargeable batteries in the Speedlites I’ll be using the next day. One set of batteries can last for hundreds of exposures. You should always have at least two sets of extra batteries on hand for each Speedlite you bring with you.

▶ Ease of use. After you arrange and configure your Speedlites, you’re ready to shoot, and you’re able to control flash output from a central location. With many older style studio flash systems, you make all of your adjustments either at the flash head (if using monolights) or at the power pack. Tricky lighting setups can involve a lot of walking back and forth from the camera, changing the flash output settings. Recent wireless systems, such as the Profoto Air and Elinchrom Skyport have solved this problem. These systems allow the power output of each light to be adjusted directly from a wireless controller mounted on your camera’s hot shoe.

3.1 Three different types of flash lighting equipment. From left to right, a Speedotron 102 flash head that connects to a 2403B power pack, an AlienBees B1600 monolight, and a Canon 580EX II Speedlite.

▶ TTL. This one’s a biggie! With studio flash systems, you don’t have the advantage of Through-the-Lens (TTL) metering. When using Canon’s version of TTL metering, E-TTL (E-TTL II), the camera automatically adjusts the flash output according to the desired exposure and measures the distance to the subject as calculated from the lens distance reading. This automatic adjustment is a huge advantage of using Speedlites — you can just set your Speedlites to E-TTL mode, set the groups and channels, and start shooting. The Canon Speedlite System and your camera do all the rest. Add to that the benefits of being able to shoot in High-speed sync mode (), and E-TTL becomes very compelling.

CROSS REF For information on setting groups and channels, see Chapter 4.

Most often, the determining factor in equipment purchases is budget. It’s likely that a set of Speedlites is a good option, especially if you like to shoot quickly, don’t need a ton of power (to overpower the sun), and need portability. After you cross the threshold of four or more Speedlites in an attempt to build up enough power for things like overpowering the sun, the Elinchrom Ranger Quadra is probably a better bet for the money and power output. Studio units have cords that people can trip over, and they contain high voltage electronics that can be dangerous when not properly maintained. However, studio flash systems offer several advantages over Speedlites in many shooting situations:

▶ Power. For sheer raw light output, pack-and-head and monolight systems can’t be beat. They offer stable light sources as long as there is a receptacle to plug in to or a battery available. They also allow you to shoot in controlled environments at higher f-stops, resulting in greater depth of field. There is, however, a price to pay for all that flash power, usually in the form of portability and cost.

▶ Recycling time. Recycling time refers to the amount of time it takes the flash to be powered up fully to make another exposure. Speedlites typically take 0.1 to 6 seconds between shots, and as batteries lose power, they take longer to recharge the flash. Power packs connected to wall outlets don’t have this issue but still need time to recycle.

▶ Modeling lights. Studio flashes usually have the capability to illuminate a subject using a modeling light. A modeling light is a secondary lighting element in the flash head that, once turned on, simulates the light output of the flash, allowing the photographer to model highlights and shadows and adjust the lighting output and placement. Although the 600EX/600EX-RT, 580EX II, and 430EX II have a modeling light feature, the modeling light isn’t continuous (only 2.5 seconds) and is of limited use to help you preview the lighting effect on the subject.

NOTE The modeling light from a Speedlite fires a 2.5-second series of flashes. It doesn’t provide constant lighting so that you can see where the highlights and shadows fall. It also rapidly depletes your battery power and can overheat your flash tube if you keep using it, requiring a costly repair. For these reasons, I never use this feature.

▶ Accessories. Studio flash systems have long offered a wide array of light modifiers and accessories. Diffusion panels, grids, snoots, barn doors, gobos, gel holders, umbrellas, octabanks, beauty dishes, and softboxes are common accessories for all commercial studio systems. In the past, small flash users often had to create their own accessories, but with the recent groundswell of small flash popularity, many vendors such as Honl Photo, ExpoImaging, and Lastolite now make modifiers specifically for these small flashes.

Only you can decide which system best meets your shooting needs. Speedlites are much less expensive than the other two types of lighting discussed, and when used correctly, they offer the photographer a powerful, lightweight option that provides beautiful light in a wide variety of shooting situations.

Color Temperature and White Balance

Light, whether it is sunlight, moonlight, fluorescent light, or light from a Speedlite, has a color that can be measured using the Kelvin scale. This measurement is also known as color temperature. Although our vision can automatically adjust for changes in the color temperature, a digital camera has to measure and approximate it in any number of lighting situations through white balance adjustments. If your Canon digital camera is set to an Automatic white balance (), it automatically adjusts the white point for the exposure you are taking because white is most dramatically affected by the color of the light source. The result of using a correct white balance setting with your digital camera is correct color in all of your photographs.

TIP If you shoot JPEG images, the white balance is set in the camera by the preset you choose. If you shoot RAW images, the white balance setting is only “noted,” and you can set or adjust the white balance in a RAW conversion program after the image is captured.

What is Kelvin temperature?

Similar to Fahrenheit and Celsius, Kelvin (K) is a temperature scale, normally used in the fields of physics and astronomy, where absolute zero (0K) denotes the absence of all heat energy and molecular movement.

Kelvin is a scale for measuring temperature. Zero degrees Kelvin corresponds to –459.67 degrees Fahrenheit. The relationship between color and Kelvin temperature is derived from heating a black body radiator (a piece of black metal) until it glows. The particular color seen at a specific temperature is the color temperature. When the black body is hot enough and begins to glow, it is dull red. As more heat is applied, it glows yellow, and then white, and ultimately blue.

For most people, Kelvin and color temperature are opposite of what you generally think of as warm and cool colors. You respond to colors and light on an emotional level that does not correspond to the Kelvin temperatures. On the Kelvin scale, what you think of as hot or warm colors represents the lowest temperatures. Blues and greens that are perceived as cool or cold colors actually represent the highest temperatures.

Choosing the white balance

Canon dSLRs offer four methods for setting white balance. Having these choices gives you flexibility to use different approaches in different shooting situations. Here are some examples that provide a starting point for using each of the three methods:

▶ Auto white balance (). When you’re shooting quickly and there is no time to perform a custom white balance, choose Auto white balance (). The camera takes into account the various ambient lighting sources and does its best to provide neutral colors.

▶ Custom white balance (). Setting a custom white balance produces very accurate color because the white balance is set precisely for the light temperature of the scene. To use this option, shoot a white or gray card (or use the ExpoDisc discussed in Chapter 5) and select that image as your desired white balance. The camera imports the color data and uses it as a new custom white balance until you change it.

CROSS REF See Appendix D for more information on how to use the gray card and color checker included in this book.

You can use the custom white balance as long as you’re shooting in the same light, but if the light changes or you add a Speedlite, you have to repeat the process to set a new custom white balance.

▶ White balance presets. For outdoor shooting, especially in clearly defined lighting conditions such as bright daylight, an overcast sky, or fluorescent light, using a preset white balance setting produces accurate color in most cases. The exception is shooting in tungsten light and using the Auto white balance () option, which I feel produces less-than-ideal color reproduction. It’s in situations like this that the ExpoDisc really shines. Otherwise, the preset white balance settings have very good color and hue accuracy, and acceptable color saturation.

▶ Manual Kelvin temperature settings. If you happen to know the specific Kelvin temperature of the lighting equipment you’re using, go ahead and choose the Kelvin (K) setting and select the temperature to match them. Please note that not all Canon dSLRs have a manual white balance setting.

The file format you choose determines whether the images are stored on the memory card in JPEG or in RAW format, and the quality level you choose determines the number of images you can store on the card, as well as the overall image quality and the sizes at which you can enlarge and print images while still maintaining quality. RAW format also allows you to set the white balance after the fact, when you are processing the images. With JPEG, you are locked in to the white balance settings you chose, so choose wisely.

Your choice of file format and quality will also be determined by the situation and intended output. For example, I shoot RAW images during portrait sessions and environmental location shoots with mixed lighting, but then I might switch to Large/Fine JPEG format () for the reception images during a wedding or luncheon because I know these images will likely be printed no larger than 8 × 10 inches. However, the majority of my work is shot in RAW () to capture the most information, to be assured of the highest image quality, and to have the widest latitude for converting and editing the images.

3.4 PhotoVision’s 14-inch calibration target

When it comes to white balance for RAW capture, several techniques are available. For my work, I prefer the ease of use and consistent results provided with the ExpoDisc. I simply cover the lens with the ExpoDisc, point the camera toward the dominant light source, make an exposure, and then select that exposure as my custom white balance. I sometimes use an alternate method in the studio where I shoot a calibration target from PhotoVision, which has three sections of black, gray, and white, and then I color-balance a batch of images during RAW conversion in Adobe Photoshop Lightroom. Both techniques work in the same general way; they only differ in when you set the white balance.

With one, you set the white balance () before shooting, and with the other, the click-balance technique, you set the white balance during RAW image conversion. However, if you are shooting a wedding and plan on presenting a JPEG slide show of your images from the day during the reception, then setting a custom white balance () as you shoot is the way to go. This will assure you correct white balance as you shoot and save you precious time when preparing your show.

Even with RAW and its ability to change white balance after the fact, it’s always a good practice to try to get an accurate white balance when shooting. By doing this, you won’t be distracted by off colors while shooting or while making selections during image editing.

White balance presets

White balance presets give you a variety of ways to ensure color that accurately reflects the light in the scene. You can set the white balance by choosing one of the preset options, by setting a specific Kelvin color temperature, by setting a custom white balance () that is specific to the scene, or by selecting Auto white balance (). These settings may not be possible on all EOS cameras. The next series of images shows the difference in white balance settings from a photo shot with multiple Speedlites. This image was captured in RAW format after performing a custom white balance off a target, and then exported as shot in each of the color presets. Each photo represents a different white balance setting, with color temperatures ranging from 2850K to 6500K. The lower the color temperature, the more blue appears in the image. The higher the color temperature, the more red and yellow appear in the image.

TIP Don’t fall into the habit of always relying on the Automatic white balance settings, because can’t always solve mixed light situations, especially when adding Speedlites. After your camera and flash are set up, it takes less than a minute to perform and set a custom color balance.

Consider these approaches regarding white balance and the use of Speedlites:

▶ Speedlites are 5500K. Speedlites produce light with a color temperature of 5500K, which is also the same color temperature as the Daylight white balance setting (). The decision about which color balance is best when shooting subjects with a lot of ambient light and Speedlites is yours, so try the different white balance presets on your digital camera to see which ones you like, gel the flashes to match the ambient light if necessary, or just keep your camera on the Auto white balance () or the Flash () preset.

▶ Cooler color temperatures appear blue. If your digital camera is set to a white balance setting that represents lower color temperatures (below 5000K), your images appear bluer, or cooler. For a creative twist, try using a Tungsten preset () and gelling your Speedlite with a tungsten-colored gel (full CTO) when you’re shooting outdoors. This will cause the background to go blue while whatever the flash is illuminating will have the correct tungsten white balance.

3.11 Creative use of color balance. Setting the camera’s white balance preset to tungsten and adding full color temperature orange (full CTO) gels to each of the six Speedlites keeps the subjects daylight balanced while everything else, especially the sky, becomes a deep moody blue tone. Refer to Chapter 6 for a lighting diagram and technical notes about this image. Exposure: ISO 100, f/10, 1/200 second with an EF 50mm f/1.2L USM lens.

▶ Warmer color temperatures appear orange. Setting your digital camera to a white balance setting that represents higher color temperatures (above 5000K) makes your images appear more orange, resulting in a much warmer appearance to skin tones.

▶ Automatic white balance settings can be very accurate. Today’s digital cameras measure a subject’s white balance very accurately. Setting your digital camera to an Automatic white balance () setting often results in images with the correct color temperature balance. When using Auto white balance () and a Speedlite with an E-TTL II–compatible digital camera, the Speedlite sends color temperature information to the camera, usually resulting in a more accurate white balance than when it is set to Flash white balance ().

By keeping your digital camera set to the Automatic white balance () setting, you can shoot quickly in RAW mode () and not worry about incorrect color temperatures. You’ll probably want to get it as close as possible, but you don’t need to be as accurate as you do when shooting JPEGs. Remember with JPEGs the color temperature is baked into the file at the time of capture. You may find that your camera’s ability to evaluate and produce a pleasing white balance is more accurate than adjusting white balance settings manually.

▶ Shoot in RAW format for ultimate control of white balance. All Canon dSLR models offer you the ability to shoot your images in RAW mode. When shooting your images in RAW format instead of JPEG, you can adjust the white balance of your images while or after you transfer the files to your computer. By using the RAW conversion software that is included with your digital camera or using Adobe Camera Raw or Adobe Photoshop Lightroom, you can adjust the white balance of an image after you’ve imported it into the computer.

Balancing for the ambient light

The Speedlite’s small size and high flash output make it ideal for professional location lighting when your scene is of a manageable size. Speedlites can be placed almost anywhere and set to produce just the right amount of light that you need to create a dramatic portrait or interior shot. The exposure controls of the camera in tandem with the settings of a compatible Speedlite make it simple to balance both ambient light and the flash light.

Sometimes you’ll find yourself shooting in locations or situations where you need all the ambient light you can get, but you still need your Speedlite to add some snap and punch to the colors. In these situations, I set my camera to the appropriate white balance preset and add a colored gel to my flash to match the ambient light. Gel kits are available from Honl Photo and ExpoImaging that provide quick and easy mounting solutions. You can also buy larger gel sheets from theatrical supply houses and cut your own.

There are three main color-correcting gels that I use on my flash:

▶ CTO. Color Temperature Orange gels are used to color-match the flash to tungsten light, resulting in a more realistic look. These are the gels I use most, as I often shoot in indoor locations and need to match the Speedlite color temperature to the ambient light. CTO gels come in 1/8, 1/4, 1/2, and full-strength versions. One full-strength CTO will usually get you back to neutral, but I often add another full- or half-strength CTO to warm up my subject.

▶ CTB. Color Temperature Blue gels are used less frequently in situations when you need to balance tungsten to daylight, for example when there is a window in the scene. CTBs come in the same strengths as CTOs.

▶ Green. For fluorescent conversion, green gels color-match the flash to fluorescent light and are great when you are shooting in office situations. There are so many flavors of fluorescent light out there now that it has become more difficult to get an exact match with gels.

The Canon 600EX/600EX-RT comes with a basic filter kit. The kit includes a padded case with two CTO filters (low and high), a color filter case, and a color filter holder for attaching filters to the Speedlite. If you’re using other commercially available filters, be sure to disable the automatic filter detection function by setting Personal Function P.Fn-05 () to 1 (disable).

CROSS REF More gel options are discussed in Chapter 5.

Using Bounce Flash

You can create a softer quality of light when shooting with a Speedlite, either on or off camera, by bouncing its light. This means aiming the Speedlite at a ceiling (preferably a white one, as color will also reflect) or a reflector (silver, white, or gold), causing its light to be reflected back onto your subject. Bounce flash provides not only softer light but also more evenly lit images.

Bounce flash is a technique used both indoors and out in many situations and can be accomplished in a couple different ways. Most commonly, your flash head needs to be positioned so the light is pointed away from the subject and toward a ceiling, wall, or reflector that bounces the light from that surface back onto your subject. If a ceiling or wall isn’t close by, you can use attachable bounce reflectors such as those by ExpoImaging, Honl Photo, F.J. Westcott, and others. ExpoImaging (www.expo imaging.com) makes an entire line of bounce flash reflectors and accessories. When I’m working with a Speedlite off the camera, one of my favorite tools for bouncing the light back onto subjects is California Sunbounce’s handheld Micro-Mini reflector with a Sunbounce flash bracket (www.californiasunbounce.com).

Why and when to use bounce flash

Bounce flash is useful when you need to soften the light falling on the subject, spread out the light to cover a larger area, or produce a more natural lighting effect. These situations can include the following:

▶ When the camera is close to the subject. If you’re positioned close to your subject when taking photos, having your Speedlite pointed directly at the subject can result in a blown-out or overlit photo. Bouncing the flash off a ceiling, wall, or reflector can help soften the light.

▶ When even illumination is desired. If you’re capturing a scene where you want more even lighting throughout the frame, bounce flash helps more evenly illuminate the entire area. For example, it helps when you’re taking photos where you want both the foreground and background evenly lit.

Courtesy of Dennis Urbiztondo

3.15 Wedding reception guests enjoy themselves on the dance floor and mug for the camera. Bouncing the flash on a white surface, in this case the roof of the venue’s tent, provides wide coverage, soft white light, and no off colorcasts. Taken with the 580EX II. Exposure: ISO 1250, f/4.5, 1/60 second with an EF 15mm f/2.8L USM lens.

▶ When shooting portraits. Directly lit portrait subjects can result in harsh skin tones, heavy shadows, and flat, unattractive lighting. Straight-on flash can create the undesirable effect of making skin look plastic, increasing skin shine, and blowing out highlights. To soften the light, you can bounce your Speedlite off a ceiling, wall, reflector, bounce accessory attachment, or an opaque umbrella. In certain situations, I use a diffusion technique where rather than bouncing the flash I shoot it through a translucent white umbrella or diffusion panel. This produces a similar effect but allows additional light to reach the subject.

Camera and Speedlite settings

When you have the 270EX II, 320EX, 430EX II, 580EX II, or 600EX/600EX RT mounted securely on your camera, you can tilt the flash head up to bounce the light off the ceiling or walls. For a solo portrait, use a longer lens somewhere in the 85-150mm range to keep you a nice distance away from the subject so that the bounced light doesn’t create shadows in the eye sockets. When bouncing light off the ceiling, adjust the flash head position and find the best angle. Shoot. Review. Adjust. Depending on the height of the ceiling or distance from the wall, angles play a major role in the direction of the light.

When using bounce flash, you need to position your Speedlite flash head, make camera settings, and then make some adjustments to your Speedlite. Follow these steps:

1. Set your camera’s exposure mode to the desired setting. Whether you prefer using Aperture Priority (), Program (), Full Auto (), or Shutter Priority () mode, make sure you have your desired exposure mode set in your camera.

2. Set the white balance. Set your camera’s white balance setting to Custom (), Flash (), or Auto (). If you are using a custom white balance, remember to create the target by also using bounce flash. Many different whites are out there, and the bounce surface will also influence the color.

3. Set the flash mode. Make sure that the flash mode on your Speedlite is set to E-TTL. You can toggle to the desired flash mode by pressing the Mode button on your 600EX/600EX-RT, 580EX II or 430EX II Speedlite.

4. Position the flash head. Tilt or rotate the Speedlite’s head by pressing the Bounce Lock Release button and moving the flash head to the desired position. The 600EX/600EX-RT and 580EX II Speedlite can tilt up 90 degrees (straight up) and rotate horizontally 180 degrees to the left and right. The 430EX II can tilt up 90 degrees and rotate horizontally 180 degrees to the left and 90 degrees to the right. The 270EX II can tilt up to 90 degrees but does not rotate. The 320EX rotates a total of 270 degrees: 90 degrees to the right and 180 degrees to the left.

5. Take a test shot. Capture an image and review the results on your camera’s LCD screen. If the image appears under- or overexposed, you can adjust the output of the flash by adjusting the Flash Exposure Compensation (FEC) or by adjusting the aperture setting on your camera. FEC only applies to the light output of the flash. Exposure Compensation values dialed into the camera, plus or minus, affect only the ambient light values in the scene. When using bounce flash, you typically lose approximately 2 to 3 stops of light. This is because bouncing the light results in less illumination on the subject than when using normal, direct flash.

Explaining Flash Exposure and Specifications

If you want to go old-school style and figure out the flash exposure yourself, it’s really not that difficult once you know how. After you know what the numbers mean and where to apply them, it becomes relatively easy. This can be a huge time-saver if you’ve been creating lighting diagrams (using a notepad or diagram-creation site such as www.lightingdiagram.com), and need to create repeatable lighting setups.

If you are using your Speedlite in the E-TTL mode, all these calculations are done for you, but it’s always good to know how to achieve the same results in Manual shooting () mode. When you know this information, you can use any flash and get solid, repeatable results.

In the following sections, I discuss how to use the guide number, the distance from the Speedlite to the subject, and the aperture to determine the proper flash exposure.

Guide number

The guide number (GN) for a Speedlite measures its ability to illuminate the subject to be photographed at a specific ISO and angle of view. A higher GN indicates a more powerful flash. You can find the GN for your specific Speedlite in the owner’s manual, and I’ve also included tables of GNs for the 600EX/600EX-RT, 580EX II, and 430EX II. The GN changes with the ISO sensitivity, so that the GN at ISO 400 is greater than the GN of the same Speedlite when set to ISO 100. The GN also differs, depending on the zoom setting of the Speedlite. Tables 3.1, 3.2, and 3.3 break down the guide numbers according to the flash output setting and the zoom range selected on the Speedlites.

If you have access to a flash meter, you can determine the GN of your Speedlite at any setting by placing the light meter 10 feet away and firing the flash. Then take the aperture reading from the flash meter and multiply by ten. This is the correct GN for your flash.

Aperture

Another factor that determines the proper flash exposure is the aperture setting. The wider the aperture (smaller f-stop number), the more light hits the sensor. The aperture or f-stop number is actually a ratio showing the fractional equivalent of the opening of the lens compared to the focal length. Confused? Really it’s not that bad; read on.

All math aside, all you really need to know is this: if your Speedlite output is going to remain the same, in order to lessen the exposure, you need to stop down the lens to a narrower aperture or move the Speedlite farther away from the subject. Bear in mind, the aperture controls the light intensity from the flash falling on your subject, and the shutter speed controls the amount of the ambient light in the exposure.

Distance

The third factor that determines the proper flash exposure is the distance from the light source to the subject. The closer the light is to your subject, the more flash exposure you have. Conversely, the farther away the light source is, the less illumination your subject receives. The amount of light falloff is based on the Inverse Square Law, which states that the quantity or strength of the light (coming from the Speedlite) landing on your subject is inversely proportional to the square of the distance from the subject to the Speedlite.

Okay — deep breath — that means you divide 1 by the distance and then square the result. So if you double the distance, you get 1/2 squared, or 1/4 of the total light; if you quadruple the distance, you get 1/4 squared or 1/16 of the total light. This factor is important because if you set your Speedlite to a certain output, you can still accurately determine the exposure by moving the Speedlite closer or farther as needed.

Guide number ÷ Distance = Aperture

Here’s where it all makes sense. Take the GN of your flash, divide by the distance the flash is away from the subject, and you get the aperture at which you need to shoot. Because you can express an equation in a few different ways, you can change this equation based on the information you already have to find out what you want to know specifically.

▶ Aperture × Distance = GN

▶ Distance = GN ÷ Aperture

The guide number represents an exposure constant for the flash unit. A guide number of 80 feet at ISO 100 means that a subject 20 feet away will be correctly illuminated with an aperture of f/4 (80 = 20 × 4) using ISO 100. For the same guide number and an aperture of f/8, the flash should be 10 feet from the subject (80 = 10 × 8).

Sync speed

The recommended sync speed of your camera is the fastest shutter speed you can shoot with and still capture the full exposure of the flash. The sync speed is based on the limitations of the shutter mechanism, usually around 1/200 to 1/250 second. The sync speed on different camera bodies differs with the type of shutter mechanism used.

When you use Canon Speedlites, the camera body prevents you from selecting a shutter speed faster than the rated sync speed, but you can select any of the slower ones. This is important when you need to bring up the value of the ambient light, often referred as dragging the shutter or when you want to shoot with wider apertures and faster shutter speeds during portrait work. When a nondedicated flash or an external flash is used via the PC terminal, there is no mechanism to make the camera aware of this, so it is possible to set a shutter speed higher than the rated sync speed. The disappointing result of this is usually a partially exposed image due to the shutter already closing while the flash is reaching its peak output. E-TTL compatible Speedlites like the Canon 600EX/600EX-RT and 580EX II allow you to override this limitation by using High-speed sync mode ().

Second-curtain sync

All Canon EOS cameras have two moving curtains in the shutter mechanism. One curtain of the shutter opens, and the other closes after the correct exposure time. The normal operation of the shutter and flash causes the flash to fire immediately when the first curtain opens. This is called first-curtain sync, and it is fine for most general flash applications. So what’s wrong with that? Say your subject is moving and you are tracking the subject using a slow shutter speed to pick up some ambient light. You press the shutter button, the shutter opens, the flash fires, and then the shutter remains open to complete its exposure. When you review the image, you see motion trails out in front of the subject you tracked, and it looks like it’s moving backward. The proper technique is to get the flash to fire right before the shutter closes, thereby showing the motion trails behind the subject, and this is exactly what second-curtain sync does. You can set this feature either on the camera or on the Speedlite, but the Speedlite will take precedence over the camera settings.

Fill flash

When shooting outdoors on a sunny day using the sun as your main light source, you usually get images that are very high in contrast. As a result, the shadows are invariably much darker than they should be. To overcome this, a technique called fill flash is used.

When your camera is set to Shutter Priority () or Aperture Priority (), the camera meter exposes for the ambient light and the Speedlite is used as a fill. When using the Manual setting on your Speedlite, you can also use fill flash but will want to reduce the power output to something below the ambient levels.

NOTE When working on bright sunny days, you may find yourself needing very fast shutter speeds to shoot at wider apertures, as is sometimes desired. Activating the High-speed sync mode () from the back of the flash will allow you to use your Speedlite with shutter speeds above the camera’s normal maximum sync setting.

For realistic-looking fill flash, I decide what ISO setting I want to use based on the time of day and ambient lighting conditions, taking into consideration whether my subjects are going to be moving. I then set my Speedlite to expose just under the ambient level, somewhere between –1 and –2 stops. Exactly matching the ambient level with the Speedlite creates flat and artificial results in my opinion, and often my goal is to try to mask the fact that I used flash at all.

To use fill flash in E-TTL mode with the camera set to Manual (), follow these steps:

1. Position your subject so that the background looks just right. Avoid having the sun shine directly in your subject’s eyes and causing the dreaded the squint effect.

2. Use your camera’s light meter to determine the correct exposure. A typical exposure for a sunny day at ISO 100 is f/16 at 1/100 second.

3. Determine the proper exposure for your Speedlite by making test exposures or by using the GN ÷ Distance = Aperture formula. Remember to take into account the focal length of the lens and the flash’s zoom head position. You can also determine the approximate distance to your subject by looking at the distance scale on the lens if your lens has one, or simply using a tape measure to determine the distance.

4. Once you have determined the exposure, set the flash to expose at 1/3 to 2/3 stop under the proper exposure. The actual amount of underexposure needed depends on the brightness of the sun and the relative darkness of the scenes.

5. On the 580EX II and 430EX II in E-TTL mode, press the Select/Set button. Turn the select dial on the 580EX II or the minus button on the 430EX II to reduce the flash output.

6. On the 600EX/600EX-RT in E-TTL mode, press Function button 2. The FEC icon () and FEC +/– scale will appear on the LCD panel. Turn the select dial on the 600EX/600EX-RT to reduce the flash output.

7. Take the picture and review it on the LCD. This helps you to decide if you need more or less flash exposure to render the scene properly. Change the Exposure Compensation value and reshoot.

NOTE When shooting manual fill flash, be sure the flash head is zoomed to the same focal length as the lens in use.

Practice Makes Perfect

In this chapter, I’ve covered some of the essentials. Consider these the building blocks of your flash photography foundation. I’ll keep adding concepts and techniques in the chapters that follow. Before you proceed, take some time and try the following practice lessons:

▶ White balance presets. With your Speedlite attached and powered on, cycle through each of your camera’s white balance presets and capture one exposure for each. Notice the color shifts that occur.

▶ Creative use of white balance presets. Pick up one small sheet gel material known as a full color temperature orange (full CTO) and attach it to the front of your Speedlite so that it covers the flash element. Change your camera’s white balance to the Tungsten setting () and photograph a subject in an exterior setting, mixing both the natural ambient light and the light from the flash. Notice how the subject’s white balance appears correct (daylight balanced) while the background shifts to a deep blue color.

▶ Bounce flash. In this exercise, you learn about two important aspects of bounce flash. First, have a model stand in a room with a white ceiling for you. Then make a flash exposure with a bare Speedlite pointing straight your subject. Next aim your Speedlite at the ceiling and make a test exposure. Notice the different, softer, broader quality of light. The light has no color shift because you bounced it onto a white surface. Next, take the same model to a room with a colored ceiling and make another bounce exposure. Now you can see distinct colorcast affecting the image and model’s skin; this colorcast has been picked up from the color of the ceiling. Therefore, always look for white surfaces to bounce into.

▶ Fill flash. Grab a piece of white foam core or find a white wall to work with. Have a model pose for you in a position opposite the foam core or white wall. Rotate your Speedlite to the side and slightly back, away from the model, pointing it toward the white foam core or wall. This will cause the light to bounce back off the white surface and cast soft fill light on the model.

▶ Sto-Fen. Your first light modifier experiment — this is big! Either inside or out, make an exposure of a model or relatively close object with bare direct flash pointed at the subject. Next, apply a Sto-Fen cap to flash and repeat the process. Notice how the light is less harsh because it has been scattered by the Sto-Fen cap’s diffusion material.