Glossary of Photographic Terms


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f/-Stop Also: Aperture The lens f-number (usually called an  f/-stop) is a ratio determined by dividing the diameter of the hole (aperture) in the lens body that lets light in by the focal length of the lens.  Since the ratio value gets larger as the diameter decreases, a lower f-number allows more light in than a larger one. Explained more completely in my article on low-light photography.
FF Front Focus An out-of-calibration condition where the camera's focusing system indicates focus, but the lens is actually focused slightly In front of the target.
FF (again) Full Frame  Refers to imaging sensors that are approximately the same size and aspect ratio as the standard 35mm film frame. 36mm × 24mm.
Fill Flash Fill-in Flash This is a technique for adding a small amount of flash to a scene to balance the subject against the ambient light. Often used to compensate for back-lighting or to brighten up shadows on subjects that are lit from the side or in bright sun.
Fisheye Fish-eye Fisheye lenses got their name from the simple fact that the front element of the lens bulges out to the point of being almost a half-sphere, making it look like a fish's eye.  These are specialized wide angle lenses that usually provide a full 180° field of view. Because no effort is made in the design to correct for spherical distortion, the images taken with these lenses are very distorted with straight lines curved heavily outward, especially toward the edges. Originally developed for taking pictures of the entire sky to record cloud formations for meteorological studies, they are now used to make images where the extreme distortion can provide an artistic effect.
FL Focal Length Technically, the distance from the nodal point of a lens to the focal plane when the lens is focused to infinity. Practically, it denoted the relative magnification of a lens with approximately 50mm equaling what the human eye sees, or 1x. Longer lenses magnify (300mm = 6x) and make objects seem closer. Shorter lenses give a wider view (24mm = .5x).
Four Thirds 4/3 This is a standard developed jointly between Kodak, Olympus, Panasonic and through Panasonic, Leica to provide a designed-for-digital format that would allow for compact, fully-functional DSLRs that use a defined sensor size and could interchange lenses between manufacturers via a standard mount. The name comes from the agreed-upon standard sensor's aspect ratio that is 4:3 which is similar to most P&S cameras rather than a typical DSLR which has a 3:2 aspect like 35mm film.
FP Focal Plane The fixed plane in a camera's design where the image transmitted through the lens is rendered in focus. The sensor or film is always mounted at the Focal Plane. On most advanced cameras it is identified on the top of the body with a ɸ symbol.
FPS Frames Per Second The number of images a camera can capture every second, whether shooting stills or movies.
FTM Fulltime Manual Focus Camera/lens setting that turns off autofocus completely and requires the lens to be focused manually.
G Grrrrrreat! (?) Designation given to the highest tier of Minolta lenses. Now used to designate the premium non-Zeiss Sony lenses.
G Gone! (?) G-type Nikon lenses are designed for use with Nikon SLRs aand DSLRs where aperture is controlled from the camera body. The lack of an aperture ring limits the backward compatibility with some older film SLRs.
GB Gigabyte Equal to 1,073,741,824 bytes (closest exponent of two to one billion). Unit of measure commonly used to denote the capacity of computer-related media such as memory chips or discs.
HDR High Dynamic Range A technique that uses two or more bracketed exposures of the same subject and blends them to create a single image that covers a wider Dynamic Range that the camera is capable of in a single shot. The result is an image that has detail in both the bright and shadowed areas and is thought to more closely represent what the human eye sees.
HS High Speed Minolta designation for lenses from their film era that were redesigned to take advantage of later model's faster focusing capability.
HSM  Hyper-Sonic Motor Sigma term for their in-lens motor technology
i-Contrast Intelligent Contrast Correction Canon 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. i-Contrast applies the changes automatically as the image is recorded or in the camera afterward if you forgot to turn it on while shooting.
IF Internal Focusing A lens that focuses by moving smaller internal components rather than the larger, heavier front elements.
ILC Interchangeable Lens Compact Sometimes referred to as  EVIL 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.
IS Image Stabilized Canon term for their lens-based image-stabilization technology
ISO International Organization of Standardization The American Standards Association (ASA) developed a scale that all film makers could use to standardize the sensitivity of film. The ASA standard was adopted by the International Organization of Standardization and the rating was changed to ISO. Digital sensors rate their sensitivity using the ISO film standard and use standard values like ISO50, 64, 80, 100, 160, 200, 400, 800, 1600 and higher with each increase doubling the sensitivity of the previous one.
i-TTL Intellegent Through The Lens This is Nikon'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.

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