56f1.2 occasionally makes humming sound after acquiring focus

[Mervyn]

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 August 4, 2017 by Mervyn

[Mervyn]

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 August 4, 2017 by Mervyn

[davidquiring]

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?

[jjesp]

Ok, an old thread. But I have this as well on my x--e3. Especially with the xf 27mm, but also other lenses. Happens both in AFS and M with back button focus. The humming sound after focusing, and it does not stop before you press again. Happens about after 10-20 focus attempt.  Did you send it in for repair?

Edited February 17, 2020 by jjesp
spelling

[yukosteel]

It's normal behavior of many Fuji XF lens, I also noticed it on XF 56mm F1.2, 23mm F1.4. Looks like it's related mostly to camera firmware controlling the lens.

[curthard89]

Just chiming in here, I also have this on a X-T5 and a 23mm XF 1.4 R (not the newer model), every 20-30 focus's the motor will just continue to make a noise until you either AEL or AF again (these are both brand new, so was checking to see who else had the issue, relieved its just not just me!)

Here is a video of the "issue", so is this normal? 

Note, this does not occur with the 16mm XF WR 2.8.

Edited December 14, 2023 by curthard89
added more details