Glossary of Photographic Terms


Home  |   A-B   |   C-E  |   F-I  |   J-R  |   S-Z  |

C-E


CA  Chromatic Aberration Refers to the inability of a lens to focus all wavelengths of light (colors) equally. Light of higher frequency (blue) is focused at a slightly different angle than low frequency light (red) which causes the different colors to focus either in front or behind the focal plane. This causes a color fringing to appear in an image and an associated loss of sharpness, especially at the corners where the light is bent at the greatest angle. Lenses can be made using coatings (expensive) and exotic glass that focuses all wavelengths more equally (more expensive) to correct for this. This is one of the reasons that those $1400 pro lenses cost the way they do and why they perform so well.
CF  Compact Flash A memory card format that is widely used in DSLR cameras because of the large capacities and high transfer speeds available. They come in two sizes (actually, one size with two thicknesses): 43×36×3.3 mm for Type I and 43×36×5 mm for Type II. Most CF-compatible cameras made in the last five years will take either size.
Center-Weighted Metering Central Area Metering A metering mode that measures the entire frame but gives more importance to the central area of the frame. This is a useful mode when the subject fill most of the frame. While it may cause some under- or over-exposure of the background, the subject will be properly exposed.
CoC  Circle of Confusion A sharp image has all in-focus areas of the image rendered on the focal plane as tiny points of light. If the focus of the image or part of the image occurs before or after the focal plane, it is rendered as a circle instead of a point with the circle getting larger as the focus moves farther away from the focal plane. That is a Circle of Confusion. Depth of field in an image is determined by how far the focus can occur before or after the focal plane without the Circle of Confusion becoming too large, causing that part of of the image to appear out of focus.
CPL Circular Polarizer This is a special type of polarizer that will filter the glare from a scene but still allows the metering and autofocus sensors to work in a DSLR (or film SLR). 
Crop Factor Focal Length Multiplier DSLRs aren’t all created equal. The 35mm film format that they are descended from used a rectangle of film that measured 24mm x 36mm. There are a few cameras that use digital sensors that use the same dimensions as 35mm film. These are referred to as “full-frame” and tend to be high-end units and rather expensive. Most of the DSLR models use a sensor that is about the same size as the frame of an APS-C film camera, about 24mm x 16mm. Because the diagonal measure of an APS-C sensor is only about 66% of a full 35mm frame, it only captures the central area of the image circle projected by the lens. The end result is that the “apparent” focal length of a lens on an APS-C camera it 1.5times what it would be on a full-frame camera (1/.66 = 1.5). This is called the “crop factor” since the effect is the same as cropping the center out of a full-frame image and enlarging it. Another player is the Four Thirds standard. It uses a sensor that has one half the area of full-frame and, therefore, a crop factor of 2.0x. A 50mm lens on a 1.5x crop factor sensor would give the same apparent magnification as a 75mm short telephoto on a full-frame sensor or 35mm film. The same lens on a Four Thirds sensor would perform like a 100mm telephoto. There are a few variations, but this illustrates the point. When looking for a lens, you need to be aware of the crop factor of your camera to have an idea of what to expect from a given focal length.
CZ Carl Ziess Designation on top-tier Sony SLR lenses indicating that they were developed in collaboration with Carl Zeiss, Inc.
D-Lighting Active D-Lighting Nikon term for image dynamic range enhancement technology implemented in their cameras that uses software to balance the highlight and shadow exposure to more closely represent how the human eye sees. Active D-Lighting applies the changes automatically as the image is recorded.
DC APS-C only Sigma term for a lens designed for the smaller image circle required by an APS-C sized sensor. Cannot be used on a film or full-frame camera without vignetting.
DG Digital Sigma term designating that a full-frame (FF) lens has been optimized for digital photography by re-shaping the rear element, additional coatings, etc..
Di  Digitally Integrated Tamron designation for lenses capable of providing focal-length & distance information to the camera they attach to. Additional coatings and rear-element designs reduce ghosting (reflections from the shiny sensor bouncing off the lens back to the sensor.)
Di-II Digitally Integrated -APS-C only Tamron designation for theit Di lenses designed for the smaller image circle required by an APS-C sized sensor. Cannot be used on a film or full-frame camera without vignetting.
DMF  Direct Manual Focus An camera/lens feature that allow fine manual focus after autofocus is achieved without having to switch from autofocus to manual focus.
DOF Depth Of Field Nearest and farthest distance from the point the camera is focused on where objects will be in acceptably sharp focus.
DRO Dynamic Range Optimization (or Optimizer) Sony term for image dynamic range enhancement technology implemented in their Alpha series camera that uses a dedicated hardware processor from Apical to measure as many as 4000 segments of an image during capture and balances the highlight and shadow exposure to more closely represent how the human eye perceives a scene. 
DR Dynamic Range The Dynamic Range is the ratio between the highest and lowest measureable values as in recording sound or light. In photography it describes the film or sensor's ability to capture a range of details in a scene from both bright and shadowed areas. Neither film nor digital has the dynamic range that the human eye is capable of, which is why images often look a lot different than you remember seeing them, with bright areas washed out and scenery hidden in shadows. Bracketing and HDR imaging can overcome this and some cameras can improve the dynamic range internally through special processing chips or software.
DSLR Digital Single-Lens Reflex An SLR with a digital sensor instead of film.
DT APS-C only Sony/Minolta designation for a lens designed for the smaller image circle required by an APS-C sized sensor. Cannot be used on a film or full-frame camera without vignetting.
DX APS-C only Nikon or Tokina designation for a lens designed for the smaller image circle required by an APS-C sized sensor. Cannot be used on a film or full-frame camera without vignetting
EF  Electro-Focus Canon lens designed for their EOS cameras, both film and digital.
EF-S Electro-Focus - APS-C only Canon designation for a lens designed for the smaller image circle required by an APS-C sized sensor. Cannot be used on a film or full-frame camera.
ED Extra Low Dispersion Nikon lens designation for their lenses that use ELD glass that refracts all wavelengths of light more equally to reduce Chromatic Aberration.
ELD  Extra Low Dispersion A type of glass that refracts all wavelengths of light even more equally than LDglass to reduce Chromatic Aberration
E-TTL Evaluative Through The Lens (Also ETTL II) This is Canon's term for their advanced electronic flash technology. It allows the camera to evaluate the exposure for the flash by using a pre-flash and measuring the exposure before firing the main burst.
EV Exposure Value A scale denoting relative illumination as it relates to photographic exposure with EV 0 equaling 1s at f/1.0 (or 2s at f/1.4) at ISO100. A typical indoor scene would be around EV 5-7 and outdoors on a sunny day would be EV 15.
EVF Electronic Viewfinder Camera viewfinder that uses video imaging linked to the camera's sensor. This refers more to a small video unit magnified by an eyepiece that outwardly resembles an Optical Viewfinder but would, technically, include using the rear LCD screen to compose.
EVIL (also ILC), Mirrorless Electronic Viewfinder, Interchangeable Lens. A class of camera that uses a larger (DSLR-sized) 4:3 or APS-C sensor in a compact camera body with an electronic viewfinder linked to the camera's sensor. This eliminates the mirror box and allows for a much smaller camera body with more compact lenses than with a DSLR. Essentially, this is a Digicam like the Sony R1, Olympus C-8080 or Minolta A2 with the ability to use an assortment of lenses. The Micro Four-Thirds standard was based on this concept but Sony and Samsung have decided to use APS-C sensors. Nikon chose the much smaller CX sensor.
EXIF Exchangable Image File Format Exif file data is embedded in JPEG files by the camera to record information about exposure, focal length, time of day, camera model and many other specific bits of information. Most editing programs and image viewers can access this data and some can add additional information like copyrights geo-location coordinates and comments.

Home  |   A-B   |   C-E  |   F-I  |   J-R  |   S-Z  |