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09-20-2011, 12:57 PM   #1
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FA 31mm Grinding sound

hi guys got my fa 31mm yesterday.

when i turn the focus ring in manual focus, there are some grinding noise to be heard.

some of the replies were that it was the gears moving.


my question is that does everyone thinks that its normal.? or is there some kind of defect present inside the mechanism..?

i have another fa the fa 50mm 1.4 and it does not exhibit this kind of grinding sound when in manual focus.

please advise on my investment.

* added video*

VID_20110920_131245~1.avi

sorry for the poor quality video.


Last edited by rx7ong; 09-20-2011 at 01:24 PM. Reason: Video added.
09-20-2011, 01:05 PM   #2
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Mine exhibits only the faintest "grinding" sound and I am certain that this is normal. It has to be nearly silent in the room to be able to hear it. It does indeed seem to be the gears turning. Have no idea how loud yours is, but I wouldn't think comparing an FA with a FA Ltd. would do you any good.
09-20-2011, 01:40 PM   #3
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If you turn camera to vertical shooting position, do you still feel that noise? It could be due to roller/gear tolerance. I have seen one that has same noise but works fine. If turn camera to vertical shooting position with lens attached, noise was gone.

I heard some FA Ltds show this feeling while others don't. Is yours new or used?
09-20-2011, 01:47 PM   #4
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QuoteOriginally posted by hyyz Quote
If you turn camera to vertical shooting position, do you still feel that noise? It could be due to roller/gear tolerance. I have seen one that has same noise but works fine. If turn camera to vertical shooting position with lens attached, noise was gone.

I heard some FA Ltds show this feeling while others don't. Is yours new or used?
yes if turn to vertical the noise disappears.

mine is new from B&H.



09-20-2011, 02:21 PM   #5
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Did you put the camera's selector to "Manual Focus"?
09-20-2011, 02:26 PM   #6
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QuoteOriginally posted by Parallax Quote
Did you put the camera's selector to "Manual Focus"?
Yes =)

probably contact B&H see what can be done about it..
09-20-2011, 03:17 PM   #7
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No, this is not normal, though practically nothing wrong with it. The major inner metal barrels should be made very smooth and sliding in and out without fiction. What happens to your lens is that one of the barrels isn't smooth enough so when they slide against each other, it grinds. It should be exchanged (not repair) for certain.
09-20-2011, 03:54 PM   #8
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If you have an optically excellent example, I definitely would not exchange it. It's just not that big of a deal. Btw, the "grinding" that I hear could not possibly be coming from barrel friction. That just wouldn't make this kind of sound. This is almost a reassuring mechanical sound.

09-20-2011, 08:19 PM   #9
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Bought a DFA 100 recently from B&H and it had a bad grinding sound and initially was hard to turn the focus ring. Eventually broke free but still had an ever so slight grinding feel to it. Sent it back and replacement had none of the above. So I did get a bad copy first time. Send it back and just get a replacement. Dave
09-21-2011, 02:40 AM   #10
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thx for the help guys.

contacted B&H for a RMA for replacement.

^^
09-24-2011, 10:50 PM   #11
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hmm, just listened to mine in complete silence and i can hear the faintest little tapping of gear teeth, presumably. It sounds like a normal sound and there is no unusual resistance anywhere throughout the focus throw. You describe your sounds as grinding which does not sound normal.
09-25-2011, 01:15 PM   #12
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QuoteOriginally posted by mikeSF Quote
hmm, just listened to mine in complete silence and i can hear the faintest little tapping of gear teeth, presumably. It sounds like a normal sound and there is no unusual resistance anywhere throughout the focus throw. You describe your sounds as grinding which does not sound normal.
That's exactly what mine sounds like, too. Description of sounds, though, is an inexact science. That exact sound could have been described as grinding by the OP.
09-25-2011, 07:59 PM   #13
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QuoteOriginally posted by DogLover Quote
That's exactly what mine sounds like, too. Description of sounds, though, is an inexact science. That exact sound could have been described as grinding by the OP.
he has since posted a video to the original message and it sounds dreadful; definitely a candidate for replacement.
09-26-2011, 04:16 PM   #14
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Looks like I've been supplied one with the same issue. It's also a bit backfocussed (+6 correction fixes this). Taking it back to the shop tomorrow. :-(
09-26-2011, 05:34 PM   #15
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QuoteOriginally posted by -Mous- Quote
Looks like I've been supplied one with the same issue. It's also a bit backfocussed (+6 correction fixes this). Taking it back to the shop tomorrow. :-(
Sorry to hear this. From my own experience and reading these forums, the FA31 is one lens to buy locally (or from a reputable seller with a good return policy) and test hard before accepting.
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