O的M9-18和14-150都是对视频优化了的 http://www.olympus-global.com/en/news/2010a/nr100203zuikoe.html # Circular aperture mechanism A circular aperture mechanism is used to assure smooth, even background defocusing. # Superior operating ease High-speed autofocus The inner focusing mechanism uses a light, compact, single-element unit to enable exceptionally fast, quiet autofocusing for smooth, stress-free still- image and movie shooting. Smooth manual focus The manual focusing mechanism is designed to offer a