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56f1.2 occasionally makes humming sound after acquiring focus

56mm 56f1.2 sound focus motor hum

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#1 Mervyn



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Posted 04 August 2017 - 12:41 PM

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I recently reacquired the Fuji 56f1.2. It's a fantastic lens and I should never have sold it.


However, my new copy of the 56 occasionally makes a humming sound that persists after acquiring focus in AF-S mode. I don't recall my old 56 ever doing this on my X-T2 so now I'm slightly concerned.


For the rest there doesn't appear to be anything wrong with it.


At about one in a 20 shots, especially at minimum range (though I've also had it happen at infinity), the auto-focus motor keeps humming after acquiring focus. Sometimes it stops after a few seconds, but I've also had occasions where it wouldn't stop until I'd press the focus button again or switch off the camera. It happens in AF-S mode.


My question is: do other people with the 56 experience this occasional after-focus hum as well, or could it be that I got a bad copy? And my second question is; could it possibly damage or shorten the lifespan of the lens when the autofocus motor keeps running after acquiring focus? I would hate to have the lens work for two years and then break just after the warranty has expired. And my last question: would you keep it and try your luck, or would you return it to the shop and exchange it for another copy?


Edit: Problem solved, see my post below.

Edited by Mervyn, 04 August 2017 - 07:52 PM.

#2 Mervyn



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Posted 04 August 2017 - 07:52 PM

To answer my own questions: Never mind, because I just discovered that my 3 year old 23f1.4 does the exact same thing! Once every 20-30 shots or so I can hear a soft humming sound from the autofocus motor that persists after it has acquired focus in AF-S mode. So I'm relieved. Because it's a new lens I pay extra attention to these things. But because my old 23 does it too, hey, I guess it must be normal. :-)


My guess now is that it's not the lenses at all; rather I think it could be the camera (X-T2) that somehow is still giving a small current to the autofocus motor of the lens after having already acquired focus. But it happens only once every 20-30 shots or so, and most often it won't happen at all. I think it's not a physical problem but rather something firmware related. Could be a small bug, but likely nothing too serious. Actually it's a very soft hum, hardly noticeable, but it's there. Much softer then the usual autofocus noise. Did anyone else notice this?

Edited by Mervyn, 04 August 2017 - 07:55 PM.

#3 davidquiring



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Posted 13 February 2018 - 02:49 AM

Hey Mervyn,


I think I have the exact same issue on 2 of my 3 lenses: the 16mm 1.4 and 56mm 1.2, but not the 55-200mm.


Approximately every 20 times I focus on something with back button AF, single point focus, and instant AF setting set to AF-S, there is a persistent humming sound of the autofocus motor until I either focus again or press the playback button. It is disconcerting for sure.


Did you end up living with it on your X-T2? Did it ever escalate into something more? Or did you send your camera back for Fujifilm to take a look?

Also tagged with one or more of these keywords: 56mm, 56f1.2, sound, focus, motor, hum


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