fourthirds
FourThirds (4/3) is a proprietary camera standard for digital cameras with interchangeable lenses. It was developed by Olympus and Kodak for digital SLR cameras and their interchangeable lenses and licensed by some well-known photo companies. The name Four Thirds (4/3) is derived from the image sensor, namely 4/3". A 4/3"image sensor has a size of 17.4 mm x 13.1 mm.
Digital cameras with interchangeable lenses in the 4/3" concept are more compact and offer interchangeability of the interchangeable lenses with those of other manufacturers.
The Micro FourThirds concept developed from the FourThirds concept is characterized by an even more compact design, because this technology works without the oscillating mirror used in SLR cameras. This redirects the image captured by the lens to the optical viewfinder. In its place is EVIL (Electronic Viewfinder, Interchangeable Lens), an electronic viewfinder and interchangeable lens mount. In addition, the Micro-FourThirds concept has smaller interchangeable lenses. These two measures halved the distance between the interchangeable lens and the CMOS sensor.
FourThirds interchangeable lenses can only be attached to Micro-FourThirds cameras with a special adapter.