A practical, alphabetical reference to photography terms, camera technology, and interchangeable-lens mounts. Choose a letter to jump to its section, or use your browser’s Find command to locate a term.
18% Gray is a commonly used reference for reflected-light exposure and is associated with the traditional photographic gray card. A gray card provides a known, neutral reflectance that can help photographers establish consistent exposure and white balance. The often-repeated 18% figure should not be confused with the exact reflectance target used by every modern camera meter.
35mm refers historically to the 35mm film format, whose standard still-photography frame is approximately 36 × 24 mm. In digital photography, a sensor of approximately the same dimensions is commonly called full frame . The term 35mm is also used as a reference when comparing focal lengths and fields of view between different sensor formats.
3FR is a Hasselblad RAW format used by some Hasselblad digital cameras.
The Minolta AF/Sony A-type SLR mount used by Minolta autofocus film cameras and Sony Alpha DSLRs. It is distinct from Sony E-mount.
Adobe RGB (aRGB) is a wide-gamut RGB color space used in some photography workflows. It can represent a broader range of greens and cyans than sRGB, but the benefit depends on compatible editing, display, and output settings.
The angle of view is the extent of a scene captured by a lens and camera combination. It depends on focal length and the dimensions of the recording format.
Aperture is the adjustable opening in a lens that controls how much light passes through. It is expressed as an f-number and also influences depth of field.
An exposure mode in which the photographer selects the aperture and the camera chooses a shutter speed for its metered exposure. Often labeled A; Canon calls this Av (Aperture value).
APS is the Advanced Photo System, a family of film formats introduced in the 1990s. APS included several image sizes, including APS-C, which later became the name for a common digital sensor format. In digital photography, APS-C sensors are smaller than 35mm/full-frame sensors and therefore have a narrower field of view with the same focal length.
ARW is Sony’s RAW image format used by many Sony digital cameras. It preserves sensor data and camera metadata for processing in compatible software.
Aspect ratio describes the proportional relationship between an image's width and height, such as 3:2, 4:3, 1:1, or 16:9. Changing the aspect ratio can crop the recorded image without changing the lens's focal length.
Autofocus is a camera system that automatically adjusts lens focus. Single-shot modes are intended for still subjects; continuous modes update focus as the subject or camera distance changes. Names and behavior vary by camera.
Back-button autofocus moves focusing from the shutter button to a separate button on the camera body. It lets the photographer focus and release the shutter independently.
Bokeh describes the appearance and quality of out-of-focus areas in a photograph. Lens design, aperture shape, focus distance, and background distance all influence how those areas look.
Exposure bracketing is a sequence of photographs made at different exposure settings to compare or combine results.
BSI stands for back-side illumination . In a BSI sensor, the wiring and supporting circuitry are positioned behind the photosensitive area rather than obstructing as much of the light-facing surface. This design can improve the efficiency with which incoming light reaches the photodiodes, particularly in smaller pixels.
Camera RAW files use manufacturer- and model-dependent extensions. Common examples include .3FR, .ARW, .CR2, .CR3, .CRW, .DNG, .ERF, .FFF, .IIQ, .MRW, .NEF, .NRW, .ORF, .PEF, .RAF, .RAW, .RW2, .RWL, .SRW, and .X3F. Compatibility can vary by camera model and software version.
CCD stands for charge-coupled device . CCDs are image sensors that convert incoming light into electrical charge and transfer that charge through the sensor for readout. CCD technology was widely used in earlier digital cameras before CMOS became dominant.
CDAF stands for contrast-detection autofocus . CDAF evaluates image contrast on the imaging sensor and adjusts focus until the measured contrast reaches a maximum. It does not directly measure the direction of defocus, so the camera may need to move the lens back and forth while finding focus.
Center-weighted Metering is an exposure-metering method that evaluates the entire frame but gives greater weight to the central portion. It is useful when the main subject is near the center or when you want less influence from very bright or dark areas near the edges.
A metering option that gives priority to the central area while measuring a relatively small spot within that area. Exact behavior and naming vary by camera; it is distinct from standard center-weighted averaging and from selectable spot metering.
Chromatic aberration is a lens error caused by different wavelengths of light being refracted differently. It can appear as colored fringes around high-contrast edges, particularly near the frame's edges.
CMOS stands for complementary metal-oxide semiconductor . CMOS is the dominant type of image sensor used in modern digital cameras. Each photosite converts light into an electrical signal, while supporting circuitry allows the sensor to be read and processed efficiently.
A color space defines a range of colors and how color values are represented. A color space affects how images are encoded, edited, displayed, and shared; common examples include sRGB, Adobe RGB, and Display P3.
Composition is the arrangement of subjects, shapes, lines, tones, and empty space within a photograph's frame. It influences where viewers look and how they interpret relationships in the scene.
CR2 is Canon’s RAW format used by many EOS digital cameras before the transition to CR3. It preserves sensor data and metadata for later processing.
CR3 is a Canon RAW format used by many newer EOS cameras. It stores sensor data and metadata and may use different internal compression options depending on the camera.
Crop factor compares a camera sensor's dimensions with a reference full-frame sensor. It describes how a smaller sensor changes the field of view produced by a given focal length.
CRW is an older Canon RAW file format used by some early Canon digital cameras. Later Canon cameras commonly use CR2 or CR3 instead.
Depth of field is the range of distances that appears acceptably sharp in a photograph. Aperture, focal length, subject distance, and sensor format all influence it. A wide aperture generally produces a shallower depth of field.
DNG (Digital Negative) is an openly documented RAW format developed by Adobe. Some cameras record DNG directly, and some RAW files can be converted to DNG; conversion does not recover information that was not captured.
Dynamic range is the span between the darkest and brightest detail a camera system can record or reproduce. Greater dynamic range can make it easier to retain detail in both deep shadows and bright highlights.
Sony’s mirrorless lens mount used on APS-C and full-frame cameras. E-mount lenses designed for APS-C are commonly marked accordingly; full-frame E-mount lenses cover the larger image area.
Canon’s autofocus SLR lens mount introduced for its EOS film and DSLR systems. EF lenses are designed for full-frame coverage and can also be used on many Canon APS-C DSLRs.
Canon’s compact mirrorless mount for its EOS M camera system, designed around APS-C sensors.
Canon’s DSLR lens mount designation for lenses designed for APS-C EOS DSLR cameras. EF-S lenses are not intended for full-frame EOS DSLR bodies.
A shutter mode that begins an exposure electronically and ends it with a mechanical second curtain. EFCS can reduce shutter vibration compared with a fully mechanical shutter, while retaining a mechanical end to the exposure. Its behavior and limits vary by camera.
A shutter mode that controls exposure timing electronically through the image sensor rather than moving mechanical curtains to start and end the exposure. Many electronic shutters read the sensor progressively, which can cause rolling-shutter distortion with fast motion or camera movement; readout speed and flash support vary by camera.
ERF is Epson’s RAW image format used by the Epson R-D1 rangefinder camera.
Canon’s multi-zone metering method analyzes brightness across multiple areas of the frame, sometimes considering additional scene information. It is intended for general-purpose exposure measurement. Other manufacturers use different names and algorithms for similar multi-zone approaches.
EVF stands for electronic viewfinder . An EVF displays a live electronic representation of the scene captured by the lens. Unlike an optical viewfinder, it can show exposure, white balance, focus aids, histograms, and other information before the photograph is taken.
Exposure describes the amount of light that reaches the camera's imaging medium during the exposure. For a given sensitivity, exposure is controlled by two variables: aperture , which determines the size of the lens opening, and shutter speed , which determines how long that opening admits light. Shutter speeds are normally expressed as reciprocal values such as 1/30 s, 1/60 s, and 1/125 s. Apertures are expressed as f-numbers such as f/2.8, f/4, and f/5.6. ISO does not change the amount of light reaching the medium; it specifies the medium's sensitivity (or, in a digital camera, the corresponding sensitivity setting).
Exposure compensation tells an automatic exposure system to intentionally make the resulting photograph brighter or darker than its meter's suggested exposure.
Exposure Value (EV) is a logarithmic way of expressing a combination of aperture and shutter speed. At ISO 100, EV = log₂(N² ÷ t) , where N is the f-number and t is the exposure time in seconds. Each increase of 1 EV represents one stop less light; each decrease of 1 EV represents one stop more light. For example, f/4 at 1/60 s and f/5.6 at 1/30 s represent the same EV because the aperture and shutter-speed changes offset one another. EV values are therefore a convenient way to compare equivalent exposures.
Nikon’s long-running SLR lens mount, used across many film and DSLR cameras. Compatibility varies by lens generation and camera body features.
Canon’s manual-focus SLR lens mount used before the EOS EF system. FD lenses generally require an adapter for use on modern interchangeable-lens cameras.
FFF is a Hasselblad RAW format associated with some Hasselblad digital backs and capture systems.
Photographic film is a light-sensitive material that records an image through a chemical change during exposure and development.
Flange Distance is the distance between a camera mount’s flange surface and the imaging plane. It is a critical dimension in interchangeable-lens systems because the lens must be positioned at the correct distance from the sensor or film to focus properly at infinity.
Flash is a brief burst of artificial light used to illuminate a subject. Its effect depends on direction, distance, power, duration, and ambient light.
Focal length is a fundamental optical measurement of a lens, expressed in millimeters. It strongly influences angle of view and magnification: shorter focal lengths generally show more of a scene, while longer focal lengths show a narrower portion of it.
Focus is the adjustment of a lens so that a chosen subject distance is rendered sharply on the imaging plane. Autofocus systems help set focus, while the photographer chooses what detail should be emphasized.
Focus breathing is an apparent change in a lens's angle of view or magnification as focus is changed. It can be particularly noticeable during video focus pulls.
The DSLR lens mount standard for the original Four Thirds system; distinct from the later Micro Four Thirds mirrorless mount.
Foveon is a sensor design associated with the Foveon X3 architecture, which records color information at different depths within the silicon rather than using a conventional single-layer Bayer color filter array. The approach is designed to capture red, green, and blue information from the same pixel location.
Fujifilm’s G-mount (often called GF mount) for its GFX medium-format mirrorless cameras and GF lenses.
Fujifilm’s GFX camera system, a family of medium-format mirrorless cameras that use the G mount and GF lenses.
A sensor readout design in which all pixels capture the exposure over the same time interval, rather than being exposed row by row. It can avoid the skew and shape distortion associated with rolling shutter during fast motion, though performance and image-quality tradeoffs depend on the sensor and camera.
A flash's guide number indicates its light output under specified conditions and is used with aperture and subject distance to estimate flash exposure.
Hasselblad’s classic medium-format SLR system and lens interface, used by many film bodies and some digital backs with appropriate compatibility.
Hasselblad’s mirrorless lens mount for its X System medium-format cameras.
HDR stands for high dynamic range. In photography it can describe a scene or image with a wide span of brightness, or techniques and formats used to capture, combine, encode, or display that range. HDR still depends on capture, processing, and display capabilities.
HEIC is a common filename extension for HEIF images encoded using HEVC. It is associated especially with Apple devices, though support and metadata handling depend on software.
HEIF (High Efficiency Image File Format) is a container format for images that can use modern compression such as HEVC. Cameras and devices may use HEIF to store images efficiently; exact capabilities and extensions vary by device.
Highlight clipping occurs when bright areas exceed the camera's recordable range and lose tonal detail. On many cameras, a histogram or highlight warning can help reveal it.
A histogram is a graph showing the distribution of image pixels from dark to bright. It helps assess tonal placement and possible clipping.
HLG (Hybrid Log-Gamma) is a high-dynamic-range transfer function used primarily for video. It encodes brightness in a way designed to support HDR displays while retaining compatibility considerations for standard dynamic-range workflows.
IIQ is a RAW format used by Phase One digital backs and cameras.
Image noise is unwanted variation in brightness or color that can become more visible as exposure conditions become challenging. High ISO, underexposure, and long exposures can all affect the appearance of noise.
The camera’s image processor is the hardware and/or integrated circuitry that interprets sensor data and performs operations such as demosaicing, noise reduction, color rendering, sharpening, and file encoding. Its capabilities and processing choices vary by camera.
An image sensor is the light-sensitive electronic component in a digital camera that converts incoming light into electrical signals. The camera reads and processes those signals to create a digital image.
Image stabilization reduces the effect of camera movement during an exposure. It may be built into the lens, the camera body, or both.
ISO is a standardized rating of the sensitivity of the imaging medium. In digital cameras, the ISO setting corresponds to the sensitivity at which the sensor signal is amplified and processed. Increasing ISO does not increase the amount of light reaching the sensor; it allows a given exposure to produce a brighter recorded image, often with increased visible noise or reduced image quality.
JPEG is a compressed image format widely used by cameras, phones, websites, and editing applications. Camera JPEGs are generally processed in-camera from the sensor data and are smaller than raw files.
Pentax’s SLR lens mount family, used across many film and digital SLR bodies, with compatibility depending on lens and body generation.
.KDC is Kodak RAW image format used by certain Kodak digital cameras. Camera support and software compatibility vary by model and version.
Kelvin is a temperature scale used to describe the color of light. Camera white-balance systems can use a Kelvin value to deliberately make an image warmer or cooler.
A mirrorless lens-mount standard used by Leica, Panasonic, and Sigma. The shared system includes full-frame and APS-C cameras and compatible lenses. It is distinct from Leica M mount.
Leica’s rangefinder lens mount, used by M-series cameras and compatible lenses. Many M lenses are manual focus.
A lens is an optical assembly that gathers and directs light to form an image on film or a digital sensor. Lenses differ in focal length, maximum aperture, focusing behavior, and optical design.
The aperture is the effective opening inside a lens that controls how much light reaches the sensor. It is determined by the diameter of that opening relative to the lens's focal length. The f-number is expressed as f-number = focal length ÷ entrance pupil diameter . A lower f-number such as f/1.4 means a larger opening; a higher f-number such as f/8 means a smaller opening. The physical opening is formed by the lens's diaphragm blades.
Lens flare is unwanted or intentionally used light produced when strong light enters a lens and reflects or scatters within the optical system. It can create veiling glare, ghosts, or streaks.
A LUT (lookup table) maps input color or tonal values to output values. In photography and video, LUTs can be used for technical transformations or creative looks; the result depends on the LUT and the color space and workflow it expects.
Macro photography is close-up imaging that records a subject at high magnification, often revealing fine detail.
An exposure mode in which the photographer sets both aperture and shutter speed. The camera may still provide a meter reading and allow automatic ISO if enabled; controls depend on the camera.
Nikon’s multi-zone exposure-metering approach. It evaluates multiple regions of the frame to estimate an appropriate exposure, using camera-specific scene analysis.
Matrix or Evaluative Metering is a multi-zone exposure-metering method that divides the frame into numerous areas and analyzes their brightness, color, and sometimes focus-point or subject information. Nikon commonly calls this Matrix metering , while Canon calls it Evaluative metering . It is designed as a general-purpose metering mode.
A shutter that uses physical curtains or blades to control when light reaches the sensor. In a typical focal-plane shutter, one curtain opens and another closes to create the exposure. Mechanical shutters can support flash synchronization and may reduce some readout-related distortion, but they have moving parts and a finite operating life.
Medium Format refers to camera systems using an imaging area larger than the traditional 35mm/full-frame format. Digital medium-format sensors vary in size, but are generally larger than 36 × 24 mm. The larger imaging area can provide different depth-of-field characteristics, field-of-view relationships, and image-quality tradeoffs.
A megapixel is one million pixels. A camera's megapixel count is a measure of the number of image pixels it records, not a complete measure of image quality.
Metering is the camera’s measurement and interpretation of scene brightness used to guide exposure settings.
Micro Four Thirds is a mirrorless camera system built around a sensor approximately 17.3 × 13 mm in size and a dedicated lens mount. It is derived from the Four Thirds format and was designed specifically without the mirror box used by Four Thirds DSLRs.
The mirrorless lens mount shared by the Micro Four Thirds system, including compatible cameras and lenses from OM Digital Solutions and Panasonic. The system uses a sensor format smaller than APS-C.
Microlenses are tiny optical elements positioned over sensor photosites to direct more incoming light toward the light-sensitive area. Their design can improve light-collection efficiency; implementations vary across sensors.
Mirror-Box is the space and mechanism inside a single-lens reflex camera that houses the movable mirror between the lens and the focusing/viewing system. The mirror redirects light to the optical viewfinder and swings out of the way when the photograph is taken.
A mirrorless camera does not use the reflex mirror and optical viewfinder arrangement found in a traditional DSLR. Its electronic viewfinder or rear screen displays an electronic representation of the scene.
Monochrome photography represents an image using one hue or a range of tones rather than full color. Black and white is the most familiar form, using shades from black through gray to white.
MRW is Minolta’s RAW image format used by some Minolta digital cameras.
NEF (Nikon Electronic Format) is Nikon’s proprietary RAW image format used by many Nikon digital cameras. It stores sensor data and metadata for later rendering and editing.
A neutral-density (ND) filter reduces the amount of light entering the lens without intentionally changing its color. It can permit longer shutter speeds or wider apertures in bright conditions.
A neutral-density filter reduces the light entering the camera, allowing longer exposures or wider apertures in bright conditions.
Nikon’s CX-format mirrorless lens mount used by the discontinued Nikon 1 camera system.
NRW is a Nikon RAW format used by certain Nikon compact digital cameras.
Optical stabilization uses moving optical elements within a lens to compensate for some camera movement during handheld shooting.
ORF (Olympus RAW Format) is the RAW image format used by many Olympus and OM System cameras.
PDAF stands for phase-detection autofocus . PDAF compares light arriving from different portions of the lens aperture to determine whether the image is front- or back-focused and, importantly, which direction and approximately how far the lens needs to move. Modern mirrorless cameras can perform phase detection using specialized pixels or areas of the imaging sensor.
PEF (Pentax Electronic File) is Pentax’s proprietary RAW format used by many Pentax digital cameras.
Pentax’s medium-format lens mount used by 645-series film and digital cameras.
Pentax’s mount for its 6×7 medium-format SLR system.
Pentax’s small-sensor mirrorless mount used by the Q-series cameras.
Perspective describes the apparent spatial relationship between objects in an image. Camera position is the primary factor controlling perspective; changing focal length while keeping the camera position fixed mainly changes framing.
A photosite is a light-sensitive location on an image sensor that collects photons and converts them into an electrical signal. Most conventional color sensors use a color-filter array, so a photosite typically measures one color component rather than a complete RGB pixel.
A pixel is a picture element: one sample in a digital image’s grid. A pixel in a finished image represents a color value, while a sensor’s photosites collect light that is later processed into image pixels.
PNG (Portable Network Graphics) is a lossless raster image format that supports transparency. It is common for graphics, screenshots, and web images, but is not a typical in-camera photo capture format.
A polarizing filter selectively reduces certain polarized reflections and can deepen the appearance of blue skies or reduce glare from some non-metallic surfaces. Its effect depends on the direction of the light and the camera's position.
A prime lens has a fixed focal length rather than a zoom range. The photographer changes framing by moving or changing lenses.
An automatic exposure mode in which the camera selects both aperture and shutter speed. Depending on the camera, the photographer may be able to adjust the combination using Program Shift.
A feature available in Program exposure mode on many cameras. It lets the photographer change the camera’s selected aperture-and-shutter-speed combination while retaining the same metered exposure, within the camera’s limits.
A quick-release plate is a removable mounting plate that attaches a camera to a compatible tripod head or support system, allowing the camera to be attached and removed quickly.
RAF is Fujifilm’s RAW image format. It stores sensor data and metadata, including information relevant to Fujifilm’s color and image-processing options.
A RAW file preserves minimally processed sensor data and metadata for later interpretation in an image editor. RAW is not a single universal file format; different manufacturers use different raw formats.
A reflector redirects existing light into a scene, often to soften shadows or brighten a subject’s darker side.
Canon’s mirrorless lens mount for its EOS R system. RF lenses are designed for the mount’s short flange distance and electronic communication.
Canon’s RF-system lens designation for lenses designed to cover APS-C EOS R cameras. They use the RF mount but provide a smaller image circle than full-frame RF lenses.
Rolling shutter records different portions of a sensor at slightly different times. Fast motion or rapid camera movement can therefore produce skew, bending, or other geometric distortions.
RW2 is a Panasonic RAW image format used by many Lumix cameras. It contains sensor data and metadata intended for later interpretation in compatible software.
RWL is Leica’s RAW image format used by some Leica digital cameras.
Sensor size refers to the physical dimensions of a camera's imaging sensor. Common formats include full frame, APS-C, Micro Four Thirds, and medium format. Sensor size influences field of view, depth-of-field behavior, and other aspects of camera design.
Shutter speed is the length of time the camera's imaging sensor is exposed to light. Faster shutter speeds can freeze motion; slower shutter speeds allow more motion blur and can create intentional effects such as blurred water.
An exposure mode in which the photographer selects shutter speed and the camera chooses an aperture for its metered exposure. Often labeled S or Tv; Canon calls it Tv (Time value).
Spot Metering measures reflected light from a very small portion of the frame, allowing the photographer to base exposure on a specific tone or subject. It is especially useful when the scene contains strong contrast, such as a backlit subject or a performer under a spotlight.
sRGB is a standard RGB color space widely used for web images, consumer displays, and general-purpose sharing. It has a relatively modest gamut compared with some other RGB spaces, and is often a practical choice when broad compatibility is important.
SRW is Samsung’s RAW image format used by certain Samsung NX cameras.
Stacked Sensor is an image sensor architecture in which the photosensitive layer is manufactured separately from additional circuitry and then combined into a stacked structure. The design can provide faster readout and processing paths, helping cameras achieve high burst rates, reduced rolling-shutter effects, and advanced video features.
A telephoto lens provides a relatively narrow angle of view and high magnification, making it useful for distant subjects such as wildlife, sports, and compressed-looking landscape compositions.
TIF and TIFF refer to Tagged Image File Format, a raster image format that can store high-quality images with different compression options, including lossless compression. Photographers commonly use TIFF for edited files, printing, and workflows where preserving image data is more important than small file size.
A tripod is a three-legged camera support designed to hold a camera steady. It is useful for long exposures, precise compositions, macro work, panoramas, video, and situations where consistent framing matters.
An ultraviolet (UV) filter is an optical filter that blocks some ultraviolet wavelengths. Modern digital cameras are already designed with substantial UV filtering, so UV filters are often used primarily for lens protection or specific optical purposes.
Vignetting is a reduction in brightness toward the edges or corners of an image. It can be caused by lens design, aperture, filters, or physical obstructions and can also be added creatively during editing.
White balance adjusts how a camera interprets the color of illumination so that neutral objects can appear neutral. Common settings include daylight, shade, tungsten, fluorescent, auto, and custom white balance.
A wide-angle lens has a relatively short focal length and broad angle of view. It is useful for interiors, architecture, landscapes, environmental portraits, and scenes where the photographer needs to include a large area.
Fujifilm’s mirrorless lens mount for its X-series cameras, which use APS-C sensors.
X-sync is the shutter speed at which a camera can synchronize a conventional flash with the shutter's full opening. Faster flash synchronization may require specialized high-speed sync technology.
X3F is Sigma’s RAW image format used by cameras with Foveon sensors.
A yellow filter passes yellow wavelengths while reducing some blue light. It is especially associated with black-and-white film photography, where filters can alter the relative brightness of different colors in the final monochrome image.
Nikon’s mirrorless lens mount used by its Z-series cameras, including full-frame and APS-C models.
A zoom lens has a variable focal length. Instead of physically moving closer or farther from a subject, the photographer can change the lens's angle of view by zooming between its focal-length settings.