Micro Four Thirds Lenses

Mirrorless Four Thirds standard, introduced in 2008 | Four Thirds digital sensor

Micro Four Thirds removed the mirror box from the earlier Four Thirds DSLR system while keeping the same 4/3-type sensor format. Announced jointly by Olympus and Panasonic in 2008, it shortened the register to mirrorless scale, reduced mount size relative to Four Thirds, and increased electronic contacts for lens-body communication. The result was not merely a smaller Four Thirds body; it was a new mount with different wide-angle and compact-lens opportunities.

The smaller sensor changes optical tradeoffs: equivalent depth of field is deeper at a given angle of view, image circles are smaller, and telephoto reach can be packaged efficiently. Wide-angle lenses also benefit from the short mirrorless register, though very small bodies can make stabilization, heat, and handling part of the system-level compromise. Video use became unusually important to the system, which shaped many zoom, focus-motor, and aperture-control decisions.

The standard's open, multi-maker nature encouraged a broad ecosystem of Panasonic, Olympus/OM System, Sigma, Voigtlander, Laowa, cinema, and specialty lenses. In the catalog, Micro Four Thirds pages show how a mature smaller-format mirrorless system balances compactness, speed, and correction.