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03-28-2013, 01:13 AM   #46
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QuoteOriginally posted by bossa Quote
could you indicate if these lenses were bought locally through a store new or used via eBay and/or if they were parallel imports?
I'm not sure why it's relevant, but for the record....

FA77 new from a B&M store in Adelaide.
DA40, DA15, DA21 and FA31 new from B&H or Adorama in three separate transactions at opportunistic prices in the first quarter of last year.
FA43 and DA70 second hand via the Forum marketplace a couple of months later.

They have all been great lenses. The only two I would consider moving on (but I'm happy to keep specifically for the K-01) are the DA40 and DA70, not because of poor performance but simply because I prefer the rendering of their FA brethren.

03-28-2013, 02:22 AM   #47
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QuoteOriginally posted by wlachan Quote
The difference between the FA31 and other Pentax small primes is that the latter have fixed group design, while the FA31 is a floating design.

A fixed group lens moves the whole inner barrel forward or backward to focus. While the while lens group might not be perfectly perpendicular to the sensor due to wobbliness, the optical alignment of the lens itself is maintained.

The FA31 however is different. 3 lens groups are moving independently of each other, and the front or the rear group (or both) may wobble due to less than perfect inner barrel dimensions (a rather loose manufacturing tolerance to reduce cost imo because imprecise barrels were not discarded). Since the dimensions of the inner barrels are fixed, the only way to address the problem is to identify and replace that(those) imprecise barrel(s) (there is nothing to be calibrated by screw etc). For service centers outside Japan, it is quite unlikely they would go this route as it will be time consuming and a hit & miss approach and may take forever because you never know how precise the new barrels will be from Japan. So they might just return your lens claiming it was within spec, or just give you a new one.

As to whether the front or rear lens group affects the optical alignment, I strongly believe it does, and I tested a few of them to confirm, especially at wide open. Whether it matters to anyone depends on your experience, expectation, subject matters, and how bad the lens is. Like the DA16-45/4, I feel Pentax had made a huge mistake by not making them probably because the optical designs are very fine. Then again, I am probably the minority to really care I guess.


Wow. This makes me wonder if I should head over to Tokyo Pentax service centre when I am there on vacation and get them to fix the wobble on my FA31mm. Wonder if they would charge or I can say its a manufacturing defect?
03-28-2013, 02:31 AM   #48
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QuoteOriginally posted by gtl Quote
Wow. This makes me wonder if I should head over to Tokyo Pentax service centre when I am there on vacation and get them to fix the wobble on my FA31mm. Wonder if they would charge or I can say its a manufacturing defect?
Lens natually aren't supposed to wobble, so this "defect" sounds like a lack of quality control to me. I don't think that they have the right to charge you for that (if still under warranty).
03-28-2013, 02:33 AM   #49
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QuoteOriginally posted by gtl Quote
Wow. This makes me wonder if I should head over to Tokyo Pentax service centre when I am there on vacation and get them to fix the wobble on my FA31mm. Wonder if they would charge or I can say its a manufacturing defect?
Good luck with that! I am 100% certain Pentax don't consider it a defect (so to millions of misaligned lenses out there by different manufacturers). I would imagine they might look at you like an alien when you tried to explain why.

03-28-2013, 02:34 AM   #50
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QuoteOriginally posted by Apapukas Quote
Lens natually aren't supposed to wobble, so this "defect" sounds like a lack of quality control to me. I don't think that they have the right to charge you for that (if still under warranty).
Unfortunately many do since the AF era, most by design, the FA31 by chance.
03-28-2013, 02:39 AM   #51
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QuoteOriginally posted by wlachan Quote
Good luck with that! I am 100% certain Pentax don't consider it a defect (so to millions of misaligned lenses out there by different manufacturers). I would imagine they might look at you like an alien when you tried to explain why.
I contacted Pentax about that:

"A very slight amount of play in the front ring of the lens is not unusual but if your FA 31mm limited lens appears to have more than this I recommend you return your lens directly to PENTAX Imaging Company at the address listed below for examination."

Just... what is slight? How it is measured?
03-28-2013, 02:44 AM   #52
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QuoteOriginally posted by Apapukas Quote
Just... what is slight? How it is measured?
I think the answer is, if still under warranty and if it bothers you, send it back to Pentax.

As long you can afford to be without it for a wee while.
03-28-2013, 02:49 AM   #53
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QuoteOriginally posted by Apapukas Quote
I contacted Pentax about that:

"A very slight amount of play in the front ring of the lens is not unusual but if your FA 31mm limited lens appears to have more than this I recommend you return your lens directly to PENTAX Imaging Company at the address listed below for examination."

Just... what is slight? How it is measured?
Highly subjective I am afraid. I bet if you tried 5 samples and they would vary in the amount of wobbliness. I would be curious in how they might fix the lens if you sent it in.

03-28-2013, 03:08 AM   #54
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QuoteOriginally posted by wlachan Quote
Highly subjective I am afraid. I bet if you tried 5 samples and they would vary in the amount of wobbliness. I would be curious in how they might fix the lens if you sent it in.
If all 31Ltd's had this wobble, it would be normal. Then Pentax could claim that this "feature" does have something to do with lens design or something. But... because other 31 Ltd are nice and tight, this wobble really doesn't look like a "necessary feature"
03-28-2013, 04:17 AM   #55
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Pentax Australia are offering 15% discount on lens buys via their Facebook page over the Easter weekend. I just bought a FA 31 Limited for AU$861 delivered to my door whereas only last month I had a chat to the local rep' and the price was still $1695 - I don't know what's changed (apart from the fact that CR Kennedy are Pentax Australia and they also distribute Sigma lenses (35/1.4)). unfortunately I'm flat broke now and can't grab the other two lenses I am interested in.
03-28-2013, 06:19 AM   #56
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QuoteOriginally posted by bossa Quote
I just bought a FA 31 Limited for AU$861 delivered to my door whereas only last month I had a chat to the local rep' and the price was still $1695
What a deal...for a great lens!
All my Pentax lenses are imported from bhphoto. Never have a problem with them. FA31 is my favourite lens for K5....
03-28-2013, 06:57 AM   #57
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QuoteOriginally posted by bossa Quote
Pentax Australia are offering 15% discount on lens buys via their Facebook page over the Easter weekend. I just bought a FA 31 Limited for AU$861 delivered to my door whereas only last month I had a chat to the local rep' and the price was still $1695 - I don't know what's changed (apart from the fact that CR Kennedy are Pentax Australia and they also distribute Sigma lenses (35/1.4)). unfortunately I'm flat broke now and can't grab the other two lenses I am interested in.
How did you get a price of $831? They are selling the lens for $1,200, 15% off still leaves a price of $1,020.
03-28-2013, 08:14 AM   #58
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I am seriously struggling to ward off my temptation to buy this used copy with a 'very slight wiggle' and save $150... It doesn't help that B&H is closed until April 3rd! lol.. I know buying new is the better path, so I am kind of hoping this used copy sells to somebody else before my funds are ready tomorrow.

Does Adorama have the same return policy as B&H? (The price is the same)
03-28-2013, 09:00 AM   #59
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Ouch now he told me he knocked another $50 off the price... Any of you happy FA31 wobblers out there, now is your time to speak up!
03-28-2013, 10:09 AM   #60
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QuoteOriginally posted by todd Quote
Ouch now he told me he knocked another $50 off the price... Any of you happy FA31 wobblers out there, now is your time to speak up!
Even with a slight wobble, FA31 is still sharp at f1.8 and very sharp by f2.8. This compares with very sharp from wide open and razor sharp by f2.8 for non-wobbler. The difference is not noticed unless you view at 100%. You would need to test the lens yourself to see if the sharpness is acceptable to you at wide open. Wobbler does feel less solid, however. The non-wobbler feels like a solid brick in comparison, much like how CZ feels (CZ feel indestructible)
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