[Aegon]

Around 2008 or 2009, assembly was moved to Vietnam and many people showed up on the forums with decentered or otherwise bad AIV copies. A search from that time period will provide examples.

I believe that when assembly was moved, quality control was not yet properly established, and AIV lenses from that period were more likely to have issues.

I also believe that quality control problems were fixed and over time AIV lenses should be on par with MIJ lenses.

Therefore, as a rule, I don't want to buy an early run AIV lens. The best way to enforce my rule is to not buy AIV FA LTD lenses at all, because I don't have the means to distinguish the early runs from subsequent runs.

YMMV

[reeftool]

Good products can be made anywhere as can bad ones. I now have several AIV lenses with no issues. The only Pentax lens that has ever broke on me is a MIJ F-35-70 where something came apart inside and it no longer zooms or focuses. I bought it used for cheap enough but am disappointed because the IQ of that lens was outstanding. I'll probably buy another.

[wlachan]

I have MIJ FA43mm and it is miles better than my AIV FA31mm, which frankly is too soft and requires a large micro adjustment. This is just my experience. Have never seen the MIJ FA31mm to compare it to. I did see some fantastic AIV FA31mm images on this forum posted by someone who rented the FA31 for travel.

Were any of the bad MIJ copies you came across later serial numbers? I've read somewhere that the best FA31mm were those with early serial numbers.

FA43/77 & FA31 are built differently. Essentially the 1st 2 are based on the M/A helicoil design and misalignment is less likely to happen because the whole lens group moves as a single unit. The 31 have 3 lens groups moving independently and are all screwed together with rollers and smooth barrels. This design requires very high precision on parts manufacturing, or at least screening afterward. IMHO Pentax fail on both, after disassembled a few samples to see what went wrong myself. This lens can be awesome, but translating the design into production is another matter.

I bought my 1st FA31 around 2003, and checked out 3 samples locally. All of them had wobble hood and the one with firm hood, the front element was scratched (and scratched inner elements is rather common with Pentax new lenses). Over the years I have come across around 6-7 samples, and the latest one was AIV black this year. Whiny focusing mechanism due to defective barrel. There have been many more brand new MIJ defective cameras and lenses I have come across over the years, more than I would like to believe. If not for the fact that I can address some of them myself, I would probably not using Pentax now (I have to admit that I have more fun fixing lenses/cameras than actual shooting).

Around 2008 or 2009, assembly was moved to Vietnam and many people showed up on the forums with decentered or otherwise bad AIV copies. A search from that time period will provide examples.

I believe that when assembly was moved, quality control was not yet properly established, and AIV lenses from that period were more likely to have issues.

I also believe that quality control problems were fixed and over time AIV lenses should be on par with MIJ lenses.

Therefore, as a rule, I don't want to buy an early run AIV lens. The best way to enforce my rule is to not buy AIV FA LTD lenses at all, because I don't have the means to distinguish the early runs from subsequent runs.

YMMV

I think what actually caused the surge of complaints is the popularity of DSLRs which allow consumers to discover misalignment and BF/FF easily, something not quite obvious with film cameras. I have purchased a # of FA lenses since 1999 and have come across many defective samples, all expensive MIJ FA primes. Brand new, not returns, not used. Even my non-photographic friend noticed Pentax QC sucked when shopping the FA31 for me from overseas. DA*16-50/2.8 still suck today with SDM & optical misalignment issues not addressed. No excuse really except HOYA didn't bother for obvious reason. Hopefully Ricoh will take QC seriously.

Good products can be made anywhere as can bad ones.

I believe so too.

[pz1fan]

I would think that's largely because FA43 != FA31 ... apple != orange

One really rotten apple and a delicious mandarin orange.

[pz1fan]

FA43/77 & FA31 are built differently. Essentially the 1st 2 are based on the M/A helicoil design and misalignment is less likely to happen because the whole lens group moves as a single unit. The 31 have 3 lens groups moving independently and are all screwed together with rollers and smooth barrels. This design requires very high precision on parts manufacturing, or at least screening afterward. IMHO Pentax fail on both, after disassembled a few samples to see what went wrong myself. This lens can be awesome, but translating the design into production is another matter.

I bought my 1st FA31 around 2003, and checked out 3 samples locally. All of them had wobble hood and the one with firm hood, the front element was scratched (and scratched inner elements is rather common with Pentax new lenses). Over the years I have come across around 6-7 samples, and the latest one was AIV black this year. Whiny focusing mechanism due to defective barrel. There have been many more brand new MIJ defective cameras and lenses I have come across over the years, more than I would like to believe. If not for the fact that I can address some of them myself, I would probably not using Pentax now (I have to admit that I have more fun fixing lenses/cameras than actual shooting).

Thanks for this post. I'll keep looking for a good copy or try to repair this one. I can't sell a subpar lens to anyone so may as well repair it.

[photocanadian]

I think the only faulty Pentax lens I ever had was a MIJ FA*300 f2.8, but I didn't have any AIV either. I thought they should have checked every lens for one that expensive, but I guess that's too much to ask.

So here is my question ... can wobbly/misaligned FA31 be DIY repaired? How is the alignment handled internally?

I have worked on similar lenses (in construction; i.e. internal floating elements using three sliding barrels on three teflon rollers) such as the Nikkor AF 85/1.8D, but that was a fairly easy lens to service. Does anyone have a parts diagram for the FA31?

Mine is in great shape, but I have a feeling that it won't be as long-lived as the helix-bases lenses (da15/fa43/fa77/etc).

[photocanadian]

I agree about the orange, but the FA31 would be more like a very exotic and rare tropical fruit that can easily turn into poison

One really rotten apple and a delicious mandarin orange.

---

Last edited by photocanadian; 09-30-2011 at 06:02 AM.

[bdery]

Fact/fiction, one opinion I heard was that the tolerances for assembly weren't quite as stringent in Vietnam.

Tolerances are as stringent as the engineer who defines them. After that it's only a matter of respecting the manufacturing procedure.

[wlachan]

So here is my question ... can wobbly/misaligned FA31 be DIY repaired? How is the alignment handled internally?

I have worked on similar lenses (in construction; i.e. internal floating elements using three sliding barrels on three teflon rollers) such as the Nikkor AF 85/1.8D, but that was a fairly easy lens to service. Does anyone have a parts diagram for the FA31?

Mine is in great shape, but I have a feeling that it won't be as long-lived as the helix-bases lenses (da15/fa43/fa77/etc).

The alignment of the FA31 relies on how precisely made the sliding barrels are. If there is/are gaps between them, the hood or the rear lens group will wobble and misalignment is to be expected. If the roller rails aren't precise, there will be misalignment as the focus changes. The rollers are there to keep them intact but not really the source of problem. That means there is no re-alignment mechanism anywhere. It can be compensated by shifting the front lens group which is held by 3 screws, but I doubt it was meant to be for that purpose. The proper way of fixing misalignment is to replace any defective barrels which aren't precisely made enough, but obviously not done by any service centres for cost reason (maybe except in Japan?). Such replacement will mean a complete strip down because those barrels form the main body which everything else attach to. The good news is, imho, the alignment of this lens won't just go wacky if it is good from the factory, unless it was dropped or the front lens group was removed afterward. If you are concerned, try not to land the lens on its hood to minimise any potential damage.

[photocanadian]

Understood (and that's what I was afraid of). However, on the Nikkor lens the "rollers" were fixed (non-rotating, so technically they were "sliders") and slightly eccentric, which meant that a slightly wobbly lens could be "fixed" up by loosening and rotating (or exchanging) the rollers. I would appreciate a pic of a stripped or at least opened FA31 if there is one as I'm still not 100% clear on how it is constructed (and the roller diameter and height measurement would help too, I still have one spare cage from the Nikkor lens so I could compare roller sizes).

Are there different rollers available for the FA31 (for AIV/MIJ perhaps)? I believe that should fix the wobble as long as all barrel slots share the same dimensions.

And thanks for the tip about not placing it on the hood, it makes total sense.

EDIT: I attached the picture of Nikkor barrels I took (for comparison with the FA31).

The alignment of the FA31 relies on how precisely made the sliding barrels are. If there is/are gaps between them, the hood or the rear lens group will wobble and misalignment is to be expected. If the roller rails aren't precise, there will be misalignment as the focus changes. The rollers are there to keep them intact but not really the source of problem. That means there is no re-alignment mechanism anywhere. It can be compensated by shifting the front lens group which is held by 3 screws, but I doubt it was meant to be for that purpose. The proper way of fixing misalignment is to replace any defective barrels which aren't precisely made enough, but obviously not done by any service centres for cost reason (maybe except in Japan?). Such replacement will mean a complete strip down because those barrels form the main body which everything else attach to. The good news is, imho, the alignment of this lens won't just go wacky if it is good from the factory, unless it was dropped or the front lens group was removed afterward. If you are concerned, try not to land the lens on its hood to minimise any potential damage.

[wlachan]

Understood (and that's what I was afraid of). However, on the Nikkor lens the rollers were fixed (non-rotating) and slightly eccentric, which meant that a slightly wobbly lens could be "fixed" up by loosening and rotating (or exchanging) the rollers. I would appreciate a pic of a stripped or at least opened FA31 if there is one.

Are there different rollers available for the FA31 (for AIV/MIJ perhaps)? Thanks for the tip about not placing it on the hood, it makes total sense.

MIJ & AIV FA31 use the same parts. There are 2 sets of rollers (but they don't rotate as you said) for the FA31, 3 each set, all perpendicular and not adjustable. Tighten or loosen them won't change their diamension. There might be tiny variations on their thickness due to manufacturing tolerance but not something for alignment purpose. If tighten up the wobbly hood is your objective, I have to tell you that won't be possible. The reason it wobbles is that 2 of the major metal barrels has tiny gap when slided together, while there should be no gap at all. The only redeem is to determine which has the wrong diameter and replace it. Some FA31 has firm hood but most not based on my limited experience.

I have never doc my repair so I cannot help you with pics, but there should be FA31 diagram on the net somewhere but I haven't the link. See if you can Google it. Or you can try to obtain the full pdf parts manual from Pentax Canada, depends on your luck. The FA31 has similar barrels as the one shown in your pic btw.

[DanielT74]

Another useless anecdote - putting my newly acquired AIV 31ltd through the works now. A very nice lens except for the PF wide open. But I take it this is a design flaw.

[wlachan]

Another useless anecdote - putting my newly acquired AIV 31ltd through the works now. A very nice lens except for the PF wide open. But I take it this is a design flaw.

I haven't used it much on dslr but PF is normal if OOF. I am not so certain if in focus.

[Blue]

A big part of the MIJ thing with the FA ltd series is more for collector value. I prefer the FA lenses with the MIJ markings. That said, I have 3 DA ltd and a DA* and a DA WR macro AIV.

[photocanadian]

Found the diagram:

http://pentax-manuals.com/manuals/service/fa31.pdf

It looks fairly straight-forward (although different than the Nikkor lenses) as far as floating group primes go. The handwritten comments made me laugh

I wonder if the wobbliness is due to the manufacturing tolerances of the rollers and not the barrels.

MIJ & AIV FA31 use the same parts. There are 2 sets of rollers (but they don't rotate as you said) for the FA31, 3 each set, all perpendicular and not adjustable. Tighten or loosen them won't change their diamension. There might be tiny variations on their thickness due to manufacturing tolerance but not something for alignment purpose. If tighten up the wobbly hood is your objective, I have to tell you that won't be possible. The reason it wobbles is that 2 of the major metal barrels has tiny gap when slided together, while there should be no gap at all. The only redeem is to determine which has the wrong diameter and replace it. Some FA31 has firm hood but most not based on my limited experience.

I have never doc my repair so I cannot help you with pics, but there should be FA31 diagram on the net somewhere but I haven't the link. See if you can Google it. Or you can try to obtain the full pdf parts manual from Pentax Canada, depends on your luck. The FA31 has similar barrels as the one shown in your pic btw.