During your time here, you may come across odd photographic terms, some familiar, others new. Here’s a list of some of the terms that I use gratuitously.
Aperture: The hole or iris in a lens through which light travels ending up on either film or a digital sensor. Aperture in the context of photography refers to the diameter of the aperture stop, measured as the focal length divided by the effective aperture diameter and listed as a ratio 1:2.8, etc. When combined with shutter speed and ISO sensitivity, the aperture size will regulate the film’s degree of exposure to light. A full 1 stop difference in aperture will either half or double the amount of light allowed through the lens. Examples of aperture settings in full stops: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22,…
Bokeh: The subjective quality of the out of focus areas in an image. Adopted from the term ‘boke’ (暈け) in Japanese meaning blur, haze, fuzzy or disoriented. (pronounced bo-keh, with a soft ‘eh/ay’ sound between an english ‘kay’ and ‘keh’ (as the ‘ke’ in Ken) if using the direct phonetic translation from Japanese BO-KE, but also pronounced ‘bo-kuh’ by some. Many have ‘defined’ this term and its relationship with photography, but there are about as many definitions as there are opinions on the matter. For me “subjective quality” as seems to be generally accepted in the definition photographically speaking, dictates just that.
CCD: Charge Coupled Device. A device integrated with a sensor to transfer digital information used in many compact cameras as well as dSLR cameras.
CMOS: Complimentary Metal Oxide Semiconductor. A style of digital circuitry design and microprocessor technology transferring analog info to a digital file format.
Cropped Frame: A sensor used in a digital camera that is built smaller than a full frame sensor. Different cameras have different sized sensors and in turn, effective focal length multipliers.
Effective Focal Length: When a smaller (relative to a “full frame”) sensor is used, the cropped image circle produces a magnified portion of the center of the lens effectively multiplying the field of view to the same angle as a longer focal length. See “Focal Length.” The effective focal length is normally referenced in direct relation to the field of view provided via standard 35mm film format, or in digital terms “full frame.”
Focal Length: The focal length of a lens determines the magnification at which it images distant objects. Focal length is measured by the distance between the rear nodal point when the lens is focused to infinity, and the film, or sensor. “Wide” angles traditionally fall at or below 35mm. “Standard” angle lenses range between 40mm and 60mm (usually a 50mm lens is considered “standard”). A “standard” focal length for a given sensor or film size is equal to the diagonal measurement of the capture surface (see Standard below). Traditional “Portrait” focal lengths usually reside between 70mm and 135mm, noted for their flattering attributes to facial features. “Telephoto” focal lengths range from about 85mm on the short side up to 800mm or more on the long side (see: Telephoto below).
Full Frame: A digital sensor measuring 24mm x 36mm or nearly identical in size to a frame of 35mm film.
HDR: High Dynamic Range. Exposing to capture dynamic range including information from highlights through shadows in a single photo. Attaining both highlight and shadow information in one exposure can be difficult without the use of special software or the combination of multiple images exposed for the differences throughout the tonal range of the scene.
ISO: Developed by the International Organization for Standardization, since 1974 has stood as the standard measurement of film, or a digital sensor’s sensitivity to light.
JPEG: (j-peg) A common lossy compression method for digital image files transferring the captured information and translating from 12-16 bits per channel down to 8 bits per RGB channel.
Micro Four Thirds: A mirrorless camera system utilizing a live MOS 4/3 sensor to view subject via the LCD screen or EVF (electronic viewfinder). Using a lens mount adapter, the cameras are able to use lenses from various lens manufacturers.
RAW: A proprietary file format that translates captured information into a digital file with minimal compression, normally in 12, 14 or 16 bits per RGB channel. This is what the camera creates before applying a level of JPEG compression.
Sensor Size: Full frame = 36mm x 24mm / 864 sq mm, APS-H = 28.7mm x 19mm / 545 sq mm, APS-C = 23.6mm x 15.7mm (Nikon, Pentax, Sony) / 370.5 sq mm, 22.2mm x 14.8mm (Canon) / 328.6 sq mm, 4/3 = 17.3mm x 13mm / 225 sq mm, NikonCX 13.2mm x 8.8mm / 116 sq mm, 1/1.7″ (compact) 7.6mm x 5.7mm / 43.3 sq mm, 1/2.5″ (compact) 5.76mm x 4.29mm / 24.7 sq mm
Shutter Speed: The measurement of time that the shutter is open at a given setting. Examples of shutter speed settings in full stops: 1 second, 1/2sec, 1/4sec, 1/8sec, 1/15sec, 1/30sec, 1/60sec, 1/125sec, 1/250sec, 1/500sec, 1/1000sec, 1/2000sec, 1/4000sec, 1/8000sec
Standard (focal length): In terms of focal length is based on the diagonal measurement of the capture medium producing a similar view to the perception of the human eye. 4/3 (17.3x13mm) = 22mm, APS-C (23.6×15.7mm) = 28mm, Full Frame (36x24mm) = 43mm, Medium Format (50.7x39mm) = 64mm / (60x45mm) = 75mm / (60x60mm) = 85mm.
Stop: A unit of change of relative aperture or exposure (with a reduction of one stop equivalent to halving it).
Telephoto: A focal length that is designed to give a large image of a distant object, or a focal length that exceeds the physical length of the lens itself, enabled by a “telephoto group” within the optical formulation of the lens.