Camera Basics - Photographic Terminology

All disciplines have terminology, Photography is no different. Just like any other field, photography terminology is necessary for photographers to talk about photography and photos. Here are some digital photographic terms you should become familiar with:

35 mm –

35 mm Single Lens Reflex cameras were first introduced around 1949 by East Germany Contax.  35mm movie film was first introduced in 1892. Photographic film was cut into strips 35mm wide and long lengths used in movie cameras. Short lengths of this film were cut to be used in the "35mm" camera to take single image photographs.  35mm film was relatively inexpensive and plentiful. In 1934 Kodak introduced 135 film designation for cartridge film 35 mm wide specifically for still photography. The film became popular in the 1960s and became the most used film size until the birth of digital cameras.  In 2009 Kodak ceased production of the famous dye based emulsion film, KodaChrome.

AF Sensor

The AF sensor is a sensor used to detect focus.

AF Servo

Essentially, motor-driven autofocus; engage it and a digital SLR's autofocus system will continuously track (focus) on a moving subject.

Aliasing

A type of digital image distortion most often seen when straight lines or edges in a digital image are enlarged to the point at which they appear jagged.

Ambient Light

The natural light in a scene.

Angle of Flash Coverage

The measurement in degrees of the angle formed by lines projecting from the center of the flash to the extremities of the field of coverage.

Angle of View

See Picture Angle.

Anti-Aliasing

An optical process that samples the edges of an image to fill in the missing areas that cause a jagged appearance.

Aperture

The circular opening inside the lens that can change in diameter to control the amount of light reaching the camera's sensor or film.

Aperture-Priority Auto Exposure

A shutter speed that is automatically selected by the camera to match the photographer's manually set lens aperture for a correct exposure. Especially useful for controlling depth-of-field.

Application

A computer program, such as an image editor or image browser.

Archival

The ability of a material, including some printing papers and compact discs, to last for many years.

ASA

Measure of a film's "light gathering" capability. Replaced by ISO for film and digital.

Aspect Ratio

The width of an image divided by its height. In still photography, common aspect ratios are 4:3 (images from digital cameras) and 3:2 (images from film cameras).

Aspherical Lens

A lens with a curved, non-spherical surface. Used to reduce aberrations and enable a more compact lens size.

Autofocus (AF)

A system of sensors and motors that allow lenses to obtain focus automatically; in some cameras, the system also allows the lens to maintain focus on a moving subject.

Automatic Balanced Fill-Flash

Nikon's TTL (through-the-lens) auto flash operation.

Automatic Exposure (AE)

With automatic exposure (AE) the camera's computer and metering system automatically select the aperture and shutter speed for a correct exposure.

Automatic Exposure Bracketing

A feature that sets the camera to take a series of pictures (usually three) at different exposure settings.

Color Space -

a three dimensional space represented by the x,y, and z axises. Each axis has a value from 0-256. Combination of varying values from each axis results in a different color in the 3 dimensional space. In the space 0,0,0 is pure black and 256,256,256 is pure white. The total number of combinations representing colors in the space exceeds 16.7 million. See color-space link to wikipedia for a more in depth discussion.

Digitize —

To convert analog information into digital format for use by a computer.

DOF ---

Depth of Field is The area of acceptable focus before and beyond the point of focus. For each f-stop and focal length lens the dept of field is different. With a 135mm lens set at F-8.0 and focused on an object at 150' the DOF is from 94-375 ft. Wider angle lenses the DOF increases. Telephoto lenses the DOF decreases. Larger aperture (smaller numbers) the DOF decreases and Smaller aperture (larger numbers) the DOF Increases. For more information see our discussion on Depth of Field.

DPI —

Dots Per Inch. Number of dots a printer or device (like a monitor) can display per linear inch. For example, most laser printers have a resolution of 300 dpi, most monitors 72 or 96 dpi, most PostScript image setters 1200 to 2450 dpi. Photo quality inkjet printers now have a resolution range from 600 x 600 dpi black  to 9600 x 2400 dpi for color.

DSLR –

Digital Single Lens Reflex.  Reflex refers to where the image passes through the lens and is reflected via a mirror through a pentaprism to the eye level view finder. Most all professional digital cameras still use the reflex system. Single Lens, derives it's name from the early design where instead of two lenses, one above the other, one for viewing and one for recording an image, a mirror was placed behind the recording lens to reflect the image via a mirror then refract (bending light by passing through a medium) it via a prism to focus it in the view finder and thereby eliminating the need for a viewing lens.

Gigabyte –

An amount equal to One Billion bytes or 1,000 megabytes. 

Image Sensor - 

The light gathering device behind the camera lens that has replaced conventional photographic film. The sensor's light sensitivity converts light to electronic signals and through Analog to Digital converters and processors compiles the image to a useable output format for storage on a memory card, printing or display on a computer screen.

JPEG —

A standardized format used by many digital cameras for storing images. This format is also commonly used for images on the web and images attached to e-mail messages. JPEG, which stands for Joint Photographic Experts Group, the group that established this file standard, is one of the most widely used formats today. JPEG is a standardized image compression mechanism designed for compressing full-color or gray scale images of natural, real-world scenes. JPEG uses lossy compression, which can degrade image quality when repeatedly re-saved after modifying with editing software. It is estimated that it takes about 10 "Save-As" to begin to notice degradation under normal enlargementKilobyte —

An amount of computer memory, disk space, or document size consisting of approximately one thousand bytes. Actual value is 1,024 bytes. 

LCD —

Liquid Crystal Display. A full-color display screen on cameras used to preview and review pictures and view information, such as menu options and camera settings. 

Memory card —

A storage device used to store data, such as picture and movie files. Available in a range of sizes, such as 2Gb (gigabyte), 4Gb and 16Gb. 

Megabyte —

An amount of computer memory consisting of about one million bytes. The actual value is 1,048,576 bytes. 

Megapixel —

A unit equal to one million pixels. The higher the resolution, the more pixels in an image and therefore the greater the image quality. An image file that is 1 megapixel (MP) can make a photo realistic print of 5 x 7 inches; a 2 MP file can make an 8 x 10-inch print; a 3 MP file can make an 11 x 14-inch print. Many professional and advanced DSLR cameras are reaching 21 MP and higher. 

Online photo service —

An online photofinishing service that lets digital and, at some sites, film camera users share and store their photos in online photo albums and order high quality prints from digital images. The sites lets users enhance pictures with editing tools, order prints online and order other photo products, like calendars and cards. 

Pixel —

(PICture ELement) The smallest element of a digitized image. One small dot of light among the many dots that make up an image on a computer screen.  Resolution —

The number of pixels in an image. A higher number correlates to a higher quality image. Also, a larger sensor with a higher number of pixels provides higher image quality. 

PPI —

Pixels Per Inch. The number of pixels per linear inch is used to describe image resolution. A higher ppi means more image detail and correlates to higher image quality. Monitors display images at 72 and 96 ppi, inkjet printers require at least 150 ppi to produce photo realistic prints and 300 dpi is realistically the highest resolution the human eye can discern. Images printed at resolutions of 1200 or 9600 DPI are essentially a waste of memory and printer ink, as images placed side by side with a 300 dpi print under normal viewing conditions the difference cannot be seen.  The term PPI is used for monitors while DPI is used for printers and the measurement and terms are interchangeable.

Photo kiosk —

A stand-alone computer-run system that allows users to edit and print pictures from negatives, prints, or digital files on a picture card, CD, or disk. The kiosks are usually located in retail store. 

RAW –

 A camera raw image file contains "minimally processed" data from the camera's image sensor. Raw files are so named because they are not yet processed and therefore are not ready to be used with a bitmap graphics editor or printed. Normally, the image is processed by a raw converter in a wide-gamut internal color-space where precise adjustments can be made before conversion to a "positive" file format such as TIFF or JPEG for storage, printing, or further manipulation, which often encodes the image in a device-dependent color-space.  

Raw file formats are becoming extremely popular in digital photography workflows because they offer creative professionals greater creative control. However, unlike the standardized JPEG  format, cameras can use many different raw formats — the specifications for which are not publicly available — which means that not every raw file can be read by a variety of software applications. As a result, the use of these proprietary raw files as a long-term archival solution carries risk, and sharing these files across complex workflows is even more challenging. Recently, Adobe® has created DNG (Digital NeGative). The Digital Negative (DNG), is a publicly available archival format for the raw files generated by digital cameras. By addressing the lack of an open standard for the raw files created by individual camera models, DNG helps ensure that photographers will be able to access their files far into the future.  Many camera manufactures now have conversion software or direct in-camera support to save files in DNG format. Also, Adobe provides the free Adobe DNG Converter which easily translates raw files from many of today's popular cameras. DNG is supported by most photo editing software, and software developers can freely download the complete DNG specification. However, before converting your images to DNG test a couple of files.  We personally found converting a JPEG file to DNG increased the file size by 3X. Since JPEG is an open source, non-proprietary, format there is no need to convert to DNG.  On the other hand with long time camera manufactures going out of businees or being sold (Minolta ->Sony) Some raw formats like Minolta's proprietary MRW may disappear from the scene leaving you high and dry wihout the ability to open and edit them a few years down the road.  The choice is yours. We recommend converting any proprietary RAW format to DNG as the file size does not increase and DNG affords you the confort and security knowing you will be able to open and edit the file well into the future.