A mirrorless camera (sometimes called a “Micro Four Thirds” camera) is a small, interchangeable lens camera (ILC) that uses the Micro Four Thirds image sensor format. It was first introduced in 2008 as an alternative to the DSLR (digital single-lens reflex) camera. These cameras are very popular in Japan and China, and have recently become more common in the rest of the world. In fact, all major DSLR Camera manufacturers now have a mirrorless camera in their line up.