The AC-FC500 is a set to replace the default focus knob with a knob that accepts the include Focus Whip with a length of 50 cm.

Using the AC-FC500 set allows you to focus without directly touching the Actus body. The Focus Whip is a flexible cord with a large knob at the end. For normal use the whip is easily detachable. Examples of practical use are with shooting video, or when a picture is needed to be taken at a critical focussing point that constantly moves. As the flexible whip can be bend over 180 degrees, it can also be used to use the left hand for focussing while holding the right hand ready for action...