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Digital Photography Definitions (M to P)


Below are definitions to many terms which come up when reading digital camera reviews and discussions of digital photography in general.

.........Term........ Definition
Micron See m
Mini "B" This is the name of cable which attaches to your digital camera on one end, and your computer on the other. The cable has a much smaller USB connection on the digital camera end, the Mini "B" end, but has a regular USB connector on the other end which connects to your computer.
MTF Chart Modulation Transfer Function; Spatial Frequency Response. If you've been a regular on DP forums and occasionally visit camera manufacturer's websites, you will come across the term, MTF, and usually a reference to a chart. MTF is a way of measuring the contrast and sharpness of a lens and its resolvant resolution qualities. An MTF Chart is a way to show photographers what they should expect from the characteristics of a lens. An MTF Chart is configured of an "X" and "Y" axis. Vertically, numbers from 0 to 1 (1 means the lens has 100% perfect contrast and sharpness) are graphed, and horizontally, numbers from 0 to 20 (or more; these numbers represent from the center of the lens and outward in terms of millimeters) are graphed. Graphing these two coordinates together measures the performance of a lens.
Multi-CAM 900 One of Nikon's AF sensor modules, which was used in several of Nikon's non-flagship SLRs and DSLRs, such as the F/N80, F/N75, D100, and D70. The AF module has 5 AF sensors and one cross-type AF sensor.
Multi-CAM 1300 This is another Nikon AF sensor module, which debuted in the F5 in 1996, the F100 in 1998, and in future pro-DSLRs such as the D1h and D1x. The AF module has 5 AF sensors--3 of them being cross-type AF sensors.
Multi-CAM 2000 This is Nikon's latest AF sensor module, which debuted in the D2h in 2003, and will also be included in the D2x. The sensor is made of 2000 pixels, designed specifically for the AF system (hence the name "Multi-Cam 2000"). The AF module has 11 AF sensors--9 of them being cross-type AF sensors.
Narrow DOF This is the same as Shallow DOF.
Noise Simply stated and generally speaking, noise is an unwanted signal in a particular image. Further, noise is signal which is converted digitally from the A/D converters of the processing engine of the imager, right alongside the image digitalization itself, and shows up on an image as pixels in red, blue, and green variations. Notice that this definition does not necessarily apply to Hot Pixels, because hot pixels are the result of a pixel which has been oversaturated with light, or is malfunctioning and does not have the same light-tolerance as its neighboring pixels. Also, noise will show up randomly on your imager at various shutter speeds, and will not have a fixed location, like a Hot Pixel would. Noise is also caused by the heat of the camera's electronics as well (see Thermal Noise, and also Amp Noise).
Perspective Perspective is the relationship between how far the foreground and the background appear to be separated from each other, or the apparent space visible in a photograph. Perspective is also the apparent size and depth of objects/subjects within an image. The perspective of an image will change if I take a photograph with an 18mm lens and a 85mm lens. Low-number focal length lenses (wide angle lenses) will create a sense of "longness", "pointedness", and will make the background of your subject appear further away than what it actually is.
Photoelectrons Photons that are detected by an imager when hitting it, create photoelectrons which are trapped in the respective pixels (i.e., "wells"). We call these Photoelectrons because a Photon has now combined with an Electron.
Photon p+. A photon is a "particle of light" as some have commented and is also referred to as a packet of electromagnetic energy. As the shutter of a camera is opened, a photon of light hits the surface of an imager, and it "stimulates" an Electron. The more photons that hit a particular area of an imager (i.e., a pixel), the more electrons are created and housed within the boundaries of that pixel until the shutter is closed.
Photovoltaic Effect This is where energy, in the form of photons, is converted into electronic energy potential (the reason we say potential, is because the imager may not detect the photons). It is also defined as the process where a photon is detected by an imager, and the imager then converts the photon into an electrical current (i.e., voltage).
PICT .pict; .pic. An image format used primarily on Macintosh computers. An image language called QuickDraw, renders the image. A problem with PICT, is with QuickDraw, because QD cannot render complex image curves or special text effects. PICT II is the latest version, and supports 24-bit color image files (like BMP files).
Picture Element See Pixel
Pixel Short term for Picture Element. It's basically the smallest element photo software can use to create text or graphics, the smallest element of a digital image, the smallest non-divisible element of a digital image, and is the smallest unit of measurement for displaying such information. Another term to remember is Resolution.
PNG Portable Network Graphics; .png; pronounced "ping" PNG is a new standard for internet and web graphics, which was intended to and is completing the replacement of the GIF format. PNG files allow for transparencies without the Jaggies inherent in GIF images. The PNG image format is mostly adopted by the latest web browsers but older browsers will not be compatible. PNG files are also larger in size than GIF files, but do support millions of colors, unlike GIFs. 24-bit color, and being a "lossless" format, are among the other features.
PPI Pixels Per Inch. It's basically a measurement of image information density. The more pixels per inch, the less you see those pixels when you view a specified printed image size. For example, 800 pixels horizontal by 800 pixels vertical will create a 2.67" x 2.67" image, at 300 PPI (800/300=2.67 horizontal, 800/300=2.67 vertical). Some allow PPI to be interchangeable with DPI.
Prime Referred to a lens that has a fixed focal length, such as a 300mm lens. Primes are the best possible quality you can get from a lens, but today, there are moderate-zoom1 lenses which come very close. However, these lenses are very expensive (such as Canon's $1700 24-70mm L IS USM, or Nikon's $1650 AF-S 17-35mm). Prime lenses are also the most expensive, and few photographers own them, which make these moderate-zoom lenses so popular.

1When I say "moderate-zoom", I mean the lens has a little room for zooming in and out, and does not indicate it's Wide, Normal, Telephoto, or Supertelephoto focal length.




Home Reviews Forums News 2013 2012 2009 2008 2007 2006 2005 2004
RSS Feeds FOV Factor Table Sensor Sizes | Definitions: A-D E-H I-L M-P Q-U V-Z | Sitemap
Articles Archived Websites (Pre-DigitalDingus): D100 Lounge E-10 Club | Contact