Olympus RF11 Ring Flash Tested Fully Working requires an FC-1 Control Unit
Olympus RF11 Ring Flash Tested Fully Working. The RF11 ring flash has a bayonet type mount, which can fit directly onto the old Four Thirds mount Zuiko Digital 14-54mm f/2.8-3.5, or Zuiko Digital ED 50-200mm f/2.8-3.5.