A-Z of cameras

A

A-mount (Sony) The lens mount used by Sony’s Alpha SLT cameras. Because these cameras have a mirror in the body, even though it’s a non-moving one, the rear of the lens is further from the sensor, so Alpha mount lenses are physically different to Sony’s E-mount lens range. You can use Alpha lenses on an E-mount camera with a lens adaptor, but not the other way round.
Accessory shoe This is the technically more accurate name for a camera’s ‘hotshoe’. These days, they’re used for more than just attaching a flashgun, and may be used for external microphones, video lights or electronic viewfinders.
ACROS (Fujifilm) Black and white film simulation mode added to newer Fujifilm cameras. It’s designed to give richer, more intense tonal rendition than the regular monochrome film simulation.
Action camera A small, simple and largely automated video camera (you can also shoot stills) designed to attach to a helmet, handlebars, surfboard or any other kind of object and provide dramatic first-person video of adventure sports and other activities. Almost all use fixed focal length super-wideangle lenses and shoot full HD video – some can shoot 4K.
Active D-Lighting (Nikon) An exposure mode on some Nikon digital cameras which balances up the exposure in high-contrast scenes. The camera reduces the exposure to make sure it captures bright highlight detail and then processes the image to brighten up dark shadows. It can be applied in different strength settings.
Adobe RGB This is a professional colour space offered by more advanced cameras and it captures a slightly wider range of colours than the usual sRGB colour space used by most consumer devices. It can be useful if pictures are destined for commercial print production, but it does introduce complications with colour profiles and monitor calibration.
AE-L/AF-L button AE/AF lock is used to fix exposure settings and focus point before taking a photo, offering flexibility in camera control.
AF Assist In dim lighting the camera’s autofocus system may struggle to lock on to your subject, but on some cameras a lamp on the front of the camera will light up in low light and shines a bright, tightly focused beam of light at your subject to help the autofocus system lock on. Not all cameras have or need this kind of focus assistance.
AF coverage Digital cameras use an array of AF points (focus points) to cover different areas of the frame, but they don’t necessarily cover all of it. The AF coverage is the percentage of the frame width and height that contains focus points. Wider coverage is a selling point.
AF fine tune Most cameras use the main sensor for focusing, but digital SLRs have a different system. They use a separate phase detection autofocus sensor which must be precisely aligned with the main sensor for the focus to be accurate. Sometimes this and different lens designs can lead to small misalignments and slight focus errors, so more advanced DSLRs have an autofocus fine tune feature to correct any discrepancies.
AF mode
AF points An area on the screen where the camera can check for sharp focus. Typically, the more focus points the better because this gives you more choice about where to focus and usually indicates a faster and more sophisticated focus system.
Alpha (Sony) ‘Alpha’ is generic name still used by Sony for all its interchangeable lenses, but it also refers to the older Alpha range of SLT cameras. This can be confusing. Sony has made cameras in two types – SLT (single lens translucent) and mirrorless models. Both are Alphas, but the Alpha A9 (mirrorless) and Alpha A99 II (SLT) are entirely different cameras with different lens mounts and lens ranges. Sony’s SLTs use Alpha A-mount lenses, while the mirrorless models use E-mount lenses.
Aperture priority (A) mode This is an exposure mode on more advanced cameras where you choose the lens aperture yourself and the camera then sets a shutter speed that gives you the correct exposure. This gives you creative control over depth of field, for example, without losing the convenience of automatic exposure.
APS-C sensor This is the most common sensor size in cameras designed for enthusiasts and experts and it’s found in consumer DSLRs, mirrorless compact system cameras and some high-end compacts. APS-C sensors are around half the size of a full-frame sensor or the 35mm negative, and measure approximately 24 x 16mm. They have a crop factor of 1.5x, which means that you have to multiply the lens’s focal length by 1.5x to get its effective focal length in 35mm/full frame camera terms.
APS-H sensor This is a relatively uncommon sensor size mid-way between APS-C and full frame. Canon used it for its EOS-1D high-speed pro sports/press photography DSLRs before these were merged with the introduction of the full frame EOS-1D X. Canon has since announced the development of a 250MP APS-H format sensor, though this has not yet been used in any commercial product.
Area AF This is a focus mode where the camera automatically selects a focus point, usually choosing the object closest to the camera. It's an effective 'standby' autofocus mode.
Aspect ratio This the picture's proportions as width versus height. DSLR sensors have a 3:2 ratio, so that photographs are 3 units wide to 2 units high. Most compact camera sensors have a slightly squarer 4:3 aspect ratio. It doesn't matter what the units are – the ratio stays the same, so a photo could measure 3 inches by 2 inches or 6 meters by 4 meters and still have the same 3:2 aspect ratio. You can shoot in different aspect ratios by cropping the sensor area. HD video is shot in a wider 16:9 ratio.
As shot (white balance) When you shoot RAW files you will be able to change the white balance setting later, but the camera will still store shooting settings you chose in the RAW file. When you open the RAW file in your software, it will read this embedded data and display it as ‘As Shot’ in the white balance settings. You can adjust the settings or apply a new white balance preset, and the ‘As Shot’ setting embedded in the file will still be available if you need to return to it later.
Astia (Fujifilm) Astia is a transparency film made by Fujifilm, and now incorporated into its digital cameras' film simulation modes. The digital version has similar saturation to Velvia but softer contrast and less obvious color shifts.
Auto exposure Where the camera measures the light and sets the shutter speed and/or lens aperture on its own.
Autofocus Practically all cameras have automatic focusing systems where they can check the focus at different points around the frame and then adjust the lens’s focus so that that point in the scene is precisely in focus. You can let the camera choose the autofocus (AF) point automatically or select it yourself (manual AF point selection). The autofocus system will either operate once only before you take the shot (single-shot AF mode) or constantly if you’re using the camera’s continuous shooting (burst) mode (continuous AF mode).
Auto ISO On simpler cameras the Auto ISO option simply increases the ISO setting in poor light to keep shutter speeds high enough to avoid camera shake. On more advanced cameras you can program in both the maximum ISO you want to use and the minimum shutter speed, which makes Auto ISO much more useful.
Auto mode A simple shooting mode offered on almost all cameras. In this mode, the camera automatically takes care of all the settings, from exposure to focusing and (usually) flash.
Auto white balance This is where the camera measures the color of the light in a scene and attempts to correct it so that the color is neutral – the color is balances so that white will appear as white.
Averaged metering This is a very simple type of exposure reading where the camera’s light meter just measures the total amount of light in the whole scene. It often leads to underexposure because bright areas in the scene have a disproportionate effect. Today’s digital cameras offer a range of more sophisticated exposure metering patterns and only a few still over averaged metering amongst these – some photographers still like it because although it’s a crude way of measuring the light, it’s quite predictable and easy to interpret.

B

Back button focus Using a button on the back of the camera to activate autofocus, not the shutter button.
Back illuminated sensor A newer type of sensor where the circuitry has been moved to the back so that the light receptors on the front are unobstructed. This gives a modest but useful improvement in light-gathering power, digital noise and overall image quality, but it’s not the dramatic technical leap that manufacturers often suggest.
Batteries Most cameras use dedicated rechargeable lithium-ion cells, but some accessories like external flashguns, battery grips and hotshoe mounted LEd panels use regular AA cells instead.
Battery charger A battery charger is a separate device plugged into a mains wall socket. You remove the battery from the device and plug it into the charger for recharging.
Battery grip This is an accessory that attaches to the bottom of some DSLRs and mirrorless cameras. It provides a longer battery life for long periods of shooting and it’s popular with sports and action photographers taking lots of shots in continuous shooting mode. Battery grips often have duplicate controls for shooting with the camera in a vertical position, which also makes them ideal for busy portrait and fashion photographers.
Battery life This is usually quoted as the number of shots you can expect to be able to take before the camera’s battery runs out. Compact cameras may only be able to take a couple of hundred pictures, while a DSLR might be able to take a thousand. Battery life is normally quoted using the CIPA standard so that battery life can be compared in standardised conditions.
Bayer sensor Most camera sensors use a single layer of photosites (pixels). These are only sensitive to light, not colour, so a mosaic of red, green and blue filters (the 'bayer pattern') is placed on top of the sensor's photosites so that individually they capture red, green or blue light. When the camera processes the sensor data to produce an image, it ‘demosaics’ the red, green and blue data, using colour information from surrounding photosites to ‘interpolate’ full colour data for each pixel.
Bayonet mount A twist-lock mechanism used almost universally for mounting lenses on camera bodies. You line up two dots, one on the lens barrel and one on the camera body and insert the lens, then twist the lens in the mount until it locks into place. The lens is released again by pressing a button on the camera body to release a catch, then twisting and removing it.
Bracketing Taking the same shot at a series of different exposures with the intention of choosing the best one later or merging them together to create an HDR image. Most cameras offer an auto exposure bracketing option. You choose the bracketing interval (the difference between the exposures, typically 1EV) and the number of frames (usually 3, sometimes 5 or even 7). Some cameras offer other types of bracketing, e.g. white balance bracketing or even focus bracketing.
Bridge camera This is a compact camera with an extremely long zoom range, sometimes as much as 50x, 60x or more, and designed to act as a ‘bridge’ between regular compact digital cameras and digital SLRs. The lens can’t be swapped, though, and bridge cameras (mostly) have small sensors, which restricts the picture quality.
Brightline frames Framing guides in direct vision viewfinders which show the area that will be captured by the lens – with interchangeable lens cameras there may be frames for different lens focal lengths. The frames are designed to catch the light and appear 'bright'.
Buffer The 'buffer' is short-term internal memory used by the camera to store image data captured by the sensor while it’s waiting to be processed and saved to the memory card. It becomes important in the camera’s continuous shooting mode because the camera can capture photos faster than it can save them, so before long this buffer fills up. The larger the buffer, the longer you can keep shooting.
Burst mode This is another name for ‘continuous shooting’ mode and it’s the term used by cheaper point-and-shoot cameras – though it’s actually the same thing. In this mode, the camera keeps taking pictures all the time you hold down the shutter button, right up until the time you release the button or the camera’s internal memory buffer fills up and it has to stop to process and save the pictures to the memory card.

C

C-AF (continuous autofocus) In continuous AF (autofocus) mode, the camera continually refocuses all the time you have the shutter button half-pressed or fully-pressed. It's used in continuous shooting mode to keep moving subjects in focus as you follow them with the camera. Continuous AF mode may include subject tracking or predictive autofocus capability.
Camera shake This is image blur caused by camera movement during the exposure. The longer the exposure (the slower the shutter speed), the more time there is for camera movement to take place. Any movement is also exaggerated with longer focal length lenses (telephotos). There is a simple way to estimate the risk of camera shake – take the effective focal length of the lens and divide it into 1 to get the minimum ‘safe’ shutter speed. So with a 30mm lens, the minimum safe shutter speed would be 1/30sec. However, today’s image stabilisation systems reduce shake and make slower shutter speeds possible.
Camera types Digital cameras come in a multitude of different types and sizes, and some of the jargon can be quite unhelpful. For example, 'compact' cameras aren't necessarily compact and the real difference is that they have non-removable lenses. DSLRs and CSCs are both examples of interchangeable lens cameras, or ILCs, and these are differentiated by their design, sensor size and intended market. Most novices start off with a compact camera, move up to a DSLR or CSC when they become enthusiasts and then upgrade to a full-frame or medium format camera if they turn professional.
CCD An older type of digital camera sensor still used on a few specialised cameras but now mostly replaced with more efficient CMOS sensors. These produce less heat and noise and are better suited to use in cameras with full time live view and video features.
Center weighted metering This is one of the various light metering patterns offered on most digital cameras. It’s a relatively crude system which averages the light across the whole scene but gives special emphasis to the centre. It’s less reliable for for novices shooting in a wide variety of conditions, but its simple response to scenes actually makes it easier for more experienced photographers to interpret the results.
CFA (color filter array) This is a grid of tiny filters placed over a sensor so that each photosite captures only red, green or blue light. This is the only way a single-layer sensor can be made to capture full color images. The most common arrangement is the Bayer array.
CFast CFast cards resemble Compact Flash cards physically, but they use a different data bus and a different set of pins. They are not physically compatible. They offer faster data transfer rates than regular Compact Flash cards and have been used in some high end video cameras, for example.
CFexpress CFexpress cards are a new format for very high speed data capture. They are physically identical to the XQD cards currently in use in some cameras – many cameras which use XQD cards are expected to get firmware upgrades to get CFexpress compatibility. CFexpress looks set to become a major high speed card format of the future.
Cinema 4K (DCI 4K, C4K) This is a version of 4K video with a slightly wider aspect ratio than 4K UHD and is actually 'true' 4K with a resolution of 4,096 x 2,160 pixels. The aspect ratio is slightly wider than the 16:9 ratio widely used in video, so it's not suitable for all productions. Not all cameras that capture 4K UHD can capture C4K.
CIPA CIPA stands for the Camera and Imaging Products Association, an independent body which reports on the state of the camera industry and sets up standards for measuring different aspects of camera performance, notably battery life. When a camera quotes CIPA after the battery life, you know it’s been measured in standardised conditions and it can be compared directly with the battery life of other cameras that quote the CIPA test in their results.
Class rating (memory cards) SD/SDHC/SDXC memory cards are given a 'class' rating to indicate how well suited they are to video capture, where a minimum sustained write speed is essential. Lower spec cards may have a Class 4 rating, better cards may be Class 6 and you need a Class 10 card or better for capturing 4K video.
CMOS This is the most common type of sensor in today’s digital cameras. One of its main advantages is its lower heat output compared to the CCD sensors used in the past. This makes it particularly suitable for cameras with larger sensors and mirrorless cameras where the sensor is always ‘on’.
Color temperature A traditional technical measurement for the white balance setting that uses temperature values in degrees Kelvin rather than named presets like ‘Direct Sunlight’, ‘Cloudy’ and so on. Colour temperature is used for choosing and controlling the colour of photographic lighting equipment and you can use it an alternative to white balance presets on more advanced cameras.
Commander mode (Nikon) A flash control mode on some Nikon DSLRs and external flashguns (Speedlights) which can fire other Speedlights remotely via infra-red. It’s possible to control quite complex lighting setups in this way, and it’s part of Nikon’s CLS (Creative Lighting System).
Compact camera You might imagine that this refers to smaller, pocket-sized cameras but the definition is a little wider than that and includes any camera with a fixed (non-interchangeable) lens. ‘Compact cameras’ include regular point-and-shoot compact cameras, high-end compacts and bridge cameras.
Compact Flash An older, larger memory card type still used in many professional cameras. It’s around twice the size of the more recent SD card format and thicker too. Compact Flash memory card capacity is measured in the same way in GB (Gigabytes) but speed standards may vary, especially for video use. Professional CF cards offer the same speeds and capacities as pro SD cards.
Compact system camera (CSC) Another name for ‘mirrorless’ cameras and used to distinguish them from digital SLRs. They are ‘system’ cameras in that they take interchangeable lenses and accessories – just like a digital SLR. However, they don’t have a DSLR’s mirror mechanism, and this ‘mirrorless’ design makes them more compact.
Continuous shooting In this mode the camera keeps taking pictures for as long as you hold down the shutter release button. The speed it can take them is the continuous shooting speed, which is quoted in frames per second (fps), and the number the camera can take is determined by the size of the image files, the quality setting (JPEG or RAW) and by the camera’s internal memory buffer capacity.
Contrast AF A relatively simple autofocus system that measures the contrast around the edges of objects and then adjusts the focus to see if the contrast goes up or down. When the contrast is highest the subject is in focus. Contrast AF is accurate because it uses the image being captured by the sensor itself, but because it uses trial and error it’s not as fast as phase detection autofocus, the system used by digital SLRs and an increasing number of mirrorless compact system cameras (CSCs).
Creative Lighting System (CLS) (Nikon) Wireless flash system used by Nikon to control one or more external Speedlights from one place. Speedlights can even be combined in 'groups' for more power or more sophisticated lighting effects.
Crop factor Used to work out the effective focal length of lenses on cameras which don't have full frame sensors. You multiply the actual focal length by the crop factor to get the effective focal length. The crop factor of an APS-C camera is 1.5, so a 50mm lens has an effective focal length of 75mm.
Crop mode Many lenses designed for APS-C format cameras can be used on larger full frame cameras, but because the lens image circle is designed for a smaller sensor the camera will switch to a 'crop mode' that only uses this smaller area on the sensor.
Crop sensor A 'crop' sensor is one that's smaller than a full frame sensor. This means that it captures a smaller area and a narrower angle of view with the same focal length lens. In effect, smaller sensors make lenses look as if they have a 'longer' focal length, and by a specific factor – or 'crop factor'.
Custom white balance This is where you use the camera to take a picture of a neutral tone, such as a 'grey card', and then create a custom white balance preset to 'neutralise' the colour of the light.

D

D-Lighting (Nikon) Exposure adjustment tool offered in some Nikon software for brightening the darkest parts of a picture without altering the rest. It's a less advanced version of the Active D-Lighting system built into Nikon cameras. Regular D-Lighting just brightens the shadows – it's too late to adjust the exposure at the software stage.
Demosaicing Process where the camera (or RAW conversion software) takes the 'mosaic' of red, green and blue pixel data from the sensor and converts it into full-colour information.
Digital stabilization This is where camera movement is counteracted digitally. It's not very effective for stills photography, where it's sometimes called 'electronic stabilization', but it can be very useful in video, where it can smooth out or remove camera movement between frames.
Diopter adjustment A small knob or lever next to the viewfinder which you use to adjust the focus of the eyepiece to match your own vision. The information in the viewfinder should appear sharp without you having to strain to bring it into focus.
Direct vision viewfinder A viewfinder that's separate to the camera's lens and shows a view of the scene 'directly'. These are found on many older cameras and a few current models. The framing is less accurate, but direct vision viewfinders are bright and clear.
DSLR This is an interchangeable lens camera where you see an optical image in the viewfinder showing what the lens sees. They do this using a mirror inside the body that reflects the image seen by the lens up into the viewfinder. When you take a picture, the mirror flips up out of the way so that the image passes through the body to the sensor at the back of the camera. DSLRs work in the same way as SLR (single lens reflex) film cameras, but substitute a digital sensor for the film.
Dual image stabilization A system that uses both in-body image stabilization and optically stabilized lenses to produce an even stronger stabilizing effect.
Dual Pixel CMOS AF (Canon) Canon's Dual Pixel CMOS AF technology enhances autofocus speed and responsiveness in mirrorless cameras and DSLRs, posing a challenge to traditional DSLR advantages.
Dust Off (Nikon) A system offered with Nikon DSLRs for dealing with dust spots on the sensor. You take a reference shot of a white card which highlights any dust spots, and then Nikon image-editing software can use this to target dust spots on your photos and process them out.
DX format (Nikon) This is Nikon’s name for its APS-C format DSLRs. Some Nikon lenses are designed specifically for these smaller format models, and they include ‘DX’ in the lens name to signify that the can’t be used on the full frame models (well, they can, but only in a ‘DX crop’ mode).
Dynamic Area AF (Nikon) A focus mode used on Nikon cameras for use in continuous shooting mode. You follow the subject using a group of autofocus points working in unison to track and maintain focus more intelligently and with a wider margin of error than a single focus point.
Dynamic range This is the brightness range the camera can capture before starting to lose detail in bright areas (like the sky) and dense, dark shadows. Generally, the larger the camera’s sensor, the better its dynamic range. RAW files capture a slightly wider dynamic range than JPEGs.
Dynamic range expansion A feature on some cameras which expands the range of tones the sensor can capture. It works by reducing the exposure to be sure of capturing extended highlight detail, then modifying the tone curve to restore midtone brightness.

E

E-mount (Sony) This is the name of the lens mount used by Sony mirrorless cameras. Regular E-mount lenses fit its APS-C format cameras, like the Sony A6500, while FE lenses fit its full-frame mirrorless cameras, including the A7 series and Sony A9. Sony also makes A-mount lenses for its Alpha SLT cameras, but these are not the same.
Effective focal length The angle of view of a lens changes according to the size of the sensor in the camera. A smaller sensor captures a narrower angle of view and makes it look as if the lens has a longer focal length. So in addition to the actual focal length, the manufacturers will usually quote the 'effective' focal length too.
Effective pixels Camera makers quote two megapixel figures. The bigger, 'gross' figure counts all the photosites on the sensor, but many of those around the edges are used for calibration and other technical purposes, so makers also quote the 'effective' pixels, which are the ones actually used to make the image. This is the important figure.
Effects (in-camera) Many cameras offer a range of special image effects, usually taking over some or all of the camera controls and using in-camera image processing too. Examples include vintage sepia toning, tilt-shift 'miniature' effects, toy camera or cross-processing effects.
Electronic rangefinder A feature which uses the camera’s autofocus mechanism to confirm focus even when you’re using manual focus mode. You turn the focus ring and the AF point lights up when the subject below it comes into focus. It can be useful when it’s hard to judge sharp focus by eye.
Electronic shutter Some cameras now offer electronic shutters which start and stop the exposure digitally rather than with a mechanical shutter. These are silent and can offer very high shutter speeds, though most use a ‘scanning’ process which makes them unsuitable for action photography because while the exposure time for any particular strip of the sensor is very short, the length of time taken to scan the full sensor area creates distortion and 'rolling shutter' effects with fast-moving subjects.
Electronic viewfinder (EVF) Essentially, this is a tiny LCD display seen through a magnifying eyepiece. They’re used on some bridge cameras and high-end compact cameras, and on many mirrorless cameras. They replace the optical viewing system you get with a DSLR.
EV compensation Used to adjust the camera’s automatic exposure setting to make the picture come out lighter or darker. Camera meters aren’t foolproof and sometimes you do need to make adjustments. Doing it this way is quicker than swapping to full manual control.
EXIF data Date, time and shooting information embedded invisibly in digital photos by the camera. It includes the shutter speed, lens aperture, ISO setting and more. EXIF data is useful later on if you want to see how certain pictures were shot or search for photos based on their settings.
Expeed (Nikon) Nikon’s own brand name for the image processors used in its digital cameras. More powerful processors are needed for higher-resolution sensors and faster continuous shooting speeds, and play a part in noise reduction at high ISOs and image quality generally.
Exposure Exposure is the science (and the art) of making sure the sensor gets exactly the right quantity of light to produce a good image. Exposure is adjusted using shutter speed (the length of the exposure), lens aperture (how much light is passed through) and ISO (the sensitivity setting of the camera). Camera's have light meters to estimate the correct exposure setting but it's sometimes necessary to override this with manual adjustments.
Exposure latitude A term used to describe a film's tolerance to overexposure and underexposure and its ability to capture tones in the brightest and darkest parts of a scene, even in high-contrast lighting. The modern-day equivalent with digital sensors is dynamic range, though sensors rarely approach the dynamic range (exposure latitude) of film.
Exposure mode This controls the camera's operation, from fully-automatic (the camera controls everything), semi-automatic (you can choose the shutter speed or lens aperture) to manual (you choose all the settings).
Exposure preview Some cameras can simulate the effect of exposure adjustments on the LCD screen or electronic viewfinder (this is not possible with an optical viewfinder), making the image lighter or darker as you adjust the exposure. It’s not a precise guide to exposure but it can be useful.
Exposure steps/increments Digital cameras offer finer exposure adjustments than whole stops (EV) values. By default, they offer 1/3EV adjustments to the shutter speed, lens aperture and ISO setting – though some cameras offer 1/2EV adjustments as an alternative, in line with older film cameras.
Exposure value (EV) A numerical value given to the amount of light in a scene. For example, bright sunlight might produce an EV of 17. In practice, cameras deal only in shutter speeds and lens apertures and you're only likely to see EV values on handheld light meters.
Eyepiece shutter A tiny blind in the viewfinder eyepiece that stops light entering and upsetting the exposure (normally the eyepiece is covered by your eye). It can be useful for long exposures or other shots where you’ve stepped away from the camera. Some cameras come with a small viewfinder cap fixed to the shoulder strap.

F

F-Log (Fujifilm) Extended dynamic range movie mode introduced by Fujifilm to handle high-contrast lighting, extending dynamic range by 200% or 400%. Other higher-end movie cameras have a similar feature. It produces flat-looking footage but with extended data in the shadow and highlight areas and the idea is that you process the video later on a computer (grading) to achieve the finished look. It's the video maker's equivalent of shooting RAW files.
Face detection Some autofocus systems identify human faces within a scene and then adjust the focus and exposure for that face. It’s popular on compact cameras and is used on some DSLRs and mirrorless cameras too.
Film simulation Image settings on some cameras which attempt to recreate the colours and tonal quality of classic films. Fuji offers Velvia, Provia and Astia film simulations to replicate its films of the same name. You can choose these in-camera if you shoot JPEGs, or apply them later to RAW files.
Firmware Programmable hardware inside the camera (somewhere between hardware and software) that handles the camera's controls, functions and features. Camera makers sometimes release firmware updates to fix bugs or add new features.
Flange distance This is the distance between the mounting plate on a camera that takes interchangeable lenses and the sensor itself. Mirrorless cameras have a shorter flange distance because there's no mirror inside the body, and this makes the cameras slimmer. DSLRs have a longer flange distance because there needs to be space inside the body for the mirror that this design gets its name from. This makes DSLR bodies thicker. This difference in flange distances means that it's sometimes possible to use lens adaptors to fit lenses of a different type, brand or lens mount to a camera. This generally works one way only – you can mount a lens with a longer flange distance (e.g. a DSLR or old film SLR lens) on a camera with a shorter flange distance (e.g. a mirrorless camera) but not the other way round.
Flash sync speed Digital SLRs and compact system cameras use focal plane shutters and these have a design limitation – there is a maximum speed at which the whole sensor is exposed at once. This is the maximum flash synchronisation speed. Beyond this, the sensor is exposed in a moving strip, which is no good for flash.
Flexible Program (Nikon) Nikon’s name for its ‘program shift’ control, where you can change the balance of lens aperture and shutter speed without having to leave the program AE mode – you simply turn the command dial until the camera displays the lens aperture or shutter speed you want.
Fn (function) button One or more buttons on more advanced cameras which can be used for quick access to useful settings such as picture style, white balance, ISO setting or more. They will have default settings already which you may find useful, so you don't have to change them.
Focal plane mark A small marking on the top plate of some cameras which indicates the position of the focal plane – the sensor surface – inside the camera. You’re unlikely to need this unless you are using manual macro photography setups based on precise focus and magnification values.
Focal plane shutter The type of shutter used by interchangeable lens cameras (ILCs) such as DSLRs and compact system cameras. The shutter is mounted directly in front of the sensor (at the focal plane) and shutter ‘curtains’ open to start the exposure and close to end it.
Focus mode Camera autofocus systems work in one of three modes: single-shot autofocus (usually abbreviated to 'S'), continuous autofocus ('C') and manual focus ('M'). If you're taking one photo at a time, use single-shot autofocus – the camera will focus once and then fire. If you're using continuous shooting mode, use continuous autofocus – the camera will keep refocusing all the time the shutter button is held down.
Focus peaking A special display mode designed to help with manual focusing when using an LCD display or electronic viewfinder. It exaggerates the edges of objects when they come into focus and can give a much more visible focus ‘snap’ than the regular display.
Focus point Autofocus systems can focus at different points around the frame – the more advanced the autofocus system, the greater the number of AF points. You can either leave the camera to choose the autofocus point with 'auto AF' mode (or 'auto area AF') or select it yourself with single-point AF mode. Some cameras offer face-detection or subject-tracking AF options.
Focus stacking A hardware and software technique for getting more depth of field in close-up and macro shots. You take a series of images at slightly different focus settings, then use focus stacking software to blend together the sharpest areas of each into a single image.
Force flash A mode where the flash is made to fire whether the light is low or not. Normally, the camera won’t fire the flash in bright light, but forced flash mode overrides this. Flash can be useful for fill-in light for portraits, even in daylight, and especially if your subject’s face is in shadow.
Format (memory card) Completely wiping a memory card so that you’re starting again with a clean slate, so to speak. It’s not essential if you only ever use one camera, but if you use the same card in more than one it will clear up unwanted files and folders left behind by other cameras.
Foveon sensor (Sigma) Sigma's Foveon sensor uses a unique layered design to capture blue, green and red light on separate layers. It mimics the multi-layer construction of colour film.
FPS (frames per second) In stills photography, this is the camera's maximum continuous shooting speed – the number of frames it can capture per second. In video, this is the number of frames of video per second, typically 30fps, though sometimes 25fps or 24fps.
Fujifilm Camera, lens (and film) maker now specialising in high-end enthusiast and professional equipment such as the X-T2 mirrorless interchangeble lens camera, X100F high-end compact camera and GFX medium-format mirrorless camera.
Full frame sensor This is a sensor the same size as the 35mm film negative, measuring 36 x 24mm. This is the most desirable camera type for most enthusiasts and pros, but full frame cameras are bigger, heavier and more expensive. Most DSLRs and mirrorless cameras use smaller APS-C sensors.
Full HD Video with a resolution of 1920 x 1080 pixels. It’s sometimes abbreviated to ‘1080 video’.
FX format (Nikon) This is Nikon’s name for its full frame DSLRs, to distinguish them from its APS-C size ‘DX’ models. Most Nikon lenses are designed to fit this larger FX format. Those that don’t have ‘DX’ in the model name – though they can still be used on an FX Nikon in ‘DX crop’ mode.

G

Gain (audio) Gain is a term you're likely to meet in video rather than stills photography. It basically means turning up the input signal strength to record a decent value. Videographers are more likely to talk about increasing the ISO setting rather than the 'gain', though it amounts to the same thing. It's still used for audio recording, where your camera or sound recorder will probably have a 'gain control' or some kind of 'AGC' – automatic gain control.
Gigabytes (GB) A unit of storage used both for computer hard disks (and SSDs) and for memory cards. 1GB is approximately 1,000 megabytes.
Global shutter An advanced kind of electronic shutter that can capture the entire image area at once, instead of scanning it strip by strip. This should eliminate the rolling shutter effect usually associated with electronic shutters and make them much more effective for capturing moving subjects. It does, however, require advanced sensor technology, especially in larger sensor sizes, and powerful image processing, which is why it's still in its infancy in the mass market.
GoPro One of the best known brands of action camera. GoPro has made its name through the activities of high-profile adventure sports personalities and even TV production companies. The cameras are small, square and tough and at the centre of a large range of camera mounts, supports, gimbals and other accessories.
GoPro mount A mounting system first developed by GoPro but now used widely by other action camera and accessory makers. In theory, any GoPro mount compatible item should be compatible with any other.
GPS GPS receivers use global positioning satellites to fix the camera’s location and embed this in the photo’s metadata. You can look this up later and many programs can show the location the photo was taken on a map. Only a few cameras have GPS built in, but it’s standard on smartphones.
Grain Film grain is caused by the random clumping of silver halide grains (black and white) or dye clouds (colour film) – the individual grains or colour spots are too small to see. Film grain looks very different to digital noise – many photographers use film grain simulation filters and tools.
Grip Also known as battery grips, these are accessories that attach to the bottom of some DSLRs or mirrorless cameras to offer extended battery life and, usually, a duplicate set of controls to make the camera suitable for extended use in portrait (vertical) mode. In some cases, a battery grip may also increase the continuous shooting speed of the camera. For example, the battery grip of the Nikon D850 increases its continuous shooting speed from 7fps to 9fps.

H

Handheld photography Any photography – obviously – where you’re holding the camera with your hands rather than using a tripod or some other form of camera support. It has special implications for night and low light photography where it’s important to use shutter speeds fast enough to prevent camera shake.
HDMI Standard digital interface for connecting video and display equipment. Cameras have HDMI ports for direct connection to TVs, for example, but more advanced models can also connect to external monitors for video recording, or external video recorders.
HDR (high dynamic range) HDR stands for high dynamic range photography. It combines a series of frames taken at different exposures to capture a much wider dynamic (brightness) range than the camera could capture with a single exposure. These exposures are merged using HDR software.
HD video ‘HD’ stands for ‘high definition’ to distinguish it from older, lower resolution video standards. HD actually comes in two formats: standard HD has a resolution of 1280 x 720 pixels, full HD is 1920 x 1080 pixels. Both use the same 16:9 aspect ratio.
Headphone socket All DSLRs or compact system cameras which shoot video will have an external microphone socket for better sound quality – but for pro videographers it’s just as important to have a headphone socket for monitoring sound levels while shooting. You only get this on more advanced models.
High speed sync High-speed sync is a flash mode that counters limited flash synchronisation speeds of focal plane shutters by pulsing the flash several times, potentially impacting flash power. Elinchrom's 'High Sync' reduces this power loss.
Histogram A graphical display of the brightness values in the picture. The darkest tones are at the left and the brightest on the right, and the vertical bars show the number of pixels for each brightness value. Histograms are an invaluable exposure aid when taking pictures, and when editing them later.
Hotshoe Accessory shoe on the top of more advanced cameras that’s designed for sliding in an external flashgun, though these days it may also be used for electronic viewfinders, wireless remote control units and more.
Hybrid autofocus Autofocus system that combines contrast autofocus and phase detection autofocus. It works using special phase-detection sensors built into the sensor. Contrast AF is typically slow but accurate, while phase detection AF is typically fast if potentially less accurate.

I

IBIS (in body image stabilisation) Short for 'in-body image stabilisation' and a term used by Fujifilm for its X-H1 pro mirrorless camera. In-body image stabilisers shift the camera sensor to counteract any camera movement during the exposure. It's the first time Fujifilm has used in-body stabilisation, but it's already used by Pentax, Panasonic, Sony and Olympus.
ILC (interchangeable lens camera) Any camera where you can change lenses. Once, this was just DSLRs, but now mirrorless cameras are included in this category and, for the sake of argument, Leica’s ‘rangefinder’ cameras should be included too. ILC is not a widely used term but it is the most correct description.
Image circle All lenses produce a circular image on the camera sensor or film, and this 'image circle' must be at least large enough to cover the full film/sensor area. Different lenses designed for different sensor sizes and formats have different-sized image circles. Lenses designed for APS-C format cameras, for example, have a smaller image circle than lenses for full frame cameras. Some specialised perspective control or tilt-shift lenses have larger image circles to allow for lens movements relative to the camera.
Image stabilizer A mechanism that counteracts camera movement during the exposure. Lens-based stabilisers use a moving lens element, while sensor-based stabilisers move the sensor itself. Image stabilisers are used to get sharper telephoto shots and low-light shots without camera shake.
Infra red A branch of photography that uses parts of the light spectrum not normally visible to the naked eye but which can still be captured on film or digitally using black and white or colour film made sensitive to infra red or a digital camera modified to remove the infra red filter that normally covers the sensor.
Intervalometer A camera setting or remote controller which fires the camera’s shutter at set intervals, stopping when it’s taken a specified number of images. The pictures can then be used to analyse movement or change over time or, more likely, combined to make a time lapse movie.
Interval timer Sometimes called an 'intervalometer', this is a feature on more advanced cameras that takes picture at fixed intervals automatically. It’s most often used for time lapse photography. You set the interval between pictures and the number of shots you want the camera to take.
ISO This setting increases the camera sensor’s sensitivity to light. Each ISO step doubles the sensitivity, so it’s easy to use ISO as another exposure control alongside shutter speed and lens aperture. The more you increase the ISO, though, the more the image quality degrades.
ISO expansion This setting increases the camera sensor’s sensitivity to light. Each ISO step doubles the sensitivity, so it’s easy to use ISO as another exposure control alongside shutter speed and lens aperture. The more you increase the ISO, though, the more the image quality degrades.

J

JPEG This is a standardised, universal file format for digital photos that can be displayed by practically any device without any kind of conversion. It uses powerful compression to reduce the file size of digital photos so that you can get more on to a memory card or a hard disk, and they’re quicker to transfer. There can be some loss of quality (often invisible to the naked eye), so for ultimate quality many photographers shoot photos in their camera’s RAW format instead. It’s only more advanced cameras that offer this RAW option, and it produces much larger files which you will need to process yourself later on.

K

Kit lens A relatively inexpensive general purpose lens sold with a camera body as a kit. Buying both at the same time is much cheaper than buying them individually. Most DSLRs and mirrorless cameras are also sold ‘body only’ for those who already have lenses.

L

LCD display The key specs here are the size, measured across the diagonal, and the resolution, measured in thousands of dots. For example, you might get a 3-inch LCD with 921k (921,000) dots.
Lens adapter In principle, you can't mix and match different types and brands of lenses with different camera bodies. Each camera maker uses its own bespoke lens mount and different mechanical and electronic connections between the camera body and lens. However, it's often possible to make lenses fit different brands and types of bodies with lens adaptors. These are usually from third-party makers and designed for users who don't mind a few compromises in camera functions. For example, you may lose autofocus functions and have to use manual focus only, and it's likely that you'll have to use manual exposure and lens aperture control rather than the camera's full range of exposure controls.
Lens corrections Lenses aren't perfect – they all have optical aberrations of one sort or another. Now, though, many software applications have lens correction to correct these digitally, either with manual controls or automatic lens correction profiles.
Lens modulation optimiser (LMO) A processing algorithm used by Fuji in some of its cameras to counteract the softening effects of diffraction at small lens apertures, and image softness at the edge of the frame. It seems likely the LMO is simply applying some intelligent sharpening.
Lens mount This is the physical connection between a lens and the body of a DSLR or mirrorless camera. It consists of a twist-lock bayonet mount and electrical connectors. The lens mount is specific to a camera brand – you have to make sure you get lenses in the right fitting for your camera.
Light meter A device for measuring light levels. Digital cameras come with their own sophisticated internal light meters, but it is possible to get external light meters where the settings have to be transferred to the camera manually. This is slower, but has advantages in some circumstances.
Live view Where the camera displays what the sensor is capturing either on the rear LCD or in an electronic viewfinder. All compact cameras and mirrorless cameras are effectively in ‘live view’ all the time. It’s only out of the ordinary on a DSLR, which has to go into a special mirror-up ‘live view’ mode.
Lomography Company which champions old, analog cameras, outdated or cross-processed film and relaunched classic lens designs. Lomography products are known for their expense, sometimes makeshift construction and general unpredictability, but also revered by their fans for these very reasons (well, probably not the expense), because they introduce the kind of randomness, unexpectedness and engagement lost in the transition to modern digital imaging.
Low pass filter A filter directly in front of most camera sensors to prevent interference (moiré) effects between any fine patterns and textures you photograph and the rectangular grid of photosites on the sensor. These filters actually blur fine detail slightly, and some makers no longer use them.
Luminance (contrast) noise The chief component in image noise and the one that's most difficult to remove because software can't easily distinguish between random image noise and real image detail. The result is that the more noise reduction you apply, the more you tend to lose fine image detail, resulting in images with obvious and objectionable ‘smoothing'.

M

Macro mode Many cameras and some telephoto lenses offer a 'macro' button or mode. This is rarely the same as true macro photography at 1:1 magnification. Instead, 'macro' is simply used as another word for close-up. This is the macro button on a Fuji X30 compact camera.
Manual exposure Where you set both the shutter speed and the lens aperture used by the camera. The camera’s exposure meter may recommend the settings, but you’re free to use or ignore this information. Manual exposure gives you total control but requires some experience.
Manual focus Useful when you want to make the most of depth of field – with often means focusing between two objects rather than on one or the other. It’s also handy for ‘zone focusing’ in shoot-from-the-hip style street photography, where you want an instant shutter response.
Mechanical shutter The traditional form of camera shutter, a physical device which blocks light from the sensor until the moment you press the shutter release, then opens to expose the sensor for the required amount of time before it closes again. Mechanical shutters are either focal plane types, just in front of the sensor, or in-lens 'leaf' types. Electronic shutters offer shorter shutter speeds on paper, but with current technology they're less effective at capturing fast-moving objects.
Medium format Professional cameras that use sensors larger than full frame. These fill the space previously occupied by 120 roll film cameras, though they are massively more expensive. ‘Medium format’ sounds like there should be a larger size still, but it harks back to the days of film when you could get large format 5x4” or 10x8” sheet film cameras.
Megapixels (MP) The number of pixels captured by the camera’s sensor. Smartphones typically have around 8 megapixels and upwards, while regular digital cameras typically have 16 megapixels or more. Megapixels used to be a good guide to image quality but now sensor size is more important.
Memory card Removable storage media used to store digital images in the camera. They come in different types (SD, Compact Flash, XQD, CFast), different capacities and speeds.
Memory card capacity This is measured in gigabytes (GB), and the larger the memory capacity the more photos and video clips you can store. It’s hard to give precise advice since cameras and user needs vary so much, but 16GB is a good starting point if you shoot RAW files as well as JPEGs, and consider 64GB-256GB if you want to shoot video, especially 4K.
Memory card speed Memory card makers quote the card’s maximum read/write speed in MB/sec, but it’s also important to know the minimum sustained speed for video recording. This is quoted using Class ratings (SD cards). Typically, you need Class 10 for 4K video as a minimum.
Metering mode Digital cameras usually use multi-pattern/multi-segment light metering, but they also offer other 'metering modes' – centre-weighted metering (simpler) and spot metering (more precise). The camera will have a button or a menu option for changing the metering mode.
Micro Four Thirds (MFT) This is a sensor and lens format used by Olympus and Panasonic for their mirrorless camera ranges. The MFT sensor measures 17.3 x 13.0mm, so it's smaller than the APS-C sensors used in rival mirrorless cameras. This does have a modest effect on overall image quality, but the payback is the both MFT cameras and lenses are substantially smaller and lighter than rival APS-C models. The MFT format also has a slightly squarer 4:3 (four-thirds) aspect ratio, which some photographers might prefer.
Microlens (sensor) In order to maximise their light gathering power, each photosite on the camera sensor is covered by a tiny domed ‘microlens’ to capture and funnel in the light more effectively. Improvements to the microlens array can improve the sensor’s performance.
Microphone Any camera which shoots video will have a microphone built in, often stereo mics. For serious video work, though, an external microphone is needed. Some types plug into the camera’s hotshoe, others are used on the end of a boom or clipped to a presenter’s clothing (lapel mics).
Mirrorless camera A relatively recent design that takes interchangeable lenses, just like a DSLR, but doesn’t use in internal mirror for its viewing system –if you take off the lens you see the sensor itself. Mirrorless cameras allow a shorter lens-to-sensor distance and full time live view.
Mirror up mode An option on more advanced DSLRs that flips the mirror up in advance of the exposure in order to give any vibrations from the mirror mechanism time to die down. It’s popular with fans of macro photography and some landscape photographers.
Mode dial Just about all digital cameras have these or an equivalent and you use it to set the exposure mode, such as full auto, program auto exposure, scene modes, movie mode and so on. More advanced cameras add PASM modes – Program AE, Aperture-priority, Shutter-priority and Manual.
Moiré A fine interference pattern sometimes visible when you photograph fine patterns. It happens when these clash with the rectangular grid of pixels on the camera sensor. Actually, you almost never see it – most cameras have anti-aliasing/low pass filters to prevent, and it doesn’t seem to be an issue for those that don’t.
Mount adapter A lens mount adaptor which lets you mount a lens designed for one camera or brand on a different make or type of camera. For example, you can get adaptors for fitting DSLR lenses on some mirrorless cameras. Mount adaptors (lens adaptors) are used widely in videography.
MP4 MP4 is a video file format used by many digital cameras. It's simple to work with because it produces a single file containing both the video and audio and it's simple to drag from one device to another. It's often provided as a similar alternative to AVCHD on Sony and Panasonic cameras.
Multi pattern metering This is the most sophisticated form of light metering used by cameras. The light values are measured at many points across the frame and compared to ‘known’ scenes so that the camera can work out what the subject is likely to be and the best way to expose it properly.
Multiple exposure Taking two shots on a single frame. In the days of film this meant locking the film advance when cocking the shutter and taking another picture on a frame of film that's already been exposed. On a digital camera, the camera stores the first image in its memory and then merges it with the second.
Multi selector A control that’s practically universal on digital cameras. It’s a circular controller on the back of the camera with up/down/left/right buttons which can be used for positioning the autofocus point, menu navigation, camera settings and more.

N

NFC Stands for Near Field Communication, a wireless transfer system that relies on very close contact between devices – sometimes you simply tap or touch the devices together to establish contact. It can be used for transferring photos from a camera to a compatible printer, for example.
NiMH battery The most common type of rechargeable AA battery, and they’ve taken over from older, less efficient Ni-Cad batteries. NiMH batteries are inexpensive and often used in cheaper compact cameras, flashguns, battery grips and LED lights.
Noise Random ‘speckling’ in an image caused by variations in the light levels captured by the photosites on the sensor. Noise is worse with the smaller photosites on small sensors and at higher ISO settings generally. You can get ‘chroma’ (coloured) noise and ‘luminance’ noise (general ‘grittiness’) the same colour as the background.
Noise reduction Camera makers use special noise reduction processing techniques to reduce the appearance of noise in photos, but the drawback is image softness and haziness and a kind of ‘watercolour’ effect where areas of fine, subtle detail are smudged beyond recognition. Bad noise reduction can do as much harm as image noise – or more.

O

OLED display OLED stands for 'organic light emitting diode'. It's a more advanced display tech than regular LCDs with wider viewing angles, faster response, better brightness and reduced power consumption. The OLED electronic viewfinder is a selling point in the Fujifilm X-T1, for example.
Optical stabiliser Image stabiliser which moves physical elements within the lens, or the sensor itself, to keep the image steady during the exposure. This is superior to ‘digital stabilizers’ which use image processing techniques to reduce blur, but which also lead to a loss in quality.
Optical viewfinder The viewfinder in a digital SLR is optical because it’s created by an image formed by the lens on a glass ‘focussing screen’. The direct vision viewfinders on some compact cameras are optical because you’re seeing the world through a set of lenses and not via a digital display.

P

PASM modes A set of four exposure modes that distinguishes a serious camera from simple point and shoot models. It stands for Program AE, Aperture-priority, Shutter-priority and Manual modes. You’ll find these on many better compact cameras and all DSLRs and mirrorless cameras.
Pentaprism This is a key part of the optical viewfinder system of a digital SLR. It's a five-sided prism inside a housing on top of the camera that reflects the image captured by the lens and formed on the camera's focusing screen so that it's the right way up and the right way round for viewing through the camera's viewfinder eyepiece. Some cheaper DSLRs use a less expensive 'pentamirror' design instead. It costs less to make but does have a slight effect on the size and quality of the viewfinder image.
Perspective correction A means of correcting converging verticals in architectural shots and other perspective issues. You can get ‘perspective control’ lenses which use complex lens adjustments to fix the problem optically, or you can use software with perspective correction tools.
Phase detect AF An autofocus system that checks the position of objects from two angles. If they don't line up the object is out of focus – and the system can use the difference to work out how far to refocus the lens and in which direction. Phase detection AF sensors are used on DSLRs and now phase detection pixels are built into some mirrorless camera sensors.
Photosite This is the correct technical name for the individual light receptors on a sensor, though many people call them pixels because each photosite corresponds to a pixel in the final image. Each photoreceptor gathers light (photons) and turns them into an electrical charge (electrons) which can be measured.
Picture Control/Style Cameras usually offer a range of picture 'styles' such as 'Standard', for neutral results, 'Vivid' for richer colours, 'Portrait' for gentler tones and more. These are applied to JPEG images saved by the camera. If you shoot RAW files you can choose the picture style later on.
Pixel The individual building block of digital images. Each individual pixel is a single block of colour, but when there are enough of them viewed from far enough away they merge to form the impression of a continuous-tone photographic image.
Point and shoot camera It’s about the easiest way of describing simple digital cameras that are inexpensive and designed for novices. They offer fully-automatic shooting modes that don’t require any particular photographic know-how and zoom lenses which cover most everyday needs. They quality is only average, though, and there’s little scope for overriding the camera.
Pop up flash Most cameras have a built-in flashgun which pops up automatically in low light or can be popped up by pressing a button. The flash can provide emergency light, but it's harsh and short range. In many instances it's best to leave the flash off and use higher ISO settings.
PowerShot (Canon) The brand name for Canon’s more advanced compact digital cameras. They include long-zoom compacts, bridge cameras and Canon’s more sophisticated high-end compact cameras, which feature extensive manual controls and larger sensors.
Predictive autofocus Here, the camera tracks subject in continuous autofocus mode and uses its movement within the frame and any changes in its distance from the camera to work where it’s going to be at the moment the shutter fires.
Program AE (P) mode In this mode, the camera chooses combinations of shutter speed and lens aperture automatically to give a good compromise between safe shutter speeds (no camera shake) and reasonable depth of field (smaller apertures).
Program shift An override option in program AE mode which shifts the shutter speed and aperture combinations in favour of faster shutter speeds or smaller apertures. This is often quicker than swapping to aperture-priority or shutter-priority mode if it’s for a single picture.

Q

Q (quick) menu A useful feature on some cameras which puts all the most commonly used camera settings on a single screen. You can then use the cursor buttons to quickly select the setting you want and change it. It's a pretty common option across all cameras, though the name may be different.
Quiet mode A very useful option if you need to take pictures in a theatre, church or museum where it's important to make no noise. Some Nikon DSLRs have a Quiet mode, though you can't completely eliminate the noise from a DSLR's shutter or mirror mechanism.

R

Rangefinder An older camera designed still used by celebrated German manufacturer Leica. The ‘rangefinder’ is used for focusing – as you turn the focus ring on the lens, a small mirror in the top of the camera rotates to line up a ‘ghost’ image with the main image in the viewfinder. When this ghost image lines up, your subject is in focus.
RAW+JPEG Cameras with the ability to shoot RAW files will almost always offer a RAW+JPEG option too. Here, the camera shoots a single image but saves two versions – the RAW file and a JPEG processed and saved with the current camera settings. The JPEG is useful because you can share it with other people straight away and it also offers a useful benchmark when you're processing the RAW file later.
RAW file Usually when you take a picture the camera will process the data captured by the sensor into an image file. More advanced cameras can save the image in its unprocessed state – a RAW file – so that you can do the processing yourself later on your computer.
RAW vs JPEG Most digital photos are shot as JPEG images. This is a universal image file format that uses sophisticated compression to keep the files small and manageable. JPEGs are created by processing the RAW data captured by the camera. Some cameras let you save these RAW files instead. The files are larger and you need to process them later on a computer, but they offer the potential for better quality.
Rear curtain flash A special slow sync flash mode which fires the flash at the end of the exposure not the start. This gives more natural-looking results with moving subjects because any movement trail will be behind your subject and not ahead of it (which looks odd).
Remote A device which fires the camera’s shutter release from a distance, either via an electrical cable or a wireless signal. It’s useful if you need to stand some distance away from the camera and avoid jogging the camera when you fire the shutter.
Reset (camera) More advanced digital cameras have many shooting and setup options – so many, that you can sometimes forget what you’ve set them up to do. To get back to the default settings you need two options: 1) Reset shooting settings; 2) Reset custom settings.
Resolution This can mean one of several things depending on the context. Camera resolution is the number of megapixels on the sensor, lens resolution is how well the lens is able to resolve fine detail. Screen resolution is the number of dots on the screen and therefore how sharp/clear it looks.
RGB RGB stands for red, green and blue, the three colour 'channels' that go to make up all the colours in a digital image. It comes in two varieties – sRGB is a 'universal' RGB that can be used and displayed by any device, whereas Adobe RGB is a more specialised alternative for pros.
Rolling shutter An image distortion effect caused by the way camera shutters operate at very high shutter speeds. Beyond a certain speed, focal plane shutters, as used in most interchangeable lens cameras, change the way they work. Instead of exposing the whole sensor at once, they expose it in a narrow strip between two shutter curtains passing very quickly across the sensor. This means that if a subject is moving very rapidly it may take on a skewed or twisted shape. This can be apparent not just in stills photography but in video too.

S

S-AF (single shot AF) mode Here, the camera focuses once when you half-press the shutter release then holds that focus point until you press the button the rest of the way to take the picture. This is the usual mode for taking one photograph at a time (as opposed to continuous shooting).
Scene mode Automatic mode designed for beginners where the camera applies the settings that best suit the subject you’re shooting (landscape, portrait, action etc). Some cameras can analyse the scene in front of you and choose a scene mode automatically. Experts don't normally bother with scene modes because they're designed solely for those who don't really want to get involved with individual camera settings. If you do know your way around a camera, you'll generally want to make your own choices about the settings.
SD/SDHC/SDXC card These are all the same size but there are important differences. Older cameras may only be able to use SD cards, but more recent ones will be able to use SDHC cards too, but may not be able to use the latest SDXC format. Check your camera’s manual before buying these.
Self timer The camera waits for a set delay before firing the shutter. This gives the photographer time to get in position for a group shot – but it’s also useful for tripod shots or long exposures where you want to fire the shutter without jogging the camera.
Sensor basics There are two main things to look for in sensors: the sensor size and the resolution, in megapixels. It’s more important to get a bigger sensor than to get more megapixels.
Sensor size This is the physical size of the sensor, which is independent of the number of megapixels it has. Bigger sensors capture more light and produce sharper, clearer images with less noise. In fact sensor size is the single most important factor these days in a camera's picture quality – megapixels are mostly secondary.
Sharpening A standard part of digital image processing either in-camera or later on a computer. Sharpening processes increase the contrast around object outlines to make them look crisper. Good sharpening is all but invisible, bad sharpening leaves edge ‘halos’ you can see under magnification.
Shutter The mechanism that control the length of the exposure. On some smaller cameras this may be in the lens (a ‘leaf’ or ‘in-lens’ shutter), but on DSLRs and mirrorless cameras with interchangeable lenses, it’s a ‘focal plane’ shutter directly in front of the sensor.
Shutter priority (S) mode Exposure mode where you choose the shutter speed and the camera selects a lens aperture to give the correct exposure. You get to choose the shutter speed manually, but the camera still takes care of the exposure automatically. On Canon cameras this is called Tv (time value) mode.
Shutter speed The length of time the shutter is open during the exposure and usually quoted as fractions of a second. Each shutter speed is half as long as the one before, for example 1/30sec vs 1/60sec. This exposure ‘halving’ is the basis for balancing up lens aperture and ISO settings. A few cameras have external shutter speed dials but most simply display the shutter speed on the LCD display – you turn a control dial to change the speed.
Silent mode A useful mode if you’re shooting in a theatre or museum, but one that’s only available on compact cameras with in-lens shutters and mirrorless cameras with electronic shutters. On compact cameras you can get the same effect by turning off the focus ‘beep’ and shutter sounds.
Slow flash/slow sync Special flash mode where the camera’s exposure is extended beyond the brief burst of the flash. This makes it possible to record some of the ambient lighting too, and it’s a popular technique for illuminating a nearby subject brightly without losing background colour and detail.
SLT (single lens translucent) SLT cameras are made by Sony as a kind of hybrid of the regular digital SLR design and the always-on live view of a mirrorless camera. They do have a mirror in the body, but it doesn't flip up and down when you fire the shutter. Instead, it has a translucent surface so that the image can pass straight through to the sensor on the back of the camera.
Smartphone Many smartphones have pretty good cameras. The best ones have sensors about the same size as those in point and shoot cameras and fixed focal length lenses. The lack of a zoom is a restriction, but otherwise the quality is just as good. There’s even a growing art movement around mobile photography.
Sony Sony is best known as a giant electronics manufacturer making devices across a range of markets, but its camera division is doing especially well. The market for compact point and shoot cameras has fallen, but Sony is doing very well with its professionally-orientated full-frame A7 series and A9 cameras. It also makes a continually expanding range of high-end professional lenses.
Spot metering A metering mode where the camera measures the light from a very small area of the scene. This might be right in the centre or, on some cameras, it’s directly beneath the selected autofocus point.
SSD A solid state storage device that uses memory chips rather than a hard disk. SSDs offer much faster data transfer rates than regular hard disks, they’re smaller and have no moving parts. They are, however, much more expensive, so while an SSD is ideal add-on storage for desktops and laptop computers, especially if you want to take your data with you on the move, they are a substantial investment.
Status LCD More advanced DSLRs have a secondary LCD display on the top so that you can check the main shooting settings without needing the rear screen. Status displays are black and white (or black on green) and usually have a backlight button for use in dark conditions.
Subject tracking AF A focus mode where the camera continually refocuses on a moving subject. The more advanced the AF system, the better it will be at keeping the subject in focus. It’s used mostly in continuous shooting mode for sports and action photography but can also be used for video.
Sync terminal/socket A cable connector for socket external flash units that’s still found on higher-end cameras like pro DSLRs but is becoming less and less common as photographers switch to wireless flash systems. These are usually triggered by a ‘master’ unit attached to the camera.

T

Tethered shooting A technique used by professional studio photographers where the camera is connected to a computer and the computer is then used for controlling the camera, checking pictures as soon as they’re taken and then correcting and enhancing them as necessary before saving.
TIFF format An image file format that uses ‘lossless’ compression but produces much larger files than JPEGs. It’s sometimes offered as a file format on more advanced cameras but it’s more useful later on as an image file format for image editing and manipulation on a computer.
Tilting screen One that tilts up and down but doesn’t flip out and rotate in all directions (an ‘articulating’ screen). Tilting screens are nonetheless useful for composing pictures with the camera at waist or ground level or above head height.
Time (T) exposure A close relative of the bulb (B) shutter speed setting and, like bulb mode, it’s used for long exposures. With time (T) exposures, though, you don’t hold the shutter button down all the time – you press once to start the exposure and a second time to end it.
Timelapse A filming technique where frames shot at intervals are combined to make a video. For example, if you shot 300 frames at 1-second intervals and turned them into a movie running at 30fps, then five minutes of real time would be compressed into a 10-second movie.
Tint (white balance) A secondary white balance adjustment used alongside colour temperature for more complex light sources like fluorescent lighting. Colour temperature works across an amber-blue spectrum, while tint adds a green-magenta axis.
Touch AF Autofocus mode where you tap on a touch-sensitive screen to choose the focus point for the picture. Some cameras also offer a touch shutter option where tapping the screen not only sets the focus point but fires the shutter too.
Touchscreen Pretty self-explanatory really – an LCD screen offering touch control for camera settings, setting the focus point, menus and more. These are becoming increasingly popular on compact cameras and mirrorless models as a way of supplementing or replacing knobs and dials.
Travel camera A more advanced version of a point and shoot camera with a much longer zoom range and, sometimes, more advanced photographic controls. The 20x or 30x zoom range makes these cameras much more versatile, but they use small sensors so the picture quality is limited.

U

UHD video This is what most people are referring to when they talk about ‘4K’ video. UHD video has a frame size of 3,840 x 2,160 pixels, so it’s slightly less than 4,000 pixels wide, but it does have a true 16:9 aspect ratio, so the picture proportions are the same as standard HD and full HD video.
UHS I/II
UHS is a new ultra high speed bus (data transfer connection) for SD memory cards. There are two versions: UHS-I and a more advanced UHS-II type. This refers to the physical construction of the card and does not directly indicate its speed. There are speed standards for UHS cards: UHS 1 guarantees a minimum speed of 10MB/s, which is suitable for full HD video recording, and UHS 3 guarantees a minimum transfer speed of 30MB/s, which is what you’d need for 4K video.
USB Standard connection between cameras and computers, though these days most photographers would remove the memory card and use a card reader to transfer photos. USB ports can also be used for charging on some compact cameras and ‘tethered shooting’ on professional cameras.

V

Video Almost all digital cameras can now shoot video as well as stills, and as well as its leisure applications, video is also increasingly important to professional photographers as clients frequently want movies as well as still images. The key specifications are the resolution (standard HD, full HD or 4K) and the frame rates (30fps, 25fps or 24fps). Some cameras offer faster frame rates for slow motion effects. High-end cameras offer 6K or, soon, 8K resolution and it's also possible to get 360-degree video cameras no larger than GoPro style action cams.
Viewfinder coverage The percentage of the scene shown by the viewfinder. In better DSLRs you see 100% of the scene that will be captured, but in cheaper models it might only be 95-97%. That small difference can lead to objects showing at the edge of the frame that you hadn’t realised were there.
Viewfinder grid These are an option on both DSLRs and in electronic viewfinders. You can use the grid to make sure horizons are level and buildings are vertical – some grids confirm to the ‘rule of thirds’ to help you get a satisfying composition.
Virtual horizon A kind of on-screen spirit level that shows you when the camera is level. This can be useful in landscape photography, for example, when the horizon isn't flat or visible. Some also have fore-and-aft levels to help avoid any tilt (and converging verticals) when shooting buildings.
VR (Vibration Reduction) (Nikon) Nikon's name for its image stabilisation technology, as built into its DSLR lenses. Tiny gyroscopic sensors detect any camera movement during the exposure and instantly shift a group of internal lens elements to compensate and keep the image steady on the sensor.

W

White balance An adjustment made by the camera to neutralise colour shifts in the lighting. Digital cameras offer an auto white balance option where they choose the correction, or you can select manual white balance ‘presets’ when you want to control the camera’s colour rendition yourself. White balance adjustments are made using 'colour temperature' and 'tint'.

X

X-mount (Fujifilm) This is the lens mount for Fujifilm's X-series mirrorless cameras. These include the Fujifilm X-T2, X-H1, X-E3 and others. Any X-mount lenses can be used on any X-mount camera, though note that Fujifilm's medium format GFX 50S uses a different mount and different lenses.
X-trans sensor A sensor layout unique to Fujifilm which replaces the usual bayer pattern of red, green and blue photosites with a more 'random' arrangement. Fujifilm says this eliminates the need for a low-pass filter to combat moiré (interference) effects, resulting in sharper fine detail.
XQD card An extra-fast memory card format currently used only in the Nikon pro DSLRs. It’s about half the size of Compact Flash but has the potential for extremely high speeds – though it’s yet to be seen whether many other camera makers will adopt it.

Z

Zebra pattern A visual warning that image highlights are being overexposed and used especially during video recording. The overbright areas are marked by moving diagonal stripes (hence zebra) leaving you to decide whether to reduce the exposure or to leave it if the highlight areas are unimportant.

0-9

1-inch sensor A new sensor size roughly half way between the small sensors in point and shoot digital cameras and the much larger ones in digital SLRs and mirrorless cameras. It’s found in more advanced high-end compact cameras from Sony and Canon, for example, and Nikon used it for its Nikon 1 mirrorless cameras. It’s been adopted by a number of makers as a way of getting better image quality from compact (non interchangeable lens) cameras.
1/2.3-inch sensor This is the smallest sensor size in widespread use for photography. You’ll find it (or sensors of a similarly small size) in smartphones, point and shoot cameras and some bridge and long zoom travel cameras.
1/2.3-inch sensor This is the smallest sensor size in widespread use for photography. You’ll find it (or sensors of a similarly small size) in smartphones, point and shoot cameras and some bridge and long zoom travel cameras.
1-inch sensor A new sensor size roughly half way between the small sensors in point and shoot digital cameras and the much larger ones in digital SLRs and mirrorless cameras. It’s found in more advanced high-end compact cameras, and Nikon uses it for its Nikon 1 mirrorless cameras. It’s been adopted by a number of makers as a way of getting better image quality from compact (non interchangeable lens) cameras.
360 camera 360 cameras create fully immersive video that extends in a full sphere around the camera position, which is usually stationary but could also be mounted on a skydiver’s helmet, for example. There are two ways of working with and watching 360-degree video. One is to use the video as raw material for creating a regular rectangular video, but with the freedom to pan around through a full 360 degrees during the editing process as you choose your viewpoint or create your own ‘panning’ shots. Another is to distribute the 360 video as-is using a suitable display system so that viewers can explore the scene on their own, choosing which direction they want to look in.
35mm camera 35mm film cameras, initially designed for the film industry, remain popular. Full-frame digital cameras with 36 x 24mm sensors are their direct counterparts.
4K video 4K video is a catch-all term for video with a horizontal resolution of around 4,000 pixels. It can include 4K UHD (3,840 x 2,160 pixels) and Cinema 4K (4,096 x 2,160 pixels).
4K UHD The latest consumer video standard, with a horizontal resolution of 4,000 pixels or thereabouts. 4K video is appearing on an increasing number of cameras and even smartphones, and 4K TVs are gaining in popularity. Strictly speaking, the dimensions for 4K video are 4,096 x 2,160 pixels and the aspect ratio is slightly wider than the 16:9 standard for HD video. In fact, what most makers and users are referring to is UHD video at 3,840 x 2,160 pixels, which does have a true 16:9 aspect ratio.
5-axis stabilization The latest kind of image stabilisation technology, where the camera’s sensor can be tilted or shifted on 5 axes to counter a much wider range and types of movement than regular lens-based image stabilisers, and it’s a particular advantage for video, where these additional movements can pose problems during handheld filming. 5-axis stabilisation used in the Pentax K-1 full frame DSLR, Olympus OM-D mirrorless cameras and the latest Sony A7-series compact system cameras.
6K video 6K video has a horizontal resolution of around 6,000 pixels, or 50% more than 4K video. It’s now starting to appear on some mid-range video cameras, but is used mostly for capturing higher resolution footage for downsampling to 4K (for higher quality) or to allow more leeway for cropping and panning effects in post production.
8K video 8K video has a horizontal resolution of around 8,000 pixels and is still in its infancy, though Canon, Sony and Nikon now all make 8K Mirrorless Cameras.