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06-29-2011, 05:29 AM   #1
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Pentax FA31mm focus collar loose and not working

There seems to be an issue with loose focus collars on the FA31mm that will in a short time not engage onto the inner focusing mechanism. Both auto and manual focus will be out of action. This seems to be on the ones from Vietnam so now I consider these to be imposters. PENTAX needs to sort this out. This is a mechanical lens and should not fail. Something has been left loose at the factory that works itself out of place.
IT IS A QUALITY CONTROL ISSUE

06-29-2011, 05:56 AM   #2
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Never heard of this ...
06-29-2011, 06:09 AM   #3
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Ive read quite a number of reports now of AIV FA31's with focus ring problems....
Sending it back for a replacement or refund would be your best option
06-29-2011, 06:24 AM   #4
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If it's under warranty, send it for replacement. For such an expensive lens, a better QC is definitely expected

06-29-2011, 06:55 AM   #5
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True, and this happening in the time when prices is increasing: increasing prices and decreasing quality control. I'm afraid the pentax is about to end.
06-29-2011, 12:24 PM   #6
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Actually loose focus ring is not uncommon with Limited lenses even those were MIJ. All my FA Limited lenses are MIJ and they all suffered from loose focus ring at some point. What happened is that the focus ring is held by 3 small screws which weren't threadlocked sufficiently in the factory. For the FA31, the front retaining ring and the hood have to come off, tighten the screws and threadlock it properly then it will never recur again. MIJ or AIV doesn't really matter.
06-29-2011, 12:38 PM   #7
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QuoteOriginally posted by Emacs Quote
True, and this happening in the time when prices is increasing: increasing prices and decreasing quality control. I'm afraid the pentax is about to end.
No. If Hoya goes under, there will be a major glass shortage. As far as I know, only Canon and Olympus are the major players that makes their own glass blanks. Nikon acquired Hikari Glass in late 2004 and 4 years later Hoya acquired Pentax.

Edit: 3 days after I made this post, Hoya and Ricoh announced 1 jul of Ricoh's purchase of Pentax optics and camera unit effective Oct 1, 2011.

Last edited by Blue; 07-13-2011 at 11:30 AM.
06-29-2011, 03:16 PM   #8
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QuoteOriginally posted by billy moon Quote
There seems to be an issue with loose focus collars on the FA31mm that will in a short time not engage onto the inner focusing mechanism. Both auto and manual focus will be out of action. This seems to be on the ones from Vietnam so now I consider these to be imposters. PENTAX needs to sort this out. This is a mechanical lens and should not fail. Something has been left loose at the factory that works itself out of place.
IT IS A QUALITY CONTROL ISSUE
I work on mechanical cars all day long that have failed. It happens.

06-29-2011, 03:56 PM   #9
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do you think that if the screws have dislodged all the way they could have made contact with the glass?
06-29-2011, 04:00 PM   #10
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All cars fail that is why service departments are always full. Some more than others. BMW and Mercedes always needing service. Ferrari on the other hand, not so often.
06-29-2011, 04:16 PM   #11
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QuoteOriginally posted by billy moon Quote
do you think that if the screws have dislodged all the way they could have made contact with the glass?
Impossible because the glasses are sealed inside the inner metal barrels. The truth it will be a 5 min job if you know how with the proper tools.
07-13-2011, 08:37 AM   #12
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I think i may have just experienced the same issue with my FA77.

While shooting yesterday, the AF suddenly would not focus to infinity and then i heard a grinding sound and when i tilted the camera away from my eye, the front assembly fell off followed by the focus ring. i am shocked and will investigate this further today with Pentax. Doing some research now to figure out why this may have happened. Not sure if it is relevant at this point, but the lens is AIV, for the record.
yikes.
07-13-2011, 10:40 AM - 1 Like   #13
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QuoteOriginally posted by mikeSF Quote
I think i may have just experienced the same issue with my FA77.

While shooting yesterday, the AF suddenly would not focus to infinity and then i heard a grinding sound and when i tilted the camera away from my eye, the front assembly fell off followed by the focus ring. i am shocked and will investigate this further today with Pentax. Doing some research now to figure out why this may have happened. Not sure if it is relevant at this point, but the lens is AIV, for the record.
yikes.
Same issue. The first sign is when the focus ring can be moved forward slightly, or when the lens fails to reach infinity. AIV or MIJ doesn't matter. The problem is threadlock was applied "after" the screws were tightened in the factory. The solution is to soak the screw thread with threadlock beforehand then it will form a secure bond once cured (~1 wk) because the threadlock being used by Pentax is Threebond 1401 which is a low strength threadlock (works great when used properly).

Last edited by wlachan; 07-13-2011 at 10:48 AM.
07-13-2011, 10:50 AM   #14
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QuoteOriginally posted by wlachan Quote
Same issue. The first sign is when the focus ring can be moved forward slightly, or when the lens fails to reach infinity. AIV or MIJ doesn't matter. The problem is threadlock was applied "after" the screws were tightened in the factory. The solution is to soak the screw thread with threadlock beforehand then it will form a secure bond once cured (~1 wk) because the threadlock being used by Pentax is Threebond 1401 which is a low strength threadlock (works great when used properly).
thanks, sounds like this is what happened. Any idea how much it will cost to get it repaired? i obviously cannot do something like this myself.
07-13-2011, 11:04 AM   #15
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QuoteOriginally posted by mikeSF Quote
thanks, sounds like this is what happened. Any idea how much it will cost to get it repaired? i obviously cannot do something like this myself.
I have no idea how much it will cost but probably a standard fee like $120? However, something like this should never happen and you might get lucky with CS. If the dropped front section and the focus ring aren't damaged, you can just put them back together and it will be good as new.

1) Unscrew the front metal retaining ring (on the filter ring) with a piece of rubber (the ring is not tight but getting a good grip can be tricky). You can also get the proper rubber tool on eBay for a few bucks only.
2) Remove 3 small screws that holds the filter ring.
3) Remove the hood.
4) Assemble the focus ring.
5) Assemble the front section and make sure the front lens group is not loose (screw tight by hand will do).
6) You should be able to see the screw marks on the focus ring, just line them up and put back the screws.
7) Check infinity.
8) Threadlock the screws.
9) Assemble the hood and everything else (remember threadlock all screws with low strength threadlock and let them cure for a week at least b4 use).

PS: These are off my head so if the fragile contact brush was damaged, then you will have to send it in.

Last edited by wlachan; 07-13-2011 at 11:11 AM.
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