The Panasonic Lumix G1 SLR-Style Digital Camera is the first camera to use the Micro Four Thirds System standard that greatly reduces camera size and weight to further enhance the inherent advantages of the original Four-Thirds System standard for digital interchangeable lens cameras.

With the Micro Four Thirds System, the camera has a 50% shorter flange back distance (mount-to-sensor distance), and a 6mm smaller lens mount outer diameter.  The camera and the lenses (particularly wide-angle and high-powered telephotos) are able to be smaller with this new standard, without reducing the image sensor's size.  Furthermore, wide-angle lens designs, in particular, will seemingly benefit from not having to clear a mirror inside the camera body-much like rangefinders, where the freedom from retrofocus wide-angle lens design allows higher central resolution and smaller sizes.

The Micro Four Thirds System will also allow users to continue using their present Four Thirds System lenses by adding a mount adapter.

Together with an innovative mirror-less structure that also dramatically downsizes the camera body, the Panasonic Lumix G1 is an incredibly small interchangeable lens camera.