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03-02-2011, 09:41 AM   #16
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At my local retailer... the 5 year extended warranty is something like 20-25% of the lens price...

Considering that the price of a repair should be less that a replacement.... in order for the warranty to make good business sense, i need to expect that there is 40-50% of the chance that the lens will break between year 1 and year 5.

Do you stile think the extended warranty is a must ?!?!?

03-02-2011, 10:01 AM   #17
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QuoteOriginally posted by JHD Quote
Do they carry DA* lenses?
Lens rentals.com does not carry any pentax mount lenses and camera lens rentals, which does, does not reveal statistics of lens failures (although they do carry all of the DA * lenses).
03-02-2011, 11:09 AM   #18
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QuoteOriginally posted by ben_leg Quote
At my local retailer... the 5 year extended warranty is something like 20-25% of the lens price...

Considering that the price of a repair should be less that a replacement.... in order for the warranty to make good business sense, i need to expect that there is 40-50% of the chance that the lens will break between year 1 and year 5.

Do you stile think the extended warranty is a must ?!?!?
An extended warranty is never a must. It all comes down to 1) the cost of the warranty, 2) the probability of failure during the period of the extended warranty and 3) the cost to fix the lens outside the warranty. The biggest problem that people face in this situation is no one actually knows the answer to number "2". Without that information, any decision an individual tried to make regarding a warranty purchase is at best an educated guess. If you're risk adverse, then buying the warranty is probably a good idea just to give you peace of mind. If you're more of a "by the numbers" person, like myself, I choose to self-insure by buying used lenses knowing the money I save can go towards the repair costs should I ever need them.
03-02-2011, 03:25 PM   #19
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Its never the DA-300, DA-200, DA-55 or the 60-250, its the 50-135 or 16-50 primarily. What that tells me is the SDM motor or linkage has more friction problems in those two troublesome lenses.

03-02-2011, 05:21 PM   #20
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QuoteOriginally posted by philbaum Quote
Its never the DA-300, DA-200, DA-55 or the 60-250, its the 50-135 or 16-50 primarily. What that tells me is the SDM motor or linkage has more friction problems in those two troublesome lenses.
But the 16-50 and 50-135 must be far more popular than the other lenses, so we would expect to see far more reports of having problems with them...
03-04-2011, 04:21 AM   #21
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Too many variables to speculate.
I do think it's prudent to take out extended warranty given the relative propensity of failure of such an expensive series of kit.

Last edited by Ash; 03-04-2011 at 05:08 AM.
03-04-2011, 04:51 AM   #22
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QuoteOriginally posted by sewebster Quote
But the 16-50 and 50-135 must be far more popular than the other lenses, so we would expect to see far more reports of having problems with them...
Yes, although I have to think the DA 17-70 is pretty popular too and there are not nearly the reports of SDM failures with it. My feeling is that it has to do with tiny motors moving heavier pieces of glass, but what do I know?
04-07-2011, 07:06 PM   #23
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QuoteOriginally posted by Class A Quote
When the SDM issues started there was a lot of hysteria and I was one of the few stating that there was too little evidence to justify a petition, etc. Since then the SDM failure reports haven't stopped. Surprisingly many have their lens fail not once, but twice or even three times.
I just had the autofocus on my 50-135 to fail for the THIRD time. It quit the first time barely after the year warranty. $200+ to fix it. Three months later it was out again. Another three months and I'm contacting the repair company again.

04-07-2011, 07:39 PM   #24
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I'm speculating here, but it sounds like you might have a lens with a lot of friction in its autofocus system, and the failing motor is the symtom of this problem. This is how I can understand some people going for years with no failures, and others having multiple (not just one). These multiple failures to my mind are better explain by something other than getting multiple dud motors in a row.
04-07-2011, 07:45 PM   #25
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QuoteOriginally posted by twitch Quote
I'm speculating here, but it sounds like you might have a lens with a lot of friction in its autofocus system, and the failing motor is the symtom of this problem. This is how I can understand some people going for years with no failures, and others having multiple (not just one). These multiple failures to my mind are better explain by something other than getting multiple dud motors in a row.
That was always one of my theories (extra friction in the AF gears).

The other theory is that let's say a motor has a 5% chance of failing (say within a year). I have no idea if that's high or low, but let's just go with it for now. The chance of someone having back to back failures would then be 0.25%. The chances of three failures is 0.0125%. Obviously you'd have to be pretty unlucky to have three failures in a row, and the odds are very small (1 in 8000), but assuming Pentax sells enough of these lenses around the worlds, under these assumptions it's actually likely to happen to a few people. And when it does happen to someone, it's more likely they're going to post about it than someone who has had 3 consecutive years of trouble free time with their DA* lens.
04-07-2011, 07:56 PM   #26
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QuoteOriginally posted by dgaies Quote
That was always one of my theories (extra friction in the AF gears).

The other theory is that let's say a motor has a 5% chance of failing (say within a year). I have no idea if that's high or low, but let's just go with it for now. The chance of someone having back to back failures would then be 0.25%. The chances of three failures is 0.0125%. Obviously you'd have to be pretty unlucky to have three failures in a row, and the odds are very small (1 in 8000), but assuming Pentax sells enough of these lenses around the worlds, under these assumptions it's actually likely to happen to a few people. And when it does happen to someone, it's more likely they're going to post about it than someone who has had 3 consecutive years of trouble free time with their DA* lens.
Yeah the odds get small after 3 motor failures that the problem is the motor and not something else. It's a "what's more likely" scenario, and although I believed it at first, I now have no faith in the theory that this forum is a gross misrepresentation of the real level of SDM problems. Many here don't join this forum for the first time just to report their SDM problem and yet after a while they report them, and there are many that will never join this forum even if they have 3 failures.

I think the SDM problem is huge (25% yearly failure rate on the 2 chief suspects, maybe more?), especially for the 16-50, 50-135. I wish that wasn't the case because I actually own one of them.

OTOH I would have no hesitation buying a DA*200 or DA*300 if I needed either, for whatever reason the deisgn of those lenses makes them far less likely to fail. I strongly suspect the motor is the same in those lenses as the problem ones, but what's different is the autofocus gears/system.
04-07-2011, 07:59 PM   #27
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QuoteOriginally posted by ben_leg Quote
At my local retailer... the 5 year extended warranty is something like 20-25% of the lens price...

Considering that the price of a repair should be less that a replacement.... in order for the warranty to make good business sense, i need to expect that there is 40-50% of the chance that the lens will break between year 1 and year 5.

Do you stile think the extended warranty is a must ?!?!?
a DA* 50-135mm WILL fail within 5 years. I stake my life on it.

Mine failed 3 times within a year before I finally clued in and got rid of it. I also used to rave about the optical quality, how special it was, blablabla. But eventually the repeated failures defeated my enthusiasm. There's only so much abuse I can take from my so-called professional gear before I start sliding into cynicism.

Don't just look at the costs involved in getting it fixed (or the extended warranty). Also take into account the amount of time you'll be without the lens while it gets fixed.

edit: at last report, an SDM motor replacement in a 50-135mm was $180 a pop. 2 Motor failures means you've already covered that extended warranty cost. After 5 years, you'll likely be paying $200+ a pop, assuming replacement parts are even still available.
04-07-2011, 08:07 PM   #28
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QuoteOriginally posted by twitch Quote
Yeah the odds get small after 3 motor failures that the problem is the motor and not something else. It's a "what's more likely" scenario, and although I believed it at first, I now have no faith in the theory that this forum is a gross misrepresentation of the real level of SDM problems. Many here don't join this forum for the first time just to report their SDM problem and yet after a while they report them, and there are many that will never join this forum even if they have 3 failures.

I think the SDM problem is huge (25% yearly failure rate on the 2 chief suspects, maybe more?), especially for the 16-50, 50-135. I wish that wasn't the case because I actually own one of them.

OTOH I would have no hesitation buying a DA*200 or DA*300 if I needed either, for whatever reason the deisgn of those lenses makes them far less likely to fail.
Don't get me wrong, I generally subscribe to the "what's more likely" scenario. Although if in fact the yearly failure rate was really 25%, then the number of people who had 3 failures in consecutive years would be pretty high, close to 2%; assuming the same person was willing to replace the motor again and give it a third try

Without seeing the real data, it's hard to say if the 16-50 and 50-135 really have that much higher of a failure rate than the other DA* lenses. I know it certainly seems that way, but if the sales figures are such that there are literally 50 times as many of those two lenses than the other DA* lenses, then it wouldn't be unexpected that the vast majority of SDM failures you read and hear about are with those two lenses.

But don't misunderstand, I'm not in any way making excuses for what is clearly an issue in terms of the reliability of the SDM motors. I just wish there was more real data out there to look at and try to better understand the issue and quantify the real chances of failure.
04-07-2011, 08:30 PM   #29
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QuoteOriginally posted by philbaum Quote
Its never the DA-300, DA-200, DA-55 or the 60-250, its the 50-135 or 16-50 primarily. What that tells me is the SDM motor or linkage has more friction problems in those two troublesome lenses.
For the record, my 60-250 AF failed after 10 months, and had an all expenses vacation to Japan.
Having said this, I would by another one in a heartbeat. The optics make any gamble of failure worth every penny.
05-05-2011, 06:18 PM   #30
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I sent my 50-135 lens back a 3rd time for failing to auto-focus and asked the repair company to see if Pentax would replace it, and they did. I received a new lens today. That made me feel a little better about Pentax, and really good about the repair company,
C.R.I.S. Camera Services in Chandler AZ, criscam.com.
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