Currently each camera manufacturer adopts their own lens mount for digital SLR cameras, which are based off what was originally a 35mm film SLR mount, resulting in lack of interoperability between different manufacturer’s camera bodies and lenses.

The “Four Thirds System” realizes high image quality and mobility, while simultaneously aiming to increase user convenience by becoming a standardized digital SLR camera system.

At the heart of the Four Thirds System image quality is the lens mount specification of being approximately twice the diameter of the image circle. With this specification providing apt room, the freedom in lens design is greatly improved, allowing for a smaller lens size while simultaneously focusing a perpendicular ray of light on the image sensor even at the perimeter, resulting in a sharp and clear image. In the end, it provides a chance to create greatly improved imaging.

This specification was jointly agreed upon by OLYMPUS CORPORATION and the Eastman Kodak Company in September 2002, followed by the foundation of the “Universal Digital Interchangeable Lens System Forum” aimed at the proliferation of the “Four Thirds System” joint adoption by other manufacturers. Currently this specification has received approval from FUJIFILM Corporation, SANYO Electric Co., Ltd., SIGMA CORPORATION, Matsushita Electric Industrial Co., Ltd. and Leica Camera AG.