[help] Nikon D3100 internal Lens AF Motor


#1
Hi owners of D3100,

Have u all experienced before that the AF motor autofocus does not autofocus at the auto mode? While i switch to A mode, it works.

The 'ch chh' sound while the autofocus motor is adjusting has also gone softer.

Have any bros encountered similiar issues before?

Is my lens faulty?

or r there any settings that i have set wrongly?

Thanks in advance
 

#3
Hi mds80

I'm actually using the default lens...

I bought it about a month ago.

previously when in automode, i could feel the AF zooming in and out, but now not anymore, the A mode still works though.. and also with a softer noise
 

ZerocoolAstra

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Mar 13, 2008
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#4
Hi mds80

I'm actually using the default lens...

I bought it about a month ago.

previously when in automode, i could feel the AF zooming in and out, but now not anymore, the A mode still works though.. and also with a softer noise
Which Auto mode is this? Is it the green 'Auto' on the mode dial of the camera?

http://images.brighthub.com/ba/b/baba7b884bb83f441f1960a60e369db18022478b_small.jpg

Or is it the 'A M' switch on the lens itself?

http://www.kenrockwell.com/nikon/18-55-ii/D3S_4471-side.jpg


If you're referring to the kit lens 18-55mm f/3.5-5.6, the front focusing ring should be turning whilst the lens is focusing.
 

Last edited:
#5
in the past, i had the mode dial on the green auto and with A mode on the lens, the autofocus could work.

However, now i had to switch to both mode dial on the A and with A mode on the lens to 'feel' the AF auto-adjusting.

and my biggest concern is the strange chh chh sound while focusing.. when it was well and good, the noise was louder and crisp. now there is like a jammed soft sound.
 

rhino123

Moderator
Staff member
Sep 1, 2006
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#6
in the past, i had the mode dial on the green auto and with A mode on the lens, the autofocus could work.

However, now i had to switch to both mode dial on the A and with A mode on the lens to 'feel' the AF auto-adjusting.

and my biggest concern is the strange chh chh sound while focusing.. when it was well and good, the noise was louder and crisp. now there is like a jammed soft sound.
Not sure what is the problem... but the simplest way was to take it down to the NSC for testing and checking.
 

ZerocoolAstra

Senior Member
Mar 13, 2008
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#7
Just note that the mode dial on the camera has nothing to do with auto-focusing.

I recall once before during a sunrise outing, one of the newbies had pressed a button like 'AF-L' or something, which locked the focus and prevented the AF from doing its thing. Not sure if D3100 has this feature.

The sound is another matter though. Perhaps foreign object kena stuck. Better be a bit more careful.
 

Oct 12, 2011
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#8
Strange for the AF mechanism to get jammed when it's so new. Either there's something stuck or it's a lemon.
 

Octarine

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Staff member
Jan 3, 2008
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#10
Strange for the AF mechanism to get jammed when it's so new. Either there's something stuck or it's a lemon.
But it's also only he kit lens: cheap and simple. The Canon equivalent has issues with the flexible ribbon cable. If it's newly purchased (means: still covered by warranty) just bring it to Service Center.
 

dougs

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Jun 7, 2010
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#11
did you locked the AF point?
 

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