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11-28-2010, 05:16 AM   #31
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I suppose the only ones who can really tell whether the failure rate of Pentax SDM is higher than Canon or Nikon is Pentax.
John: A bigger strawman has rarely been built. I am not talking models but the SDM motor, and your comparison lacks logic, models are obsolete the moment a competitor releases a new one. All the same, I wish your SDM motors live long and prosper. Mine did not. While on the topic, I shoot with all of K, M, A, FA and DA lenses. The K 30mm f2.8 is one of my favorites. The screw-drive in the F and FA lenses has lasted quite well (coming close to 20 years, right?). I am frankly skeptical of the lasting power of SDM motor in the DA* lenses, when mine struggled to live out 18 months of sporadic use.

11-28-2010, 06:45 AM   #32
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If SDM failure is truly a very sporadic event, then it would be unlikely to happen to the same person more than once. But I have seen several users who have talked about having multiple SDM failures.
11-28-2010, 08:08 AM   #33
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QuoteOriginally posted by mfdesalas Quote
I suppose the only ones who can really tell whether the failure rate of Pentax SDM is higher than Canon or Nikon is Pentax.
John: A bigger strawman has rarely been built. I am not talking models but the SDM motor, and your comparison lacks logic, models are obsolete the moment a competitor releases a new one. All the same, I wish your SDM motors live long and prosper. Mine did not. While on the topic, I shoot with all of K, M, A, FA and DA lenses. The K 30mm f2.8 is one of my favorites. The screw-drive in the F and FA lenses has lasted quite well (coming close to 20 years, right?). I am frankly skeptical of the lasting power of SDM motor in the DA* lenses, when mine struggled to live out 18 months of sporadic use.
So what you are saying is that your lenses without motors have had no motor failures? Hey, me too, as well as everyone else with motorless lenses!

I empathize with those that have had SDM problems. It must suck. But how do we distinguish between a bunch of unlucky but statistically minor group vs a real issue? I remember someone posting a message from a lens rental place - IIRC they gave no indication that SDM motors failed at a significant rate.

I've had computers fail me, defective phones, cars recalled, and myriad other devices stop working. It's just the price you pay for increasingly complex devices.

If you really believe this is an issue than I suggest a more coordinated effort to get it addressed, i.e., a letter writing campaign to a consumer protection organization, a more statistically valid survey of DA* owners, or even a class action suit.

Finally, my straw man isn't nearly as big as the one you started this thread with LOL!
11-28-2010, 08:52 AM   #34
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QuoteOriginally posted by mfdesalas Quote
Hi Ash,

I didn't say SDM was a flop, I said it was a failure. How many of the current crop do you expect to see still around in 10 years time? .........?
By that logic, LP records, Apollo spacecraft, B&W TVs, the Model T, Polariod cameras, VHS recorders were all "failures" because there are few to none around any more.

11-28-2010, 09:38 AM   #35
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QuoteOriginally posted by Parallax Quote
By that logic, LP records, Apollo spacecraft, B&W TVs, the Model T, Polariod cameras, VHS recorders were all "failures" because there are few to none around any more.
Your list refutes his logic only by completely changing the parameters.

Of your list, I believe only the Apollo spacecraft was not still around 10 years after its introduction. Big difference between "not around 10 years later" and "not still around today".
11-28-2010, 09:58 AM   #36
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QuoteOriginally posted by Mike Cash Quote
Your list refutes his logic only by completely changing the parameters.

Of your list, I believe only the Apollo spacecraft was not still around 10 years after its introduction. Big difference between "not around 10 years later" and "not still around today".
You are correct in the strictest sense; but the point was that the fact that something doesn't last for any arbitrarily specified time period has noting to do with rather it can be classed as a failure or not. If something does what it is supposed to do, and people buy it in sufficient quantities to make it profitable and keep it in production, it is successful. It is irrelevant to the success/failure argument whether it takes a year, a decade, or a century for it to be superseded by better technology.
11-28-2010, 10:15 AM   #37
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We expect lenses to last for ever!

...even though we are upgrading our DSLRs every year or so as the technology improves, we are used to lenses that last for ever. I still have some of my original Pentax lenses that I bought new in 1978 and I have only ever experienced one lens failure when the aperture linkage broke.

Now that lenses are getting electronic components, miniature motor drives and more mechanical complexity, we are getting more failures, but I suspect the original mindset still exists. The Pentax SDM failures may not have been widespread, but were still more frequent than folks expected, leading to some disappointments when expectations weren't met.

I suspect the new DC motor is a simpler, cheaper, more rugged micro-motor that we may see in more consumer to mid range lenses.

Mike
11-28-2010, 10:17 AM   #38
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QuoteOriginally posted by Stringmike Quote
We expect lenses to last for ever!
True; but since forever isn't here yet, there is no way of knowing whether any particular sample will or won't.

Just to clarify: I don't own a SDM lens, nor will I. I don't trust them. The new DC system will hopefully be what the SDM was supposed to have been.

11-28-2010, 10:35 AM   #39
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QuoteOriginally posted by Parallax Quote
True; but since forever isn't here yet, there is no way of knowing whether any particular sample will or won't.
Don't worry, the world will end somewhere in 2012; or so they say. Just 'pray' that your SDMs last till then.
11-28-2010, 12:30 PM   #40
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Screwdrive is apparently superceded technology. But screwdrive lenses continue to produce images like they always have. That is the real difference in this argument about SDM longevity. Whilst SDM lenses can continue to do so as well, even after a motor failure, no-one wants an excellent MF lense when it was intended as an AF one.

As far as I'm concerned, no technology can supercede or make obsolete the FA ltd series. Newer bodies are making AF quicker even for these lenses, so even then the lenses continue to be 'better' with time...
11-28-2010, 01:53 PM   #41
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QuoteOriginally posted by Ash Quote
Screwdrive is apparently superceded technology. But screwdrive lenses continue to produce images like they always have. That is the real difference in this argument about SDM longevity. Whilst SDM lenses can continue to do so as well, even after a motor failure, no-one wants an excellent MF lense when it was intended as an AF one.

As far as I'm concerned, no technology can supercede or make obsolete the FA ltd series. Newer bodies are making AF quicker even for these lenses, so even then the lenses continue to be 'better' with time...
If they could make screwdrive as silent as SDM then I'd agree 100%. But there are situations where silence is golden, and I'd hate to negate the silence of the K-5 shutter with the whining of the screw drive motor under certain sensitive circumstances.
11-28-2010, 02:17 PM   #42
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QuoteOriginally posted by johnmflores Quote
If they could make screwdrive as silent as SDM then I'd agree 100%. But there are situations where silence is golden, and I'd hate to negate the silence of the K-5 shutter with the whining of the screw drive motor under certain sensitive circumstances.
I might be uninformed, but is there anything in the construction of the screw drive that necessarily makes it noisy? One motor to rule all kinds of lenses, thing?
11-28-2010, 03:02 PM   #43
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I think by definition, in lens motors will all eventually burn out. This is true for Canon and Nikon as well as for Pentax. I guess the question is whether or not SDM actually serves as some sort of improvement over screw drive in other respects. The answer is 'no' in terms of speed -- it is roughly equivalent and 'yes' in terms of noise.

At the same time, in order to get the optics of the DA * lenses, you have to deal with this uncertainty and if that is the most uncertain thing in my life, then I am in pretty good shape.
11-28-2010, 05:54 PM   #44
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QuoteOriginally posted by Edgar_in_Indy Quote
The screw drive can't be used when SDM fails? Before I had decided against the DA* 50-135mm (due to SDM), I had figured that worst case scenario I could always use the screw drive if SDM failed.
The K20d, K200d, K-m, K-7 can't. Don't know about the K-5 and K-x. The first version firmware of the K10d can. Pentax would need to do a firmware patch to allow screwdrive. I was concerned enough about SDM that when I got a DA* 300mm at the beginning of the year, I paid $60 for a 3 year warranty.
11-28-2010, 05:58 PM   #45
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QuoteOriginally posted by Ash Quote
The only statistic users can be sure of is whether their own copy is a failure or not.

The couple of polls on the rates of SDM failures had relatively low response rates with high likelihood of responder bias (users with failed lenses tending to respond more than those with working ones).

So in the absence of accurate data there can only be speculation. But it's no fun when you're a statistic.
The existing evidence tends to lean against Pentax in this regard. Many of the failed lenses failed more than once which is the really stunning part. Plus, Pentax isn't the greatest in the world on repairs and customer service. Nikon uses there butts for a broom and their heads for a mop in this regard to clean the floor.

Edit: To put this into context, how many screw drive failures have their been?
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