Flange 19.25 mm · Micro Four Thirds 2×
Olympus and Panasonic released the Micro Four Thirds standard in 2008, and Panasonic's Lumix G1 came first that October. The sensor has a crop factor of 2, so a lens frames like twice its focal length would on full frame. With a 19.25mm flange, almost any lens with a longer flange can be adapted, and old SLR lenses picked up a cult following on the system. Olympus and Panasonic even sold their own adapters for a few older mounts.