Glossary
Aberration
Failing in the ability of a lens to produce a true image. There are many forms of aberration and the lens designer can often correct some only by allowing others to remain. Generally, the more expensive the lens, the less its aberrations (More attention to optical quality). While no single lens is called a ‘perfect lens’. The “ideal” lense would reproduce a subject in a faithful, clearly defined image on film. Aberrations, which can be divided into six basic faults, affect the Ideal performance in an optical system.
AE (Automatic Exposure)
AE-L (Automatic Exposure Lock)
Auto exposure Lock. Metering feature that used to hold the exposure setting when used in the automatic mode. Used most commonly in situation where off centering of the subject in composition and wish to retain the exposure setting of the subject OR where the level of exposure reading both the subject of interest and the background exposure reading is different eg. back lighting. Used to hold an automatically controlled shutter speed and/or aperture. Recommended when the photographer wants to control an exposure based on a scene’s particular brightness area with Center Weighted or Spot Metering.
Ambient Light
The available natural light completely surrounding a subject. Light already existing in an indoor or outdoor setting that is not caused by any illumination supplied by the photographer i.e. not by artificial light source.
Aperture
Lens opening. The hole or opening formed by the metal leaf diaphragm inside the lens or the opening in a camera lens through which light passes to expose the film. The size of aperture is either fixed or adjustable. Aperture size is usually calibrated in f- numbers-the larger the number, the smaller the lens opening. Aperture affects depth of field, the smaller the aperture, the greater is the zone of sharpness, the bigger the aperture, the zone of sharpness is reduced. The hole or opening formed by the metal leaf diaphragm inside the lens; controls amount of light and depth of field, prevents vignetting and reduces lens aberrations; the size of the aperture is indicated by its f-number, i.e., the ratio of the diameter of the opening to the focal length of the lens; a large aperture is indicated by a small numerical f-number.
Aperture Priority
Nikon – A, Canon – Av
An exposure mode on an automatic or autofocus camera that lets you set the aperture while the camera sets the shutter speed for proper exposure. If you change the aperture, or the light level changes, the shutter speed changes automatically. Apart from the sport or action arena, aperture priority is the most common & effective automatic preference in photography. It can also explained as automatic exposure system in which the lens aperture is set by the photographer, and the camera sets the shutter speed. Can be used in the stop-down mode with any lens that does not interfere with the metering system.
Artificial Light
Light from a man-made source, usually restricted to studio photo lamp and domestic lighting. When used to describe film (also known as Type A or Type B) invariably means these types of lighting.
Aspect Ratio
The ratio of width to height in photographic prints – 2:3 in 35 mm pictures to produce photographs most commonly measuring 3.5 x 5 inches or 4 x 6 inches.4.
Auto Exposure Bracketing (AEB)
Auto Exposure Bracketing performs automatic exposure bracketing with varied shutter e speed and/or aperture. Can be used to capture multiple exposures for a HDR photograph.
Autofocus (AF)
System by which the camera lens (most popular) or the camera body (on professional cameras) automatically focuses the image of a selected part of the picture subject.
B (Bulb) Setting
A shutter-speed setting on an adjustable camera that allows for time exposures. When set on B, the shutter will stay open as long as the shutter release button remains depressed.
Backlighting
Light coming from behind the subject, toward the camera lens, so that the subject stands out vividly against the background. Sometimes produces a silhouette effect. Always use something (a hand, a lens shade to avoid the light falls onto the lens – to avoid lens flares).
Bounce Lighting
Flash or tungsten light bounced off a reflector (such as the ceiling or walls) or attachment that fits on the flash to give the effect of natural or available light.
Burning-In, Burn Tool
Basically, a darkroom process that gives additional exposure to part of the image projected on an enlarger easel to make that area of the print darker. In PhotoShop the Burn tool is used to darken specific areas of the photograph.
Camera shake
Movement of camera caused by unsteady hold or support, vibration, etc., leading, particularly at slower shutter speeds, to a blurred image on the film. It is a major cause of un-sharp pictures, especially with long focus lenses.
Candid Pictures
Unposed pictures of people, often taken without the subject’s knowledge. These usually appear more natural and relaxed than posed pictures.
Chromatic aberration
A lens aberration producing an overall blurred image; the inability of a lens to bring all wavelengths of light (especially red and blue) into the same plane of focus; usually present in regular large-aperture telephoto and super-telephoto lenses; does not improve by stopping down the lens; correctable through the use of Iow Dispersion (ED, LD SD) glass. Basically, this aberration is caused by light rays of different wavelengths coming to focus at different distances from the lense. Blue will focus at the shortest distance and red at the greatest distance. Since the natural rays of light are a mixture of colors, each aberration will give a different value corresponding to each color thus producing blurred images.
Close-Up
A picture taken with the subject close to the camera-usually less than two or three feet away, but it can be as close as a few inches.
Colour temperature.
Description of the colour of a light-source by comparing it with the colour of light emitted by a (theoretical) perfect radiator at a particular temperature expressed in kelvins (K). Thus “photographic daylight” has a colour temperature of about 5500K. Photographic tungsten lights have colour temperatures of either 3400K or 3200K depending on their construction.
Continuous Servo AF Focus
Autofocus term used by Nikon, the AF sensor detection continues as long as shutter release button is lightly pressed and the reflex mirror is in the viewing position. Useful when the camera-to-subject distance is likely to change.
Cropping
Printing only part of the image that is in the negative or slide, usually for a more pleasing composition, in medium format, esp the 6 x 6, some form of cropping is necessary for publishing on A4 magazine format. May also refer to the framing of the scene in the viewfinder.
Depth of Field
The zone of acceptable sharpness in front of and behind the subject on which the lens is focused; extends approx. one-third in front of and two thirds behind the in-focus subject; dependent on three factors: aperture, focal length, and focused distance; the wider the aperture, the longer the focal length, and the closer the focused distance, the less the depth of field, and vice versa; in comparison to a normal lens, wideangle lenses have inherently more depth of field at each f-number and telephoto lenses have less.
Diffuse Lighting
Lighting that is low or moderate in contrast, such as on an overcast day.
Diffusing
Softening detail in a print with a diffusion disk or other material that scatters light.
Dodging, Dodge Tool
Dodging is the process of making areas of a photo lighter. Dodging is the opposite of burning.
Element
A single glass lens, most camera lenses contain multiple elements.
EV - Exposure value
Method of measuring scene brightness.
Exposure compensation
Exposure compensation for available light is activated by changing the shutter speed and/or lens aperture. This is done by using AE L AF-L (Auto Exposure/Autofocus Lock) button or exposure compensation button.
Exposure Meter
An instrument with a light-sensitive cell that measures the light reflected from or falling on a subject, used as an aid for selecting the exposure setting. The same as a light meter.
F-Number
The f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) of an optical system is the ratio of the lens’s focal length to the diameter of the aperture. Smaller F-Numbers mean larger apertures.
Fill-In Light
Additional light from a lamp, flash, or reflector; used to soften or fill in the shadows or dark picture areas caused by the brighter main light. Called fill-in flash when electronic flash is used.
Fisheye lens
Ultra-wide angle lens giving 180 angle of view. Basically produces a circular image on 35 mm, 5-9 mm lenses showing whole image, 15-17 mm lenses giving a rectangular image fitting just inside the circle, thus representing 180 across the diagonal.
Flash
The artificial light souce in the dark. Electronic flash requires a high voltage, usually obtained from batteries through a voltage-multiplying circuit. It has a brief, intense burst of light,usually used where the lighting on the scene is inadequate for picture-taking. They are generally considered to have the same photographic effect as daylight. Most flash will correct the color temperature back to 5000 kelvin – the daylight color.
Focal Length
The distance between the camera sensor and the the lens front of of the lens when the lens is focused on infinity.
Focal-Plane Shutter
An opaque curtain containing a slit that moves directly across in front of the sensor in a camera and allows image-forming light to strike the film.
Hot Shoe
The connection on the top of the camera where you can mount the flash.
Infinity
Infinite distance. In practice, a distance so great that any object at that distance will be reproduced sharply if the lens is set at its infinity position.
ISO
In film photography, ISO was used to measure film speed. Higher number meant that you could use faster shutters but they resulted in more grain. In digital photography the same concept applies, just that higher numbers introduce noise.
K – Kelvin
A scale use to measure the colour temperature. 5000 K refer to normal daylight.
Lens
One or more pieces of optical glass or similar material designed to collect and focus rays of light to form a sharp image on the camera sensor.
Lens aberration
Optical flaws which are present in small amounts in all photographic lenses; made up of chromatic aberration, spherical aberration, curvature of field, distortion, etc.; a perfect lens would show the image of a point as a point and a straight line as a straight line, but in practice, lenses are never perfect: they reproduce a point as a patch and a straight line as a more or less curved band; most of the trouble is caused by aberrations, inherent in the lens construction; it’s the job of the lens designer to control most of the aberrations as much as possible by combining a number of single lenses in such a way that the aberrations of one lens tend to be cancelled out by opposing aberrations in the others.
Lens Shade/Hood
A collar or hood at the front of a lens that keeps unwanted light from striking the lens and causing image flare. May be attached or detachable, and should be sized to the particular lens to avoid vignetting.
Lens 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. Determined by the maximum aperture of the lens in relation to its focal length; the “speed” of a lens is relative: a 400 mm lens with a maximum aperture of f/3.5 is considered extremely fast, while a 28mm f/3.5 lens is thought to be relatively slow
Aberration
Failing in the ability of a lens to produce a true image. There are many forms of aberration and the lens designer can often correct some only by allowing others to remain. Generally, the more expensive the lens, the less its aberrations (More attention to optical quality). While no single lens is called a ‘perfect lens’. The “ideal” lense would reproduce a subject in a faithful, clearly defined image on film. Aberrations, which can be divided into six basic faults, affect the Ideal performance in an optical system.
AE (Automatic Exposure)
AE-L (Automatic Exposure Lock)
Auto exposure Lock. Metering feature that used to hold the exposure setting when used in the automatic mode. Used most commonly in situation where off centering of the subject in composition and wish to retain the exposure setting of the subject OR where the level of exposure reading both the subject of interest and the background exposure reading is different eg. back lighting. Used to hold an automatically controlled shutter speed and/or aperture. Recommended when the photographer wants to control an exposure based on a scene’s particular brightness area with Center Weighted or Spot Metering.
Ambient Light
The available natural light completely surrounding a subject. Light already existing in an indoor or outdoor setting that is not caused by any illumination supplied by the photographer i.e. not by artificial light source.
Aperture
Lens opening. The hole or opening formed by the metal leaf diaphragm inside the lens or the opening in a camera lens through which light passes to expose the film. The size of aperture is either fixed or adjustable. Aperture size is usually calibrated in f- numbers-the larger the number, the smaller the lens opening. Aperture affects depth of field, the smaller the aperture, the greater is the zone of sharpness, the bigger the aperture, the zone of sharpness is reduced. The hole or opening formed by the metal leaf diaphragm inside the lens; controls amount of light and depth of field, prevents vignetting and reduces lens aberrations; the size of the aperture is indicated by its f-number, i.e., the ratio of the diameter of the opening to the focal length of the lens; a large aperture is indicated by a small numerical f-number.
Aperture Priority
Nikon – A, Canon – Av
An exposure mode on an automatic or autofocus camera that lets you set the aperture while the camera sets the shutter speed for proper exposure. If you change the aperture, or the light level changes, the shutter speed changes automatically. Apart from the sport or action arena, aperture priority is the most common & effective automatic preference in photography. It can also explained as automatic exposure system in which the lens aperture is set by the photographer, and the camera sets the shutter speed. Can be used in the stop-down mode with any lens that does not interfere with the metering system.
Artificial Light
Light from a man-made source, usually restricted to studio photo lamp and domestic lighting. When used to describe film (also known as Type A or Type B) invariably means these types of lighting.
Aspect Ratio
The ratio of width to height in photographic prints – 2:3 in 35 mm pictures to produce photographs most commonly measuring 3.5 x 5 inches or 4 x 6 inches.4.
Auto Exposure Bracketing (AEB)
Auto Exposure Bracketing performs automatic exposure bracketing with varied shutter e speed and/or aperture. Can be used to capture multiple exposures for a HDR photograph.
Autofocus (AF)
System by which the camera lens (most popular) or the camera body (on professional cameras) automatically focuses the image of a selected part of the picture subject.
B (Bulb) Setting
A shutter-speed setting on an adjustable camera that allows for time exposures. When set on B, the shutter will stay open as long as the shutter release button remains depressed.
Backlighting
Light coming from behind the subject, toward the camera lens, so that the subject stands out vividly against the background. Sometimes produces a silhouette effect. Always use something (a hand, a lens shade to avoid the light falls onto the lens – to avoid lens flares).
Bounce Lighting
Flash or tungsten light bounced off a reflector (such as the ceiling or walls) or attachment that fits on the flash to give the effect of natural or available light.
Burning-In, Burn Tool
Basically, a darkroom process that gives additional exposure to part of the image projected on an enlarger easel to make that area of the print darker. In PhotoShop the Burn tool is used to darken specific areas of the photograph.
Camera shake
Movement of camera caused by unsteady hold or support, vibration, etc., leading, particularly at slower shutter speeds, to a blurred image on the film. It is a major cause of un-sharp pictures, especially with long focus lenses.
Candid Pictures
Unposed pictures of people, often taken without the subject’s knowledge. These usually appear more natural and relaxed than posed pictures.
Chromatic aberration
A lens aberration producing an overall blurred image; the inability of a lens to bring all wavelengths of light (especially red and blue) into the same plane of focus; usually present in regular large-aperture telephoto and super-telephoto lenses; does not improve by stopping down the lens; correctable through the use of Iow Dispersion (ED, LD SD) glass. Basically, this aberration is caused by light rays of different wavelengths coming to focus at different distances from the lense. Blue will focus at the shortest distance and red at the greatest distance. Since the natural rays of light are a mixture of colors, each aberration will give a different value corresponding to each color thus producing blurred images.
Close-Up
A picture taken with the subject close to the camera-usually less than two or three feet away, but it can be as close as a few inches.
Colour temperature.
Description of the colour of a light-source by comparing it with the colour of light emitted by a (theoretical) perfect radiator at a particular temperature expressed in kelvins (K). Thus “photographic daylight” has a colour temperature of about 5500K. Photographic tungsten lights have colour temperatures of either 3400K or 3200K depending on their construction.
Continuous Servo AF Focus
Autofocus term used by Nikon, the AF sensor detection continues as long as shutter release button is lightly pressed and the reflex mirror is in the viewing position. Useful when the camera-to-subject distance is likely to change.
Cropping
Printing only part of the image that is in the negative or slide, usually for a more pleasing composition, in medium format, esp the 6 x 6, some form of cropping is necessary for publishing on A4 magazine format. May also refer to the framing of the scene in the viewfinder.
Depth of Field
The zone of acceptable sharpness in front of and behind the subject on which the lens is focused; extends approx. one-third in front of and two thirds behind the in-focus subject; dependent on three factors: aperture, focal length, and focused distance; the wider the aperture, the longer the focal length, and the closer the focused distance, the less the depth of field, and vice versa; in comparison to a normal lens, wideangle lenses have inherently more depth of field at each f-number and telephoto lenses have less.
Diffuse Lighting
Lighting that is low or moderate in contrast, such as on an overcast day.
Diffusing
Softening detail in a print with a diffusion disk or other material that scatters light.
Dodging, Dodge Tool
Dodging is the process of making areas of a photo lighter. Dodging is the opposite of burning.
Element
A single glass lens, most camera lenses contain multiple elements.
EV - Exposure value
Method of measuring scene brightness.
Exposure compensation
Exposure compensation for available light is activated by changing the shutter speed and/or lens aperture. This is done by using AE L AF-L (Auto Exposure/Autofocus Lock) button or exposure compensation button.
Exposure Meter
An instrument with a light-sensitive cell that measures the light reflected from or falling on a subject, used as an aid for selecting the exposure setting. The same as a light meter.
F-Number
The f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) of an optical system is the ratio of the lens’s focal length to the diameter of the aperture. Smaller F-Numbers mean larger apertures.
Fill-In Light
Additional light from a lamp, flash, or reflector; used to soften or fill in the shadows or dark picture areas caused by the brighter main light. Called fill-in flash when electronic flash is used.
Fisheye lens
Ultra-wide angle lens giving 180 angle of view. Basically produces a circular image on 35 mm, 5-9 mm lenses showing whole image, 15-17 mm lenses giving a rectangular image fitting just inside the circle, thus representing 180 across the diagonal.
Flash
The artificial light souce in the dark. Electronic flash requires a high voltage, usually obtained from batteries through a voltage-multiplying circuit. It has a brief, intense burst of light,usually used where the lighting on the scene is inadequate for picture-taking. They are generally considered to have the same photographic effect as daylight. Most flash will correct the color temperature back to 5000 kelvin – the daylight color.
Focal Length
The distance between the camera sensor and the the lens front of of the lens when the lens is focused on infinity.
Focal-Plane Shutter
An opaque curtain containing a slit that moves directly across in front of the sensor in a camera and allows image-forming light to strike the film.
Hot Shoe
The connection on the top of the camera where you can mount the flash.
Infinity
Infinite distance. In practice, a distance so great that any object at that distance will be reproduced sharply if the lens is set at its infinity position.
ISO
In film photography, ISO was used to measure film speed. Higher number meant that you could use faster shutters but they resulted in more grain. In digital photography the same concept applies, just that higher numbers introduce noise.
K – Kelvin
A scale use to measure the colour temperature. 5000 K refer to normal daylight.
Lens
One or more pieces of optical glass or similar material designed to collect and focus rays of light to form a sharp image on the camera sensor.
Lens aberration
Optical flaws which are present in small amounts in all photographic lenses; made up of chromatic aberration, spherical aberration, curvature of field, distortion, etc.; a perfect lens would show the image of a point as a point and a straight line as a straight line, but in practice, lenses are never perfect: they reproduce a point as a patch and a straight line as a more or less curved band; most of the trouble is caused by aberrations, inherent in the lens construction; it’s the job of the lens designer to control most of the aberrations as much as possible by combining a number of single lenses in such a way that the aberrations of one lens tend to be cancelled out by opposing aberrations in the others.
Lens Shade/Hood
A collar or hood at the front of a lens that keeps unwanted light from striking the lens and causing image flare. May be attached or detachable, and should be sized to the particular lens to avoid vignetting.
Lens 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. Determined by the maximum aperture of the lens in relation to its focal length; the “speed” of a lens is relative: a 400 mm lens with a maximum aperture of f/3.5 is considered extremely fast, while a 28mm f/3.5 lens is thought to be relatively slow