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GLOSSARY accessory flash Any flash unit that is separate from the camera itself, but that can be attached (via direct connection or wirelessly) to the camera. ambient light The light, natural or artificial, that already exists in the scene. Often referred to as existing or available light. aperture The opening, usually but not always circular, in the lens that controls how much light passes through the lens to the sensor. Lens aperture size is controlled by the f-stop setting and the smaller the number (f/2, for example), the larger the opening; the larger the number (f/16) the smaller the opening. The aperture, along with the shutter speed, are the two controls that regulate the light entering the camera. angle of view The scope, described in degrees, horizontally and vertically of what a lens sees. Wide-angle lenses, for example, have a broad angle of view. Aperture Priority mode An exposure mode that lets you set the lens aperture (f-stop). The camera chooses the correct corresponding shutter speed. Auto exposure mode In this exposure mode the camera chooses both the aperture and shutter speed settings and typically turns the built-in flash on when the light gets too dim for safe handheld shutter speeds. On many cameras using this mode also sets the white balance automatically and doesn’t allow overriding any exposure settings. backlighting Light that strikes a subject from behind. A subject is backlit when it is directly between you and the light source. ballhead One of two main types of tripod heads (the other kind is pan/tilt). The head consists of a metal ball in a locking collar and allows you to position the camera in any direction. The head mounts at the top of the tripod base or legs and the camera (or quick mount) mounts to the ballhead via a threaded connector. bounce flash The technique of bouncing the light from an electronic flash off of another surface, typically a ceiling or wall. This requires a flash with an adjustable head or off-camera capability. bracketed exposure A series of exposures of the same subject from the exact same position, typically one stop overexposed and underexposed from the exposure setting recommended by the meter. The purpose of a bracketed exposure is to capture slight variations of the suggested exposure; useful in difficult situations. cable release A cable, either mechanical or electronic, that allows you to release the shutter of the camera without physically touching the camera — it is very useful for long exposures where pressing the shutter release button might jiggle the camera. camera obscura A dark box, ranging from shoe-box to room size with an opening at one end that allowed a light image to form on the opposite end of the box. A predecessor of the modern camera and used for centuries by artists as an aid in drawing. According to Wikipedia, Abu Ali Al-Hasan Ibn al-Haitham (965-1039 CE), is credited with the discovery of the camera obscura. catch light A small, usually circular, reflection of light in a portrait subject’s eyes. CCD chip CCD is short for charge-coupled device. This is the type of chip used as a sensor in most consumer digital cameras. center-weighted meter A light metering mode in which the center area of the viewfinder is given significant priority in measuring the light reflecting from a scene. CMOS chip Short for Complementary metal oxide semiconductor. It is an alternate type of sensor chip used in digital cameras. CMOS chips typically produce lower signal noise. color cast An overall color shift or tint usually caused by a mismatch between light source and white balance. color temperature The measurement, in Kelvin, of the color of a particular light source. Daylight for example has a color temperature of between 5000 to 5500 Kelvin, depending on time of day and sky conditions. continuous lighting Any source of light that provides a constant illumination (the sun and incandescent bulbs, for example). contrast range The ratio of tones between the lightest and darkest tones in a scene. Also referred to as the dynamic range. crop factor The factor used to calibrate the difference in field of view (and therefore effective focal length) between a 35mm frame and that of a digital sensor in a dSLR camera. Because a 35mm frame is bigger than the CCD sensor on a dSLR, lenses designed for 35mm will have a longer effective focal length when used with them. The lens focal length is multiplied by the crop factor to estimate the effective focal length of the lens with that sensor. A 100mm lens used on a camera that has a 1.5x crop factor, for example, will have an effective focal length of 150mm (100mm x 1.5=150mm). depth of field The near-to-far distance in a scene that is in acceptably sharp focus. Factors include lens focal length, subject
distance, and aperture. See also aperture and focal length. depth of field scale A series of markings on a lens barrel, typically in both feet and meters, that indicates the depth of field for a given aperture setting and subject distance. design Another word for composition. It is the arrangement of subject elements within a scene. diffuser Any type of translucent material placed in front of a light to soften its intensity; or a device used to bounce flash to make the light softer. digital noise See noise. digital zoom A feature found on many digital cameras that simulates an extensive zoom range by digitally cropping the image. The results are vastly inferior to an optical zoom. See also optical zoom. directional light Light that strikes a subject from a particular (and usually obvious) direction. Examples are backlighting, sidelighting, front-lighting. See also backlighting and sidelighting. dSLR Digital single-lens-reflex camera. A camera design that uses a 45-degree mirror behind the lens to bounce the image into an optical viewfinder. dynamic range See contrast range. exposure The amount of light that reaches the sensor determined by a combination of aperture and shutter speed settings. exposure bracketing See bracketed exposure. external flash See accessory flash. fill-in flash The technique of using flash outdoors (usually in bright sun) to open up shadows and reduce contrast. Most frequently used in portraiture to lighten facial shadows. Also called fill flash. f-stop Another word for lens aperture (see aperture ). Also, the number indicating the size of the lens opening. flash sync speed The shutter speed(s) at which the camera syncs with the flash. In order for the camera to record the light of the flash, it must be synchronized so that the shutter is open when the flash fires. Cameras are designed to sync only at certain specified shutter speeds. focal length In simplest optical terms, the distance from the front lens element to the point where the light rays come into sharp focus when the lens is focused at infinity. With camera lenses, typically measured in millimeters. focal plane The plane at the back of the camera where the lens image comes into sharp focus; also, the plane position of the digital sensor. golden hour Approximately the first hour to 90 minutes after sunrise and before sunset when the light from the sun is warmest and at a low angle. It is considered a favorite time to shoot outdoor scenes, particularly landscapes. graduated neutral density filter A lens filter that holds back light in one portion of the filter, fading to an area of clear filter, and designed to hold back light from only a portion of a scene. Most common use: to hold back bright sky lighting while exposing for dark or shadowed foreground detail. These are extremely useful in landscape photography. gray card A card that reflects 18% of the light striking it that, in photographic terms, represents the exact middle tone between pure black and pure white. All photographic meters are calibrated to provide a correct exposure based on 18% reflectance. high key Any scene in which light tones and values predominate: a white rose against a white background, for example. See also low key. histogram A feature found on most digital cameras that provides a graphic representation of the tonal range in a particular scene in the LCD screen. On most digital cameras the histogram is only viewable after the image is made. hot shoe A device for connecting an accessory flash unit to your camera. JPEG JPEG is the standard method for compressing image data and was developed by the Joint Photographic Experts Group. Compression makes image files small enough to store greater quantities of them on memory cards. JPEG image files are considered lossy in that they get rid of some of the image data when they are compressed. Kelvin The color or temperature of light is measured in Kelvin (K), named after the nineteenth century physicist William Thomson, 1st Baron Kelvin (1824-1907). In the light spectrum, 5500K is white (daylight at noon is typically measured close to 5500K), and higher color temperatures are blue and are cooler in appearance; lower temperature colors, like yellow, orange, and red, are warmer in appearance (tungsten lamps, for example, are 3200K).
