• Sorry, there are no items in your basket

Our shops are open

You will be able to Click and Collect from Burgess Hill and London again. You can also still order online or call us to chat to our experts! Next day delivery available!

Photography Terms, Acronyms, & Abbreviations

While manufacturers such as Canon, Nikon, Sigma, Sony, and Tamron have an excellent range of camera lenses available for digital SLR cameras & mirrorless cameras, there is a long list of technical acronyms, terms, and abbreviations in photography that accompany these lenses. We've compiled this rather lenghty list of terms to help alievate any confusion.

Canon have their acronyms, so do Nikon, and Sigma and Tamron have theirs too - all of which largely mean the same thing.

Rather than having to memorise the entire list, simply bookmark this page (CTRL+D on Windows or CMD+D on Mac) to keep it for reference or for future guidance.

Find out which lens is best for you with our Camera Lenses Explained guide

Glossary of Camera & Lens Terms & Acronyms

General list of acronyms, abbreviations and terminology used to describe digital camera lenses for photography.

There are some terms and acronyms that are common across many photographic brands and across photography in general. These general photographic terms can be used to describe cameras or lenses.


Switch between Auto Focus and Manual Focus

AI Servo

AI Servo is a focus mode on Canon DSLR cameras that’s known as focus tracking or continuous focus on other makes of camera. The AI refers to Artificial Intelligence algorithms that predict where a subject is going to be and tracks a subject as it moves around the image frame, constantly maintaining focus on that subject.


In digital camera sensors, APS-C is known as a ‘crop sensor’ and measures 23.5 x 15.6mm with an aspect ratio of 3:2. Canon’s APS-C sensor are a bit smaller than Nikon’s APS-C sensor and have a crop factor of 1.6x rather than 1.5x in the Nikons. APS-C sensors are commonly found in entry-level or mid-range digital SLR cameras, mirrorless cameras, and some premium compact cameras.


An aperture is simply the hole or opening in your camera lens that lets light travel through it. The aperture can be adjusted across the f/stop range to control the amount of light entering the camera. By controlling the opening of an aperture you change the cone angle of light rays that are focussed on the camera’s focal plane, and thus determine the depth-of-field of an image.

Aspect Ratio

The aspect ratio of an image is the ratio of the width to the height of the image. It’s commonly written as W:H, for example 16:9 is a common aspect ratio for cinematic movies, 3:2 is the ratio for a full-frame digital SLR camera, and 1:1 is a square.


Autofocus, or shortened to AF, is the system in a digital camera that uses a combination of a sensor, control system, and motor to determine the correct focus of an automatically or manually selected point in an image and then adjust the focus of the lens to bring that point into focus. The three main types of autofocus in use in modern digital cameras are Contrast Autofocus, Phase Detection Autofocus, and Hybrid Autofocus.


CIPA is the Camera & Imaging Products Association, an international group of camera, imaging and photographic companies who have established a worldwide set of standards. These standards give customers the assurance that all products are measured the same, so when figures are quoted, they are all using the same scale. Learn more about the CIPA Standard on our blog.

Compression (lenses)

Lens compression is the effect that using a long focal length lens has on subject matter by 'compressing' the apparent distance between objects. All those famous photos of a huge moon rising over a city looking absurdly out of proportion - that's down to lens compression. It's the same reason why portraits are usually shot with a wider angle lens.

Depth of Field

The depth of field of an image is how much of the image is in focus at any one time. A camera lens can only focus on one single point at any time, but the amount of the image before and after that point that retains focus is governed by the size of the lens aperture. A 'wide open' aperture (f/1.2 for example) will give an extremely shallow depth of field, whereas a small aperture (such as f/22) will give a very long depth of field. Additionally, the depth of field changes depending on the type of lens you use - a wide angle lens will be less affected by changes in aperture, whereas a telephoto lens will experience a more pronounced depth of field.

Digital Image Stabilisation

As opposed to optical image stabilisation, digital image stabilisation works by cropping the image to a portion of the total sensor and digitally moving this image around the sensor to compensate for camera shake.

Filter Thread

On the front of most lenses is a screw thread that can be used to attach filters (and occassionally other accessories) - this is the filter thread and will be usually given in milimetres - for example '52mm filter thread'.


The F-stop (or F/stop or F-number) is a unit of measurement to describe the ratio of a camera lens' focal length to the diameter of the entrance pupil. The f-stop is essentially a calculation, which is why it's always written as, for example f/4. To work out an f-stop number you divide the lens' focal length by the entrance pupil diameter and it's expressed as an equation where the 'f' is the focal length. For example, a 100mm lens with an entrance pupil measuring 25mm will have an f-stop of f/4 (because f/4 means 100mm divided by 4 = 25mm).

Focal Length

The focal length of a camera lens is measured in millimetres and expressed as the widest value to the longest value. For example a lens with a foal length of 24-70mm covers an area from 24mm (relatively wide) and zooms to 70mm (mid-range).

Focal Plane

The focal plane is the point at which light focused by a camera lens reaches the focal point. The focal plane can be moved by focusing a camera lens in and out, and when the focal plane is the same as the shutter plane, the image will be in perfect focus.

Full Frame

A full frame camera is one that uses a sensor measuring approximately 36 x 24mm and is commonly referred to as '35mm full frame' as it is the digital replacement to the 35mm film equivalent.

Lens Adapter

A lens adapter (or adaptor) allows lenses from one manufacturer to be used on another manufacturers camera, or lenses of one size to be used on a camera with a different sized lens mount. For example, there are lens adapters from Metabones and Sigma that allow Canon and Nikon lenses to be used on Sony E-mount mirrorless cameras or Olympus & Panasonic micro four thirds cameras. There are also branded lens adapters, such as from Canon that allow you to use EF-mount lenses on EF-M mount mirrorless cameras.

Lens Converter

A lens converter is used to adapt a lens to a new purpose. Conversion lenses come in many forms, such as adapter rings, wide-angle converters etc. The most common and popular type of lens converter however, is the teleconverter. These are used to extend the focal length ability of a lens by a certain factor, for example a 1.4x converter.


Macro lenses are used to capture images of small objects or objects that are close to the end of the camera lens. There are generally two types of macro lenses; those that are purpose built in order to capture small and intricate details, and those that are classed as ‘macro’ because they have a short closest focusing distance. Learn more about choosing a Macro lens on our blog.

Maximum Aperture

For example: f/2.8 or f/3.5-5.6. If a lens has one number then that is the lenses maximum aperture across its entire focal range (lower numbers have larger apertures and are faster, shorter depth of field but are far more expensive). If a lens has two numbers then the first one eg f/3.5 is its maximum aperture at its widest and the smaller number is its maximum aperture at its longest.

Micro Four Thirds

Micro four thirds is a system developed jointly between Olympus and Panasonic in 2008 with a number of benefits over both DSLR cameras and compact digital cameras. Being mirrorless cameras, they do away with the internal mechanism found in DSLRs which means they are smaller and lighter and the shorter flange distance means the lenses can be mounted closer to the focal plane, offering sharper images from edge to edge.

Minimum Focusing Distance

The minimum focusing distance is what makes a macro lens a macro lens. Any lens can technically be a macro lens if it has a life-size reproduction ratio (1:1) and a short minimum focusing distance. If a lens can’t focus on something close up – it’s likely to be fairly useless as a macro lens.


Mirrorless cameras, alternatively known as CSC or Compact System Cameras, are compact, lightweight, and powerful digital cameras with interchangeable lenses and advanced feature sets. Often compared to Digital SLR cameras in terms of their performance, mirrorless cameras typically use either an APS-C or micro four thirds sized sensor, although some cameras do feature full-frame sensors.

Neutral Density Filter

Neutral Density filters (ND filters) are used in photography to reduce the overall amount of light entering the camera. ND filters don’t affect the hue or colour rendition as the intensity of all wavelengths of light is affected equally. Neutral density filters allow photographers to longer shutter speeds.

Optical Image Stabilisation (O.I.S)

Optical image stabilistion, often called O.I.S or simply IS by some manufacturers, is a system of stabilisation in camera lenses (as opposed to in-body image stabilisation which moves the sensor to compensate for camera shake). Lens based optical image stabilisation systems use a mechanism in the lens to shift the optical path of the image and effectively compensating for shake.

Optical Zoom

Optical zoom is a term typically used in compact and bridge digital cameras to indicate that the lens zooms using optics alone, rather than digital zoom which simply magnifies the image digitally resulting in a loss of quality. Optical zoom changes the focal lenght of the lens and thus maintains a full-resolution image when captured.

Polarising Filter

A polariser filter is used to remove haze and increase contrast in images without the need to do it in photoshop, they will also remove reflections from surfaces such as water by altering how the light enters the camera.

Prime Lens

A prime lens is the opposite of a zoom lens in that it has a fixed focal length. Prime lenses tend to be of higher optical quality than zoom lenses as the lens only has to perform one function at one focal length, rather than performing across a focal range.

Pull Focus

Pull focus is a lens based technique used in filmmaking where the focus point is changed during a still shot. This creative technique is also referred to as Rack Focus, Focus Throw, or Defocus.


See Lens Converters.


A telephoto lens occupies the longer focal length spectrum, generally accepted to be a focal length of 85mm or longer. Just like other lens types, they come in zoom or prime versions, with primes providing the very best image quality. Zooms are extremely popular though, because unlike a prime lens where you are restricted to a very narrow field of view which limits the subject matter you are able to capture, a zoom lens gives you much greater flexibility in your photography. Image stabilisation is a common and well-appreciated feature on telephoto lenses as it cuts down on the shake and vibration within the lens, which is far more apparent at longer focal lengths.


Similar to an f-stop for still camera lenses, a T-stop is used for Cine lenses to describe the relative brightness value of that lens. It stands for Transmission stops and is an equation to express an f-stop number adjusted to account for light transmission efficiency. A T-stop is calculated by dividing the f-stop number by the square root of the light transmittance of that lens. For example, a lens with an f/2.0 aperture with 75% transmittance will have a T-stop of 2.3 because 4 divided by the square root of 0.75 (0.866) equals 2.309. If a lens had 100% light transmittance (which no real lens does), then the T-Stop lens would have the same value as an equivalent F-stop lens.

Ultra-Wide Angle

An ultra-wide angle lens is a lens with a focal length wider than a typical wide-angle lens (so less than approximately 24mm), but not so wide that it is considered a fish-eye lens. An ultra-wide angle lens differs from a fisheye lens in that it will replicate the straight lines in a scene as straight, uncurved lines in the image, minimising the amount of distortion that is typical of a fisheye lens.

UV Filter

UV, or Ultraviolet filters are used in photography to protect sensors from harmful ultraviolet rays. They also protect the front element of a lens against dust, dirt, and accidental damage from scratches. UV and Skylight filters act as sacrificial elements to protect the main, much more expensive, lens.

Wide-Angle Lens

A wide angle lens is traditionally considered to be any lens with a relative focal length of 35mm or wider (but not so wide that it is considered a fish-eye lens). It is worth noting that focal lengths vary depending on the size of sensor the camera is using – so while a 35mm lens will be ‘wide angle’ on a full-frame DSLR, it will equate to a 56mm on a Canon APS-C and 52.5mm on a Nikon APS-H DSLR, and even longer on a micro four thirds or smaller sensor.

Zoom Lens

A zoom lens is the opposite of a prime lens in that it operates over a variety of focal lenghts within a given range, rather than at a fixed focal length.

Canon Lens Abbreviations & Acronyms

How Canon describe their EF and EF-S or L series lenses

find out what canon lens abbreviations and acronyms mean

Canon produce an wide range of lenses for EOS cameras which married with Sigma, Tamron and Tokina gives Canon owners a collosal choice of Canon Fit SLR Lenses. The abbreviations used by Canon are as below.

EF Mount

Electronic Focus. Lens mount fitting the entire Canon EOS DSLR system.

EF-S Mount

As above but only fitting on a Canon's APS-C sized digital SLRs. The S stands for "short back focus," meaning that the back of the lens is much closer to the CMOS sensor than with EF lenses.

Shop for Canon EF-Mount lenses at Park Cameras


USM is Ultrasonic autofocus. There are two types is USM. Micro-USM (a direct replacement for the systems on older FD motors) and a faster 'Ring USM' which includes manual overide.


Diffractive optics. A technology which allows Canon to make lenses with long focal lengths without the normal increase in physical size.


Tilt-shift lens for architectural photography. altering the perspective of converging lines and depth of field. Much like using a style 'Sinar' camera.


Canon's professional lenses. Refers to their optical quality not necessarily anything specificaly functional. Usually white in colour. always havng a red ring around the end.

Find out more about Canon L-Series lenses at Park Cameras


Macro Photo Electronic are for macro work through the use of electronic aperture control.


Image Stabilisation, A system designed to reduce shake. Nikon have their own version called VR (Vibration Reduction) and Sigma use the term OS (Optical Stabilisation).

Nikon Lens Abbreviations & Acronyms

How Nikon describe their FX and DX format digital SLR camera lenses

find out what Nikon camera lens abbreviations and acronyms mean

Nikon also produce a significant range of lenses with their own abbreviations (as below). Sigma, Tamron and Tokina also make Nikon Fit SLR Lenses making the selection almost equally as wide.

AF DC Nikkor Lenses

Defocus-image Control that adjusts the spherical aberration and therefore the blur giving rounded defocussing effect often used in portraiture.


(Close-Range Correction) : Used in fisheye, wide-angle, Micro, and limited medium telephoto, offering high quality at closer focusing distances.

DX Nikkor

As with Canon EF-S lenses, DX lenses are optimised for cameras with smaller sensors. They will fit on other cameras but this is not recommended.


Extra-low Dispersion glass. Gives superior sharpness and optimal colour by correcting the diferences between the angles that blue and red light travel in as they pass through the lens.

FX Nikkor

Similar to Canon's EF-mount, Nikons FX format indicates that the lens is designed for a full-frame sensor camera.

Shop for Nikon F-Mount lenses at Park Cameras


Internal Focusing. the focussing mechanisms are within the lens ensuring the lens remains the same size as focal length is changed.


Lens designed to capture subjects closer to the lens.


No aperture ring. Aperture is adjusted electronically by the camera body.

Nano Crystal Coat

Non-reflective coating for clearer images with increased detail by reducing reflection from inside the lens.


Vibration Reduction : Nikon's version of Canons IS system, designed to cut down on the effects of hand shake.


Perspective Control similar to Canon's Tilt and Shift Lenses.


Rear Focusing. Uses the rear group of lens elements to focus giving faster and smoother AF.

Silent Wave Motor

Silent Auto focussing (as Canons USM)

Sigma Lens Abbreviations & Acronyms

Acronyms and abbreviations for Sigma lenses to fit Canon, Nikon, Sony E-mount and Sigma digital cameras.

find out what sigma camera lens abbreviations and acronyms mean


Pro lenses offering highest optical quality.


Like EF lenses, DG lenses are designed to be used with both full frame and cropped frame sensor cameras. Sigma DG lenses also include additional coatings to reduce reflection.


Short for Digital Crop. They canonly be used on cropped frame cameras. they are also lighter and often less expensive.


Aspherical lens. Smaller than normal lenses.


Apochromatic lenses with low dispersion glass to limit chromatic aberration.

Shop for Sigma camera lenses at Park Cameras


Optical Stabilisation. As Canon IS or Nikon VR.


Hypersonic Motor. As Canon's USM system.


Rear focus. The rear elements are moved for quieter and faster focusing.


Inner focus lenses move the middle lens elements, ensuring the lens remains the same length throughout its focal range. This is useful on longer shots as it reduces hand shake.


Dual focus. Does not rotate while autofocusing.


Can be used with Sigma teleconverters.

Tamron Lens Abbreviations & Acronyms

Acronyms and abbreviations for Tamron camera lenses to fit Canon, Nikon, Sony E-mount cameras.

find out what tamron camera lens abbreviations and acronyms mean


Aspherical Glass.


Anomalous Dispersion. Reduces chromatic aberration.


As Sigma DG lenses, Tamron Di lenses are designed to be used with both full frame and cropped frame sensor cameras.


For APS-C frame sized cameras (as Canons EF-S).


Internal focus. Lens stays the same length reducing hand shake at longer telephoto lengths.

Shop for Tamron camera lenses at Park Cameras


Low Dispersion Glass to reduce chromatic abberation


For focusing on nearer subjects


Super Performance. Tamron's best lens range.


Extra Refractive Glass for improved optical results.


Vibration Control as found on Canon's IS, Sigma's OS and Nikon's VR