Ambient Light The natural light in a particular scene, such as daylight or room lighting. Angle Of View Term used to describe how much a lens ‘sees’. Measured in degrees. Aperture The variable opening inside the lens, which regulates the intensity of light striking the image sensor. Measured in f-stops, the lower the number the larger the aperture. A side-effect of altering the aperture is the change in depth of field, which declines as the aperture opens wider. Backlighting Term used to describe shooting towards the light, so your subject is lit from behind.Backlight Compensation A control on some digital cameras that adjusts the exposure for subjects that might otherwise be silhouetted against a bright light source.Bounce Flash Technique used to improve the quality of light from a portable flashgun. The light is bounced off a wall, ceiling or reflector so it is softened and spread before reaching the subject.Brightness Range The difference in brightness, often measured in stops, between the highlights and shadows in a scene.Buffer A memory reservoir built into digital cameras that stores the photos before they are written to the memory card.Cable Release An accessory which allows you to trip your camera’s shutter release without touching it. This helps to prevent camera shake and means you can take pictures with long exposures easier.Compact Flash Card A common type of digital camera memory card.Contrast The difference between the darkest and lightest areas in a photograph. Cropping Method of reducing the size of an image to improve the composition.Depth Of Field The distance between the nearest and farthest points. The DOF varies with the lens aperture, focal length and distance to subject.Exposure The total amount of light allowed to fall on a digital camera’s sensor during the process of taking a photograph.F-stop The ratio of the lens focal length divided by the apparent aperture of the lens. The larger the aperture, the smaller the f-stop.Ghost images Bright spots of light, often taking the shape of the aperture, which appears in the camera viewfinder or in the final photograph.Interchangeable Lens Lens designed to be readily attached to and detached from a cameraLens Speed The largest lens opening (smallest f-number) at which a lens can be set. A fast lens transmits more light and has a larger opening than a slow lens.Macro Lens A lens that provides continuous focusing from infinity to extreme close-ups, often to a reproduction ratio of 1:2 (half life-size) or 1:1 (life-size).Overexposure A condition in which too much light reaches the film, producing a dense negative or a very bright/light print or slide.Pan (Panchromatic) Designation of films that record all colors in tones of about the same relative brightness as the human eye sees in the original scene, sensitive to all visible wave-lengths.Rangefinder Instrument for measuring distances from a given point, usually based on slightly separated views of the scene provided by mirrors or prisms.Scale. Focusing method consisting of set of marks to indicate distances at which a lens is focused.Shutter Blades, a curtain, plate, or some other movable cover in a camera that controls the time during which light reaches the film.Tone The degree of lightness or darkness in any given area of a print; also referred to as value.Variable focus lens Lens which the focal length can be continuously varied between set limits.Wide-Angle Lens A lens that has a shorter focal length and a wider field of view (includes more subject area) than a normal lens.Zoom Lens A lens in which you adjust the focal length over a wide range of focal lengths.