In 2008, Olympus and Panasonic announced a new camera format that made mirrorless, interchangeable lens camearas possible. This system is built on the four-thirds system, and has many of the same advantages and disadvantages. However, the specifications remove the mirror box and pentaprism, allowing for even smaller camera bodies and lenses to be designed.
The micro four-thirds system specifies a new lens mount with a focal distance of under 20mm, which is half as deep as the focal distance for lenses conforming to the four-thirds system. Because the wide lens mount, the system allows for the use of existing lenses with the use of adaptors.
Because of the removal of the mirror and viewfinder, all viewing from the photographer is done using the camera's LCD screen, or in some models, a built-in electronic viewfinder, which can be helpful when a typical LCD screen becomes hard to read in bright sunlight.
The micro four-thirds format also specifies contrast-detection autofocus, which is favored in point and shoot cameras, instead of phase-detection autofocus, which is generally used in digital SLR cameras.
Micro four thirds cameras fill the camera market between super high-quality SLR cameras, and small, highly portable point-and-shoot cameras. Because of the benefits afforded by this new range of camera, expect this system to continue to grow, improve, and gain broader acceptance.