Source: Wikipedia. Pages: 33. Chapters: Olympus OM-D E-M5, Olympus PEN E-P1, Olympus PEN E-P2, Olympus PEN E-P3, Olympus PEN E-PL1, Olympus PEN E-PL2, Olympus PEN E-PL3, Panasonic Lumix DMC-G1, Panasonic Lumix DMC-G10, Panasonic Lumix DMC-G2, Panasonic Lumix DMC-G3, Panasonic Lumix DMC-GF1, Panasonic Lumix DMC-GF2, Panasonic Lumix DMC-GF3, Panasonic Lumix DMC-GF5, Panasonic Lumix DMC-GH1, Panasonic Lumix DMC-GH2, Panasonic Lumix DMC-GH3. Excerpt: The Micro Four Thirds system (MFT) is a standard created by Olympus and Panasonic, and announced on August 5, 2008, for mirrorless interchangeable lens digital cameras and camcorders design and development. However, unlike the preceding Four Thirds System, it is not an open standard. 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, allowing smaller bodies to be designed, and a shorter flange focal distance and hence smaller lenses to be designed. Virtually any lens can be used on MFT camera bodies, as long as an adapter exists. For instance, Four Third lenses can be used with auto focus using the adapters designed by Olympus and Panasonic. Drawing showing the relative sizes of sensors used in most current digital cameras, relative to a 35mm film frame.The image sensor of Four Thirds and MFT is commonly referred to as a 4/3" type or 4/3 type sensor (inch-based sizing system is derived from now obsolete video camera tubes). The sensor 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 40% less than the APS-C sensors used in other manufacturers' DSLRs, yet is around 9 times larger than the 1/2.5" sensors typically used in compact digital cameras. The Four Thirds system uses a 4:3 image aspect ratio, in common with other compact digital cameras but unlike APS-C or full-frame DSLRs which usually adhere to the 3:2 aspect ratio of the traditional 35 mm format. Thus "The Four Thirds refers to both the size of the imager and the aspect ratio of the sensor". Note that actual size of the chip is considerably less than 4/3 of an inch, the length of the diagonal being only 22.5 mm. The 4/3 inch designation for this size of sensor dates back to the 1950s and vidicon tubes,