A digital single lens reflex (DSLR) camera standard from Olympus and Kodak. Introduced in 2002, Four Thirds cameras are smaller and lighter than their DSLR predecessors. Using a large CCD with a 4:3 aspect ratio, the lens mount opening is twice the size of the CCD image circle. Because CCD sensors are set in slightly from the surface of the chip, this lets light enter the CCD at less of an angle in order to reach all sensors more equally. Four Thirds cameras require Four Thirds lenses, and the first camera to employ the system was the Olympus E-1.
Micro Four Thirds - Smaller SLR Cameras
Introduced in 2008, the Micro version relies on the LCD screen for preview rather than the through-the-lens view. The mirror is thus eliminated, which reduces the distance between the lens mount and the sensor and enables a slimmer profile camera to be built. See
mirrorless camera.
Micro lenses are 6mm smaller; however, with an adapter ring, the larger Four Thirds lenses can also be used. See
DSLR.