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01-27-2015, 07:12 PM   #16
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QuoteOriginally posted by Docrwm Quote
Glad you are happy and knew what you were getting. From what I understand the 60-250 can not be converted. When you charge a premium for a supposed premium lens it ought not to have a fundamental design fault and if it does you should acknowledge it and offer free repairs - Pentax dropped the ball on SDM.
Ya, and Nikon dropped the ball on the D600 oil spot issue and got their product banned from Russia and China, then came out with the D610m without looking after the people who bought the D600. Do I really have to go on and on? This stuff happens to camera companies. There will always be un-informed individuals who think they know what the most reasonable thing to do is. The one thing we never found out... what percentage of SDM 16-50s failed? That's kind of critical to that kind of assumption.

QuoteQuote:
From what I understand the 60-250 can not be converted.
I look at my 60-250 and I see a female coupling for the screw drive... so, I guess it could be a dummy, but I'm disinclined to believe that.. without a source.

01-27-2015, 07:26 PM   #17
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QuoteOriginally posted by normhead Quote
I look at my 60-250 and I see a female coupling for the screw drive... so, I guess it could be a dummy, but I'm disinclined to believe that.. without a source.
The 60-250 works as a screw drive on bodies that don't support SDM. On my K100D it focuses fine as a screw drive. But on my K-5 it's currently manual focus until I get around to getting it fixed. As an engineer, I understand motor failures but since it's been shown that it can be addressed in part through firmware, it would be nice if Pentax would give owners that option.
01-27-2015, 10:06 PM   #18
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QuoteOriginally posted by Docrwm Quote
The SDM apologists will always cite stories but the data says that SDM is not as reliable as DC or screw drive and the zooms are more prone to fail.
QuoteOriginally posted by normhead Quote
SDM nervous nellies will always cry the sky is falling, but current SDM is as good as any internal electric drive out there.
The data clearly show the 16-50 and 50-135 had issues beyond normal failure rates. Pentax went so far as to actually mention (gasp) that the issue (or non-existent issue) was fixed with new parts. On the other hand the data show hardly any issues with the 60-250 and 300. Based on angry posts on other forums, less issues than Nikon and Canon who certainly have their own complainants about motor failures. No motor drive lens is going to be as reliable as old fashioned screw drive no matter what brand. If 100% reliability is your priority stick with screw drive.

The real issue with SDM is that it is as slow as molasses. I wish Ricoh would refresh the * line and put a new faster motor in them, the lenses themselves are great.

It is a shame that Pentax's premium line has less trust than their dirt cheap kit lens, SDM is a black mark that is not going to go away as long as the internet exists, whether the fault is real or imagined.

And as for DC motors: my 18-135 has been repaired twice, which is double the repair rate of my 16-50.
01-27-2015, 11:21 PM   #19
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I have never had a problem with that lens, but my 16-50 sometimes refuses to focus. Try cleaning the contacts on the lens using a soft pencil eraser this works for my 16-50mm.

01-28-2015, 05:00 AM   #20
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QuoteOriginally posted by jatrax Quote
The data clearly show the 16-50 and 50-135 had issues beyond normal failure rates. Pentax went so far as to actually mention (gasp) that the issue (or non-existent issue) was fixed with new parts. On the other hand the data show hardly any issues with the 60-250 and 300. Based on angry posts on other forums, less issues than Nikon and Canon who certainly have their own complainants about motor failures. No motor drive lens is going to be as reliable as old fashioned screw drive no matter what brand. If 100% reliability is your priority stick with screw drive.

The real issue with SDM is that it is as slow as molasses. I wish Ricoh would refresh the * line and put a new faster motor in them, the lenses themselves are great.

It is a shame that Pentax's premium line has less trust than their dirt cheap kit lens, SDM is a black mark that is not going to go away as long as the internet exists, whether the fault is real or imagined.

And as for DC motors: my 18-135 has been repaired twice, which is double the repair rate of my 16-50.
The failure rate does vary across SDM lenses as I have said, but it is dramatically more of a problem than for the DC motors. Yours and one other report are the only ones that I can find on the 18-135. Add to that the n involved in each category (the 18-135 has sold as one of the kit lens for the flagship since its introduction which means far more in circulation than the SDMs) and you have a clear contrast among "silent" motor Pentax lenses. I do agree that their speed is another reported issue which taken with their unreliability as a group makes their role as "premium" lenses a real problem. Again, the SDM apologists ignore the data and tell anecdotes but the facts contradict the " all is right in SDMland" story.
01-28-2015, 08:48 AM   #21
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QuoteOriginally posted by Docrwm Quote
The failure rate does vary across SDM lenses as I have said, but it is dramatically more of a problem than for the DC motors. Yours and one other report are the only ones that I can find on the 18-135. Add to that the n involved in each category (the 18-135 has sold as one of the kit lens for the flagship since its introduction which means far more in circulation than the SDMs) and you have a clear contrast among "silent" motor Pentax lenses. I do agree that their speed is another reported issue which taken with their unreliability as a group makes their role as "premium" lenses a real problem. Again, the SDM apologists ignore the data and tell anecdotes but the facts contradict the " all is right in SDMland" story.
Did Hoya or Ricoh or Chris's Camera Repair or Precision Camera Repair ever release any statistics on failure rates, warranty repairs, or dealer returns for SDM lenses? All I have been able to find is third party conjecture based on anecdotal evidence. On the internet, that's as good as gold, but I don't think it counts as "facts".

Regardless, the DA* line could use a face-lift. Maybe Ricoh can have an "Under New Management - Grand Opening" party for their release. I'm sure people are still grumbling in the hallways at Pentax over the SDM issue.
01-28-2015, 09:01 AM   #22
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QuoteOriginally posted by AquaDome Quote
Did Hoya or Ricoh or Chris's Camera Repair or Precision Camera Repair ever release any statistics on failure rates, warranty repairs, or dealer returns for SDM lenses? All I have been able to find is third party conjecture based on anecdotal evidence. On the internet, that's as good as gold, but I don't think it counts as "facts".

Regardless, the DA* line could use a face-lift. Maybe Ricoh can have an "Under New Management - Grand Opening" party for their release. I'm sure people are still grumbling in the hallways at Pentax over the SDM issue.
Part of the problem is just this, we have had surveys here but somehow thats never good enough for the SDM apologists. Pentax has not released stats on ANYTHING because it would harm them. They indirectly acknowledged the problem, as has been repeatedly referenced here in this any many other threads, by saying the problem was solved in 2012. Not sure what it would take for some here to believe - a burning bush perhaps?l
01-28-2015, 09:55 AM   #23
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QuoteOriginally posted by Docrwm Quote
Part of the problem is just this, we have had surveys here but somehow thats never good enough for the SDM apologists. Pentax has not released stats on ANYTHING because it would harm them. They indirectly acknowledged the problem, as has been repeatedly referenced here in this any many other threads, by saying the problem was solved in 2012. Not sure what it would take for some here to believe - a burning bush perhaps?l
Funny how every problem is because people just don't listen to you? Do you have any experience at all with survey design, the methodology used to try and make sure surveys attain accurate results? You are in way over your head, and really, I don't have the time ti educate you.

But... there are many good reasons why forum polls are neither accurate data or meaningful data.

QuoteQuote:
They indirectly acknowledged the problem, as has been repeatedly referenced here in this any many other threads, by saying the problem was solved in 2012. Not sure what it would take for some here to believe - a burning bush perhaps?
You always take the negative slant on these things. I mean, you have a really limited and negative imagination.

OK. I'm looking at this SDM thing.

They said the problem was solved in 2012.
They know how many SDM lenses were sold.
They know how many were returned under warranty.
They know how many have never needed any repair at all.

The fact that they improved the motor in 2012 tells you nothing more than in their evaluation, there was too high a failure rate for their standards, and they dealt with it. Every manufacturer of anything out there goes through the same thing. Every car manufacturer has to go through the process, do we recall or do we just let the parts fail and have better designed replacements.

But the main thing is, no one but Pentax knows what the breakdown was. Should they have replaced every SDM motor out there if 10% of them were failing? Without knowing the numbers, it's impossible to second guess the way they handled the situation. That's 3 times the normal Pentax rate (which is still better than anyone else's in the camera industry) but would that be high enough to replace all motors... and who's going to pay for that. Because in the long run we all do. If Pentax has sold 2000 of those lenses and 200 of them failed, do Pentax users want to pay for the replacement of the other 1800 even thought they are likely to have productive lives, just to satisfy a few whiners? Because the cost would get passed on to all of us. Or, the lenses in question would be priced out of this world.

What I see here is people who were early adopters and tried out new and largely untested technology, getting upset because some of it failed. Understandable... but why should the rest of us pay, because you were an early adopter?

There are lots of reasons why Pentax forum polls are meaningless. There is absolutely no research done that shows that Pentax forum polls in anyway represent reality. Are people more likely to report negative experiences? Are the guys who have working product less likely to participate? Based on the number of lenses sold , are the two hundred or so represented in Pentax forum posts any representation of anything other than an indictment of the type of person who comes on the forum?

You don't know what you're talking about, and you should be little less certain that you're right. As a person brought up with an understanding of cooked statistics, your analysis is fraught.. (fraught I say ) with weaknesses that render it meaningless.

I can't refute what you say, but I have lots of good reason to not believe you, reasons that to me are more compelling than the arguments you use to make your case. Not the least of which is the small and biased sample size used to reach your conclusions.


Last edited by normhead; 01-28-2015 at 11:38 AM.
01-28-2015, 10:40 AM   #24
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Another aspect of this story is that - like it or not - there's so far no alternative to most of DA* lenses. The bad is that even when they refresh the whole DA* line and install super good failure-proof SDM motors, there will always be rumors about SDM.
01-28-2015, 11:33 AM   #25
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QuoteOriginally posted by zzeitg Quote
Another aspect of this story is that - like it or not - there's so far no alternative to most of DA* lenses. The bad is that even when they refresh the whole DA* line and install super good failure-proof SDM motors, there will always be rumors about SDM.
They can call that new line of lenses DC* and everybody will be happy, even if contains the improved SDM motor instead of the DC motor (if there is any difference, I don't know).

I think the problem currently is that it's unknown which lens is 'safe' to buy. Buy a DA* and there is a risk that you get a pre-2012 version. With a DC* marking, buyers can be sure that they will get the newer model.
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