[truonganh]

well...
I did the DIY repair all the way to unstucking motor shaft and back together, didn't appear to help. Thanks to the manual, it is very easy to do, but I wasn't able to unstuck the motor shaft.

i cleaned the SDM contacts. no go either.

out of desperation i tried masking the SDM contacts and the extra pin, but could not fool the camera to work with in-body AF.

manual focus is a pain. I'M NOT BUYING ANY MORE SDM LENSES. I really think lenses are suppose to outlast camera. Lens is the reason i go with Pentax. The lens failure make it a pointless rationale. Especially in the light what should appears to be a viable, easy firmware upgrade or future inclusion on new camera bodies.

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Last edited by truonganh; 10-21-2011 at 10:09 PM.

[Moe49]

Have anyone tried disabling all the SDM contacts? it looks like SDM lens has 3 extra contacts over manual screw lens. I wonder if the camera will revert the DA* lens to screw mount AF drive. that could be a permanent solution.

I tried this about a week ago, but this procedure did not 'trick' my K7 into using it's screw-drive to auto-focus a DA*16-50.

What others have clammered for here at PF: it will take a K7 firmware upgrade to get screw-drive AF of SDM lenses.

[blackcloudbrew]

Well, I tried this on a DA 17-70 (SDM). It's been balky at focusing lately and I'm feeling like it may have SDM problems to come, so after reading this I gave the DIY solution a try. One thing that's different from the DIY guide is that there is a hole over the SDM motor so you only have to remove the 5 outside screws to be able to turn the SDM motor per the guide. I guess, if my motor actually freezes, I may need to do this again.

[photocanadian]

Here is an out-of-the box question:

Can we take out the SDM motor/gears, thus converting the lens to AF via screw-drive only? I really like the da* optics, but the SDM sucks, plain and simple. I don't have any broken da* lenses to try this, unfortunately ...

Well, I tried it today on my 16-50 and it didn't work. I opened the lens several times to repeat the procedure to no avail. The first time I rotated the screw it was really stuck, so maybe the motor seized. As it stands I guess I'll have to send it in for repair, not much fun using manual focus.

It's not really hard to open the lens if you follow the guide, just be careful and remember, if you need to apply force you're doing it wrong.

[RayGunn]

Here is an out-of-the box question:
Can we take out the SDM motor/gears, thus converting the lens to AF via screw-drive only?

It would be my guess there is a chip in the lens, which sends exposure and focal length info to the body, also sends a message telling the body the lens is SDM, so do not use the screw drive focus.mechanism. If true, it's too bad there isn't a menu option for which focus system the body should use.
RayGunn

[Class A]

Can we take out the SDM motor/gears, thus converting the lens to AF via screw-drive only?

The problem is the camera. Only the K10D with an older firmware (and IIRC the K100D super) can drive an SDM lens via screw drive. All current DSLRs will only use the SDM mechanism.

Search this forum for an SDM petition to persuade Pentax to include a firmware option that allows switching to screw drive. IIRC, it had over 1000 signatures. Personally I believe as much as it would be a nice feature to have, if Pentax were open to include it, they would have done it already.

[photocanadian]

The problem is the camera. Only the K10D with an older firmware (and IIRC the K100D super) can drive an SDM lens via screw drive. All current DSLRs will only use the SDM mechanism.

Search this forum for an SDM petition to persuade Pentax to include a firmware option that allows switching to screw drive. IIRC, it had over 1000 signatures. Personally I believe as much as it would be a nice feature to have, if Pentax were open to include it, they would have done it already.

Bummer ... Another possibility would be to reprogram the lens to report a non-sdm lens id ... but that would only be easily doable if there is a discrete eeprom chip.

Perhaps someone list the part numbers off the chips if they open up an SDM lens like that ...

[falconeye]

The problem is the camera. Only the K10D with an older firmware (and IIRC the K100D super) can drive an SDM lens via screw drive. All current DSLRs will only use the SDM mechanism.

Search this forum for an SDM petition to persuade Pentax to include a firmware option that allows switching to screw drive.

I agree that screw drive should be a firmware option.

However, AFAIK, it remains an open question if most SDM failures aren't due to a failure of the screw/SDM clutch. If so, such firmware option wouldn't actually help.

Maybe, insight from this thread (from people who did the repair) can be used to clarify this question (or mounting a failing SDM lens onto a screw-drive body -- hey, maybe turning the screw in a lens with failing SDM would make it work again; anybody actually tried? )

[calicojack]

<snip> hey, maybe turning the screw in a lens with failing SDM would make it work again; anybody actually tried? )

No, it doesn't help. I have a DA*50-135 that experienced an SDM failure shortly after the warrantee expired. Before I had a chance to send it for out of warrantee repair, I lost my job so money priorities had to go other directions. Since I own a K10D, I was fortunate enough to be able to back the firmware version down to V-2, which doesn't allow SDM and continue using this fine lens via the screw drive focus system. It works fine for me and my style of shooting.
Out of curiousity, every second month (or so), I try the lens on my wife's K200D which uses SDM. It never works. I haven't tried the open up the lens and turn the screw repair yet, simply because the lens works fine with my K10D's screw drive system. I'm still unemployed so that new K5 is still waiting for me a B&H and SDM isn't too much of an issue, for me, at this point.

[OldPentaxian]

About a year back, I posted this solution:
(The following tip will not work for all, but it helped me twice over a period of time)

Mount the SDM lens (e.g., 16-50mm) on an autofocus [SLR] body which has no SDM-compatible contacts, e.g. the ZX-/MZ-7. Activate the screw-driven autofocus and allow the camera to focus the lens several times over a wide distance range. Obviously this tip can only work with DA* lenses which support both screw-driven AF and SDM.
In my case, this seemed to "un-jam" the SDM (and jammed manual focus override [of the 16-50mm]) when I returned it to the [...] K20D. I've never had to have my SDM lens serviced. [-thankfully, yet (!)]

In other words, you won't need to look for a used K10D just to "jiggle" the autofocus mechanism. Any old Pentax SLR with K-Mount and AF can serve (for the DA* 16-50 mm, at least). I doubt that it can be done by simply hand-turning the screw-driven AF on the lens; that wouldn't give it enough of a jolt. Covering the lens contacts will not force a K20D or newer DSLR to switch over to screw-driven-AF mode, since the lens signal-to-camera seems to be electronically coded, not a simple electric-circuit signal.

We all need to encourage Pentax's new owners to take these SDM AF problems seriously. More crucially than some work-around firmware update to newer DSLRs, we need SDM quality assurance. Nothing else will secure the future of fine lenses and the Pentax brand so well as QA. (Yes, I'm for the Pentax brand because I own equipment that I want to continue using and upgrading; if the quality of SDM AF lenses causes enthusiasts to go "Canikony", I lose / we lose). Nonetheless, I agree that the work-around firmware enhancement to our DSLRs is an important indicator of how well Pentax is listening to and feeling for its less fortunate customers. Sooner or later, they, too, should have their best SDM lenses functioning again - at an affordable repair price. Such customer-friendly service would be a feather in Pentax's cap when contrasted to other lens makers whose silent/sonic AF motors sometimes, BTW, also fail.

[OldPentaxian]

LensRentals.com - Lens Repair Data 4.0 is not meant as a comment on how good (or bad) a lens may be. It merely allows us to reflect on the fact that other lens manufacturers' autofocus systems also, by the way, do fail.

[truonganh]

Other manufacturers allow their lenses to fail at a rate is no excuse especially when Pentax have an "out" to produce a firmware update as backup to SDM failure. I have a stack of lenses, the only one with problem is the SDM version. What a shame. How many of us have a fast fifty with autofocus? every time i used it, i'm pleased: sharp as tack just a stop down, wonderful focus, small, cheap (way back then), reliable work horse after all these years, that tradition should continue so we can all be proud as pentaxian.

[tcbubbleleo]

Hi, I just got given an DA*16-50mm which cannot be auto-focused on a KAF2 camera. I have no prior experience on SDM lens, have not used/seen one before. This one has no sound/noise/don't move at all when both lens and camera are in AF modes, also it shows MF on the camera. My question is: this a typical SDM prob.? or I just forget DIY repair it, and just send it in to Pentax...?

[falconeye]

Hi, I just got given an DA*16-50mm which cannot be auto-focused on a KAF2 camera. I have no prior experience on SDM lens, have not used/seen one before. This one has no sound/noise/don't move at all when both lens and camera are in AF modes, also it shows MF on the camera. My question is: this a typical SDM prob.? or I just forget DIY repair it, and just send it in to Pentax...?

Please specify your camera.

The KAF2 mount does not support SDM autofocus, so this thread does not apply to your problem. A film camera's power contacts are for power zooms. However, the DA*16-50 should work flawlessly with cameras not supporting SDM because the lens supports screw-drive AF too. Maybe, the lens is confused when it sees power on the AF contacts which aren't SDM?

Again, please specify your camera.

EDIT: if, as Rondec assumes, your profile is correct, you have a K-x. The DA*16-50 should work of course then. But if the K-x shows the lens as MF, I guess there is a problem with contacts. Try to clean contacts on both sides. If the problem persists, try to find another body (you could visit a shop to try out a K-5) and see if the DA*16-50 still fails to work. If it does then it is a case for service.

[Rondec]

Hi, I just got given an DA*16-50mm which cannot be auto-focused on a KAF2 camera. I have no prior experience on SDM lens, have not used/seen one before. This one has no sound/noise/don't move at all when both lens and camera are in AF modes, also it shows MF on the camera. My question is: this a typical SDM prob.? or I just forget DIY repair it, and just send it in to Pentax...?

You have a kr, right? It should focus and I think it would be worthwhile to send it in. Probably would just check first to make sure contacts are clean, that the MF/AF switch is set to AF, but sure sounds like the motor isn't working right.