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.
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.
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.
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.
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.
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.
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.
Drone Any remote control flying craft that can carry a camera. The drones available to the public are helicopter-style ‘multi-rotor’ devices – typically ‘quadcopters’ rather than the aircraft used by the military. The rotors are controlled by a central computer for easier flight controls.
Dual image stabilization A system that uses both in-body image stabilization and optically stabilized lenses to produce an even stronger stabilizing effect.
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.
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.
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.
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.
Grading The video equivalent of the image-enhancement stills photographers carry out on their images. Videographers 'grade' video to match the colours and exposures between clips, to create a certain 'look' or to edit video shot in a 'log' mode for extra dynamic range.
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.
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.
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.
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 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.
Lavalier (lav) mic This is a small microphone designed to attach to a speaker's clothing for interviews or presentations, for example. They're usually small and unobtrusive, they're hands-free and they help exclude other background noises. They may also be called lapel mics. Some are connected to the camera or sound recorder by wire, others work wirelessly.
LED lighting New type of ‘continuous lighting’ that uses relatively little power but still provides enough light for video, still lives or portrait shots. Small LED panels can clip to a camera’s hotshoe, larger ones have their own stands and control panels.
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.
LUT (lookup table) LUT stands for 'lookup table'. Essentially, it takes the colours in an image and remaps them on to new ones. It really is a table consisting of a large grid of colour swatches and how they should be adjusted in the converted images. Its closest equivalent is the device profiles used in colour management systems, which work on a similar principle, but LUTs are usually designed for creative effects rather than colour correction.
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.
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).
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.
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.
Neutral density (ND) filter A filter which reduces the amount of light passing through the lens or reaching the sensor without affecting it in any other way. It allows longer exposures in bright daylight (useful for creative blur effects) or controls bright light in a camera with limited exposure controls.
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.
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.
Quadcopter A type of drone which uses four independently powered rotors. This is the most common type available to consumers though there are drones which use more rotors in order to achieve greater lifting power. When people say ‘drone’ they usually mean quadcopter.
Rig (video) In video, a 'rig' is a harness, a camera mount, a gyroscopic stabiliser or any apparatus designed to make it easier to carry and use a video camera. A rig may also have mounting points for video lights and microphones.
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.
Run and gun (video) A style of videography where you're not shooting from a static position, but following the action on foot as you film. You'd typically use it for action sequences. It takes a good deal of skill and it's best used for deliberate effect, not simply to make up for any lack of planning or direction!
Shotgun mic A shotgun mic is a highly directional microphone usually used to capture audio from a subject a little way from the camera. They're popular for on-camera use when it's not possible to place a microphone on or near your subject. Shotgun mics are 'unidirectional', which means they capture sound from one direction only over quite a narrow angle. This makes them more effective at excluding unwanted background noise.
Slow motion Video shot at a higher frame rate and played back at a normal frame rate. For example, video shot at 60fps and played back at 30fps would appear to be running at half speed. Higher frame rates require more processing power, so not all cameras offer them.
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.
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.
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.
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 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.
Variable ND filter Variable ND filters are useful in video because here it's often important to maintain the same aperture (iris) setting and shutter speed (or 'shutter angle') to keep a consistent visual effect even in changing lighting – you can adapt to different light levels by adjusting the ND effect.
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.
Video light A lighting unit designed specifically for video, typically small and light enough to mount on the camera or alongside it on a video rig. Some flashgun makers are now building a small video light into their flash units.
Wind cut A feature on some microphones that attempts to cut out loud roaring, whistling noise that you might not notice when shooting but which spoils the sound quality. It can be effective, but it’s even better to use a muffler on an external microphone.
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.
16:9 ratio This is the aspect ratio of full HD and 4K UHD video and it’s been widely adopted as the aspect ratio for domestic TVs and computer monitors. The 16:9 ratio means that the picture is 16 units wide by 9 units high. These units can be anything from pixels to centimetres to inches, but the point is that the ratio between them always remains the same at 16 wide to 9 high.
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.
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.