It has been reported that some lenses with VR (Vibration Reduction), IS (Image Stabilization) and lenses with OIS (Optical Image Stabilizer) produce some noise.
On Canon and Nikon lenses, noise appears when the image stabilization (or VR,IS, ...) mechanism is activated, for example when the shutter is half pressed.
But on some Fuji lenses, the sound appears as soon as the camera is turned on and is permanent, no matter the camera or lens settings (OIS on or off, AF on or off...). On the fuji XF 50-140mm the sound is like some sort of annoying white noise sound, which could remind of a stream in the mountains but is higher pitched and far from being as soothing and pleasant.
The sound may be produced by some form of a permanent feedback loop to allow a movable lens element to "float" in the air, but does any one know what is, precisely, the origin of the sound? And why it is permanent on Fuji lenses with OIS?
It makes me think of a door maintained open by an electromagnet, sometimes the electromagnet will produce a vibrating sound.