Glossary of Photographic Terms


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

J-R


JPEG Joint Photographic Experts Group A JPEG image is a compressed bitmap image format that was developed in the early '90s and is available as a recording option in virtually all digital cameras. Files are appended with ".jpg".
L AsphericaL Designation given to the highest tier of Canon lenses that use advanced lens materials and designs to optimize image quality.
LD Low Dispersion A type of glass that refracts all wavelengths of light more equally than normal glass to reduce Chromatic Aberration
Macro Close Focusing Macro lenses are specially-designed to focus down to extremely short distances and produce a flat field of focus for copying documents and such. True macro lenses will focus close enough that the image produced on 35mm film or a full-frame sensor is life-size. In other words, if you took a 35mm slide of a dime, the image on the slide would be the same size as the dime. This is called a 1:1 macro. You’ll see a lot of zoom lenses with “macro” tacked onto their names. These lenses focus close, but seldom give more than a 1:4 ratio (the image on the film would ¼ the size of the dime). Macro lenses are usually f/2.8 and come in 50mm - 200mm fixed focal lengths. Whether 50mm or 200mm, they seldom get closer than 1:1 but the longer the lens, the farther away you can be from the subject at 1:1. This is useful for photographing small living things that get nervous as things get closer.
Matrix Metering Automatic Multi-Pattern, Evaluative, Honeycomb A metering mode that measures many parts of the frame and based on a set of pre-programmed evaluations, balances the exposure to give the best overall exposure to the scene. This mode performs a "best guess" based on the pattern detected by the metering and will automatically fire the flash to fill an under-exposed area or over-expose the background if the program perceives the subject (it will try to guess the subject based on the pattern) to be under-exposed. Over the years the "best guess" has evolved into a remarkably accurate process.
MB  Megabyte Equal to 1,048,576 bytes (closest exponent of two to one million). Used to denote the capacity of computer-related media such as memory chips or discs.
Mb    (Mbit) Megabit Equal to 1,000,000 bits. Most commonly used as a measure of transfer speed of binary data (Mb/s). Because capacity is measured in megabytes (8 bits x 1024 x 1024) and speed in bits, a one megabyte file would take 8.38 seconds to transfer from a camera to a computer at 1 Mb/s.
MF Medium Format A class of cameras that use much larger film or sensors than cameras based on 35mm film cameras. Their exceptional image quality comes at a price that mostly limits their use to businesses and working professionals. 
MF  Manual focus A camera or lens that is focused manually. Not autofocus. (Yup, it's just that simple!)
Mirrorless  Also ILC Compact camera with a large sensor and interchangeable lenses capable of DSLR quality images in a small package.
MLU  Mirror Lock Up  A feature on some SLRs and DSLRs that allows the reflex mirror to be locked into it's shooting position. This feature is used in long telephoto and macro work to eliminate the vibration caused by the slap of the mirror as it flips up out of the way when the shutter is released. Many DSLRs with this feature will include MLU in the 2 second self-timer function so the mirror is flipped up and the camera waits 2 seconds before releasing the shutter to allow the vibration to die down.
NEX  New E-mount eXperience Sony's Mirrorless camera series that features extremely compact bodies with large APS-C sensors. Unlike the Alpha series, they do not feature in-body stabilization and rely on lens-based stabilization in optics made for the new E-Mount.
OOF  Out Of Focus Not in focus. A soft image may be soft for a number of reasons. OOF is a common reason. Also refers to areas in an image that are intentionally not in focus.
OS Optical Stabilizer Sigma term for their lens-based image-stabilization technology
OVF Optical Viewfinder Camera viewfinder that used lenses, either a separate assembly synchronized with the camera's lens or directly through the main lens via a mirror. 
PF  Purple Fringing An aspect of Chromatic Aberration that appears as a purple fringe  most often on the edges of high contrast areas between blue sky and darker objects like tree branches of the edges of buildings.  
RAW Raw file Not an acronym. It refers to the unprocessed image format available in higher-end digital cameras. Sort of a digital "negative". The RAW format contains the basic image data that the sensor records before it is processed by the camera into a JPEG. A RAW file can be manipulated after-the-fact for exposure compensation, white-balance, noise-reduction, sharpness, contrast, color settings and almost any other adjustment options that the camera offers. Because each camera maker uses it's own RAW format, applying the adjustments requires either the proprietary software from the camera manufacturer, a dedicated RAW processing package like Bibble or a higher-end editing program like the ones available from Adobe or Corel. RAW is used by professional photographers where critical adjustments may be needed in post-production and over-used by general photographers "because the pros use it". (Though generally factual, that last part was a bit of editorializing.)
RF  Rear Focus A lens that moves the rear element group to focus. Usually found in a larger telephoto where moving the huge front element to focus would be impractical.
RF  Range Finder (e.g. Leica's M8)  A camera that uses a dual image parallax rangefinder system to focus.
RP  Release Priority A camera setting in an autofocus camera that allows the shutter to be released even if the focusing system does not confirm that focus has been achieved.

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