What Is Micro Four Thirds? A Beginner's Guide
Micro Four Thirds is a mirrorless camera system built around a 17.3 x 13 mm sensor and a shared lens mount used by Panasonic, OM System, and others. This guide explains what that means in practice, without the jargon.
What Micro Four Thirds actually is
Micro Four Thirds (often shortened to MFT or M43) is a mirrorless interchangeable-lens camera system. It was introduced in 2008 by Panasonic and Olympus as an open standard, which means any company can build cameras and lenses that work together on the same mount. A lens from one brand fits a body from another with no adapter.
The name comes from the sensor format. A Micro Four Thirds sensor measures 17.3 x 13 mm. That is smaller than the APS-C and full-frame sensors used in most other interchangeable-lens cameras, which is the single fact that shapes almost everything else about the system.
The 2x crop factor, explained simply
Because the sensor is smaller, it captures a narrower slice of the scene than a full-frame sensor would with the same lens. This is described as a 2x crop factor. In practice it means you multiply a lens's focal length by two to understand its field of view in full-frame terms.
A 25mm lens on Micro Four Thirds frames the scene like a 50mm lens on full frame. A 300mm telephoto behaves like a 600mm. This is why the system is popular with wildlife and sports photographers: you get a lot of reach from a relatively small, affordable lens.
Who makes Micro Four Thirds cameras and lenses
Because it is an open standard, the lineup spans several brands. The main camera makers today are Panasonic (the Lumix G line) and OM System (formerly Olympus, the OM and PEN lines). Blackmagic also makes Micro Four Thirds cinema cameras.
On the lens side, alongside Panasonic and OM System you will find native options from Sigma, Viltrox, and TTArtisan, among others. Every one of these lenses mounts on every Micro Four Thirds body. Browse the full M43 lens database to see what is available.
- Panasonic: Lumix G stills and video bodies, plus Leica DG branded lenses
- OM System: OM and PEN bodies, M.Zuiko lenses, strong in-body stabilisation
- Blackmagic: Micro Four Thirds cinema cameras
- Sigma, Viltrox, TTArtisan: native third-party lenses
What the smaller sensor means for you
The trade-offs are straightforward. A smaller sensor gathers less light than a larger one, so full-frame cameras have an edge in very low light and can produce shallower background blur. In return, Micro Four Thirds cameras and lenses are smaller, lighter, and usually cheaper, and the crop factor gives you more telephoto reach for the money.
For a deeper look at how the format compares, see the dedicated breakdowns of Micro Four Thirds against full frame and against APS-C.
What Micro Four Thirds is used for
Micro Four Thirds is used across a wide range of photography and video. Wildlife and bird photographers are drawn to the telephoto reach the 2x crop factor provides. Travel photographers value the compact system size. Video shooters, particularly documentary and run-and-gun filmmakers, use Panasonic GH-series bodies for their video feature set and stabilisation.
Macro photographers benefit from the slightly greater depth of field at equivalent magnification. Street photographers use compact M43 bodies like the Panasonic GM and Olympus PEN series because they are small enough to go unnoticed. The system is also widely used in broadcast, cinema, and scientific imaging through the Blackmagic Design cameras and industrial body manufacturers that use the M43 mount.
A brief history of the format
Micro Four Thirds was announced in August 2008 by Panasonic and Olympus. The first camera, the Panasonic Lumix G1, launched in September 2008 with a 12 megapixel sensor. Olympus followed with the PEN E-P1 in 2009. Over the following decade both brands expanded their lineups significantly, and the format attracted third-party lens makers including Sigma, Cosina Voigtlander, and later Viltrox and TTArtisan.
In 2020 Olympus sold its imaging division to Japan Industrial Partners, which rebranded as OM Digital Solutions and continued producing cameras and lenses under the OM System name from 2021 onward. The format remains active in 2026 with new bodies and lenses released each year by both Panasonic and OM System.
Who Micro Four Thirds suits
- Travel and street photographers who want a light, compact kit
- Wildlife and bird photographers who want long reach without huge lenses
- Video shooters who value strong in-body stabilisation
- Anyone moving up from a phone who wants quality without full-frame size or cost
If your priority is the absolute best low-light performance or the shallowest possible depth of field, a larger format may serve you better. For most other photography, Micro Four Thirds is a complete, capable system.