Glossary
AE (Automatic Exposure) A general-purpose shooting mode where the camera automatically sets the aperture and shutter speed using its metered reading. On some cameras, the ISO settings are also automatically set.
AE/AF Lock A camera setting that allows you to lock the current exposure and/or autofocus setting prior to taking a photo. This button lets you recompose the scene without holding the shutter button halfway down.
AF-assist illuminator Useful in low-light and low-contrast shooting situations, a feature that automatically projects a red grid onto your subject to aid the camera’s autofocusing system. The AF (autofocus) assist illuminator is located on the bottom front of the flash. The AF-assist beam is compatible with most recent Canon cameras, helping the camera to focus properly in poor light.
ambient light The natural or artificial light within a scene. This is also called available light.
aperture Also referred to as the diaphragm or f-stop setting of the lens. The aperture controls the amount of light that is allowed to pass through the lens. The higher the f-stop number setting, the smaller the aperture opening on the lens. Larger f-stop settings are selected by lower numbers, such as f/2 or f/1.2. The larger the aperture, the less depth of field the image will possess. A smaller aperture means that the image will have more depth of field, and that more of the background will be in focus.
Aperture Priority (Av) A camera exposure setting where you choose the aperture, and the camera automatically adjusts the shutter speed according to the camera’s metered readings. Aperture Priority is often used by photographers to control depth of field.
background light Light that is generally placed behind the subject and pointed toward the backdrop to create separation between the subject and background. Also known as a separation light.
backlighting Light that is positioned behind and pointing to the back of the subject, creating a soft rim of ligwht that visually separates the subject from the background.
bokeh The shape and illumination characteristics of the out-of-focus areas in an image, depending on the focal length, optical design, and aperture blade pattern of the lens.
bounce flash A technique of pointing the flash head in an upward position or toward a wall, thus softening the light falling on the subject. Bouncing the light often eliminates shadows and provides a much smoother light for portraits.
bracketing To make multiple exposures, some above and some below the average exposure calculated by the light meter for the scene, either by flash output or exposure settings. Some digital cameras can also bracket white balance to produce variations from the average white balance calculated by the camera.
bulb A shutter speed setting that keeps the shutter open as long as the shutter button or cable release is fully depressed.
cable release An accessory that connects to a port on the camera and allows you to trigger the shutter by using the cable release instead of pressing the shutter button, to reduce camera/shutter vibrations over slow or timed exposures.
Canon EOS Speedlite System Also referred to as simply “Speedlite System,” a lighting system that allows for multiple flash capabilities in a wireless environment, taking advantage of communication of exposure information between the camera, master flash unit, and remote Speedlites. Presently, the Canon lighting system includes the 600EX/600EX-RT, 580EX II, 430EX II, 320EX, 270EX II, 270EX, ST-E3-RT and ST-E2 wireless transmitters, MT-24EX Macro Twin Lite, and MR-14EX Macro Ring Lite.
catch-light panel A pullout panel located on the top front of the 320EX, 270EX II, 580EX II, and 600EX/600EX-RT Speedlites. Using the catch-light panel while pointing the flash head straight up provides the light needed to create sparkle in a portrait subject’s eyes, called a catch-light, and a small amount of fill flash.
channel Also referred to as communication channel. To avoid interfering with other wireless flash users in the same location, the master and slave units can communicate on one of four channels. Communications in the Speedlite System are partially based on setting the master and all additional Speedlites to the same channel. If by chance another photographer is using the same channel as you are, your Speedlite System units may fire from the other photographer’s controls. To avoid this, you can set the master and your other Speedlites to a different channel.
chimping Reviewing images on the LCD right after you’ve taken them. This is derived from photographers making the “ooooh-ooooh” chimp sound when reviewing impressive images.
color balance The color reproduction fidelity of a digital camera’s image sensor and of the lens. In a digital camera, color balance is achieved by setting the white balance to match the scene’s primary light source. You can adjust color balance in image-editing programs using the color Temperature and Tint controls.
colored gel A color gel or color filter, or a lighting gel (or simply gel), is a transparent, colored material that is used in theater, photography, videography, and cinematography to color light and for color correction. Modern gels are thin sheets of polycarbonate or polyester, placed in front of a light source. Gels are often used to change the color of a black background when shooting portraits or still-life photos. The name gel stems from the early form of filters used in theaters, which were typically made from gelatin.
color temperature A numerical description of the color of light measured on a Kelvin scale. Warm, early, and late-day light have a lower color temperature. Cool, shady light has a higher temperature. Midday light is often considered to be neutral light (5500 K) and flash units are often calibrated to 5500–6000 K.
daylight balance A general term used to describe the color of light at approximately 5500 K, such as midday sunlight or an electronic flash.
dedicated flash A flash unit designed to work with one particular camera system, and which can operate in conjunction with the camera’s internal metering. Dedicated flash units exchange information with the camera via a proprietary digital data line. These lines require small data pins on the flash hot shoe to communicate.
depth of field The distance in front of and behind the subject that appears in acceptably sharp focus.
E-TTL and E-TTL II mode Evaluative Through-the-Lens metering is a Canon EOS flash exposure system that uses a brief preflash before the main flash to obtain a more correct exposure. Like TTL, the sensor is internal to the camera and takes its exposure reading via the lens so any filters added to the lens will also affect the E-TTL readings, giving more accurate exposure information to the camera.
Exposure Compensation A setting that allows you to adjust the exposure, in 1/2 or 1/3 stops from the metered reading of the camera, to achieve correct exposure under mixed or difficult lighting conditions.
fill light Subordinate in power to the key light, fill light lightens shadow areas and is generally placed opposite the key light. Fill light can be either a dedicated Speedlite or a reflector.
first-curtain sync The default setting that causes the flash to fire at the beginning of the exposure when the shutter is completely open. See also second-curtain sync.
flash color information communication Color temperature information is automatically transmitted to the camera, providing the camera with the correct white balance setting, and giving you accurate color in your image when you shoot photos with a Speedlite.
Flash Exposure Bracketing (FEB) This concept is similar to Auto-Exposure Bracketing (AEB), only instead of changing ambient exposure settings, you shoot a series of three photographs with normal, positive flash compensation and negative flash compensation. You can apply the bracketing value in half, third, or full stop values. FEB auto-cancels after you’ve taken the three-photograph sequence and uses whatever drive mode your camera is set to. FEB can be used in conjunction with both Flash Exposure Lock (FEL) and Flash Exposure Compensation (FEC).
Flash Exposure Compensation (FEC) Adjusting the flash output by +/–3 stops in 1/3-stop increments. If images are too dark (underexposed), you can use FEC to increase the flash output. If images are too bright (overexposed), you can use FEC to reduce the flash output.
Flash Exposure (FE) Lock A feature that allows you to obtain the correct flash exposure and then lock that setting in by pressing the FE Lock button. You can then recompose the shot, with the main subject either on the right or the left, and take the picture with the camera retaining the proper flash exposure for the subject.
flash head The part of the Speedlite that houses the flash tube that fires when taking a flash photo. Flash heads can be adjusted for position. See also flash head tilting.
flash head tilting Adjusting the flash head horizontally or vertically by pressing the Bounce Lock Release button and repositioning the flash head. This is often used to point the flash in an upward position, such as when using bounce flash. You tilt the flash head up toward the ceiling when using the catch-light panel on the 580EX II or 600EX/600EX-RT.
flash mode The method the flash uses to determine flash exposure. On most EX-series Speedlites, flash modes include E-TTL, Multi-stroboscopic mode, and Manual mode.
flash shooting distance and range The actual range in which the Speedlite has the ability to properly illuminate a subject. The range, determined by the guide number, is typically between 2 and 60 feet, and dependent on the ISO sensitivity, aperture setting, and zoom head position.
flash sync mode A mode which, set in conjunction with camera settings, allows you to take flash photos in either first-curtain or second-curtain sync. For most flash photos, the default is first-curtain sync. When using first-curtain sync, the flash fires right after the shutter opens completely. In second-curtain sync, the flash fires just before the shutter begins to close. Using second-curtain sync in low-light situations avoids unnatural-looking photos due to subject or camera movement. See also first-curtain sync and second-curtain sync.
front light Light that comes from behind or directly beside the camera to strike the very front of the subject.
f-stop A number that expresses the diameter of the entrance pupil in terms of the focal length of a lens; the f-stop number is the focal length divided by the “effective” aperture diameter. A larger f-number denotes a smaller aperture opening, while a smaller f-number means a larger aperture opening. See also aperture.
gobo Short for “Go Between,” this is typically a piece of material with a pattern of holes or shapes that’s placed in front of the light source to cast a pattern. Many common household objects, such as lattice and house plants, can be used as gobos to create interesting and inexpensive patterns.
gray card A card that reflects a known percentage of the light that falls on it. Typical grayscale cards reflect 18 percent of the light. Gray cards are standard for taking accurate exposure-meter readings and for providing a consistent target for color balancing during the color- correction process using an image- editing program.
grid Available in fabric for softboxes and plastic for Speedlites, this light modifier shapes the light into a narrow beam and is also useful in reducing glare.
grip A general term that includes but is not limited to clamps, light stands, extension arms, and any hardware used to attach and support lights and other equipment.
group A collection of Speedlites, where each flash shares the same output setting controlled by the master flash unit.
guide number (GN) A number that indicates the amount of light emitted from the flash (at full power). Each model Speedlite has its own guide number, indicating the Speedlite’s maximum capability. The guide number is calculated based on an ISO setting, flash zoom head position, and the distance to the subject.
highlight A light or bright area in a scene, or the lightest area in a scene.
high-speed sync This feature allows you to shoot with flash up to the maximum shutter speed of the camera. With high-speed sync, the camera actually changes the way the flash fires. Rather than a single, strong burst, it tells the flash to send out an ultrafast series of low-power flash pulses. Because the flash pulses are so short, the light appears to be continuous. When the High-speed sync mode is not engaged, the camera with a hot shoe–mounted Speedlite does not allow you to set the shutter speed to faster than the camera’s rated sync speed. High-end flashes, such as the 580EX II and the 430EX II, have this feature. See also sync speed.
hot shoe A camera mount that accommodates a separate external flash unit. It is called a hot shoe because it also provides an electronic connection between the flash and the camera. Inside the mount are contacts that transmit information between the camera and the flash unit, and that trigger the flash when the shutter button is pressed.
ISO sensitivity The ISO (International Organization for Standardization) setting on a camera indicates the camera’s light sensitivity. Lower ISO settings provide better-quality images with less image noise; however, the lower the ISO setting, the more exposure is needed.
Kelvin Different than Fahrenheit and Celsius degree scales, the Kelvin scale for measuring color temperature. The lower the Kelvin number is the warmer the color of the light is and conversely, the higher the Kelvin number is, the cooler the color of the light is. The scale is used in photography to quantify the color temperature of light.
key light Also known as the main light, this is the dominant light source in a scene. Often, you direct subjects to look toward the key light.
kicker light Also known as rim or edge light, this is side light that can come from either the left side, the right side, or both. When working with kicker light in conjunction with natural light, pay careful attention to where the shadows are falling. Avoid creating unnatural opposing shadows that don’t occur in nature. In the studio, you have much more latitude with kicker light placement.
leading line An element in a composition that leads the viewer’s eye toward the subject or deeper into the scene.
lighting ratio A ratio used to describe the difference in brightness between two light sources. A 1:1 ratio means both light sources are equal. A 1:2 ratio denotes that the second light is half as bright as the first, a 1:4 ratio describes the second light as being one-fourth as bright as the first, and so on.
Manual exposure A mode in which the photographer adjusts the lens aperture and/or shutter speed to achieve the desired exposure. Many photographers need to control aperture and shutter speed independently because opening up the aperture increases exposure but also decreases the depth of field, and a slower shutter speed increases exposure but also increases the opportunity for motion blur.
master The flash unit that is mounted on the camera when using multiple Speedlites in a wireless flash configuration. The master flash unit controls the flash output of all remote units. The built-in Speedlites of some camera models can also act as a master flash. The master flash unit is also sometimes called a commander. See also remote and slave.
metering Measuring the amount of light utilizing the camera’s internal light meter. For most flash uses, Speedlites emit a preflash for the camera’s light meter in order to achieve a properly exposed photo.
midtone An area of medium brightness; a medium-gray tone in a digital image or photographic print. Midtones are usually found halfway between the darkest shadows and the brightest highlights.
mirror lock-up A camera function that allows the mirror, which reflects the image to the viewfinder, to flip up without the shutter being released. This is done in order to reduce vibration from the mirror moving on slow or timed exposures or to allow manual sensor cleaning.
modeling light A secondary light, usually tungsten or halogen, built into a studio strobe in order to visualize what the flash output will look like. The Canon EX series Speedlites have a modeling “flash” that fires a short burst of rapid flashes that allow you to see the effect of the flash on the subject.
multiple flash setup A configuration that uses multiple Speedlites, wired or wirelessly, to illuminate a subject and/or scene. This allows the photographer to create natural-looking photographs by creatively placing multiple flashes in different positions (and/or flash output) to achieve the desired lighting results.
noise Extraneous visible artifacts that degrade digital image quality or that are creatively added in post-production for effect. In digital images, noise appears as multicolored flecks, also referred to as grain. Noise is most visible in high-speed digital images captured at high ISO settings.
Program Auto Exposure A mode where the shutter speed is automatically set to the camera’s sync shutter speed when using a Speedlite. On the camera, the shutter speed and aperture are automatically set when the subject is focused.
Quick flash A state the Speedlite enters into before recycling to full power as indicated on the flash by a green ready light. Quick flash fires the unit at 1/6 to 1/2 power but enables it to fire faster. For full flash, wait until the pilot lamp turns red. The Quick flash only will fire in Single drive mode, not in Burst mode.
Red-eye Reduction A function of certain EOS cameras that is used to prevent the subject’s eyes from appearing red. The camera emits a bright light before the shutter is opened that shrinks the pupils. As a general rule, the farther the flash head is located from the axis of the camera lens, the less chance you have of experiencing the red-eye effect. You can combine Red-eye Reduction with slow-sync in low-light situations.
remote A radio device that triggers cameras or off-camera flashes to fire. See also master and slave.
scene modes Available on some cameras, automatic modes in which the settings are adjusted to predetermined parameters, such as a wide aperture for the Portrait scene mode and high shutter speed for the Sports scene mode.
second-curtain sync A camera/flash setting that allows the flash to fire at the end of the exposure, right before the second or rear curtain of the shutter closes. With slow shutter speeds and flash, this feature creates a blur behind a moving subject, visually implying forward movement. See also first-curtain sync.
Shutter Priority (Tv) A camera exposure setting where you choose the shutter speed and the camera automatically adjusts the aperture according to the camera’s metered readings. Action photographers often use Shutter Priority to control motion blur.
shutter speed The length of time the shutter is open to allow light to fall onto the imaging sensor. The shutter speed is measured in seconds, or more commonly, fractions of seconds.
side lighting Light that strikes the subject from the side, often utilized to show the texture of the subject.
silhouette A view of an object or scene consisting of the outline and a featureless interior, with the silhouetted object usually being black. The term has been extended to describe an image of a person, object, or scene that is backlit, and appears dark against a lighter background.
slave A Speedlite used in a multiple flash configuration that is not attached to the camera; also a remote triggering device. The Speedlite attached to the camera is called the master, while all the other Speedlites are referred to as remotes, or slaves. See also master and remote.
stroboscopic flash A flash mode on the 580EX II that fires multiple flashes with which to capture multiple images of a moving subject in a single photographic frame. A dark background helps greatly for successful multi-stroboscopic images.
sync speed The fastest shutter speed that you can set the camera to and have the flash expose for the whole exposure duration. Canon cameras prevent you from setting a faster shutter speed when a Speedlite is powered on and attached to the camera or when the pop-up flash is in the open position. See also high-speed sync.
TTL (Through-the-Lens) A flash metering system that reads the light passing through the lens that will expose film or strike an image sensor.
tonal range The range from the lightest to the darkest tones in an image.
tungsten lighting Common household lighting that uses tungsten filaments. Without filtering or adjusting to the correct white balance settings, pictures taken under tungsten light display a yellow-orange color cast.
vignetting The darkening of edges on an image that can be caused by lens distortion, using a filter, or using the wrong lens hood. This is also used creatively in image editing to draw the viewer’s eye toward the center of the image.
white balance A setting that you use to compensate for the differences in color temperature common in different light sources. For example, a typical tungsten light bulb is very yellow-orange, so when adjusted properly, the camera’s white balance setting adds blue to the image to ensure that the light looks like standard white light.
wireless remote A controller that communicates with its respective devices via infrared (IR) signals (and in some cases, via radio signals) and that can be used to trigger cameras or flashes. See also master and slave.
zoom head Also referred to as the Speedlite’s flash head, the mechanism that can automatically move the flash tube forward or backward during automatic flash operations to match the focal length of the lens being used.