Glossary - Photographic - Neils Resource Web
|Summary of Content|
|A collection of Photographic terms and relevant explanations. A good memory jogger.|
The following glossary is not a precise technical definition of terms, but instead is an attempt at explaining photography terms in a simple format.
|Glossary of photographic terms|
|Ambient light||The natural light in a scene.|
|Aperture||Also referred to as f/stop, f/value, aperture value. A "fast" lens is one with a large maximum aperture. A small, circular opening inside the lens that can change in diameter to control the amount of light reaching the camera's sensor as a picture is taken. The aperture diameter is expressed in f-stops; the lower the number, the larger the aperture. For instance, the aperture opening when set to f/2.8 is larger than at f/8. The aperture and shutter speed together control the total amount of light reaching the sensor. A larger aperture passes more light through to the sensor. Many cameras have an aperture priority mode that allows you to adjust the aperture to your own liking. See also shutter speed.|
|Aperture-Priority||Select an aperture (f/stop) and the camera chooses the best shutter speed. Use this mode to control the depth of field, e.g. select a small f/stop for landscape photography to ensure maximum depth of field, and a large f/stop for portrait photography to throw everything, except the subject, out of focus.|
|Archival||The ability of a material, including some printing papers and compact discs, to last for many years.|
|auto focus||The camera will try and access the correct sharpness of the picture.|
|Boke||Japanese word meaning "fuzzy" and referring to the out-of-focus (OOF) portions of a picture. A lens is said to have "good boke" if the OOF is pleasant and does not detract from the main subject. A lens with good boke produces out of focus smooth-edged highlights and reproduces an out of focus point of light as bright in the middle and progressively getting fainter with a fuzzy edge. (pronounced BOH-KEH), and increasingly referred to in print as "Bokeh"|
|Buffer||Memory in the camera that stores digital photos before they are written to the memory card.|
|Burning (in)||Selectively darkening part of a photo with an image editing program|
|CCD (Charge Coupled Device)|| This is the name of the sensor inside of the camera that is sensitive to light and converts the image into a digital format that the camera can save on its memory card. CCD's
have different numbers of points on them that are sensitive to light and in general the more of them, the better the picture quality. The number of pixels (or dots) in the picture that it outputs
is what is called the 'resolution' of the camera. It may also be recorded in 'megapixels' (or millions of dots).
One of the two main types of image sensors used in digital cameras. When a picture is taken, the CCD is struck by light coming through the camera's lens. Each of the thousands or millions of tiny pixels that make up the CCD convert this light into electrons. The number of electrons, usually described as the pixel's accumulated charge, is measured, then converted to a digital value. This last step occurs outside the CCD, in a camera component called an analogue-to-digital converter.
|Crop||Cropping a picture simply means to cut out a portion of the picture. For example, you may have extraneous details in your picture you do not want to display or print, so you "crop" it out. Notice, no enlargement is performed when you crop a picture. Often, you will read the term "100% crop" and all it means is that the photographer does not want to post the complete picture (could be 3MB+ in size) and so crops out the relevant part and post that as a "100% crop." No enlargement or reduction performed.|
|CCD||Charge Coupled Device: one of the two main types of image sensors used in digital cameras. When a picture is taken, the CCD is struck by light coming through the camera's lens. Each of the thousands or millions of tiny pixels that make up the CCD convert this light into electrons. The number of electrons, usually described as the pixel's accumulated charge, is measured, then converted to a digital value. This last step occurs outside the CCD, in a camera component called an analog-to-digital converter.|
|CD-R||CD-Recordable: a compact disc that holds either 650 or 700 MB of digital information, including digital photos. Creating one is commonly referred to as burning a CD. A CD-R disc can only be written to once, and is an ideal storage medium for original digital photos.|
|CD-RW||CD-Rewritable: similar in virtually all respects to a CD-R, except that a CD-RW disc can be written and erased many times. This makes them best suited to many backup tasks, but not for long term storage of original digital photos.|
|CMOS||Complementary Metal-Oxide Semiconductor: one of the two main types of image sensors used in digital cameras. Its basic function is the same as that of a CCD. CMOS sensors are currently found in only a handful of digital cameras.|
|CMYK||Cyan, Magenta, Yellow, Black. The four colors in the inksets of many photo-quality printers. Some printers use six ink colors to achieve smoother, more photographic prints. The two additional colors are often lighter shades of cyan and magenta.|
|CompactFlash™||A common type of digital camera memory card, about the size of a matchbook. There are two types of cards, Type I and Type II. They vary only in their thickness, with Type I being slightly thinner. A CompactFlash memory card can contain either flash memory or a miniature hard drive. The flash memory type is more prevalent. This is a type of memory card. Canon, Nikon and Pentax are just some of the manufacturers of digital cameras whose cameras use this storage medium. It is the most common of all memory cards. Storage sizes and speeds are improving all the time, e.g., 2mb 80x are available for under £200.|
|Compression||This is what a camera or a piece of imaging software does to a picture to make the file size smaller. Basically a picture that takes up a lot of memory can be compressed so that it doesn't take up so much. This has the advantage that it uses up less space so that you can save more on your card, but has the disadvantage that in reducing the file size, you usually reduce the quality of the picture.|
|Contrast||The difference between the darkest and lightest areas in a photo. The greater the difference, the higher the contrast.|
|Depth of Field||The distance wherein objects are in focus. The smaller the aperture, the greater the depth of field achieved.|
|Digital zoom||This is a zoom where the camera takes the individual dots that make up the centre of the picture and make them bigger so that the image ends up to a larger size. This is very useful because it does not require any further re-framing (which could be done later on on a computer but would be an extra thing to do). However, because the resulting image is only using information from the middle part of the picture and blowing it up, the image quality is worse than if the digital zoom is not used. Hence it is better to get a camera with a large enough optical zoom to suit your needs.|
|Dodging||Selectively lightening part of a photo with an image editing program.|
|Download, downloading||The process of moving computer data from one location to another. Though the term is normally used to describe the transfer, or downloading, of data from the Internet, it is also used to describe the transfer of photos from a camera memory card to the computer. Example: I downloaded photos to my PC.|
|DPI||Dots per inch: A measurement of the resolution of a digital photo or digital device, including digital cameras and printers. The higher the number, the greater the resolution.|
|EXIF||Exchangeable Image File: the file format used by most digital cameras. For example, when a typical camera is set to record a JPEG, it's actually recording an EXIF file that uses JPEG compression to compress the photo data within the file.|
|Exposure (Control)||The different modes the camera provides for controlling exposure, e.g. Auto, Manual, Shutter Priority, Aperture Priority. See also: Shooting Modes.|
|File||A computer document.|
|File size output||Some cameras claim to have a 6 million pixel output. This is not a lie but it does mislead many people. Many of the Fuji cameras, for example, have 3 million pixel CCDs but will save an image that has 6 million pixels. This is a good feature to have but when comparing these cameras to others, it is best to compare the effective number of pixels on the CCD.|
|Fill flash||A flash technique used to brighten deep shadow areas, typically outdoors on sunny days. Some digital cameras include a fill flash mode that forces the flash to fire, even in bright light.|
|Fire||Slang for shooting a picture. Example: I pressed the shutter button to fire.|
|FireWire||A type of cabling technology for transferring data to and from digital devices at high speed. Some professional digital cameras and memory card readers connect to the computer over FireWire. FireWire card readers are typically faster than those that connect via USB. Also known as IEEE 1394, FireWire was invented by Apple Computer but is now commonly used with Windows-based PCs as well.|
|Greyscale||A photo made up of varying tones of black and white. Greyscale is synonymous with black and white.|
|Highlights||The brightest parts of a photo.|
|Histogram||A graphic representation of the range of tones from dark to light in a photo. Some digital cameras include a histogram feature that enables a precise check on the exposure of the photo.|
|Image Sensor||The image sensor is the equivalent of 'film'.An image sensor contains millions of pixels (megapixels) arranged in a matrix whose job is to catch and record light when you take a
picture. Each pixel registers the brightness -- or, intensity -- of the light falling on it. By using coloured filters and an array of small lenses, the image sensor is able to record colour
values in a small footprint.|
A high resolution image sensor (3 megapixels and up) can capture much more variation in light than a low resolution image sensor (less than 3 megapixels), and can therefore reproduce an image more faithfully and realistically.
The size of an image sensor also contributes to the quality of the images captured. In general, the larger the image sensor, the less noise in the images. So, all things equal, a 1/1.8 in. 4 megapixels image sensor will capture less noisy images than a 1/2.7 in. 4 megapixels image sensor.
|ISO speed||A rating of a film's sensitivity to light. Though digital cameras don't use film, they have adopted the same rating system for describing the sensitivity of the camera's imaging sensor. Digital cameras often include a control for adjusting the ISO speed; some will adjust it automatically depending on the lighting conditions, adjusting it upwards as the available light dims. Generally, as ISO speed climbs, image quality drops but will suit darker enviroments without a flash.|
|JPEG||A standard for compressing image data developed by the Joint Photographic Experts Group, hence the name JPEG. Strictly speaking, JPEG is not a file format, it's a compression method that is used within a file format, such as the EXIF-JPEG format common to digital cameras. It is referred to as a lossy format, which means some quality is lost in achieving JPEG's high compression rates. Usually, if a high-quality, low-compression JPEG setting is chosen on a digital camera, the loss of quality is not detectable to the eye.|
|Light Metering||How the camera measures the amount of light available to expose a picture.|
Centre-Weighted: Readings are taken at various part of the picture, with a special emphasis for the centre.
Spot: Readings are taken at a specific point.
Besides the above two light metering options, each camera manufacturer has its own variations, such as Matrix Metering, Multi-Pattern Metering, etc.
|Macro Photography||Photographing small objects, by usually moving close up. A steady tripod and a macro ring light ensure well exposed pictures.|
|Media||Material that information is written to and stored on. Digital photography storage media includes CompactFlash cards and CDs.|
|Megabyte (MB)||A measurement of data storage equal to 1024 kilobytes (KB).|
|Megapixels, effective||Megapixel – Equal to one million pixels.|
Millions of pixels (usually used in reference to the resolution of an image sensor).
A digital camera can have an image sensor that is rated 4.2 megapixels but delivers an effective resolution of 4.0 megapixels. The higher the effective resolution, the higher the quality of the picture that can be recorded (providing the lens is able to produce the quality image in the first place).
Some digital cameras might advertise the "interpolated" pixels. As an example, Fujifilm's Super CCD image sensor can capture "effective" pixels of 3.1 megapixels, then its software kicks in and interpolates them up to 6 megapixels. Do bear in mind a digital camera that outputs 6 interpolated megapixels will never deliver the same quality that a real 6 effective megapixels digital camera will, and should still be compared to a 3 effective megapixels digital camera.
What is important when comparing resolution of different image sensors in digital cameras is the effective megapixels.
|Memory Cards||These are the digital equivalent of film. A memory card can hold a certain number of pictures, depending on the size of the card (expressed in Megabytes or MBs) and the size of the pictures to be stored on it. This varies enormously between the different settings on different cameras but as a very simply guide you can say that you get a reasonable picture quality (but not the best) from a file size which is about 1Mb so on a 64Mb card, you can get about 64 pictures.|
|Memory Stick®||A memory card slightly smaller than a single stick of chewing gum. Like CompactFlash and SmartMedia, it is flash-based storage for your photos.|
|Microdrive||This is a type of memory card. It is actually a very small hard drive and come in very large capacities allowing you to save thousands of pictures all on one card. The card is very similar in size to a compact flash card and many cameras that can store pictures on compact flash can also use microdrives as a cheaper way to store hundreds of photos.|
|MultiMedia Card||This is a type of memory card, abbreviated to MMC. Canon digital camcorders that have digital camera functions built-in are just some of the hardware available today that use this storage medium.|
|NiMH||Nickel Metal-Hydride: a type of rechargeable battery that can be recharged many times. NiMH batteries provide sufficient power to run digital cameras and flashes.|
|Noise reduction||When a slow shutter speed is used (1/30 sec. and lower), the image degrades due to the build-up of electronic signal ("noise"). Software in the digital camera automatically
compensates to reduce that noise. What is important is a camera with noise reduction that starts at shutter speeds of 1/30 sec. and lower.|
Similarly, when a high ISO is used, noise starts to show in images. For now, most consumer digital cameras are not good at high ISOs, even though the camera might offer them.
|Optical zoom||This is usually expressed as a multiplicative factor (such 2x or 3x or even up to 10x on some models) and tells you how much a camera will zoom in compared to how wide the picture is. It is best to get as large a zoom as possible to cope with different situations and to be able to get the subject of the frame to fill the frame rather than just be a little dot in the middle. Please double check that a camera is referring to its optical zoom (as opposed to a digital zoom) since there is an important distinction - see below.|
|Panning||A photography technique in which the camera follows a moving subject. Done correctly, the subject is sharp and clear, while the background is blurred, giving a sense of motion to the photo.|
|paintshop pro||Image editing software. The 2nd most popular (My opinion).|
|Photoshop||Image editing software. CS2 is even better. The most popular (My opinion).|
|Photoshop Elements||Only slightly cut down version of above. Quick and simple. Good organiser.|
|Pixel / MegaPixel||A 'Pixel' is another name for a dot. Lots of pixels (or dots) make up a digital picture captured on a digital camera. Different digital cameras can record different amounts of pixels in a picture. The more pixels that a camera can record the more information there is in the picture and so therefore the better the quality of the image. To be able to print good quality larger images you will need a camera with a CCD with a large number of pixels. Basic cameras have less than 1 million pixels (or 1 Mega pixel), while if you are looking to produce good quality images at greater than 6"x4" then you will need a camera with at least 2 million pixels (or 2 Mega Pixels). There are now cameras available that record over 5 million pixels in a single picture so make sure you get a digital camera with a large number of pixels.|
|Pre-focusing||A technique to allow you to focus on a subject that is not at the center of the screen. By default a camera will focus at the center of the screen. By pressing the shutter release button half-way you can lock focus on your off-center subject, then recompose and depress the shutter release fully to take the shot.|
|Resolution, Sensor||For our purpose, let's just define this as the number of pixels used to capture an image. In reality, excellent image resolution is achieved by a combination of pixel
count (image sensor resolution) and lens resolution.|
If the image sensor resolution is expressed as numbers such as 2048x1536, just multiply them out and divide by 1 million to get the resolution in megapixels. In this case, we get 3+ megapixels.
Usually the higher the image sensor resolution, the better the image quality.
|RAW||The RAW image format is the data as it comes directly off the CCD, with no in-camera processing is performed. Most suited for post processing.|
|Red-eye||The red glow from a subject's eyes caused by light from a flash reflecting off the blood vessels behind the retina in the eye. The effect is most common when light levels are low, outdoor at night, or indoor in a dimly-lit room.|
|RGB||Red, Green, Blue: the three colours to which the human visual system, digital cameras and many other devices are sensitive.|
|Saturation||How rich the colours are in a photo.|
|Secure Digital Card||This is a type of memory card, abbreviated to SD. It is very similar to a MultiMedia Card in that it is exactly the same size and many cameras and other devices that use MultiMedia cards can also use Secure Digital (although this is not true for every single electronic device and the opposite is not necessarily true). Secure Digital cards have extra features over and above Multimedia cards but this depends on the device (cameras usually don't have any extra features with SD cards than MMC cards but some devices, like mp3 players do make use of the extra features).|
|Sensitivity||See ISO speed.|
|Serial||A method for connecting an external device such as a printer, scanner, or camera, to a computer. It has been all but replaced by USB and FireWire in modern computers.|
|Shooting Modes||The amount of control you have in choosing how your digital camera captures an image.|
All digital cameras usually have an Auto mode: the camera decides for you the best shutter speed/aperture settings.
Shutter Priority: Allows you to decide the shutter speed (e.g. fast at 1/500 sec. for stop action photography, or slow at 2 sec. for night photography), and the camera decides the best aperture.
Aperture Priority: Allows you to choose the aperture (e.g. large at F1.8 for portrait, of small at F16 for landscapes).
Manual: You have complete creative control in selecting both the shutter and aperture.
Scene Modes: Pre-set exposure control (shutter/aperture combination, plus other adjustments, such as white balance, exposure compensation, etc.) for various common picture situations, such as Night Scene, Portrait, Landscape, Action, etc.
|Shutter-Priority||Select the shutter speed and the camera chooses the best aperture. Use this mode to freeze fast moving action or emphasize motion. For example, select a fast shutter speed (e.g. 1/1,000 sec.) to freeze a cyclist zooming by. Or, select a slow shutter speed (e.g. 1/30 sec.) to capture the cyclist as a blur to emphasize the speed of the motion.|
|Sharpness||The clarity of detail in a photo.|
|Shutter Speed||The amount of time the shutter blades stay open to allow light into the camera. The longer the shutter stays open (e.g. 1/30 sec.), the more light; the shorter the shutter stays open (e.g. 1/1,000 sec.), the less light. Snapshots and action photography usually requires a fast shutter speed to freeze action; landscapes usually requires a small aperture for maximum depth of field, and hence a longer shutter speed for properly exposed pictures.|
|SmartMedia™||A wafer-thin, matchbook size memory card. This is also a flash-memory based storage medium. This is a type of memory card, abbreviated to SM. Fuji and Olympus are just some of the manufacturers of digital cameras whose cameras use this storage medium.|
|Sony Memory Stick||This is a type of memory card. Sony was the first company to use these as a storage medium, although a few other manufacturers have also started to use Memory Sticks.|
|Storage Media||The digital medium that replaces film. A number of competing storage media cards are offered, with the most common ones being CompactFlash (CF) and SmartMedia. [Sony uses its own proprietary Memory Stick, Olympus has introduced its proprietary xD-Picture Card.]|
|Thumbnail||A small version of a photo. Image browsers commonly display thumbnails of photos several or even dozens at a time. In Windows XP's My Pictures, you can view thumbnails of photos in both the Thumbnails and Filmstrip view modes.|
|White balance||When a digital pictured is captured, it can be manipulated, either using a image editing software (such as Photoshop) on your computer, or right at the time of taking the picture in the digital camera. White balance refers to the ability to adjust colours based on white as a reference colour to give as true a white as possible; in the process, all the other colours are also corrected. Some preset white balance settings are daylight, cloudy, tungsten, or fluorescent. Using white balance properly is essential in digital photography.|
|USB||Universal Serial Bus: a protocol for transferring data to and from digital devices. Many digital cameras and memory card readers connect to the USB port on a computer. USB card readers are typically faster than cameras or readers that connect to the serial port, but slower than those that connect via FireWire.|
|xD Picture Card||This is a type of memory card. Fuji and Olympus are the two main manufacturers of digital cameras whose cameras use this storage medium. It is the newest storage medium, cards are available of up to 8GB in size.|
|Zoom, Optical vs. Digital||Whereas an optical zoom uses the optics (lens) of the digital camera to move you closer to your subject, a digital zoom simply uses the existing image and enlarges it digitally.|
Enlarging the image digitally reduces picture quality, and should therefore usually be avoided. However, a judicious use of digital zoom may sometimes yield images that are of quite acceptable quality. So, use with caution.
What is important when comparing digital cameras is the optical zoom. Digital zoom can always be achieved later in an image editing software, such as Photoshop, so should not really be a determining factor when choosing a digital camera.
|Photonotes.org||A link to a more comprehensive dictionary|
|Fotofinish.com||A Dictionary with pics|
|Hyperlink titles may have been abbreviated, (right click on the link and select properties for the full URL)|
Last Updated: 04/08/2008 - Glossary of Photographic Terms - Photography - Neils Resource Web