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08-12-2009, 09:08 PM   #1
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Got my 16-50 replaced; now sending it AND the K-7 in for repair

Had front-focusing issues with my DA* 16-50, so I sent it in to Pentax hoping for a fix. Several weeks later, a replacement lens arrived. My heart leapt knowing I would finally have my walkaround lens back. However, my joy was quickly crushed.

This replacement lens still had front-focusing issues. Even worse, the focusing mechanism is really "crunchy." Instead of feeling a smooth motion, I can definitely notice the ball bearings grinding as I rotated the focus ring; this issue definitely was not present on my previous copy of the lens.

Although I could have let this issue go, the issue that was a real show stopper was the fact that the focus would sometimes get stuck now! Trying to utilize the AF on my K-7, I noticed that the lens could not move the focus. Thinking maybe the SDM was dead, I tried to rotate the focus ring. The focus ring moved, but the actual focus element didn't; I confirmed this by noting that the distance indicator on the top of the lens wasn't moving.

This lens has to go back. I'm so frustrated with this front focusing issue already. I've been several weeks without my walkabout lens. And after it returns, it still has the issue. So, I'm going to send back the K-7 as well.

This is a nightmare. JohnCPentax, help!

- Jason

08-12-2009, 09:28 PM   #2
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QuoteOriginally posted by inferno10 Quote
Had front-focusing issues with my DA* 16-50, so I sent it in to Pentax hoping for a fix. Several weeks later, a replacement lens arrived. My heart leapt knowing I would finally have my walkaround lens back. However, my joy was quickly crushed.

This replacement lens still had front-focusing issues. Even worse, the focusing mechanism is really "crunchy." Instead of feeling a smooth motion, I can definitely notice the ball bearings grinding as I rotated the focus ring; this issue definitely was not present on my previous copy of the lens.

Although I could have let this issue go, the issue that was a real show stopper was the fact that the focus would sometimes get stuck now! Trying to utilize the AF on my K-7, I noticed that the lens could not move the focus. Thinking maybe the SDM was dead, I tried to rotate the focus ring. The focus ring moved, but the actual focus element didn't; I confirmed this by noting that the distance indicator on the top of the lens wasn't moving.

This lens has to go back. I'm so frustrated with this front focusing issue already. I've been several weeks without my walkabout lens. And after it returns, it still has the issue. So, I'm going to send back the K-7 as well.

This is a nightmare. JohnCPentax, help!

- Jason
Oh gosh... But why send the K-7 back as well? I thought only the lens has a problem. Is the issue that bad that it can't be corrected via camera?
08-12-2009, 09:30 PM   #3
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The product quality is the main issue holding me back from buying a DA*16-50mm.
Its an expensive lens, and looks good - on paper. The chances of getting a bad copy seems rather high, from other user feedback.

I'm thinking I'd rather spend the money on a cheaper 3rd Party lens - Tamron and Sigma look like they have good alternatives, lower specs. perhaps and no weather sealing, but I can be more confident it will work properly up front.
08-12-2009, 09:32 PM   #4
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The first time I sent the lens in, the FF could not be corrected on the K-7; -10 AF correction still had FF issues. The replacement copy also had FF issues that went beyond -10 AF again. The K20D at least could get focus right at -7 or -8. Therefore I think it's a combination problem.

- Jason

08-12-2009, 09:40 PM   #5
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16-50 SDM is well known for it various quality control defects

Theres a sticky thread here dedicated to defective 16-50mm serial numbers. If you read thru all the pages you'll see one dealer resold a known defective 16-50mm to another forum poster as new. Silly seller didn't know of the known data base of defective 16-50 SDM lenses:


https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/22297-da-16-50...-database.html
08-13-2009, 08:26 AM   #6
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QuoteOriginally posted by kittykat46 Quote
The product quality is the main issue holding me back from buying a DA*16-50mm.
Its an expensive lens, and looks good - on paper. The chances of getting a bad copy seems rather high, from other user feedback.

I'm thinking I'd rather spend the money on a cheaper 3rd Party lens - Tamron and Sigma look like they have good alternatives, lower specs. perhaps and no weather sealing, but I can be more confident it will work properly up front.
ditto here. i was ready to spring for the 16-50, but looks like the recent batches have their issues as well, maybe not as much as the previous years.

08-13-2009, 10:37 AM   #7
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QuoteOriginally posted by opiedog Quote
ditto here. i was ready to spring for the 16-50, but looks like the recent batches have their issues as well, maybe not as much as the previous years.

The QC issues of early samples of the DA* 16-50 were largely related to centering defects. (I had one of them.) As far as I can tell, that particular problem has been resolved. I do not doubt that there may be various problems with newer samples, but it seems that they are sporadic, not systemic. Rest assured that the same thing happens with lenses from other manufacturers as well.

Rob
08-13-2009, 12:10 PM   #8
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QuoteOriginally posted by inferno10 Quote
The first time I sent the lens in, the FF could not be corrected on the K-7; -10 AF correction still had FF issues. The replacement copy also had FF issues that went beyond -10 AF again. The K20D at least could get focus right at -7 or -8. Therefore I think it's a combination problem.

- Jason
I know how it feels to wait then find a repair was not done right, its like no one in the world cares; QC is something that died some years ago . I had kinda the same problem with Sigma, I fought back, researched them at the BBB (Better Business Bureau) office they fall under, looked at their record and started writing my complaint. I let some upper management know at Sigma about it, and a new lens was sent to me in two days. Now I also had a problem getting my GX10 back from Samsung, they are huge and hard to fight. But things worked out in the end.

Pentax has a rating of F from the BBB, they do not belong to the BBB. But you can find info on them here. And you can still file a complaint. If you feel its truly justified. But you must contact and talk to someone at Pentax, its the right thing to do before filing a complaint, be fair.

PENTAX Imaging Company - Manufacturers & Producers - Better Business Bureau

Your repair is a redo, let them know this and the turn around time should be shorter.

08-13-2009, 12:34 PM   #9
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QuoteOriginally posted by inferno10 Quote
This replacement lens still had front-focusing issues. Even worse, the focusing mechanism is really "crunchy." Instead of feeling a smooth motion, I can definitely notice the ball bearings grinding as I rotated the focus ring; this issue definitely was not present on my previous copy of the lens.

Although I could have let this issue go, the issue that was a real show stopper was the fact that the focus would sometimes get stuck now! Trying to utilize the AF on my K-7, I noticed that the lens could not move the focus. Thinking maybe the SDM was dead, I tried to rotate the focus ring. The focus ring moved, but the actual focus element didn't; I confirmed this by noting that the distance indicator on the top of the lens wasn't moving.

Are you sure the lens wasn't focused to the end of the scale? It is possible to turn the focus ring further, but no lens elements are moving. Both the zooming and focusing is a bit jerky on this lens. Your describtion could fit a completely OK 16-50.....
08-13-2009, 02:14 PM   #10
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Wow, Pentax USA is awarded an F grade from BBB !!!

Wow, Pentax USA is awarded The "F" grade from BBB !!!


I had no idea.


Thanks for the handy BBB Pentax USA Failure rating Business link from Denver Colorado, Home Town of Pentax USA.





QuoteOriginally posted by jamesm007 Quote
I know how it feels to wait then find a repair was not done right, its like no one in the world cares; QC is something that died some years ago . I had kinda the same problem with Sigma, I fought back, researched them at the BBB (Better Business Bureau) office they fall under, looked at their record and started writing my complaint. I let some upper management know at Sigma about it, and a new lens was sent to me in two days. Now I also had a problem getting my GX10 back from Samsung, they are huge and hard to fight. But things worked out in the end.

Pentax has a rating of F from the BBB, they do not belong to the BBB. But you can find info on them here. And you can still file a complaint. If you feel its truly justified. But you must contact and talk to someone at Pentax, its the right thing to do before filing a complaint, be fair.

PENTAX Imaging Company - Manufacturers & Producers - Better Business Bureau

Your repair is a redo, let them know this and the turn around time should be shorter.
08-13-2009, 03:31 PM   #11
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QuoteOriginally posted by Pål Jensen Quote
Are you sure the lens wasn't focused to the end of the scale? It is possible to turn the focus ring further, but no lens elements are moving. Both the zooming and focusing is a bit jerky on this lens. Your describtion could fit a completely OK 16-50.....
I'm 100% positive that the focus wasn't at the end of travel when it was getting stuck. It almost seems that the quick shift isn't quickly shifting back to manual control once AF is complete. Trying to continue turning in the last direction traveled by AF doesn't work until I turn the focus ring in the opposite direction then back. At other times, the AF will hit a point where it seems to get stuck and can't continue to focus; when this happens you can tell the AF is still trying to work but is physically unable to. I'll try and record some video of the AF struggling to turn the focus to prove my point. But I'm sure this 16-50 isn't completely OK, as the focus mechanism on my previous copy was smooth as butter in both AF and manual operation.

- Jason
08-13-2009, 11:03 PM   #12
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As promised, I have created a movie demonstrating the new issue I'm having with my 2nd copy of the 16-50: YouTube - JRO_0660

Sorry about the low volume and the other noises.

- Jason
08-14-2009, 08:07 AM   #13
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Sorry to hear your tale of woe, Jason. I've just sent my new DA*16-50 back to B&H for exchange. I don't know how new mine was as far as inventory, but it had decentering problems as well as not being sharp at any aperture. I didn't think to try to manually focus it, some of the problem might have been AF issues. It wouldn't have made much difference since it was clearly blurrier on the left side. Thanks for posting your experience - I'll check that when I get the replacement lens.

The only lens I've had AF issues when using the K-7 has been the 12-24. Sometiimes it doesn't go all the way to infinity when it should, someone else reported having the same thing happen with theirs (but I can't find the comment now to see how they resolved it, if they did). Otherwise I've had no trouble with either my SDM or screw AF lenses.
08-14-2009, 08:45 AM   #14
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Very nice video to show your problem(s), well done! I hope you speak with someone and make sure to note its a redo, send them the old repair invoice and write it in big red letters (lol) so things I would hope go faster. Good luck.

I must say the video from the K-7 and sound is great! Hmmm maybe I need to rethink why I dislike video in a dSLR.
08-16-2009, 12:31 AM   #15
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I decided to cut this copy of the lens as a loss and buy another copy. After shelling out another $700, I finally have a good copy! Guess I'll send in the old one for repair and sell it...

Video taken w/ the good copy: YouTube - San Francisco Hang Player

- Jason
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