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View Poll Results: What Has Been Your SDM Experience?
DA* 16-50/2.8: No SDM problems 3838.00%
DA* 16-50/2.8: Bad SDM 1313.00%
DA* 200/2.8: No SDM problems 1111.00%
DA* 200/2.8: Bad SDM   00%
DA* 300/4: No SDM problems 1818.00%
DA* 300/4: Bad SDM   00%
DA* 50-135/2.8: No SDM problems 5656.00%
DA* 50-135/2.8: Bad SDM 1010.00%
DA* 55/1.4: No SDM problems 66.00%
DA* 55/1.4/2.8: Bad SDM   00%
DA* 60-250/4: No SDM problems 88.00%
DA* 60-250/4: Bad SDM 11.00%
DA 17-70mm/4: No SDM Problems 1313.00%
DA 17-70mm/4: Bad SDM 22.00%
Multiple Choice Poll. Voters: 100. You may not vote on this poll

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12-18-2009, 03:22 PM   #31
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QuoteOriginally posted by LeDave Quote
Wow the results from the 16-50 is surprising. I used to have the 50-135 but sold it, it has never failed on me and hopefully it doesn't fail on that person.
I am also surprised. I suspect that as the days draw on, we will get less bad and more good, though the incidence of bad 16-50 definitely is disturbing.

Steve

12-18-2009, 04:19 PM   #32
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QuoteOriginally posted by stevebrot Quote
1-10% failure rate within warranty would not surprise me at all nor would a higher rate outside warranty. The repair incidence for dSLR bodies across brands is 3-5% (consumerreports.org) with Canon and Nikon leading the pack for failures. I would take that as an indicator of the QA target for that class of goods, lenses included.
The best argument about SDM lens failures I've heard is: where are the 50 posts saying the DA 18-55mm failed, (has to be the current most sold Pentax lens), the 50 posts saying the FA 50mm f1.4 failed, ... on down to the 50 posts saying the least popular Pentax lens failed? Let's be fair, where are the 50 posts total saying any and all F, FA, or DA lenses combined that failed for the same reason? That's what, 40 years of lenses?

What would be the worst, the FA 28-70mm with its lens element separation?

Thank you
Russell

Last edited by Russell-Evans; 12-18-2009 at 04:35 PM.
12-18-2009, 06:19 PM   #33
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I wish I could vote twice since I had two 50-135's SDM go out.

I agree with Russell. I have never read about a focus mechanism failure on any Pentax lens, ever...until SDM.
12-18-2009, 06:28 PM   #34
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QuoteOriginally posted by Russell-Evans Quote
The best argument about SDM lens failures I've heard is: where are the 50 posts saying the DA 18-55mm failed, (has to be the current most sold Pentax lens), the 50 posts saying the FA 50mm f1.4 failed, ... on down to the 50 posts saying the least popular Pentax lens failed? Let's be fair, where are the 50 posts total saying any and all F, FA, or DA lenses combined that failed for the same reason? That's what, 40 years of lenses?

What would be the worst, the FA 28-70mm with its lens element separation?

Thank you
Russell
I am not quite following you here Russell. Are you saying that because there have been a rash of complaints about a popular lens line, that the problem must be pervasive and epidemic? Does not follow...might it be that sales have been brisk and that we are seeing complaints based the 1-10% (your numbers) of bad units. That is why I am doing the poll. From what I can see, there appears to be a serious problem, at least within those of our users that are inclined to take part. Evidence rather than inference. It looks to be a bad enough problem that I personally would not consider purchase of ANY DA* SDM lens. The price is too high to accept that level of quality.

Are you asking whether there are issues with any of the slot-drive lenses? There was the occasional complaint when I first joined this forum, though I don't recall any recent ones. Things like AF binding, housings breaking, grinding noises, etc.. So the short answer is that yes people had AF issues before SDM, though not so prevalent.

First F-series lens to present = 22 years (1987), Forty years ago Pentax were still using M42 screw mount.

Steve

12-18-2009, 06:32 PM   #35
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QuoteOriginally posted by PentaxPoke Quote
I wish I could vote twice since I had two 50-135's SDM go out.
I wish I could have captured that data. Same lens pre/post repair? There is some concern that repairs are being done using the same parts/construction as the units that failed.

Steve
12-18-2009, 06:38 PM   #36
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QuoteOriginally posted by stevebrot Quote
I wish I could have captured that data. Same lens pre/post repair? There is some concern that repairs are being done using the same parts/construction as the units that failed.

Steve
No, I sent in the first one that failed just after the warranty. Pentax kindly sent me a brand new lens (different SN entirely). After a few months, the new lens' SDM went through the traditional "sometimes doesn't move" mode, until I would go to great lengths to wake it up.

Worse than Peter's "moody mode." My 50-135's had a "whatever" mode. Like "Whatever. I'll get to focusing when I'm damn-well ready."
12-18-2009, 08:51 PM   #37
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QuoteOriginally posted by Russell-Evans Quote
I've seen three posts of this type of failure. When your lens comes back, would you mind replying to this with what was documented as the failure, please?

Thank you
Russell
Not at all; I'll keep you posted.
12-18-2009, 09:11 PM   #38
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QuoteOriginally posted by stevebrot Quote
I am not quite following you here Russell. Are you saying that because there have been a rash of complaints about a popular lens line, that the problem must be pervasive and epidemic? Does not follow...might it be that sales have been brisk and that we are seeing complaints based the 1-10% (your numbers) of bad units.
No I'm saying that if a 1-10% failure rate was an industry or even only a Pentax norm, then there would have been as many posts about other current lenses as there are about SDM lenses.

There can be no brisker selling lens than that of the DA 18-55mm in all its flavors. As the k200D out sold the K20D, as the K-X is out selling the K-7, the DA 18-55mm will outsell the SDM lenses.

QuoteOriginally posted by stevebrot Quote
at least within those of our users that are inclined to take part. Evidence rather than inference.
Same problem with all polls, all people affected or a majority have to take part to have valid data. It isn't a random sample either, therefore the interpretation of the poll data it is still inference. You'll see this argument brought up on the polls already taken at DPR for this issue. Of coarse there the argument will only be used if the poll data infers that there is an issue with SDM. :ugh:

QuoteOriginally posted by stevebrot Quote
Things like AF binding, housings breaking, grinding noises, etc.. So the short answer is that yes people had AF issues before SDM, though not so prevalent.
AF binding would an AF issue. Housings breaking, grinding, and noises, wouldn't be. Be fair, we are taking about a single issue, failed SDM motor, effecting a set of seven lenses, not a compilation of all issues affecting seventy plus lens types, but yes, not so prevalent would be the point.

See above: if 1-10% SDM failures is a norm, when did it become the norm as you yourself are saying failure was not as prevalent, i.e. 1-10% failure isn't the norm.

QuoteOriginally posted by stevebrot Quote
First F-series lens to present = 22 years (1987), Forty years ago Pentax were still using M42 screw mount.
My bad, so we only have lenses that have lasted 22 times longer instead of 40 times.

Thank you
Russell

12-18-2009, 09:47 PM   #39
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QuoteOriginally posted by stevebrot Quote
I am not quite following you here Russell. Are you saying that because there have been a rash of complaints about a popular lens line, that the problem must be pervasive and epidemic? Does not follow...might it be that sales have been brisk and that we are seeing complaints based the 1-10% (your numbers) of bad units. That is why I am doing the poll. From what I can see, there appears to be a serious problem, at least within those of our users that are inclined to take part. Evidence rather than inference. It looks to be a bad enough problem that I personally would not consider purchase of ANY DA* SDM lens. The price is too high to accept that level of quality.

Are you asking whether there are issues with any of the slot-drive lenses? There was the occasional complaint when I first joined this forum, though I don't recall any recent ones. Things like AF binding, housings breaking, grinding noises, etc.. So the short answer is that yes people had AF issues before SDM, though not so prevalent.

First F-series lens to present = 22 years (1987), Forty years ago Pentax were still using M42 screw mount.

Steve
Steve, it is true that there are some problems as well with the older versions or the DA versions of the Pentax. but those problems are the one that should be considered as a real minority or is not of any real concern at all, except maybe the FA28-70 which was reported to have a poor adhesion and haze. as to housing breaking, it can be attributed to shock, wear and tear (mind you that these lenses survived for the last 20-30 years which is much longer than the lifespan or history of the DA*. not so much on AF binding. I did experienced a grinding and shuddering noise with my used FA100/2.8, but that was because it has a misaligned element and a bust-up clamp. that problem however had nothing to do with engineering but rather misuse by the former owner which caused the lens to act as such (I'm glad my K-7 didn't break because of that lens). other than that, the older lenses are very reliable and much much much more reliable than the DA* zooms. and that reliability should atleast be equaled by the DA* zooms.

p.s. as someone pointed out, if we are going to do some statistics, the DA kit lenses are much more reliable than the DA* zooms. I think someone should make a poll regarding kit lenses as well so that we can see a clear and obvious picture if there is a real problem or not, concerning some of the modern lenses. a side by side comparison of lens failure or defect.

well, even if we include a poll with the older lenses' reliability, I'm pretty confident that the finding would be the same and unanimous.

Last edited by Pentaxor; 12-18-2009 at 10:58 PM.
12-18-2009, 10:40 PM   #40
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QuoteOriginally posted by Russell-Evans Quote

See above: if 1-10% SDM failures is a norm, when did it become the norm as you yourself are saying failure was not as prevalent, i.e. 1-10% failure isn't the norm.
Russell, I am not arguing. If something is the norm, that doesn't make it acceptable. To me, 1-2% defect rate is more in line with my expectations. The 3%-5% defect rate of dSLRs is abominable. Ditto for lenses. To have that high a failure rate for something in that price range...

Traditionally (at least since about 1960 or maybe the mid-1950s), purchase of a name-brand Japanese 35mm camera or lens meant acquiring a precision crafted tool that would provide a lifetime of use with reasonable care and maintenance. A good example would be the "Sightseeing Screwmount" Pentax SV that I had the privilege of using for two weeks this last summer. In the current market dynamic, photography goods have a life expectancy of 3-5 years maximum before being replaced for something "better". As a result, our expensive cameras and lenses are manufactured to that standard. As noted in several other threads, it is cheaper to replace a defective unit than to build it right in the first place.

One can argue the validity of our little poll, but the trend is clear to me. The final numbers may be a little less damning than the current picture, but I have seen enough.

Only one question remains in my mind. Do users of other systems have it much better? One reason I went with Pentax was the poor build quality of Canon's consumer grade lenses. Ditto for Nikon. There have been improvements since then, but I still have my doubts. As a result, I am unlikely to jump ship any time soon. Besides...I have lots of lenses and have my needs pretty well covered. With any luck, there will be good FF options at a moderate price by the time my K10D fails (2 years, 9 months and counting...) and I can make a fresh choice then.

Steve
12-18-2009, 10:44 PM   #41
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QuoteOriginally posted by Russell-Evans Quote
My bad, so we only have lenses that have lasted 22 times longer instead of 40 times.
I am starting to have doubts about the MF drive motor and sensor that I use with my 40-year old lenses.

Steve
12-19-2009, 08:07 AM   #42
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QuoteOriginally posted by stevebrot Quote
I am starting to have doubts about the MF drive motor and sensor that I use with my 40-year old lenses.

Steve
I do find it a little amusing when people compare the SDM driven lenses to the manual focus lenses that "last forever," because of course, you can continue to use these lenses as manual focus lenses forever, even if the SDM burns out.
12-19-2009, 08:19 AM   #43
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QuoteOriginally posted by Russell-Evans Quote
I've seen three posts of this type of failure. When your lens comes back, would you mind replying to this with what was documented as the failure, please?

Thank you
Russell
I sent it in due to focusing errors (failure to lock in certain situations), and got it back a month ago. The problem was primarily at quite short distances, but closeup shots were a hassle as the AF became unsure at 50-70mm.

It is better now, but not completely well, still.

Edit:
I was told it was shipped to Germany. The documents claimed it was overhauled and tested, I did not notice anything else than the lens barrel being a little 'wobblier' than before.
12-19-2009, 12:13 PM   #44
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QuoteOriginally posted by Rondec Quote
I do find it a little amusing when people compare the SDM driven lenses to the manual focus lenses that "last forever," because of course, you can continue to use these lenses as manual focus lenses forever, even if the SDM burns out.
first, they weren't suppose to burn-out (after a few months or a year), otherwise, what's the use of it being an AF lens. second, they weren't suppose to have BF/FF issues than the older lenses.
12-19-2009, 12:36 PM   #45
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I know with the AF system on a screwdrive lens, the camera drives the lens pretty hard right to the stop, essentially slamming something together.

I noticed with the SDM, the same thing happens. Could it actually be a problem with how violently the camera hits the stops at the extreme ends of the focus?
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