Straw Poll - SDM reliability...

Discussion in 'Pentax' started by jptreen, Apr 1, 2009.

  1. OK - having read a few things about the SDM motors in Pentax products possibly being a bit less reliable than the old screw drive system (makes sense, a motor is more likely to fail than a driveshaft), I thought it might be an idea to conduct a straw poll to see what peoples' general experience has been with these things. If people with SDM lenses could spare a second and say what SDM lenses they have, how long they've had them, what level of usage they've been subjected to, how much the weather sealing has been tested and whether they've had any problems... the end, if there's sufficient response, I could cobble together some rough stats (not pretending genuine scientific method here, just a rough idea...)
    I'll kick off...
    DA*50-135 - had it 9 months, used twice or three times a month, used in rain and snow, no issues
  2. Don't have any SDM lenses but have plenty of Canon USM lenses, which is the same thing. There are hardly ever any reports of ring USM motor failure in the Canon forum. It make sense as the technology used in these motors is far cleverer and far simpler than traditional arc drive motors.
    Based on the design I would expect USM/SDM to suffer from an exceedingly low rate of failure compared to arc drive electrics coupled to a drive shaft.
  3. wow just read the post a few threads down! Suspect it was a manufacturing defect rather than SDMs being inherently more prone to failure.
  4. I have owned the DA*50-135mm for about a year. I've taken thousands of shots with it indoors and outside. With the K20D attached it is the one rainy day setup I can trust. Never had a problem.
  5. John-Paul, I have had my DA 50-135 for a year and a half. Use it weekly, more than any of my other lenses. No problems.
  6. Sounds good so far, I want to know what Javier says though...he puts his kit through a lot :)
  7. Well, I have the DA*16-50, DA*50-135, DA*200 and DA*300 and have never had an SDM problem. I have bought them all pretty much with in a day or two of their release. But in all honesty, I also use them very little.
  8. mountainvisions

    mountainvisions Moderator

    I personally believe there is a problem with the dual SDM/slot drive and while I applaud Pentax for not abadoning recent ist and K series buyers, the fact is they should have just went SDM from the start since the release of the SDM lenses was 9 months or more post K10D launch, and Pentax already had more SDM bodies released or pending. Most of the buyers of the 50-135mm were people who needed a higher end lens, and had the income to buy a new body. I am doubtful a lot of 50-135s were mounted to ist DLs and K100D (non supers).
    I disagree with Geoff, I have seen reports of in lens motors failing and needed service on both Canon and Nikon. Lindy also comments on how the older USM canon lenses are not servicable anymore.
    Do I think this is a reason to not buy the SDM lenses? No, but I've noticed HSM, USM, and AF-S all seem to have shorter working lifes than good old slot drive. I wouldn't hesitate to buy a 10 year old Nikon or Pentax slot drive, even if it was physically beat up, I'd have a hard time buying a similar AF-S/SDM lens.
    So this is an instance of being careful what you ask for, don't forget for years the knock on Pentax was that it was the last camera maker without micro motors in the lenses. So old school, so 1990s and such, but the reality is the slot drive lenses seem to last for decades while I bet most of the AF-S, USM, and other micro motor lenses have significantly shorter lives when given the same workload.
    So I for one will not EVER complain that it's currently impossible to put an SDM motor into the Limiteds, and those who are complaining might regret it in a few years if the technology does allow it.
  9. My only SDM lens is a DA17-70/4 and I haven't had it long enough to make any statement about reliability. While the quietness is pretty cool, I don't think it's as nice an addition as the quick-shift focus ring clutch that Pentax managed to implement nicely on drive-shaft AF lenses as well. I'm hoping that whatever lessons Pentax learned with the earlier DA* SDM implementation went into the more recent DA17-70/4 and that I'll be spared some of these gremlins. Fingers crossed. It does seem that Pentax probably should have allowed disabling of SDM in the body firmware so that the dual-drive DA* lenses could be used old-school if desired.
  10. also claim that the Sigma 70-200 HSM is failing a lot more for them than the Tamron...
    Geoff: SDM is not the same as USM. SDM is a micromotor...USM is a ring motor w/ less moving parts as I understand it...
  11. I've had my DA* 300mm for almost a year. I've given it fairly light use with no problems yet. SDM is kind cool, I guess but I can't say I prefer it.
  12. On a side note. I used to believe that the SDM lenses focused faster, but the more I use them, I am not sure about that. I am guessing that it is the same as the screw drive.
  13. SDM is a supersonic motor right?
    You can only call something supersonic drive (or ultrasonic... or silent wave...) if it uses piezoelectric supersonic motor technology. You cannot call a micro-motor drive "supersonic." And it would not be quiet.
    I know that Wikipedia is hardly authoritative, but..
    Notice that everyone (other than Nikon and Canon) suddenly came up with supersonic drive very recently? expiration of Canon patents. Nikon as I understand it had to develop their own different technology for AF-S or maybe they cross-licensed it from Canon.
  14. Geoff: SDM is not the same as USM. SDM is a micromotor...USM is a ring motor w/ less moving parts as I understand it...​
    I was under the impression that supersonic drive motor, was just Pentax's name for USM and same as Sigma HSM, ie ring motors. If it is not a ring motor but I micromotor then I stand corrected but then that is very sad for Pentax.
    Justin I would not argue that USM is foolproof, but it is important to make like for like comparisons. Nearly every Nikon and Canon pro grade lens uses USM and no doubt some of these are subject to constant daily use and abuse by hard working pros. There is seriously no one in the Canon or Nikon forum that wishes for non USM lenses on the basis of percieved unreliability.
    Unrepairable Canon lenses are only those that are discontinued and for which parts are no longer available. Though I would agree that by putting any electronics into lenses it means they are no longer forever, as all electronics will fail at some stage. Still most Canon lenses from 1986 when the EOS system was introduced are still functioning fine or have given up for other reasons, such as being dropped, fungus, broken switches, etc.
  15. mountainvisions

    mountainvisions Moderator

    The SDMs do reverse faster, but I don't think the track objects moving on a single axis any better.
    As an example, if a cyclist is coming at me, I don't think SDM is any better at tracking it, but if a hockey player is coming at me, then moving away, I do think the SDM is (slightly) faster. Could I be wrong, absolutely, but it seems to be the case.
    Again, (and Geoff noted this some time ago), I do think if Pentax had went full SDM from the start and no dual system, the focus would be even faster. I would like to know if anyone with dual SDM/slot lenses and SDM only lenses can comment on differences in focus speed.

    Either way, I truly believe that the SDM only lenses will be more reliable. I have a bad feeling the dual system caused some issues, and yes, I have had an issue with an SDM lens myself, although not the 50-135, which I have had the longest, and used the most thus far.
  16. I haven't used any SDM lenses, but I have used some mid-range Canons (17-55/2.8 and 70-200/4L IS) and the USM drive on those lenses is amazingly fast, even on an entry-level body.
    But Canon has been at it for more than 20 years, while the current SDM is Pentax's first attempt. If you read the Wikipedia article I've quoted, ultrasonic motors were developed by Matsushita, Canon , and ALPS (a disk drive manufacturer).
    So it's no surprise that current-generation Canon USM is the gold standard, they've been at it for a long, long time.
  17. I had in my hands a while ago, a Pentax 50-135, which could not focus between fl 90 to 135mm, a crippled lens.
    I now have a Sigma 70-200mm macro HSM II, which is so far fine.
    The problem with the Pentax SDM lens, especially the 50-135, from the forums, is that it seems to fail a bit too often; to make things worse, Pentax has the worst warranty -- 1 year. Sigma has 4 year, while Tamron has 6 or 7.
    As far as the SDM HSM technology, I could be wrong, but didn't Pentax use micro something on the 50-135, while the new Sigma 70-200 HSM II uses the ring motor? (and Canon uses ring motor, I guess, which is newer, and more reliable, comparing to the motor Pentax used in the 50-135).
  18. Well, I think Geoff has a point. Likely a manufacturing problem, not a design problem. This thread is very useful. If it were a design problem, failures would be more universal, but they are not. Most lenses appear to hold up fine. A new thing for Pentax, and like the DA* 16-50mm, there were some manufacturing bugs.
    As to speed, Photozone measured and rated the speed of the DA* 200mm f/2.8 SDM as very fast, and yet it has both slot-drive operation as well. They likewise rate the FA* 300mm f/4.5 as very fast, which has the screw slot drive only. Very fast vs. very fast. So either can be a fast-focus lens. And either can be a slower-focus lens.
    In considering long-term wear, with a lot of use, it seems reasonable that any motor will wear out before a simpler slot drive will. But with moderate use, it becomes a non-issue.
  19. I should add my own small experience- I just got the DA* 200mm f/2.8, just a few test shots. My DA* 50-135mm of last summer, I've had on a few outings of light service, with no sign of a problem. Perormed very well with excellent IQ. Knocking on wood for luck- maybe I should also carry a rabbit's foot in my bag... can dust off a lens surface with it too.
  20. Geoff&Orlando: current SDM is *not* ring motor. It's a micromotor connected to the slot that also connects to cameras w/ a screw drive. In effect, it acts like a quiet screw drive motor, which is why it doesn't have as much torque as a real ring motor. That's how I understand it from cutaway images I saw a year ago. Pentax claims they'll do a real ring motor on "high performance" lenses and the 60-250/4 would have been the first good big heavy lens to try that on but it's still supposedly a micromotor.
    They did this for backwards compatibility w/ screw drive AFAIK...
  21. Ken that is very interesting and if true and somewhat sad for Pentax.
    From what I know, Canon brought ring USM motors (the kind you want) to lenses aimed at pros and prosumers and then invented micro USM (the kind you don't want) as a cheap way of getting the name USM on some entry level lenses. The micro USM went into some of Canon's very cheap consumer grade junk such as the 75-300 f4-5.6 USM and some kit 28-90 f4-5.6 lenses as a slight $20 upgrade over arc drive motors.
    When Canon names a lens with USM it doesn't destinguish between ring and micro but the Canon forum is all to eager to point out which is which because there is a big difference.
    Ring USM supports full time manual focusing and typically goes with a rear internal focus design. Micro USM on the other hand typically does not support FTM focussing and often goes with a front focussing design and rotating front element. Micro USM is typically fairly slow and not much faster than an arc drive motor. Its only real adavantage, if any, is it is a bit quieter. It may well be more unreliable.
    The is only "serious" Canon lens that uses a micro USM, which supports FTM focussing, is the Canon 50 f1.4. This lens is widely regarded as having slower focus and being much more prone to breakdown than other Canon lenses in the same grade such as the 28 f1.8 and 85 f1.8, which are ring USM designs.
    If Pentax has gerry-rigged a micro USM/SDM to support FTM focussing and slot drive based on the mechansim Canon used to get micro USM in the 50 f1.4 then that is very sad. They won't be fast focussing and they may well be unreliable. Sigma's HSMs are mostly ring motors eg Sigma 10-20 f4-5.6 EX HSM, but I suspect some of their recent upgrades have been micro HSM as well, eg 18-50 f2.8 EX HSM.
  22. We've used the 16-50mm continuously for a year and a half - zero issues.
  23. Thanks guys,
    Seems like a really balanced set ot views has certainly enlightened me!
  24. By the way, since this thread I have spent quite a bit of time with my SDM lenses and I can say with a certainty. When Af is set to AF.C. The auto focus is considerably quicker and more positive with the SDM lenses. So for tracking af.c is the way to go!
  25. I have a 16-50mm that is going back to Pentax soon. Currently it takes me about a minuet to get it working where it is focusing, then it is fine until the next day when I have to go through the process again. Every month it is taking a little longer to start working. I am sure total failure is coming, so I will be sending it back to Pentax now out of warranty. When I get it back if it is working I will sell it and get a Sigma or a Tamron.
  26. I've bought DA*50-135/2.8 and it failed to autofocus in four month after purchasing. Used two or three times for a week with K200D body.
    When shutter button is half-pressed no focusing operations are performed. When shutter button is full pressed out of focus mark is blinking and no picture are taken. It is a very pity because of good mechnical and optical lenses quality. Manual focus works very well. Tomorrow I will try to return lenses back to the shop. Seems that USM drive are broken :-(
  27. I should know this but will the DA*50-135 work as a screw drive autofocu lens?
  28. Yes both the DA* 16-50 and 50-135 will work as scew drive lenses.
    I've owned both bor about 18 months, The 50-135 is used a few times a month no issues and a wonderful lens. My 16-50 was used weekly. The focus started sticking and was very slow to lock on SDM but worked on on screw drive. It was warrenty exchanged by Pentax's Colorado service center after owning it for about eight months. The replacemenmt has been fine but I don't use it nearly as often since I bought the Tamron 28-75 while it was off for repair.

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