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| 580EX "Speedlite" by Canon |
FLASH PHOTOGRAPHY 101
A BEGINNER’S GUIDE
INTRODUCTION
At Mark Jordan Photography, we primarily employ Speedlites as a "fill light" while allowing the ambiant light to capture your family portrait. Our portraits use just enough fill to add a touch of sparkle to the eyes and teeth, as well as lighten the depth of shadow. Should you like to see examples of our Orange County family portraits, drop by our website, Mark Jordan Photography, take a look around and contact us if you like.
FLASH PHOTOGRAPHY IS EASY ONCE YOUR UP TO SPEED
If you find using flash to be a frustrating experience, have no fears. For most beginning photographers, mastering flash photography is considerably more complicated than ambient light photography. However, when you come to understand the intricacies of Speedlites and what occurs during flash (just a few milliseconds after you press the shutter button), you'll be well on your way to taking consistent flash photographs, AND with predictable results.
Before we begin, you should be aware that just about all the information provided below, as well as in the following three parts, is thoroughly covered in The EOS Flash Bible. The EOS Flash Bible document, however, is both comprehensive and long. Thus, I thought this short guide might not only be more beneficial but serve you down the road as a reference source.
Now then, let's begin.
THE BASICS
Before you venture into the world of flash photography you first need to understand the basics of exposure. Our guide makes the assumption that you're knowledgable of how shutter speed affects exposure and crispness/motion blur, how aperture affects exposure and depth-of-field, and how the ISO setting affects exposure and digital noise. If you not yet up to speed and possess a working grasp of these essential concepts, you would do best to put aside this guide for a spell, and first master the basics of your camera before venturing off into the depths of flash photography.
PART 1
FACTS THAT EVERY FLASH SHOOTER MUST UNDERSTAND
Whether you’re using the camera’s built-in flash, a hotshoe-mounted flash unit, or studio strobes, the first four facts are universal and pertinent to all of them.
Flash Fact 1
Every flash photograph is two exposures in one – an ambient light exposure and a flash exposure. This is a critical fact to remember. The shutter opens, the flash fires, the shutter closes. During this time, both ambient light and flash will contribute to the recorded image. Flash photography requires managing both exposures.
Flash Fact 2*
Flash exposure is not affected by shutter speed. The entire burst of light from the flash begins and ends while the shutter is open, so keeping the shutter open longer won’t help with flash illumination. The flash exposure and the effective range of your flash unit will be affected by aperture and ISO settings, but not the shutter. Of course, the ambient light component in a flash photograph is affected by shutter speed. So changing the shutter speed is one way to manage the amount of ambient light that contributes to a flash photograph.
Flash Fact 3
Flash illumination is dramatically affected by distance. This is known as the inverse square law. Think of it this way: Suppose you’re using a lens that gives you a 4 x 6 ft. field of view at a distance of 10 feet. That same lens will give an 8 x 12 ft. field of view at a distance of 20 feet.
So when you double the distance, the same light is covering an area four times larger (96 square feet vs. 24 square feet)! So you need four times as much light to get the same illumination. This phenomenon, sometimes referred to as flash falloff, will affect any image with more than one subject at different distances.
Whenever your subject distance increases by a factor of roughly 1.4 (the square root of 2), the flash illumination will be cut in half. Suppose you’re taking a large group portrait. The people in the first row are 10 feet away, and the people in the back row are 14 feet away. With on-camera flash as the primary light source, the front row will be a full stop brighter than the back row!
In the image below, each cup is one stop brighter than the one behind it, and one stop darker than the one in front of it. It would take 16 times as much light to properly expose the cup at 11 feet verses the cup at 2.8 feet. Do those distance numbers look familar? They're the same as standard f/ stops for aperture settings, and the relationship is identical. This thread from PhotosGuy gives an example of how to use this relationship in the field.
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| Photo Courtesy of PhotosGuy |
Your camera measures ambient light and flash illumination separately. In Av, Tv or P modes, it will attempt to expose properly for the ambient light by adjusting either the shutter speed, aperture, or both. The fact that you have your flash turned on has no effect on this** ( one exception is that in P mode it will not use a shutter speed slower than 1/60 with flash). The camera’s metering system cannot predict how much illumination will be gained by the flash, so it doesn’t try. In manual mode, the meter in the viewfinder measures only ambient light, because that’s all it has to measure.
Fact 5 refers to any form of automatic flash metering, including older “auto thyristor” flash units, TTL film cameras, and E-TTL or E-TTL II digital cameras.
Flash Fact 5
With automatic flash metering, the flash illumination is measured after the shutter button is pressed, and the flash output is adjusted accordingly. There are technical differences between the various types of flash metering, but all of them operate independently from the camera’s metering of ambient light, and all of them work by adjusting the output of the flash, not by changing the camera’s exposure settings.
Facts 6 and 7 apply to any camera with a focal plane shutter (all SLR cameras with a mechanical shutter).
Flash Fact 6*
Every SLR camera with a mechanical shutter has a maximum flash sync shutter speed (1/200 or 1/250 on current Canon DSLRs). This has to do with the way focal plane shutters work. At slower shutter speeds, the first curtain opens, the flash fires, and after the specified time duration, the second curtain closes behind it. At shutter speeds faster than flash sync, the second curtain begins to close before the first curtain is completely open. The second curtain follows the first across the frame, exposing only a slice of the image at any given moment. Firing a flash during this process would illuminate only part of the image.
Flash Fact 7* [Applicable to modern electronic cameras only]
If you set your shutter speed faster than flash sync, or use Av mode with an aperture setting that requires a shutter speed faster than flash sync for proper exposure, the camera will automatically revert to flash sync speed when the shot is taken if a built-in or hotshoe-mounted flash is turned on. Usually this results in overexposure (unless you have a “safety shift” custom function enabled). If you’re getting overexposed images when using flash outdoors, this is probably the reason. The image is not overexposed because of light from the flash. It’s overexposed from ambient light because the shutter speed was too slow. If you’re using flash for fill in bright situations, it’s necessary to stop down the aperture or lower the ISO setting to get the shutter speed below flash sync.
Flash Fact 6*
Every SLR camera with a mechanical shutter has a maximum flash sync shutter speed (1/200 or 1/250 on current Canon DSLRs). This has to do with the way focal plane shutters work. At slower shutter speeds, the first curtain opens, the flash fires, and after the specified time duration, the second curtain closes behind it. At shutter speeds faster than flash sync, the second curtain begins to close before the first curtain is completely open. The second curtain follows the first across the frame, exposing only a slice of the image at any given moment. Firing a flash during this process would illuminate only part of the image.
Flash Fact 7* [Applicable to modern electronic cameras only]
If you set your shutter speed faster than flash sync, or use Av mode with an aperture setting that requires a shutter speed faster than flash sync for proper exposure, the camera will automatically revert to flash sync speed when the shot is taken if a built-in or hotshoe-mounted flash is turned on. Usually this results in overexposure (unless you have a “safety shift” custom function enabled). If you’re getting overexposed images when using flash outdoors, this is probably the reason. The image is not overexposed because of light from the flash. It’s overexposed from ambient light because the shutter speed was too slow. If you’re using flash for fill in bright situations, it’s necessary to stop down the aperture or lower the ISO setting to get the shutter speed below flash sync.
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* The exception to facts 2, 6 and 7 is FP Flash, sometimes referred to as “high-speed sync.” That topic is covered in Part 4.
**With some Canon cameras there is a poorly-documented phenomenon called NEVEC (negative evaluative exposure compensation) which will adjust the ambient exposure by up to a full stop when the flash is turned on, but that’s also a topic for another chapter.
Part 2
Part 3
Part 4
Mark
Mark Jordan Photography
Orange County Family Portrait
Orange County Beach Portrait
Orange County Senior Portrait
Orange County Children Portraits
Orange County Headshot
Belly Art Photography
Wordle™ Puzzles
Part 2
Part 3
Part 4
Mark
©Photosical - the photographic and philosophical observations of Orange County Photographer, Mark Jordan
Mark Jordan Photography
Orange County Family Portrait
Orange County Beach Portrait
Orange County Senior Portrait
Orange County Children Portraits
Orange County Headshot
Belly Art Photography
Wordle™ Puzzles
Orange County Photographer, Mark Jordan Photography, an Rancho Santa Margarita Photographer, specializes in crafting stunning contemporary, traditional, classic, and storytelling family portraits (high school seniors, children portraits, babies, maternity, pregnancy), headshots and pets. Mark Jordan, a Photography Hall of Fame photographer (with a Rancho Santa Margarita portrait studio), and provides portrait photography throughout Orange County and Southern California. Mark Jordan's Orange County portrait studio also serves San Diego County and Inland Empire. Studio Photography Services are also provided in Riverside County and Los Angeles County. Local Cites where Mark Jordan photography studio services are offered are as an Aliso Viejo Photographer, Anaheim Photographer, Costa Mesa Photographer, Coto de Caza Photographer, Dana Point Photographer, Dove Canyon Photographer, Huntington Beach Photographer, Irvine Photographer, Ladera Ranch Photographer, Laguna Beach Photographer, Laguna Hills Photographer, Laguna Niguel Photographer, Lake Forest Photographer, Mission Viejo Photographer, Newport Beach Photographer, Northwood Photographer, Orange Photographer, Orange Park Acres Photographer, San Clemente Photographer, San Juan Capistrano Photographer, Santa Ana Photographer, Tustin Photographer, Villa Park Photographer, Westminster Photographer, Yorba Linda Photographer, Corona del Mar Photographer, Riverside Photographer, Temecula Photographer, Chino Hills Photographer, Loma Linda Photographer, Rancho Bernardo Photographer, Carlsbad Photographer, Coronado Photographer, Del Mar Photographer, Escondido Photographer, San Diego Photographer, San Marcos Photographer, Solana Beach Photographer, Carmel Mountain Ranch Photographer, Rancho San Diego Photographer, Rancho Santa Fe Photographer, and San Diego Country Estates Photographer, Turtle Rock Photographer, Shady Canyon Photographer. Portrait Photographers everywhere (photographers in O.C. as well) are welcome to contact our portrait studio for mentoring/guidance.
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