WTB: DA*16-50 or DA*50-135 with SDM failure


Link Posted 25/11/2020 - 19:10
Hi guys

I'm looking to buy a copy of one of the above that is suffering from SDM failure. The reason for this is that I've been looking into repairing the SDM unit itself and I'd like to have a go.

The lens itself must be in good optical and mechanical condition with a faulty (but not damaged/repair attempted) SDM unit.



Link Posted 26/11/2020 - 14:22
I have both a 16-50mm and 50-135mm that need "waking up" before they autofocus, not sure if they are any good to you as they always work after about 30 seconds of pressing the AF button.

Strangely they have always been like that but they don't get any use as I don't have a APS-C body ... although I have used the 50-135mm a couple of times on the K-1.
. My Flickr


Link Posted 26/11/2020 - 15:03
It's interesting that the behaviour has been so consistent over the years, Mike. I've not had a lot of experience with a failing one as previously I would just convert to screwdrive.

I'm looking for a fully dead one to be honest as it'll be a bigger challenge (and hopefully cheaper). I managed to revive a 'creeping' SDM and got it fully working with no massaging required so I'm keen on seeing how the same method works.

Essentially I am lubricating the SDM unit and then flushing it, hopefully to remove any residue that is causing the failure.


Link Posted 26/11/2020 - 15:35
I try to remember to mount them on the K1 at least once a month as people say that's the thing to do with them but usually fail miserably. I realised when I read your thread that it must be 6 months at least since I last did it so just got them out and put them on the camera.

The one thing I have noticed is that if you use liveview they spring into life much much faster than normal AF, I just wonder if LV used more current through the contacts.
. My Flickr
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