A camera system announced by Olympus and Kodak in 2002. It was a DSLR system with a sensor smaller than APS-C and an aspect ratio of 4:3. Most DSLRs used a 3:2 ratio. The sensor gives a crop factor of about 2. The first camera was the Olympus E-1 in 2003.
The last Four Thirds camera was the Olympus E-5 in 2010. The system was replaced by Micro Four Thirds, a mirrorless system from Olympus and Panasonic introduced in 2008. It uses the same sensor size but has no mirror, so the cameras are smaller.
Do you have a better definition? Share it in the comments.
