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07-31-2010, 04:12 AM   #1
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31mm - How loose is too loose?

Hello. This week I received a new 31mm from B&H. I have read the posts about possible QC issues about the new Vietnam-assembled 31s, but I wasn't concerned. Should I have been?

The focusing barrel - not the ring, the actual barrel that extends forward when focusing - is noticeably loose. Not really, really loose, but loose enough. It's hard to quantify. When fully extended, if I firmly grasp the lens body and give it a gently shake, you can hear it wobbling. I'd say it's about as loose as the barrel on my Sigma 105mm macro when it's about half extended. My other primes - K50/1.2, FA77/1.8(MIV), A100/2.8 - are rock solid in this respect.

I plan to send it back unless I hear from others that this is normal behavior for this particular lens. I would be surprised if that were the case considering its cost and reputation. Please let me know what you think. Thanks!

- Mike

07-31-2010, 05:22 AM   #2
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I don't think that this kind of behavior is normal. I'd exchange the lens if I were you.

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07-31-2010, 05:44 AM   #3
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Mine has hardly any play in it, but it is an older model. A wonderful lens to have.
Better to deal with B&H then pentax service.
07-31-2010, 10:44 AM   #4
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No play at all in my silver Made in Japan FA31.

07-31-2010, 01:56 PM   #5
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QuoteOriginally posted by mmphilp Quote
Hello. This week I received a new 31mm from B&H...The focusing barrel ... is noticeably loose. Not really, really loose, but loose enough. It's hard to quantify. My other primes -..., FA77/1.8(MIV), ... - are rock solid in this respect.

I plan to send it back unless I hear from others that this is normal...
The new black FA 31 I received from B&H this week is as tight as my FA 77. Both are marked "Made in Japan." The 31's SN is 0023XXX. Earlier I saw a 2008 rave review where the SN of the subject was 0028XXX, so I don't know the age of my copy. Looks like B&J has been out beating the bushes for product and I lucked out.

May I suggest that you make sure you are not just suffering from "buyer's remorse," a common affliction we all get when we pay close to retail for something considered really expensive? Quickly give it a good workout and verify its ability to deliver satisfactory IQ. With mine, I needed an AF adjustment of -2 on my K-7. Now, when stopped down and locked on focus, it's so sharp that I'm almost afraid I'll cut my cornea. All lenses have a learning curve. For me... so far, so good.

Anyway, I understand... Like you, I figured the MIJ 31 edition was no longer available. When I placed the order, I was not overly concerned about getting a Vietnam version based on other user reports. B&J has a reputation for being fair, honest and treating their customers right, so I'm sure all will turn out OK for you.

Good luck and cheers...
07-31-2010, 02:34 PM   #6
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I have handled a few FA31 all MIJ, also owned 2 over the years. Only one sample had firm front section, the rest were kind of loose in varies degree. The one I have now is somewhere in the middle. You have to realize that though the finish appears similar to other Pentax primes, the FA31 has no helical at all. The front section is supported by 2 smooth inner barrels guided and retained by 3 teflon rollers. Similar design can be founded on many FA lenses with IF. If you shake them, they exhibit the same wobbliness. Whether yours is looser is hard to judge w/o comparing to other samples.

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