X-Pro1 : Noise... not in the image but in the camera

Hello,

My configuration is the following : X-Pro1, Fujinon 18-55, auto focus single, OIS type 1

If I listen carefully to my camera when power on and AF not active (no shutter release half pressed neither AE-L/AF-L ) it is (the camera or the lens) slightly noisy, just as a small engine is running inside and that with OIS on or off.

Do you hear the same ? What is it ? And what could be the impact on the battery charge lifetime which I feel abnormally short when using this combination body-lens.

Thank you.

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Cheers - Philippe