Speedlight/Speedlite:2 Definition
Speedlight has become a generic term. It is interchangeable with flash, strobe, etc. For the purposes of this book, its definition is very specific. All of the pictures were made using Nikon or Canon shoe-mountable flash heads. These flash units work with their respective manufacturerâs digital cameras in new and exciting ways. While most of the processes can be done easily and automatically, certain features allow for an unprecedented array of possibilities and creative control. Since there will always be newer and more advanced cameras and flash units arriving on the market, we want to state what makes the current products distinct and revolutionary.
There are two key attributes to the current state-of-the-art Speedlight:
The Speedlight can be wireless. Communication between compatible lights is accomplished with light pulses. No wires or external devices are needed to fire off camera lights. Although there is usually a Master Speedlight mounted on the camera, even a single Speedlight can be separated from some cameras by using the pop-up flash as a Commander.
Beauty Shot
At some point in every photographerâs career, he/she has to tackle the beauty shot. What seems like a simple portrait can be a lot more complicated. These straight-on shots emphasize all sorts of âdefects,â like unsymmetrical faces, blemishes, proportions, etc. Since it is intended to show off a model to her agency or to potential clients, the lighting has to have a lot of punch to show off the best in a modelâs face, but it has to be soft enough not to create its own set of problems.
Recently, beauty dishes have become more prevalent than umbrellas or softboxes when doing beauty shots (see Beauty Dish on page 120). They produce a slightly âharderâ light than bank lights so they must be used with caution.
This shot required only one light which shows how effective just one Speedlight can be. However, there is a large mirror propped up below the modelâs face and two large white reflectors on each side. The aggregate effect is a very flat lighting with âbiteâ and an interesting catch light in the eyes. Mastery of minimum equipment is essential to the building of your lighting skills.
Multiple Speedlight units can be used and controlled wirelessly by a master flash from your camera position. The master flash can also control multiple groups comprised of more than one Speedlight.
While all of these features may evolve, and other companies may eventually add these capabilities to their camera and flash units, we believe this step in technology is significant and well worth the effort to master, no matter what your level of photography.
Several independent manufacturers produce flash units that interface to varying degrees with the TTL flash metering systems of the Canon and Nikon digital cameras. A few are fully compatible and we will deal with them in later chapters. This book however deals specifically with the Canon 580EX-RT, 550EX, 580EX, 580EX MkII, 600EX, and 600EX-RT; and the Nikon SB800, SB900, and SB910 TTL professional Speedlights.
All future references to Speedlights, flash, or strobes pertain to this narrow definition, unless otherwise indicated.
A flash with a guide number of 160 (for ISO 100, and 50mm zoom head setting) makes a versatile lighting tool capable of actually overpowering sunlight. A flash with a guide number of 160 provides f/16 worth of flash at a ten foot flash-to-subject distance, i.e. 160/10=f/16. A standard ISO 100 sunlight exposure (based on âsunny 16â exposure guidelines) is 1/60 sec. at f/16. With most current digital cameras, flash can be used up to 1/250 sec. The flash exposure can be made at 1/250 sec. at f/16, underexposing the sunlight by two stops, and making the flash the predominant light source.
Guide Number
Manufacturers express the light output of their flashes as guide number. Guide number defines the maximum intrinsic aperture value worth of flash available from a flash unit at any given flash-to-subject distance, giving the photographer a realistic expectation of the capabilities and maximum power of the flash. A guide number may be expressed in feet or meters, and is dependent on ISO, flash reflector efficiency, zoom head setting, and flash power. Guide numbers are useful and meaningful when applied in a simple traditional equation:
(guide number divided by the flash-to-subject distance = aperture value etc.)
This equation can also be expressed as:
guide number = Aperture Ă Distance
Fundamentals of Electronic Flash
To effectively use electronic flash, it is useful to know how it works.
Electronic flash has a hollow glass flashtube filled with the rare gas xenon.3 Xenon (notice the similarity to the word neon) produces blue light when exposed to electric current. Electronic flash stores voltage from the batteries or AC current source in a capacitor. The capacitor discharges electricity into the flashtube. The amount of electricity discharged, the âflash power,â determines how long the flashtube is lit, i.e. the flash duration. The brightness of the flashtube remains constant. The flashtube only âturns onâ for longer or shorter periods of time.
The flash duration of TTL electronic flash is very brief, 1.2 milliseconds or less. Therefore, if the shutter is open longer than the flashtube is illuminated, the shutter speed itself will have no effect on the amount of flash in the photograph.
The quantity of flash recorded by the camera is a function of the flash duration, the flash-to-subject distance, the ISO, and the aperture. Electronic flash is always expressed as an aperture value worth of light. At any given shutter speed, âf/16 worth of lightâ falling on the subject is more light than âf/8 worth of light.â
FIGURE 1.1 FLASH SCHEMATIC
Flower Girl
She kept looking over her shoulder at all the people. Kneeling in the center aisle gave me the perfect vantage point at her eye level. My knee served as a brace for the long lens. The 80-200 zoom gave the intimate perspective and isolated her from the surroundings. The existing light was soft, wonderful, and warm. A touch of flash from a Speedlite mounted on a flash bracket idealized the contrast and cleaned up the color (see Flash Brackets on page 126).
Flash photography is no longer formulaic and uncertain. I did not want too much flash here. It was important to maintain the feel, the mood, and the moment. With film, I would have to run calculations in my head, figure, guess, not until days later see if my decisions were sound. Digital allows me to respond visually, emotionally, technica...