Compact System/Mirrorless Cameras
DSLR quality in a smaller package
Mirrorless Cameras, Compact System Cameras, or CSC cameras all share the features of a DSLR apart from the direct through-the-lens viewing provided by the SLR's mirror and ground glass viewing screen.
By eliminating the mirror, the camera can be made in a far more compact form. This also extends to the design of the lenses meaning much smaller, lighter and faster models. The short flange distance from the rear lens element to the sensor means that with the use of adaptors, you can use pretty much any old SLR or rangefinder lens on your camera!
The Leica and Sony Alpha FE and E mount cameras use a mix of both Full frame and APS-C sized sensors found in professional DSLRs. The Fuji X and new Canon EOS M ranges all use APS-C sized sensors found in enthusiast level DSLR cameras. Panasonic Lumix G Series cameras use a slightly smaller Micro 4/3 sensor. The Nikon 1 system uses its own even smaller sensors and lens mounts.