Metabones has a released a new lens adapter for Panasonic Micro Four Thirds cameras. The Metabones T Speed Booster ULTRA 0.71x adapter will adapt Canon EF lenses to Panasonic MFT cameras like the Panasonic GH4.
The new Speed Booster increases maximum aperture by one stop and makes the lens 0.71x wider than in otherwise would be on the Micro Four Thirds camera. It allows Panasonic Micro Four Thirds cameras to achieve autofocus with either Canon EF lenses. It can be powered by either the camera body or an external 5v power source.
Aperture is also controlled by the camera body and image stabilization is supported on lenses that provide this feature. A detachable tripod foot is compatible with Arca Swiss ball heads.
The Metabones T Speed Booster ULTRA 0.71x adapter retails for $649 and is expected to ship in early October. Check it out here at B&H Photo.