Photography glossary terms
Table of Contents
A
AE (AUTO EXPOSURE)
When the camera is set to this mode, it will automatically set all the required modes for the light conditions. I.e. Shutter speed, aperture and white balance.
AE (PROGRAM MODE)
The camera will choose the shutter speed and aperture automatically, effectively making your SLR a 'point-and-shoot'. It will normally assign a shutter speed of 60th of a second or higher if possible.
AE (APERTURE PRIORITY)
You choose the aperture setting and the camera will automatically choose the shutter speed according to the lighting conditions. The best setting for controlling the depth of field.
AE (SHUTTER PRIORITY)
You choose the shutter speed and the camera will select the correct aperture as long as there is enough light. Good for sports or action photography where you need control over the shutter speeds.
AE LOCK
This enables you to lock the current exposure reading and re-frame the shot using the same setting. A half-press of the shutter is normally required to activate this function, fully pressing only when you want to capture the image.
AF (AUTOFOCUS)
All digicams and most modern SLR lenses have this function now. The lens automatically focuses on the subject as quick as the eye. The only difference is that with an SLR you can normally select manual focus if necessary.
APERTURE
The lens opening allows more, or less light onto the sensor formed by a diaphragm inside the actual lens.
AE (APERTURE PRIORITY)
When using this mode, the user selects the aperture giving control over the Depth of Field. A large aperture letting more light in gives a small depth of field, meaning not much will be in focus.
ASPECT RATIO
The ration of horizontal to vertical dimensions of an image. For example, 35mm slide film = 3:2, TV = 4:3, HDTV = 16:9, 4x5 Film = 5:4.
B
BACKLIT
Meaning the subject is lit from behind which can cause underexposing. Is also used for portrait photography for special effects and bringing catchlights to the hair.
BIT DEPTH
Refers to the colour or greyscale of each individual pixel. For example, a pixel with 8 bits per colour (red, green and blue), gives a 24-bit image. 24-bit resolution is 16.7 million colours.
BITMAP
The method of storing information that actually maps an image pixel bit by bit. Formats include; .bmp, .pcx, .pict, .tif, .tiff, .gif. Most picture files are bit-mapped.
BRACKETING
Can apply to flash or exposure. It is used to create usually 3 photographs. One photo is exposed by the camera’s meter automatically, one underexposed and one overexposed by a predetermined number of stops.
BRIGHTNESS
Value of a pixel in a digital image giving its value of lightness from black to white, with o being black and 255 being white.
C
CENTRE (WEIGHTED)
A term used to describe an automatic exposure system that uses just the centre portion of the image to adjust the overall value. So in effect, the exposure will be weighted to what you see towards the centre of your viewfinder.
CMYK
Colours are used by most printers to produce your prints. Colour shifts can be caused when the colour management system tries to convert your PC's RGB files to CMYK (Cyan, Magenta, Yellow, and Key).
COMPRESSION
A Digital photograph creates an image file that is enormous. To enable image files to become smaller and more manageable cameras employ some form of compression such as JPEG.
D
DEPTH OF FIELD (DOF)
The range of items in focus in an image. This is controlled by the focal length and aperture opening of a lens. A large or wide aperture gives a shallow depth of field and a smaller or narrow aperture give a large depth of field.
DIGITAL ZOOM
Digital magnification of the centre is 50% of an image. These give less than sharp images because the new zoomed image has been interpolated. The optical zoom gives much more clarity to an image.
DYNAMIC RANGE
This is a measurement of the accuracy of an image in colour or grey level. More bits of dynamic range result in much finer gradations being preserved.
E
EV (EXPOSURE VALUE)
The ability to override the auto exposure system to under or overexpose the image.
EXPOSURE
The amount of light that hits the image sensor of the film is controlled by the shutter speed and aperture.
EXPOSURE BRACKETING
The camera will take 3 or 5 images and varies the exposure up or down for each photograph ensuring at least one will be well exposed.
EXPOSURE COMPENSATION
You can lighten or darken the image by under or overexposing the image.
F
F-STOP
A number indicating the size of the aperture. It is an inversely proportionate number as in F2.8 is a large opening and F16 is a small opening.
FILE
A collection of information like data, text or images which are saved on a CD. DVD or hard drive.
FILE FORMAT
Type of program or data file. Includes JPEG, TIFF and BMP.
FIXED APERTURE
The aperture remains constant regardless of the lens' focal length. I.e. The Canon 'L' series has a constant fixed aperture when zooming.
FIXED FOCAL LENGTH
Basically a non-zoom lens. 100mm, 50mm, 200mm and so on.
FOCAL LENGTH
A lens' angle of view. Such as Wide-angle, standard or telephoto.
G
GIF
A graphic file format is mainly used for Web graphics or small animated (GIF) files. Not good for photographs as it only contains a maximum of 256 colours.
GRADATION
A smooth transition between black and white, one colour and another or colour and no colour.
GREY LEVEL
This is the brightness level of a pixel representing its lightness from black to white. It is usually defined as a value from 0 to 255, with 0 being black and 255 being white.
GREYSCALE
A term used to describe an image containing shades of grey rather than colour. Most commonly referred to as a black and white photograph.
H
HISTOGRAM
A histogram is a bar graph analysis tool that is used to identify the contrast and dynamic range of any image. Histograms are found in the more advanced digicams and software programs, such as Adobe Photoshop.
HOT SHOE
A flash connector is generally found on the top of the camera that lets you attach an external flash unit and trigger it in sync with the camera’s shutter.
I
IMAGE RESOLUTION
This relates to the number of pixels per unit length of the image. E.g. pixels per inch, pixels per millimetre, or pixels wide and so on.
IMAGE STABILIZATION (IS)
An optical or digital system built into a lens for removing or reducing camera movement, most effective with telephoto or telephoto zoom lenses.
ISO
The speed of light sensitivity of a captured image is rated by ISO, International Standards Organisation, numbers such as 100, 400, 800 and so on. The higher the number, the more sensitive to light it is.
J
JPEG
Joint Photographic Experts Group. This is the name of the committee that designed the standard image compression algorithm. JPEG was designed for compressing full colour or greyscale digital images of natural scenes.
M
MB (MEGABYTE)
Memory term meaning 1024 Kilobytes. Used to denote the size of a flash memory card such as 4MB, 8MB and so on. MB is often confused with Mb (megabit), there are 8 bits in a byte so 256Mb = 32MB.
MEGAPIXEL
This is the CCD (or CMOS) resolution of one million pixels. Digicams are commonly rated by Megapixels. You multiply the horizontal resolution by the vertical resolution to get the total pixel count.
METERING
Metering is used to calculate the exposure from the existing light conditions. Includes Matrix Metering, Spot metering and Center-weighted metering.
MULTI-POINT FOCUSING
The autofocus system uses several different portions of the image to determine the correct focus.
MULTI-ZONE FOCUSING
Many digital cameras now offer multi-zone focusing. The camera will automatically determine which zone (centre, left, right, upper or lower) to use to perform the autofocusing.
N
NOISE
Relates to pixels in your image that were misinterpreted. Normally occurs when you shoot a long exposure (beyond 1/2-second) or when you use the higher ISO values from 400 or above.
O
OPTICAL ZOOM
This means that the camera has a real multi-focal length lens, this is not the same as a 'Digital Zoom' which magnifies the centre portion of the picture. Optical zoom gives better quality than digital zoom.
OVEREXPOSURE
This is an image that appears much too bright. The highlights and colours are totally lost and usually unrecoverable even by top software. Either the shutter speed was too long or the aperture was too wide.
P
PANORAMA
This means capturing a series of images to create a picture wider than what you could capture in a single image, by 'Stitching' the photographs together. Needs special software to allow and help you do this.
PIXEL
The individual output point of a display device. This is what is meant by the figures 640x480, 800x600, 1024x768, 1280x960 and so on when dealing with the resolution of a particular digicam.
PIXELIZATION
The stair-stepped appearance of a curved or angled line in digital imaging. The smaller the pixels, and the greater their number, the less apparent the 'pixelization' of the image. Also known as the 'jaggies'.
POLARIZER (POLARISING FILTER)
A filter for eliminating glare and reflections is attached to the front of your lens (normally just SLR's). Just like your polarized sunglasses it will get rid of glare, the polarizer filter does the same for your digicam.
PRE-FLASH
Some digicams use a low power flash before the main flash to automatically set the exposure and white balance.
R
RAW
These files store the unprocessed image data at 12 bits per channel. Directly from the camera's imaging chip to its memory storage device.
RESOLUTION
The quality of any digital image, whether printed or displayed on a screen, depends on its resolution, or the number of pixels used to create the image. More, smaller pixels add detail and sharpen the edges.
RESOLUTION (OPTICAL)
An absolute number that the camera's image sensor can physically record.
RESOLUTION (INTERPOLATED)
Adds pixels to the image using complex software algorithms to determine what colour they should be. It is important to note that interpolation doesn't add any new information to the image, it just makes it bigger.
RGB (RED, GREEN AND BLUE)
The primary colours from which all other colours are derived. The additive reproduction process mixes various amounts of red, green and blue to produce other colours. information to the image, it just makes it bigger.
S
SATURATION
The degree to which a colour is undiluted by white light. If a colour is 100% saturated, it contains no white light. If a colour has no saturation, it is a shade of grey.
SEPIA
The (brownish) mono toned effect is seen in images from the original 19th and early 20th Century cameras. This is now a feature often found as a special image effect on some digicams and/or editing software.
SHUTTER LAG
The time between pressing the shutter and actually capturing the image. This is due to the camera having to calculate the exposure, set the white balance and focus the lens.
SHUTTER PRIORITY AE
This is where the user chooses a shutter speed and the aperture is automatically determined by lighting conditions. Shutter speed priority is used to control motion capture.
SLOW SYNC
A flash mode in some digicams opens the shutter for a longer than normal period and fires the flash just before it closes. Is used for illuminating a foreground subject, but allowing a darker background to also be well exposed.
SPOT METERING
The camera's auto exposure system is focused on a very small area in the centre of the viewfinder to adjust the overall exposure value just for that area.
STITCHING
Combining a series of images to form a larger image or a panoramic photo. Requires special post-editing software.
T
TIFF (TAGGED IMAGE FILE FORMAT)
An uncompressed image file that is lossless and produces no artefacts as is common with other image formats such as JPEG.
U
UNDEREXPOSURE
A picture that appears too dark because insufficient light was delivered to the imaging system. Opposite of overexposure.
V
VIGNETTING
The term describes the darkening of the outer edges of the image area due to the use of a filter or add-on lens. Most noticeable when the zoom lens is in full wide-angle.
W
WHITE BALANCE
Refers to the adjustment of the brightness of the red, green and blue components, so that the brightest object in the image appears white. See 'AWB'.
WIDE-ANGLE
The focal length gives you the widest angle of view. I.e. 10mm, 16mm, 24mm and so on.
Z
ZOOM LENS
A variable focal length lens. The most common digicams have a 3:1 ratio, such as 35-105mm. Detachable zoom lenses include, for example, 24-70mm, 70-200mm and 100-400mm.
Thank you for taking the time to read this article. Hopefully, this has provided you with insight to assist you with your business.
