Photography Terms

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Aperture A circle-shaped opening in a lens (a hole, really) through which light passes to strike the film. The aperture is usually created by an iris diaphragm that is adjustable, enabling the aperture to be made wider or narrower, thereby letting in more or less light. The size of the aperture is expressed as an '-number, like '/8 or '/11.

Aperture Priority A function or shooting mode of a semi-automatic camera that permits the photographer to preset the aperture and leaves the camera to automatically determine the correct shutter speed. What does that mean? You select the aperture setting you want and the camera then automatically calculates the appropriate corresponding shutter speed for proper exposure. It's like a fully-automatic camera except you totally control the aperture.

Barrel Distortion Image distortion produced when the position of the camera lens is at its widest angle. Lines you expect to appear perpendicular are not. It is most noticeable when you have a straight edge near the side of the frame, such as when taking a wide angle shot of a building. Barrel distortion causes the edges of an image to look curved or at a skewed angle. Most barrel distortion can be corrected using image editing software.

Depth of Field (DOF) The range of distance in a scene that appears to be in focus and will be reproduced as being acceptably sharp in an image. Depth of field is controlled by the lens aperture, and extends for a distance in front of and behind the point on which the lens is focused.

Digital Camera A camera that takes pictures without film, but instead records the image on an image sensor chip in a format that is readable by a computer.

Exposure (1) Exposure occurs when light is permitted to strike film - i.e. when the film is exposed to light. (2) Exposure is the total amount of light striking the film or other photographic material. (3) Also refers to a combination of shutter speed and aperture used in exposing the film in a camera, as in “My light meter shows an exposure of 1/125 second at ƒ/11.” A particular aperture and shutter speed combinations are often referred to as “exposure settings.” “Proper exposure” refers to exposure that produces an image satisfactory to the photographer.

Fill Flash Flash that is used in a supplementary manner to fill in a subject’s shadow area with light, thereby reducing contrast. Also known as “flash fill” and “fill-in flash.”

Filter Tinted glass, gelatin or plastic discs, squares or rectangles that modify the light passing through them. Filters are used in photography to change the appearance of a scene by emphasizing, eliminating or changing color or density, generally so that the scene can be recorded with a more natural look, on a particular film.

Fisheye Describes an extreme wide-angle lens that has an angle of view exceeding 100° - sometimes more than 180° - and that renders a scene as highly distorted.

Focal Length Focal length is the distance between the focal point of a lens and the film plane when the lens is focused at infinity. It is used to designate the relative size and angle of view of a lens, expressed in millimeters (mm). A particular lens' focal length can generally be found engraved or printed on the front of the lens.

ISO Film speed is designated by a single, almost universally-accepted common system developed by the International Organization for Standardization which uses the initials “ISO” before the film-speed number - e.g. ISO 100. (Note that many sources will tell you that the initials I.S.O. stand for "International Standards Organization," but they do not.)

Macro Lens A lens with the ability to focus from infinity to extremely closely, allowing it to capture images of tiny objects in frame-filling, larger-than-life sizes. Sometimes called a "Close-up lens," although a close-up lens is usually a lens attachment for close-ups and does not generally have the ability to focus on infinity.

Macro Photography Photography of a subject where the image is recorded in the same or larger than actual size.

Metering Measures the amount of light when framing a photo and determines the best exposure. The main digital camera metering types are: Matrix (Evaluative), Spot and Center-weighted.

Neutral Density (ND) Filter Filter for use in front of the lens that absorbs all visible wavelengths to a more or less equal extent. ND filters can be used with both monochrome and color films, since they have no effect on color balance.

Noise This is the grainy look you find in a digital image caused by image artifacts.

Optical Zoom The focal length of the lens extends and retracts so an image is magnified by the lens itself. Whatever the focal length of the lens, image resolution stays the same. Optical zooms produce the best photo quality (see digital zoom).

Parallax The difference between what is seen through the viewfinder and what the camera records on film, caused by the viewfinder being separate from the camera lens.

Parallax Error Also known as “Parallax effect” - the viewfinder camera’s main disadvantage, making it almost useless for careful composition of close-up subjects. The scene viewed by the photographer through the camera’s viewing frame is different from the scene the lens will capture because the viewing frame is offset from the lens.

Photography The process or art of producing images of objects on sensitized surfaces by the chemical action of light. The word "photography" derives from the Greek and means, literally, “light writing.”

Pixel Abbreviation for PICture ELement, a pixel is a small square of colored light that forms a digital image. It is the smallest unit in a digital image.

Polarizing Filter A polarizing filter ("Polarizer" or "Polarizing screen") is an adjustable filter, with an inner ring that screws onto the lens and an outer ring that can be rotated. Turning the outer ring reduces or increases the filter’s effectiveness. The polarizer absorbs glare, reducing or eliminating reflections and darkening blue skies. It works by transmitting light that travels in one plane while absorbing light that travels in opposing planes.

Shutter Lag Using a digital camera, the delay that occurs between pressing the shutter release button and the actual moment the picture is taken.

Shutter Speed Controls the duration of an exposure - the faster the Shutter speed, the shorter the exposure time.

White Balance Adjusts the brightest part of a scene so it appears white. How a digital camera records color is affected by the source of light.

Zoom The action of varying the focal length of a zoom lens to enlarge (zoom in) or reduce (zoom out) the image.

Zoom Lens A lens in which focal length is variable. Elements inside a zoom lens shift their positions, enabling the lens to change its focal length - in effect, providing one lens that has many focal lengths. (Also called a "Variable focus lens.")

[A] [B] [D] [E] [F] [I] [M] [N] [O] [P] [S] [W] [Z]

Aperture	A circle-shaped opening in a lens (a hole, really) through which light passes to strike the film. The aperture is usually created by an iris diaphragm that is adjustable, enabling the aperture to be made wider or narrower, thereby letting in more or less light. The size of the aperture is expressed as an '-number, like '/8 or '/11.
Aperture Priority	A function or shooting mode of a semi-automatic camera that permits the photographer to preset the aperture and leaves the camera to automatically determine the correct shutter speed. What does that mean? You select the aperture setting you want and the camera then automatically calculates the appropriate corresponding shutter speed for proper exposure. It's like a fully-automatic camera except you totally control the aperture.
Barrel Distortion	Image distortion produced when the position of the camera lens is at its widest angle. Lines you expect to appear perpendicular are not. It is most noticeable when you have a straight edge near the side of the frame, such as when taking a wide angle shot of a building. Barrel distortion causes the edges of an image to look curved or at a skewed angle. Most barrel distortion can be corrected using image editing software.
Depth of Field (DOF)	The range of distance in a scene that appears to be in focus and will be reproduced as being acceptably sharp in an image. Depth of field is controlled by the lens aperture, and extends for a distance in front of and behind the point on which the lens is focused.
Digital Camera	A camera that takes pictures without film, but instead records the image on an image sensor chip in a format that is readable by a computer.
Exposure	(1) Exposure occurs when light is permitted to strike film - i.e. when the film is exposed to light. (2) Exposure is the total amount of light striking the film or other photographic material. (3) Also refers to a combination of shutter speed and aperture used in exposing the film in a camera, as in “My light meter shows an exposure of 1/125 second at ƒ/11.” A particular aperture and shutter speed combinations are often referred to as “exposure settings.” “Proper exposure” refers to exposure that produces an image satisfactory to the photographer.
Fill Flash	Flash that is used in a supplementary manner to fill in a subject’s shadow area with light, thereby reducing contrast. Also known as “flash fill” and “fill-in flash.”
Filter	Tinted glass, gelatin or plastic discs, squares or rectangles that modify the light passing through them. Filters are used in photography to change the appearance of a scene by emphasizing, eliminating or changing color or density, generally so that the scene can be recorded with a more natural look, on a particular film.
Fisheye	Describes an extreme wide-angle lens that has an angle of view exceeding 100° - sometimes more than 180° - and that renders a scene as highly distorted.
Focal Length	Focal length is the distance between the focal point of a lens and the film plane when the lens is focused at infinity. It is used to designate the relative size and angle of view of a lens, expressed in millimeters (mm). A particular lens' focal length can generally be found engraved or printed on the front of the lens.
ISO	Film speed is designated by a single, almost universally-accepted common system developed by the International Organization for Standardization which uses the initials “ISO” before the film-speed number - e.g. ISO 100. (Note that many sources will tell you that the initials I.S.O. stand for "International Standards Organization," but they do not.)
Macro Lens	A lens with the ability to focus from infinity to extremely closely, allowing it to capture images of tiny objects in frame-filling, larger-than-life sizes. Sometimes called a "Close-up lens," although a close-up lens is usually a lens attachment for close-ups and does not generally have the ability to focus on infinity.
Macro Photography	Photography of a subject where the image is recorded in the same or larger than actual size.
Metering	Measures the amount of light when framing a photo and determines the best exposure. The main digital camera metering types are: Matrix (Evaluative), Spot and Center-weighted.
Neutral Density (ND) Filter	Filter for use in front of the lens that absorbs all visible wavelengths to a more or less equal extent. ND filters can be used with both monochrome and color films, since they have no effect on color balance.
Noise	This is the grainy look you find in a digital image caused by image artifacts.
Optical Zoom	The focal length of the lens extends and retracts so an image is magnified by the lens itself. Whatever the focal length of the lens, image resolution stays the same. Optical zooms produce the best photo quality (see digital zoom).
Parallax	The difference between what is seen through the viewfinder and what the camera records on film, caused by the viewfinder being separate from the camera lens.
Parallax Error	Also known as “Parallax effect” - the viewfinder camera’s main disadvantage, making it almost useless for careful composition of close-up subjects. The scene viewed by the photographer through the camera’s viewing frame is different from the scene the lens will capture because the viewing frame is offset from the lens.
Photography	The process or art of producing images of objects on sensitized surfaces by the chemical action of light. The word "photography" derives from the Greek and means, literally, “light writing.”
Pixel	Abbreviation for PICture ELement, a pixel is a small square of colored light that forms a digital image. It is the smallest unit in a digital image.
Polarizing Filter	A polarizing filter ("Polarizer" or "Polarizing screen") is an adjustable filter, with an inner ring that screws onto the lens and an outer ring that can be rotated. Turning the outer ring reduces or increases the filter’s effectiveness. The polarizer absorbs glare, reducing or eliminating reflections and darkening blue skies. It works by transmitting light that travels in one plane while absorbing light that travels in opposing planes.
Shutter Lag	Using a digital camera, the delay that occurs between pressing the shutter release button and the actual moment the picture is taken.
Shutter Speed	Controls the duration of an exposure - the faster the Shutter speed, the shorter the exposure time.
White Balance	Adjusts the brightest part of a scene so it appears white. How a digital camera records color is affected by the source of light.
Zoom	The action of varying the focal length of a zoom lens to enlarge (zoom in) or reduce (zoom out) the image.
Zoom Lens	A lens in which focal length is variable. Elements inside a zoom lens shift their positions, enabling the lens to change its focal length - in effect, providing one lens that has many focal lengths. (Also called a "Variable focus lens.")