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The (Ever-Growing) Glossary of Photographic Terms


In every art practice, there is a language built around its theory and mechanism. This ever-expanding glossary outlines some key terms used in photography.

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Ambient light

Also known as available light, ambient light is any light that isn't deliberately set up by the photographer. This includes both natural and artificial lighting.



The opening of a lens diaphragm through which light passes. Aperture dictates the brightness/darkness and overall depth of field (DoF) in an image. A larger aperture opening permits more light but renders less depth of field (less in focus). A smaller aperture reduces the light reaching the sensor but allows for more depth of field (more in focus).

An aperture with a smaller opening is signalled by a larger f-number. An aperture with a larger opening is designated a smaller f-number. So an aperture of f/2.8 is physically larger than the opening in an aperture of f/16.


Aperture Priority

A mode on some cameras that allows a photographer to set a specific aperture value (see f-number) while the camera automatically selects a shutter speed to make an appropriate exposure. Aperture priority is frequently abbreviated to A or Av.


Aspect ratio

The aspect ratio of an image defines the ratio of its width to its height. expressed with two numbers separated by a colon. To calculate the aspect ratio, divide the original height by the original width and then multiply this number by the new width to get the new height. There are several calculators like Omni Calculator online that make the calculating process a little easier. Common aspect ratios in photography include 4:3, 3:2, and more recently, 16:9.


Auto (Automatic) mode

Auto mode or Automatic mode is an exposure setting that allows the camera to automatically set the shutter speed, aperture, and ISO for each shot.


Autofocus Modes

Camera focus modes or autofocus modes are different modes that allow the internal lens motors and software within a lens to focus an image. This is in contrast to manual focus modes, where the user must manually adjust the focus of the lens by using the focus ring on the outside of the lens.

There are several autofocus modes to select, each setting suited to a specific scenario. Setting Single Autofocus mode (AF Single), also known as AF-S or ONE-SHOT AF will make the camera lock focus on a single static subject. If the subject moves, this mode will not adjust focus to compensate. This mode is best used for static subjects such as architecture, still life and portraits.

Continuous Autofocus Mode (AF Continuous), also known as AF-C or AI Servo is best suited to photographing moving subjects. Once focus is established, the camera will track the subject as they move within the frame, maintaining focus as well as possible. AF continuous mode is not as efficient as Single AF mode for static subjects. In addition, this mode also requires more processing power and lens adjustments, so it will drain a battery more quickly. Continuous Autofocus is suited to subjects like sports, airborne aviation and wildlife photography.

Automatic Autofocus Mode (AF-C Mode, AI Servo AF, AF-A) is designed for scenarios where a user isn't sure whether to use Continuous Autofocus or Single Autofocus. In this mode, Automatic AF detects subject motion, switching to AF continuous to track them, and switching back to AF Single when a subject is still. This mode is best used for unpredictable subjects and scenarios.




Banding occurs when there is a visible change from one colour to another. Instead of a smooth gradient, banding appears jagged and is usually an unwanted manifestation. Baning occurs most frequently in photographs of the sky and is caused by either a monitor's inadequate bit depth or the compression or bit depth of the digital image itself. To reduce colour banding, try to avoid photographing scenarios with low-contrast or subtle gradients. In addition, work with image formats such as RAW in-camera, and use formats like TIFF or PSD when editing to support a greater bit depth. Trying to minimise colour correction in post-processing, using dithering (adding noise to an image) and avoiding compression of the final image as much as possible can also help reduce banding.



Bit depth is the number of colours that can be displayed in a digital image. The higher the bit depth, the more colours are available in the image. Higher bit depth files create larger file sizes. JPEG files have always worked in an 8-bit depth format, meaning the file records less colour data than RAW files which support bit depths from 12 to 16 bits. The higher the bit depth, the more data a photographer has available to work with without reducing image quality overall.


Blue Hour

Blue Hour occurs during twilight (in the morning or evening) when the Sun has completely disappeared about 4 to 6 degrees below the horizon. At this time, the remaining sunlight takes on a predominantly blue hue. This time of day is particularly favoured by artists and photographers who seek out the tranquil quality of the light. Blue hour is an aesthetically atmospheric period and can be favourable for shooting portraiture as well as architectural and landscape subjects.



Bokeh is a Japanese word that translates to haze or blur. Bokeh is defined as the way a lens renders unfocused points of light. Depending on inherent aberrations and the shape of the lens diaphragm, the out-of-focus quality renders differently. Photographers often employ a shallow depth of field to create images with prominent out-of-focus regions, coaxing out the bokeh effect.

bokeh on a rainy night colourful night photography iris28



The buffer in a camera is the memory used to store image data before or while it is written on the memory card. The size of the buffer determines how many images can be taken in one sequence before the camera runs out of room and pauses to allow the camera to catch up. For example, when shooting in High-speed Continuous mode, it's possible to fill the buffer with image data faster than the camera can write them to the card. When this occurs, the camera will stop making photographs until the buffer empties again.


Bulb mode

Often used in star-trail photography, Bulb mode is a setting on a camera that holds the shutter open for as long as a photographer holds the shutter-release button down. Bulb also works with the use of a shutter release cable/remote.

star trail photography glossary of photographic terms iris28

Burst Mode(Continuous Shooting Mode)

Burst mode (also known as continuous shooting mode) is a shooting mode in cameras where several photos are captured in quick succession when the shutter button is pressed or held down. Mainly used when a subject is in continuous motion within a frame, a photographer can make a sequence of images and then select the best image later, increasing the chance of a visually pleasing shot. The speed and duration of a burst is mainly based on the processing power of the camera, the buffer and the memory card equipped.



Camera shake

Camera shake is caused by the physical movements made by a photographer or camera. During long exposures, camera shake can manifest in blurry photographs. Using a tripod or a monopod, setting a faster shutter speed and utilizing a remote shutter trigger will help reduce or stop the effects of camera shake.

Another method used by photographers to steady a camera is to stop the shutter speed from dipping below the focal length of the lens. In addition, holding the camera with both hands, with elbows tucked close to the body can reduce camera shake. Some photographers even suggest taking a deep breath and holding it while making an exposure in this position.

Camera shake can also be caused by the internal mechanisms of the camera moving during an exposure. Also known as mirror slap, this type of camera shake can be reduced by using Live View Mode. Some cameras also have Mirror Lock-up mode which allows a photographer to press the shutter button once to open the mirror mechanism, and then a second time to shoot the exposure. Mirror slap is not an issue in mirrorless cameras, because they function without the use of a mirror.


Camera Shake Reduction

Camera Shake Reduction is an algorithm used in Photoshop that is capable of detecting the path of a camera's movement through a shake, compressing the path into a less-blurred image.


Car trails

Car trail photography is a type of light trail photography made during long exposures in darker environments, with an ND filter or in the evening/night/early morning. In car trail photography, the photographer sets the camera for a long exposure near a busy roadway. The resulting photographs exhibit the bright streaks of light caused by the head and tail lights of travelling cars.

a long exposure on a highway at night generates glowing car trails in black and white photography iris28



A chemigram is an intersection of painting and photographic chemistry. The experimental technique involves applying a substance or resist to a sheet of photographic paper and subsequently immersing the paper in developer and/or fixer. The resist repels and interacts with the darkroom chemistry, causing unique and abstract manifestations. Not to be confused with the Chemogram.



Chemograms are made by partially processing an enlarged image on photographic paper in the darkroom. When sufficiently developed, the paper is then exposed to light and selectively painted over with developer, fixer and other chemicals. This differs from the chemigram process in that chemigrams are made under consistently well-lit conditions with a substance applied directly to a sheet of photographic paper before development.


Colour Space

The specific organization of colours through mathematical modelling. While different creative pursuits use colour differently, photographers rely mostly on transmitted light (made up of red, green and blue) because it is used to create images in hard copy and on digital screens. The colour spaces most commonly used in photography are sRGB, Adobe RGB and ProPhoto RGB.



The ratio of different tones in an image. A key element in photographic composition, contrast measures the degree of difference between tones in a photograph. Tonal contrast refers to the difference in brightness and is especially relevant in black-and-white photography. If a photograph has a wide range of times from pure white to pure black, it is described as a medium contrast image. If there is a range of middle tones and lacks pure whites and blacks, the photo is a low-contrast image. If the image has both very dark and very bright tones, it has high tonal contrast.


Contrast Detection(AutoFocus)

Contrast detection is one of two autofocus systems, the other being phase detection. Contrast detection involves the autofocus system directly measuring data from the camera sensor to focus and is therefore more precise. However, it is slower to lock focus, making it better for slow or static subject matter. Contrast detection occurs when autofocus via the rear LCD screen is used, while phase detection occurs when a user autofocuses via the viewfinder.



Depth of field (DoF)

Depth of field refers to the distance between the nearest and the furthest points in an image that are in focus. DoF describes the level of blurriness or sharpness around a subject. For example, a shallow depth of field is a small area of focus.


Digital Single Lens Reflex (DSLR)

A digital single-lens reflex camera (DSLR) is a digital camera that uses a mirror and prism system that allows a user to see a composition live through the viewfinder before the image is made. When the shutter button is pressed on a DSLR camera, the mirror component flips up, permitting light to pass through to the sensor to record an exposure. This is in contrast to a mirrorless camera system, which completely removes the complex network of mirrors found in the SLR or DSLR camera.


Dragging the shutter (shutter drag)

Shutter drag involves using a slower shutter speed in conjunction with a flash. In an environment with little light, the flash exposes the immediate subject, while the shutter continues dragging more detail out of ambient light.


Dynamic Range

Dynamic Range is a term that describes the ratio between the brightest and darkest parts of an image. Dynamic range is measured from the blackest blacks to the whitest whites in a photographic image and is described in stops (where one stop brighter equals twice as much light).

The dynamic range of a camera sensor is the ratio between the max signal that can be captured by the sensor and the noise floor of the sensor. The noise floor is the point when an image would be indistinguishable from an image taken in complete darkness. For example, at the base iso, the Canon R5 has a dynamic range of 14.6 stops. The greater the stops in dynamic range, the better in terms of detail retention in highlights and shadows.

Dynamic range is increased with the size of the sensor. For this reason, many landscape and architectural photographers often favour full-frame cameras for maximum detail.




Exposure describes the amount of light that reaches the camera sensor or film. Exposure is a term that is also used to describe the action of taking a photograph, eg. the photographer made an exposure.

Exposure describes the amount of light that reaches the camera sensor or film. However, exposure is a term that is also used to describe the action of taking a photograph, eg. the photographer made an exposure.


Exposure Compensation

The exposure compensation function on a camera is designed to override exposure settings selected by the camera light meter. camera meters evaluate light reflected off subjects and are standardized on middle grey. When a camera lens is pointed at a very dark subject, the meter will work to brighten it by boosting the exposure. At the opposite end of the spectrum, a very bright subject will cause the meter to darken the exposure. This system usually works fine, but in more dynamic conditions the light meter may create underexposed or overexposed images. To rectify this, exposure compensation allows a photographer to manually control the brightness/darkness of an image in-camera.


Exposure Modes

Exposure modes (also known as shooting modes) define the way a camera operates when making an exposure. In Auto mode, the camera evaluates a scene and assigns shutter speed, aperture and ISO values. In Shutter priority or TV, the photographer can adjust the shutter speed, while the ISO and aperture inputs are selected by the camera. In Aperture Priority mode the user adjusts the aperture while the shutter and ISO are dictated by the camera itself.

Other settings often available on cameras are tailored scene modes designed for different occasions. Automatic modes like Sports mode increase ISO values and use a faster shutter speed to capture action shots, while Portrait Mode widens the aperture to exaggerate bokeh in the subject background.



File Format

When a photo is taken with a digital camera, the camera records image data in a specific way. A file format defines the way the image data is recorded and recovered so that images can be edited, viewed and stored for various requirements, with different advantages and drawbacks.

JPEG images are compressed the moment they are captured, so some detail is lost, rendering a lower-quality image. However, due to their small size, many more images can be stored on a memory card than with TIFF and RAW files. They are also faster to transfer from the camera to the computer or phone.

TIFF files are usually uncompressed, so they’re high quality and offer the opportunity for extensive post-processing. However, because they are uncompressed, TIFF files are quite large quickly filling up space on a memory card and/or your computer.

RAW files store all of the information originally captured by the camera. This allows major adjustments to white balance, exposure, contrast, saturation, and sharpness in post-processing. Like TIFF file formats, RAW files take up a significant amount of space and they can only be viewed with software like Photoshop, Camera Raw, Lightroom or Capture One.



A flash is a device used in photography to produce a brief burst of light to illuminate a dark scene and freeze moving subjects. Battery-operated speedlights are attached to a camera, providing the ability to comfortably handhold the camera while achieving a more balanced exposure. Battery or mains-powered monolights are more powerful than speedlights but are less portable. A pack-and-head system is the bulkiest flash option, but they are the most powerful and offer the fastest recycle speeds.

A studio flash photography setup iris28


Flash Sync Speed

Flash synchronization or flash sync is the synchronization of a flash with the opening of the shutter during exposure. Flash sync speed represents the fastest shutter speed a camera and flash can synchronize. Usually, the sync speed is from 1/200s to 1/250s. If a flash sync speed is 1/250s and a photographer shoots at a faster shutter speed while using a flash, the shutter closes before the flash can be fully captured by the sensor, resulting in black bands in the image.


Focal length

Focal length measures the distance between the optical centre of the lens and the camera’s sensor (or film plane) in millimetres with the camera focused to infinity. Lenses are named by their focal length, and you can read this information on the exterior of the lens barrel.



Focus is the region in an image with the potential to be as sharp as possible. Focus can be manipulated automatically or manually. Automatic focus or Autofocus occurs when the camera system assesses a scene and adjusts the elements within a lens to get the sharpest point possible. Manual focus involves turning a ring or mechanism on the lens to achieve satisfactory focus.


Freeze (frozen motion)

Frozen motion is achieved when the shutter speed of the camera is high enough to catch a sharp rendering of motion occurring in a scene. The result is a subject that appears to be frozen in time with little-to-no motion blur.


F-Stop (f-number)

An f-stop or f-number is a camera setting that indicates the aperture of a lens. While f-stops aren't uniform across all photography equipment, there are common values that make up the standard aperture scale:

a diagram of popular aperture sizes in photography iris28

On a DSLR, these values can be seen in-camera through the viewfinder and on the LCD screens. The f-stop value can be altered directly in Manual mode and Aperture Priority mode. The larger the value of the f-stop number’s denominator, the less light will enter the lens and the more depth of field is generated.



Golden Hour

The last hour before sunset and the first hour after sunrise. Photographers refer to this period as the golden hour because the ambient lighting provides a window of opportunity for visually dramatic photography.



HDR Photography

High Dynamic Range or HDR photography is a technique that is used when a subject exceeds a camera's dynamic range. When this occurs, shadows become too dark and whites are washed out. To combat this, photographers take photographs of the same scene at different exposure levels and combine them in post-processing.



A histogram shows the distribution of lightness and darkness of a photograph on a graph. The scale along the bottom of the histogram goes from left to right, from 0% brightness to 100% brightness. The taller the peak in an area, the more pixels of that brightness are present in an image.

Histograms can indicate if there is an issue with exposure. A spike on the right, that touches the edge of the graph indicates that highlights are overexposed to the point of lacking no detail. If there is a spike on the left edge, indicates that part of an image is completely black. In this case, adjusting exposure to make the image brighter can be ideal. However, having part of an image completely black can still be visually acceptable.


HSS (High-Speed Sync)

HSS synchronizes flash pulses to the movement of a camera shutter, allowing for shutter speeds up to 1/8000 second. Without a HSS system, photographers can only sync with flash up to a shutter speed of 1/250s.



ICM (Intentional Camera Movement)

Intentional Camera Movement (ICM) is a photographic technique that involves purposely moving the camera over a long exposure. The results are dynamic, abstract renderings of an environment and lighting conditions. More on ICM photography here.

ICM intentional camera movement example by Megan Kennedy on iris28



ISO first referred to the sensitivity of film to light. The higher the ISO, the greater the sensitivity of the film. For digital photography, ISO refers to the signal gain of the camera's sensor, producing more brightness when set to a higher ISO value. However, the higher the ISO, the greater the digital noise in a photograph.




See File Format



Light Painting

Light painting is a photographic technique employed to illuminate a subject or space or to draw by moving an object emitting light during a long exposure. Man Ray, Barbara Morgan and Pablo Picasso all used various light painting techniques to create painterly photographic renderings of light.

Light painting photography glossary of terms iris28

Light painting requires a slow shutter speed, usually at least one second in duration. During an exposure, a subject moves a light source, creating paths of light that are traced out in the exposure.



Macro Photography

Macro photography is a field of photography that produces photographs of small subjects at larger-than-life sizes. Macro photographers often use specialised equipment to capture subjects at a level of detail that is usually missed by the naked eye.


Manual Mode

Manual mode is a mode on the camera that allows for full manual control of both Aperture and Shutter Speed. In this mode, the aperture and the shutter can be set to any value, granting a photographer greater command over an exposure in any scenario.