SDM Failure


JAK

Link Posted 08/01/2018 - 14:44
smudge wrote:
The DA*200 is a great lens. I don't think you will be disappointed.

Agreed on that. DA*300 ditto.
John K

doingthebobs

Link Posted 08/01/2018 - 23:10
I have a manual focus DA50-135. Lovely lens but have not got it fixed yet. Rather begrudge paying to get it fixed.

I also have the DA200. This one is full AF and has never had any problem with the SDM. Definitely one of Pentax's best lenses, touched by the angels!
Bob

ronniemac

Link Posted 09/01/2018 - 17:52
Sorry to hear about the problems experienced by Phil, Peter and Philip. I will inevitably post a message here if the SDM motor fails in any of my lenses, it's perfectly understandable that users do this. When everything is fine and ticking along nicely, it's not newsworthy.

On the other hand:

I have been fortunate in that to date, all of my SDM lenses (7) have given good and uninterrupted service. I hope others have similar experience too, and share this information.

I don't post this to gloat, my intention is just to help give a balanced perspective.

davidstorm

Link Posted 09/01/2018 - 20:54
johnriley wrote:
This stems from some early problems with a design fault in a couple of SDM lenses and it was tackled years ago by Pentax. There will always be some failures of any item, but SDM should be as fine as any other focusing system motor. WE haven't heard much about the issue for a very long time.

Sorry John, but I think you are sticking your head in the sand and not being realistic. The SDM problems are not just on early samples, they affect all SDM's, particularly on 16-50 and 50-135 lenses, right up to the present day. This is obvious by the number of reports of second or third failures after motors have been replaced with 'updated' ones.

The users on here are not stupid, we make our own minds up about these things. It's a shame because in other regards these lenses are superb and for me it's worth taking the risk. My 50-135 is on its way out, after having been repaired once with the 'updated' motor that supposedly fixed the issue.........

I think I speak with the majority of view on this subject?

Regards
David
My Website http://imagesbydavidstorm.foliopic.com

Flickr

Some cameras, some lenses, some bits 'n' bobs

johnriley

Link Posted 09/01/2018 - 21:20
The point I would make David is that we don't actually know. We know of some failures (how many?) but we don't know, as ronniemac points out, those that didn't fail as that isn't something that's newsworthy. It's anecdotal as it stands and I wouldn't let it stop me buying an SDM lens. In fact, we have some and they haven't been any different to the DC lenses or the screw drive ones for reliability. But that too doesn't mean anything.

I have some statistics somewhere on the failure rate of VHS video recorders, from about 1980 or so, and in the first year some 35% of them failed for some manufacturers. Now if that happened with SDM lenses we would have a crisis. But we simply don't have the data to judge, and that's the only point I make.
Best regards, John

RobL

Link Posted 09/01/2018 - 22:34
I cannot believe that a firm like Pentax doesnít know or are uninterested in how many repairs have been needed to their lenses, gleaned from numbers of replacement motors supplied. Basic quality control. And presumably some of these have been done under warranty. Of course they may choose not to share such information for commercial reasons but they have a reputation to maintain.

CMW

Link Posted 10/01/2018 - 22:13
Is the following survey the best we have (provided the results are treated as indicative rather than gospel)?

https://www.pentaxforums.com/articles/photo-articles/pentax-sdm-failure-survey-r...

SDM implementation on certain lenses does (did? ó the survey was five years ago) seem to be questionable. The 16-50, 17-70: and 50-135 stand out, not in a good way. There are all sorts of cautions and caveats that need to attach to the figures, but the results of the limited survey donít strike me as inherently implausible.
Regards, Christopher

ChristopherWheelerPhotography

davidstorm

Link Posted 10/01/2018 - 22:23
CMW wrote:
Is the following survey the best we have (provided the results are treated as indicative rather than gospel)?

https://www.pentaxforums.com/articles/photo-articles/pentax-sdm-failure-survey-r...

SDM implementation on certain lenses does (did? ó the survey was five years ago) seem to be questionable. The 16-50, 17-70: and 50-135 stand out, not in a good way. There are all sorts of cautions and caveats that need to attach to the figures, but the results of the limited survey donít strike me as inherently implausible.

Hi Christopher, yes, I'd seen that survey before and although not huge numbers it bears out what the majority say on here about the SDM lenses, particularly the three highlighted as the least reliable in the survey. What's also interesting is that these survey numbers are approaching the 'crisis levels' John has quoted for VHS recorder failures. Now that's an eye-opener, if some SDM lenses approach the unreliability levels of VHS video recorders when they first came out, then indeed there is something to worry about and something that Pentax should have come clean about a long time ago.

Regards
David
My Website http://imagesbydavidstorm.foliopic.com

Flickr

Some cameras, some lenses, some bits 'n' bobs

richandfleur

Link Posted 11/01/2018 - 07:59
Yikes!

Typically surveys are slanted towards the negative (those most aggrieved are more likely to complete a survey) but regardless those numbers don't look good.

RobL

Link Posted 11/01/2018 - 08:14
Contrast with Leicaís response to similar problem:
https://www.getdpi.com/forum/attachment.php?attachmentid=126076&d=1491290969

ilovesaabs

Link Posted 12/01/2018 - 00:30
ronniemac wrote:
Sorry to hear about the problems experienced by Phil, Peter and Philip. I will inevitably post a message here if the SDM motor fails in any of my lenses, it's perfectly understandable that users do this. When everything is fine and ticking along nicely, it's not newsworthy.

On the other hand:

I have been fortunate in that to date, all of my SDM lenses (7) have given good and uninterrupted service. I hope others have similar experience too, and share this information.

I don't post this to gloat, my intention is just to help give a balanced perspective.

I was aware of the issues but that hasn't prevented me from owning 3 SDM lenses (DA*) and repairing 2 (one twice). I've actually looked at it as the lenses completing their PDI (pre-delivery inspection) or major service and coming back from JPSS or Asahi Photo like new. I have had three items repaired because I have been totally inept and careless, and the work done by JPSS has been perfect. Just a shame the motors are unpredictably unreliable.

I have a lens and camera that needs to go to Nikon becase sharpness at 400mm on the new 80-400G VR attached to the D500 is apalling, it wasn't always like that but either the camera or the lens is developing a fault.

I just have to treat this as a sad fact of life
AKA Welshwizard/PWynneJ
Assorted Pentax/Nikon/Mamiya stuff

Lev

Link Posted 30/01/2018 - 19:57
Guys, fresh experience here with my already ex 50-135. I've sent it back today for replacement.

Well, bought 3 weeks ago from B&H. I've sent email to support team prior purchase asking them to check the lens if its production date is relatively new. Their response was quick explaining that they are unable to verify it. Spending a lot of time searching the way how to get this information I found one way to ask them whether a packaging box is grey or black, as far as I know grey one means it relatively new. Ok, thanks to B&H I was sure that the box is grey. Some kind of insurance that my SDM will last some reasonable time without worrying much. Please take into account the fact that I was waiting a whole year before finally made decision to buy this lens.

Ok, here it is, finally got it, brand new, shiny, newly manufactured, $1000 star class lens! I'm so excited!

First thing I've immediately noticed was loose focusing ring or backlash. I've even measured it and it was somewhere 0.25 or 0,30mm, but the worst feeling about it was the fact that this loose feeling was more noticeable at the one side of the focusing indicator. There was also a clacking noise when I was starting to rotate it in opposite direction. Ok, thanks to you guys, I decided to keep the lens and forget about it.

Next thing was even more frustrating. Went out in a beautiful, sunny day, took some pictures and was so disappointed to see that 80% of my shots were out of focus. I started to blame myself not focusing correctly as I was shooting mostly at 2.8 and 4.0. I thought I have to do something different than I mostly do with my other lenses. Took even more pictures but this time very carefully - most of my pictures out of focus. Took the lens at lab to test auto focus system and there I saw really heartbreaking results. The auto focus accuracy at wide angles was so terrible that the focus point was either at +3 or -3 on test chart.

Came home to test it again and make some decisions what should I do and guess what? The focusing mechanism started to squeak, well not entirely but somewhere in the middle of the focusing throw.

Sent it back and god knows what I will get in replacement.


So I think it's not really related to manufacturing date. I think it's either a design flow, or just too big tolerances in components, and a weakest point here in this regard goes to SDM mechanism.

davidstorm

Link Posted 30/01/2018 - 20:08
Hi Lev

Sorry to hear of your SDM issues, some of which also affect my DA*50-135 and some of which also affected another SDM I used to own. The biggest frustration I have is not the motor failing (although I think it is on its way out as it takes longer and longer to 'wake it up'). No, the biggest issue is exactly what you have noticed - the variation in focusing accuracy at wide apertures. I find it virtually impossible to calibrate the 50-135 to my camera bodies, because sometimes it back focuses and sometimes it front focuses. I have to try and get a 'happy medium', which really is not acceptable for a lens that costs close to £1000. The same issue afflicted my former DA 17-70, more so with some camera bodies than others.

The problem is worst when shooting in low light, which I suppose is to be expected, but that's what I need this lens for! I suppose we all have to live with it if we want to own a DA*50-135, which I certainly do because when it is good, it is stellar, I've taken some of my best shots with this lens.

Regards
David
My Website http://imagesbydavidstorm.foliopic.com

Flickr

Some cameras, some lenses, some bits 'n' bobs

Lev

Link Posted 30/01/2018 - 20:35
Hi David,

Thanks to god someone agrees that it's not me and it's a focusing system...
I forgot to mention that the guy at shop showed me one of his fast Canon glass, 1.8 as I remember and told me that he sees lenses with similar problem very often but excuse me it's not that fast, it's 2.8. I can accept some errors but not so huge differences.

Now, while my old lens is on its way to B&H I seriously think to exchange it to 70-200 but something is holding me, it's a whole different beast, big, heavy and costly....

David how do you think, is that a camera/lens combination problem or just lest itself?
Last Edited by Lev on 30/01/2018 - 20:38

davidstorm

Link Posted 30/01/2018 - 20:50
Lev wrote:

David how do you think, is that a camera/lens combination problem or just lest itself?

Hi Lev

I think it is a bit of both, mostly the lens design, specifically the motors, but it also is affected by the camera. For example, regarding my DA*300, which also a SDM lens, it focuses much more accurately with my K-3 than it does with my K-5iis. My DA*300 is miles more consistent than my DA*50-135, but still varies a bit. The funny thing is I think the DA*50-135 is more consistent on my K-5iis than it is on my K-3, which is the opposite of what I would expect. However, it is a definite trait of my 50-135 that I cannot rely on it when shooting wide apertures, unless I take a lot of shots and re-focus every time. I don't need this when shooting gigs, particularly as the organisers rely on my images and I am working so fast I don't have time to waste loads of shots.

I still would not part with the 50-135 though, it is one of my favourite lenses, I won't say my absolute favourite due to the erratic and slow focusing, but it's definitely up there with the best in terms of image quality. If I were you I would get another one and hope that it's a good one.

Regards
David
My Website http://imagesbydavidstorm.foliopic.com

Flickr

Some cameras, some lenses, some bits 'n' bobs
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