digitaldingus Reference

Digital Photography Definitions

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September 30, 2015

Term Definition
QE Quantum Efficiency. A percentage of light that is detected by an imager. In a perfect imaging device and in a perfect world, a every photon hitting an imager would produce a photoelectron, and a QE rating would be 100%. Of course, this does not happen in the real world. Where do you see a QE spec? Usually if you read the published specifications sheet from imaging manufacturers, such as Kodak. QE is expressed in terms of RGB, which give a percentage rating of each color channel. For example, a rating of ".32, .38, .34" would mean the Red channel had 32 photons detected by the imager out of 100, etc.
Raster Data A picture or image composed of columns and rows of data cells--usually used to represent spatial information. These data cells are pixels which have a specific color value associated with them. You probably won't hear this term used too much as it mostly applies to geographical images, but if you see the term used, this is what it means.
RAW The data collected directly from the image sensor without any processing or interpolating. RAW files are generally large, because they have not been compressed.
Resolution First of all, when the topic of resolution is brought up in digital photography, it can mean several things. One is how many pixels are in an image, or another meaning could be the dpi settings on your printer. It's best to know the differences and in what context the term resolution is being used. Generally, resolution deals with how many pixels are in an image. For example, a Nikon D100 JPEG FINE image is 3008x2000. 3008 pixels horizontal, and 2000 pixels vertical. The resolution is a tad over 6 Megapixels.
Secure Digital SD. Introduced in 1999, Secure Digital is one of the newer types of storage media for digital cameras and other devices. About the same size as a MMC media card, both MMC and SD cards have the feature of encryption of data between host devices and the card, but MMC cards did not survive the competitive digital marketplace, and SD soon prevailed. SD cards are slowly obtaining larger capacities, and will most likely dominate the consumer DSLR world due to the smaller and portable cameras needing smaller media cards to accommodate. SD cards are only 2.1mm thick, and are 32mm x 24mm in size. January 2000 marked the launch of the SD Association, started by Matsushita Electric Industrial Co., Ltd. (Panasonic), SanDisk Corporation, and Toshiba Corporation. Much more information can be found at
Shallow DOF This means the image has a very limited area of sharpness, and the majority of the image is Out Of Focus (OOF), or is blurred.
SLD (Sigma) Special Low Dispersion. This is Sigma's term to describe the kind of glass element which reduces chromatic aberrations in the lens. The more SLD glass elements, the better the lens.
Slow Lens A lens which has a high f-number setting, such as f/5.6. or higher, is often referred to as a "slow" lens. It will not have an f/2.8 setting. This does not mean you should avoid this lens, as there are many telephoto zoom lenses which are fantastic (Sigma 150-600mm f/5.6-6.3 Sports, Nikon 200-500mm f/5.6E). As a rule of recommendation, if you shoot closer, such as 24mm to 70mm, you'll want a fast lens (which also allows for a potential Teleconverter to be added without much issue).
SmartMedia SM; Solid State Floppy Disk Card. If you're new to the DSLR world, you may not even know this portable media storage format existed. SmartMedia, designed by Toshiba, had a few major features going for it: It's size and weight. Measuring only 45mm x 37mm, having a thickness of 0.76mm, and weighing only 2g, it was thought SM would be the new dominant storage format in compact digital devices, rivaling CompactFlash. Unfortunately, this never happened. By late 2001, CompactFlash wasn't necessarily getting cheaper, but it offered higher capacities which photographers desperately needed. Today, the largest capacity SM card is 128MB. 256MB was planned, but never happened. SmartMedia is no longer being produced, but there are plenty of SM cards that are brand new, circulating on various retail websites and even in stores.
Substrate A spporting surface where that an imager is bonded to. This prevents cracking of the imager, and also allows controller components to be connected to the imager as well.
SWD (Olympus) Supersonic Wave Drive. This definition is mostly taken from Olympus themselves: Two high-powered (and compact) SWD devices power AF at an ultra-high speed by exciting unique elliptical oscillations, while an ultra-compact 5.3mm x 4.3mm optical encoder detects and controls the lens drive position using direct rotation detection without reduction gear. This enables it to achieve a level of precision that's accurate to 5 microns (5/1000 mm). Focusing speeds as quick as 170ms are possible.
SWM (Nikon) Silent Wave Motor. This is Nikon's term for using ultrasonic wave technology to move the components of the lens. SWM provides a more quiet, quick, accurate focusing behavior versus non-SWM lenses.
Thermal Noise Dark Noise; Dark Current. This is noise created from the heat of the imaging engine and other related components in the camera. The longer a digital camera is used, the more noise will be prevalent. Thermal noise will also be random, and may not show up on some photos because of the contents and color distribution of the image itself, and due to the randomness of thermal noise in general. Electrons within an imager, sometimes move around at the same speed of the operating temperature of the device. The higher the temperature, the more this happens. If there is enough thermal energy created, an electron will be ejected from the imager, and will be mistakenly recorded by the imager as a photoelectron.
Thinning Back-thinning .When you want to create a BCCD, you need to "thin" it. Thinning is a process that uses an acid bath to reduce the size of a CCD to approximately 5-15 microns thin. The acid eats away at the silicon. Wax is usually used to hold the imager to a supporting substrate since the wax is not affected by the acid.
TIFF Tagged Image File Format; Tagged Interchange File Format (rare) TIF; .tif. A graphic file format developed by Aldus Corporation, Hewlett-Packard, and Microsoft, in 1986. A TIFF file, is an uncompressed bitmap image format file, and is primarily designed for Raster Data sharing.
UC (Sigma) Ultra Compact. This refers to a Sigma lens which is considered ultra-compact for a lens of its size and weight in comparison with other lenses in the same category.
Ultrasonic Lens Technology Canon, Nikon, and Sigma have their own versions of this technology. Olympus was working on this technology as well when this definition was originally written, and now they have their branded SWD (Supersonic Wave Drive) lenses. What exactly is ultrasonic technology and how does it apply to photography? Ultrasonic traveling waves inside a lens barrel, move in a spiral pattern. A motor is positioned on top of the waves, and these ultrasonic waves move the motor above it, which in turn moves the lens focusing system. It is much more accurate than a non-USM lens, because the camera must be the motor source which drives the lens. This creates a slight delay in Camera-Lens communication, as well as inferior focusing when dealing with fast-moving objects or subjects.
USB Universal Serial Bus. A type of cable with "slits" on either end, and has a data rate of 1.5 Mb/s or 12 Mb/s (and up to 127 peripheral devices). This data rate varies per camera, media card, your computer specs, and other factors. Note that this data rate is Megabits Per Second, NOT Megabytes Per Second.
USB 2.0 The cables look the same as a USB cable but the actual card attached to your computer port (usually will be a PCI slot) or any device which has a USB 2.0 designation, will be rated at 480Mb/s. It is the latest USB offering and is featured on newer scanners, high-end digital cameras (though I wish all cameras would support this), and many other portable and electronic devices.
USB 3.0 As of July 2013, USB 3.1 delivers up to 5 Gbit/s (625 MB/s). USB 3.0+ cables have the designation SuperSpeed.
USM (Canon Ultrasonic Motor. This is Canon's term for using ultrasonic wave technology to move the lens focusing system, providing a more quiet, quick, accurate focusing behavior versus non-USM lenses. Canon makes two types of USM motors. The first is a Ring-type USM (found in their more expensive large aperture and zoom lenses and in super-telephoto zoom lenses), and the second is Micro-USM (found in smaller and compact lenses, like the 28-90mm f/4-5.6 and the 20-35 f/3.5-4.5).


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