Micro Four Thirds System

The Micro Four Thirds system (MFT or M4/3) is a standard released by Olympus and Panasonic in 2008, for the design and development of mirrorless interchangeable lens digital cameras, camcorders and lenses.
Camera bodies are available from Blackmagic, DJI, JVC, Kodak, Olympus, Panasonic, and Xiaomi.
MFT lenses are produced by Cosina Voigtländer, DJI, Kowa, Kodak, Mitakon, Olympus, Panasonic, Samyang, Sigma, SLR Magic, Tamron, Tokina, Veydra, and Xiaomi, among others.

MFT shares the original image sensor size and specification with the Four Thirds system, designed for DSLRs. Unlike Four Thirds, the MFT system design specification does not provide space for a mirror box and a pentaprism, which facilitates smaller body designs and a shorter flange focal distance, and hence smaller lenses. With adapters, most lenses can be used on MFT camera bodies, including those produced by Canon and Nikon, and lenses produced for cinema (eg, PL mount or C mount).

The image sensor of Four Thirds and MFT measures 18 mm × 13.5 mm (22.5 mm diagonal), with an imaging area of 17.3 mm × 13.0 mm (21.6 mm diagonal), comparable to the frame size of 110 film. Its area, ca. 220 mm², is approximately 30% less than the quasi-APS-C sensors used in other manufacturers' DSLRs, yet is around 9 times larger than the 1/2.3" sensors typically used in compact digital cameras.

The Four Thirds system uses a 4:3 image aspect ratio, like compact digital cameras. In comparison, DSLRs usually adhere to the 3:2 aspect ratio of the traditional 35 mm format. Thus, "Four Thirds" refers to both the size of the image and the aspect ratio of the sensor. However, the chip diagonal is a half inch shorter than 4/3 of an inch. The 4/3 inch designation for this size of sensor dates back to the 1950s and vidicon tubes, when the external diameter of the camera tube was measured, not the active area.

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