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04-18-2015, 10:39 AM   #1
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18-135 AF whine

I purchased a used 18-135 from Japan this week and got in yesterday. The AF is really fast and very accurate from all indications. My only concern with this lens is that when the motor has to move focus by a reasonable amount, there is an audible whine. Not like a gear grinding screech or squeak, just a whine. Not nearly as loud as screw drive, but louder than my Sigma HSM motors. Is this normal with the 18-135 or should I expect failure? All the reviews I have seen mention silent AF, so I was surprised to hear this. It is quieter than my K3 shutter, so it isn;t very loud.


04-18-2015, 11:12 AM   #2
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I just checked mine. Its very very whining sound at all through the whole zoom range. I only have 5 AF lenses and the 18-135 is the quietest by far.
Sorry to make your day worse with the news......lets see what others say ?
04-18-2015, 11:26 AM   #3
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I was afraid of that. It sounds a bit like a servo or RC car. Just checked it against my ring-type HSM sigma and the micro HSM sigma and both are quieter. I can live with the sound, it is exponentially quieter than the screw drive, but I just don't know if this should be a warning sign.


And of course, after scouring the forums using the wrong search terms, I ended up just finding a thread that contained the same issue in question. The video in this thread is exactly the sound I am hearing.

I am surprised this was not detailed further or more recently.

Last edited by willskywalker93; 04-18-2015 at 11:34 AM.
04-18-2015, 11:45 AM   #4
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I'm going to have to change my post. There is an audible whine on mine that isn't present on my Sigma 8-16 HSM. It's barely audible but noticeable. The first image in my library taken with this lens was Aug. 8, 2011... I doubt it means anything. Mine is about the same volume as the K-3 makes when it's locking focus. And the K-3 makes that noise whether Sigma 8-16 or Pentax 18-135, I actually didn't think it was there. I had to actually test the two lenses to understand what you're probably talking about.

The noise is also not present on my SDM lens. It must be a normal function of the DC motors.

Last edited by normhead; 04-18-2015 at 12:02 PM.
04-18-2015, 12:21 PM   #5
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Alright, good to know! I did some more searching on the interwebz and found this youtube video in German (Sounds like it anyway), and his lens makes the same noise.

I feel much better about it now. I can deal with the noise, I just did not want to deal with a failing DC motor, rare as they may be.
04-18-2015, 01:53 PM   #6
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The AF sound in that video is perfectly normal. I think I've only ever come across one or two cases of DC motor failure here on the forum, so chances are you're good to go

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04-18-2015, 01:54 PM   #7
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Thanks, Adam, and thanks everyone!

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