What does the L-Fn button do on a Olympus camera?
Found on the barrel of select Olympus M.Zuiko Digital Lenses, the L-Fn button makes it easy to change shooting settings without taking your eye off your camera’s viewfinder. Quickly activate functions like:
• Auto Focus (AF) Stop
• AF Location Home
• Digital Teleconverter
• Magnify
• Focus Peaking
Source: Olympus US