PMA 2009 saw the announcement of this lens for the micro-four-thirds system. The lens is very small and uses a complex design of 16 elements in 12 groups, with 2 aspherical elements. As the four-thirds system mount produces a 2x ''crop factor,'' the lens produces an effective field of view of 14-28mm when mounted on a Panasonic G-1 or GH-1.
The lens features a constant ƒ/4 aperture and a fixed lens hood; the large protruding front element precludes the use of screw-mounted filters. Read the whole review here