I just got this lens the other day and noticed that it makes a vey quiet, yet noticeable grinding sound when focusing manually. Is that normal? It also makes a noise when focusing automatically. I have the panasonic shotgun mic attached to the GH3 for audio recording and it definitely picks up the sound. Is my lens defective or is this normal for this lens? I don't notice it on my 17mm or 45mm, but haven't tested.
Would love some direction on this. You can hear it in this video at around the three second mark - small clicking sounds.
https://vimeo.com/61436718