The operating sound of the lens may sometimes be recorded when shooting movies in certain situations. The mechanical sound is more easily heard when recording movies in a very quiet environment. In most shooting situations it is difficult to hear the operational sound.
If you set the Movie Audio Rec option in the Setup menu to Off, no sound will be recorded during movie recording.
When swinging the camera quickly up and down or from side to side, the noise may be easily recorded. Do not move the camera quickly, but hold it steady during movie recording.
In addition, using of an optional external microphone (sold separately) can help reduce the mechanical noise.