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04-04-2022, 09:16 AM   #1
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Da*16-50 2.8 sdm

Hello, I have two copies of this lens and they both suffer from intermittent autofocus issues. They both will work after working the focus for a while. But If I quickly turn the camera on to take a pic the focus never works. I was considering sending one off to be repaired and converting the other to screw drive. So my question is for those people who had there lens repaired did it resolve the issue? Or did it return after some time. In the later years of production did they ever resolve the issue?

04-04-2022, 09:32 AM   #2
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From
Pentax Engineer on SDM Failure and Pentax DC. A brief conversation answers all our questions.
PTXF .com/news/jens-petersen-on-pentax-sdm-failure.html#page_4

Q: Has this SDM quality control issue been resolved?
A: Yes. The components used in the 16-50mm and 50-135mm lenses have been redesiged, and all lenses produced in 2012 or later should no longer fail.
04-04-2022, 10:16 AM   #3
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QuoteOriginally posted by brianmquinn Quote
From
Pentax Engineer on SDM Failure and Pentax DC. A brief conversation answers all our questions.
PTXF .com/news/jens-petersen-on-pentax-sdm-failure.html#page_4

Q: Has this SDM quality control issue been resolved?
A: Yes. The components used in the 16-50mm and 50-135mm lenses have been redesiged, and all lenses produced in 2012 or later should no longer fail.
But can we tell when they were actually made rather when bought having sat on the shelf?
04-04-2022, 12:36 PM   #4
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This could be a good starting point i guess

https://www.pentaxforums.com/forums/pentax-serial-number-database/?do=viewserials&id=5


Last edited by Sakura; 04-04-2022 at 12:43 PM.
04-04-2022, 01:42 PM   #5
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I will wade in. I have seen multiple lenses over the years that get multiple SDM replacements and continue to fail. I am convinced (well maybe not fully) that something in the lenses outside of the SDM motors is contributing to the failures. I suspect (but can't prove) that additional drag, friction, something is sometimes involved that causes repeat failures. Other lenses like my own 50-135 that was refurbished work fine without repeat failures - suggesting that it's a bit of a crap shoot. Screwdrive conversion simply works so my recommendation is that unless you like gambling you either convert both to screwdrive or you sell one or both and buy the newly redesigned PLM version.
04-05-2022, 05:22 AM   #6
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I have a 17-70mm SDM. When the camera+lens is not used for some time, the autofocus does not work. After some time (can be minutes!) turning the manual focus ring, the autofocus starts to work.
What I found: when I switch the camera to live view, almost immediately the autofocus starts to work. When switching back to the optical viewfinder the autofocus still works perfectly. This only takes seconds!
Perhaps you can try this with your 16-50mm SDM.

Last edited by PJvE; 04-05-2022 at 08:33 AM.
04-05-2022, 12:28 PM   #7
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QuoteOriginally posted by UncleVanya Quote
buy the newly redesigned PLM version.
First I have heard of this, nor have I seen it offered among Pentax lenses. Only the new DA* 16-50mm f/2.8 PLM, then the first PLM- the DA 55-300mm. If true, it would certainly be the right move, to match up with the DA* 16-50mm f/2.8 lens.

In fact, I just checked B&H, who list only the old SDM version, which is not in stock but offered on special order, to arrive expectedly in 2-4 weeks.


Last edited by mikesbike; 04-05-2022 at 12:41 PM.
04-05-2022, 01:14 PM   #8
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QuoteOriginally posted by mikesbike Quote
First I have heard of this, nor have I seen it offered among Pentax lenses. Only the new DA* 16-50mm f/2.8 PLM, then the first PLM- the DA 55-300mm. If true, it would certainly be the right move, to match up with the DA* 16-50mm f/2.8 lens.

In fact, I just checked B&H, who list only the old SDM version, which is not in stock but offered on special order, to arrive expectedly in 2-4 weeks.
I’m sorry we seem to be on different wavelengths.

The new 16-50 PLM is what I referenced. I’m confused by the response and clearly missing some nuance of what I said or implied vs what you said.
04-05-2022, 01:42 PM   #9
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QuoteOriginally posted by brianmquinn Quote
From
Pentax Engineer on SDM Failure and Pentax DC. A brief conversation answers all our questions.
PTXF .com/news/jens-petersen-on-pentax-sdm-failure.html#page_4

Q: Has this SDM quality control issue been resolved?
A: Yes. The components used in the 16-50mm and 50-135mm lenses have been redesiged, and all lenses produced in 2012 or later should no longer fail.
I have a DA55*/1,4SDM produced after 2012 and it failed.
Many DA*300 which have been repaired after 2012 and failed again.
04-05-2022, 01:51 PM   #10
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QuoteOriginally posted by UncleVanya Quote
I will wade in. I have seen multiple lenses over the years that get multiple SDM replacements and continue to fail. I am convinced (well maybe not fully) that something in the lenses outside of the SDM motors is contributing to the failures. I suspect (but can't prove) that additional drag, friction, something is sometimes involved that causes repeat failures.
I think it is just the design of the SDM motor itself.

Even the new redesigned ones often failed again.
I think this SDM motor is just to weak for the weight it has to move.

Screwdrive conversion is the only real solution, I feel repairing it with another SDM motor is a waste of money.
I know of quite a few people having sent their DA*300 in for repair, again and again it failed.

Really tricky it is for those lenses which can't be converted, like the DA*55/1,4 or the DA 17-70.
The DA*55/1,4 is more likely to fail than the DA17-70 though.
04-05-2022, 02:03 PM   #11
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QuoteOriginally posted by UncleVanya Quote
I’m sorry we seem to be on different wavelengths.

The new 16-50 PLM is what I referenced. I’m confused by the response and clearly missing some nuance of what I said or implied vs what you said.
Ha! I'm the one who has had no coffee yet! I'm thinking of the DA* 50-135mm so much (wishful thinking to complement what has been reissued) I lost track! I'm fortunate and knocking on wood, my now 10 year-old-plus copy of this fine tele zoom lens is still working, though I only use it when I need its capabilities. Sorry for my not being with it!

From all the many reports here, it appears photogem is right. I wonder, should this become an issue, if the conversion could be done on a K20D. I do have older bodies, like a K100D Super, but the K20D is the oldest I keep charged and ready.

---------- Post added 04-05-22 at 02:11 PM ----------

QuoteOriginally posted by photogem Quote
Really tricky it is for those lenses which can't be converted, like the DA*55/1,4 or the DA 17-70.
The DA*55/1,4 is more likely to fail than the DA17-70 though
This is so unfortunate. Another very fine lens example that cannot be converted is the DA* 60-250mm.
04-05-2022, 02:26 PM   #12
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QuoteOriginally posted by mikesbike Quote
I wonder, should this become an issue, if the conversion could be done on a K20D. I do have older bodies, like a K100D Super, but the K20D is the oldest I keep charged and ready.
Any up to the K5IIs can do it. No idea about the small ones as K-m/x/r but the K20D for sure.
K100Dsuper as well but because sometimes the AA-only versions can have batterycontact problems I use them for such work with the external powersupply. If the battery if the K20D is healthy, this one is perfect.
04-05-2022, 05:13 PM   #13
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QuoteOriginally posted by mikesbike Quote
Ha! I'm the one who has had no coffee yet! I'm thinking of the DA* 50-135mm so much (wishful thinking to complement what has been reissued) I lost track! I'm fortunate and knocking on wood, my now 10 year-old-plus copy of this fine tele zoom lens is still working, though I only use it when I need its capabilities. Sorry for my not being with it!

From all the many reports here, it appears photogem is right. I wonder, should this become an issue, if the conversion could be done on a K20D. I do have older bodies, like a K100D Super, but the K20D is the oldest I keep charged and ready.[COLOR="Silver"]
The K100D Super is a fine option. I use a K100D mainly but I have converted using the K100D Super. You need a prepared SD card to use the K100D Super. The K100D works without anything except button presses. I use rechargeable AA's in both cameras without issues.

For the record the DA 17-70 was one of the highest failure rate SDM lenses supposedly. I have had a charmed life with SDM refurbished lenses. I had and gave to my niece the 17-70/f4 - a brilliant lens btw. It has never given us a bit of trouble. I have and still use a 50-135 that came out of the Pentax offices in Colorado we think. It was non-working on arrival but a little elbow grease and manipulation and it has worked ever since. I think it was merely slight stiction after repair that caused it to not work at that time.

It is also possible that some user camera body related issue is involved with SDM failures - but it's hard to know - the repeat failures affecting not only the same lens but multiple suggest that either user or camera somehow involved. So far as I have said I have never had an SDM failure. I own the DA* 200, DA* 60-250, DA* 55, DA* 50-135 currently and previously owned the DA 17-70. I own a screwdrive converted DA* 16-50 (bought with failed SDM). I also do not subscribe to the belief that idle non-use is the culprit as many lenses that sit for years seem unaffected. I do know that it would stick in our minds and could seem that way to most users. My lenses get bursts of use and then sit idle for a long time as I have too many lenses to keep them all happy.

In any case to steer this back - a DA* 16-50 can easily be converted and I (biased as I might be) highly recommend this as a course of action. I also recommend this for any failing DA* that can be converted (300/200/50-135/16-50).
04-05-2022, 06:57 PM   #14
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QuoteOriginally posted by UncleVanya Quote
You need a prepared SD card to use the K100D Super. The K100D works without anything except button presses. I use rechargeable AA's in both cameras without issues.
Oh, there's a difference between these two, other than the Super's ability to use the SDM lenses? Maybe that is it- the original is screw-drive only, and cannot AF with lenses having AF motors. I do still have the old original K100D as well. I enjoyed them way back when, but neither has been used for many years.

I too have long had the DA* 200mm though not quite as long as I've had the DA* 50-135mm. There have been some periods of at least two years where one or the other sat unused, and still are mainly used when their advantages are needed. I've used them on numerous camera bodies- the K20D, K-5, K-r, K-5 IIs, K-S2, and the KP, which has seemed to beckon for the quality of these lenses, along with their relative compactness for the large aperture. They're great with the KP, especially for low light conditions, where with their larger aperture, they can provide even more ISO range for the low-noise KP.

Last edited by mikesbike; 04-05-2022 at 07:03 PM.
04-05-2022, 07:12 PM   #15
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QuoteOriginally posted by mikesbike Quote
Oh, there's a difference between these two, other than the Super's ability to use the SDM lenses? Maybe that is it- the original is screw-drive only, and cannot AF with lenses having AF motors. I do still have the old original K100D as well. I enjoyed them way back when, but neither has been used for many years.
K100D is great as a conversion platform. I can test the screw drive function prior to doing anything by simply mounting out and using it on the k100D. Additionally no special sd card debug effort via file is needed simply a set of button presses.
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