Developed jointly by Olympus and Panasonic, the Micro Four Thirds system was the first true mirrorless interchangeable lens camera system available.

The imaging sensor has an aspect ratio of 4:3, unlike many other cameras that stick to the same 3:2 aspect ratio of 35mm film. There's also a crop factor of 2x, which means a 25mm lens is required to provide the same angle of view of a 50mm lens used on a 35mm camera.

Currently, Micro Four Thirds camera owners have the widest range of lenses to choose from, with lenses from both manufacturers being compatible with all Micro Four Thirds cameras. Due to the wide support this system enjoys, third-party lens and accessory manufacturers such as Sigma and Voigtlander also supply compatible products. Adaptors for a wide range of lenses are available to enable them to be mounted on Micro Four Thirds cameras.

Panasonic Lumix DMC-GX1

Price: £530/$950
Spec: 16MP, 1080p video, 3-inch LCD touchscreen, extensive manual control

Aimed at enthusiasts and experienced photographers, the Panasonic Lumix GX1 sports plenty of manual control options in a compact, rugged metal body. Adjustments can be made via the camera's physical controls or via the 3-inch touchscreen interface.

A resolution of 16MP enables large high-quality prints to be produced, and video can be recorded at 1080p in the popular AVCHD format. Support for SD, SDHC and SDXC cards is also included, providing plenty of storage options.

Although no optical viewfinder is included, an accessory port on the rear enables an electronic viewfinder to be attached with relative ease. Other stand-out features include a maximum continuous shooting speed of 5.5 frames per second (fps) and an electronic level, which will help to ensure your images don't suffer from wonky horizons and leaning buildings.

Read our full Pansonic Lumix DMC-GX1 review

Panasonic Lumix DMC-G3

Price: £480/$650
Spec: 16MP, 1080p video, 3-inch swivel LCD touchscreen, built-in EVF

The Panasonic Lumix G3 squeezes advanced controls, an electronic viewfinder (EVF) and a 3-inch swivel touchscreen interface into a svelte lightweight body with DSLR styling.

20fps continuous shooting is possible at a reduced resolution of 4MP, and a not too shabby rate of 4fps at full resolution, making this camera suitable for capturing fast-moving action.

Generally well received at its launch, the Panasonic Lumix G3 also produces high resolution 16MP images, suitable for reproduction at large sizes, and 1080p video recording in the popular AVCHD format.

Read our full Panasonic Lumix DMC-G3 review

Panasonic Lumix DMC-GF3

Price: £390/ $450
Spec: 12.1MP, 1080p video, 3-inch touchscreen, built-in flash

Currently the smallest, lightest Micro Four Thirds camera with a built-in flash, the Panasonic Lumix GF3 packs a raft of user-friendly features into a slim, compact body with a 3-inch touchscreen interface. Those wishing to travel light will do well to look at pairing the camera with one of the Panasonic range of pancake lenses.

Although this camera is aimed at snap-shooters who like the creative flexibility a compact system camera can offer, manual controls are still available alongside the Intelligent Auto mode and a comprehensive range of pre-programmed scene modes.

12.1MP images provides ample resolution for high-quality prints sized up to around A3, and full 1080p HD video recording is also possible.

Read our full Panasonic Lumix DMC-GF3 review

Panasonic Lumix DMC-GH2

Price: £700/$970
Spec: 16.1MP, 1080p video, 3-inch swivel LCD touchscreen, EVF, 60fps continuous shooting

Although the Panasonic GH2 is an older model, largely superseded by the revamped Panasonic lineup, it is still available. The body is larger and chunkier than the G3, with a deep sculpted finger grip providing a firm hold over the camera. Continuous shooting speeds up to 60fps are possible at reduced resolutions, and 5fps is the maximum rate at the full 16.1MP resolution.

Video recording is the strong point of the GH2. It is possible to record Full HD 1080p video footage at an impressive 60fps. This provides smooth footage, and even opens possibilities for slow-motion replay.

An interesting 3D photo function is also included, enabling you to combine images taken from slightly different viewpoints for viewing back on a 3D-capable television.

Read our full Panasonic Lumix DMC-GH2 review

Olympus OM-D E-M5

Price: £1150 Spec: 16MP, 1080p Video, 3.0" OLED tilting screen, Dust and splash proof magnesium alloy body, Built in EVF

Harking back to the classic design of Olympus OM 35mm SLR cameras, the OM-D E-M5 mixes retro styling with modern sophistication. A 16 megapixel LiveMOS sensor, capable of recording images at sensitivities up to ISO 25600 and full HD video, is encased with a weather-sealed magnesium alloy body with a built-in electronic viewfinder and a tiltable three inch OLED screen.

Being aimed at serious photographers, the OM-D sports quick access to manual exposure functions. A newly developed five-axis sensor-shift image stabilisation system also promises to keep images sharp across the frame by compensations for body movement as well as vertical and horizontal camera movements. This new system also works during video recording.

Read our hands on Olympus OM-D E-M5 review

Olympus PEN E-P3

Price: £690/ $900
Spec: 12.3MP, 1080p video, 3-inch OLED touchscreen, dual control dials, built-in flash

Don't be fooled by the chunky retro styling, the Olympus PEN E-P3 is the most advanced CSC from Olympus to date. Housed in the robust metal frame is a 3-inch OLED capacitive touchscreen to aid quick menu navigation. Capacitive touchscreens tend to be more responsive than the resistive type found on most digital cameras, resulting in a slicker user experience, although it isn't possible to use a non-conductive stylus for greater accuracy.

Aimed at experienced photographers and enthusiasts, two control dials give direct access to shutter and aperture functions when shooting in manual exposure mode. Interchangeable finger grips are available too, to customise handling.

This is the first flagship Olympus PEN model to include a built-in flash, which is handy for fill-in and for illuminating dark scenes. As with all Olympus PEN models, image stabilisation is built into the body rather than the lens, so all lenses benefit from this technology. The 12.3MP Live-MOS sensor provides ample resolution for prints up to A3 in size, and Full 1080p HD videos can be recorded with stereo sound.

Read our full Olympus PEN E-P3 review

Olympus PEN Lite E-PL3

Price: £470/ $620
Spec: 12.3MP, 1080p video, 3-inch tiltable LCD screen, choice of four colours

Taking up the mid-range place in the Olympus PEN range, the E-PL3 combines a compact metal body with a 3-inch tilting LCD screen and is available in a range of different coloured finishes. 12.3MP images can be recorded, as can 1080p videos.

Being so compact, there's no room in the body for a pop-up flash, so a tiny separate flash unit comes included with the camera kit, which attaches to the accessory port on top. This can be left at home if not required, retaining the sleek, compact profile of the camera.

A comprehensive range of manual and automatic exposure programs are at your disposal, along with a range of 'art filters' that apply certain effects to images as they're taken, such as a toy camera effect, or one for dramatic contrast. With these features, this camera suits enthusiasts and casual snap-shooters alike.

Read our full Olympus PEN Lite E-PL3 review

Olympus PEN Mini E-PM1

Price: £370/ $460
Spec: 12.3MP, 1080p video, 3-inch LCD screen, choice of six colours

Currently the most compact of the Olympus PEN range, the E-PM1 sports a slim body, available in one of six colours. The same 12.3MP Live-MOS sensor found in other current Olympus PEN CSCs takes care of image and HD video recording, which means there have been no compromises made in image quality.

A simplified control layout, designed with snap-shooters in mind, makes the camera very simple and straightforward to get to grips with. Easy access to common features such as automatic exposure programs and art filters is provided through the menu.

A Live Guide feature takes you through each setting and how it will affect your images. This can be especially useful for inexperienced snappers, and especially those who would rather not be delving into the instruction manual.

Read our full Olympus PEN Mini E-PM1 review