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07-02-2019, 03:31 AM   #1
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SDM issue?

K5IIs DA*16-50
Is it normal behaviour that autofocus with this lens not to work, when SR is disabled?

John

07-02-2019, 04:22 AM   #2
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QuoteOriginally posted by BakDinitzen Quote
K5IIs DA*16-50
Is it normal behaviour that autofocus with this lens not to work, when SR is disabled?

John

No that is not normal.

The DA*16-50 was one of the early SDM motors (AF motor in the lens) and one of the most troublesome. Try waking it up by manually moving the focus to the two extremes and try again.
07-02-2019, 04:40 AM   #3
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QuoteOriginally posted by BakDinitzen Quote
K5IIs DA*16-50
Is it normal behaviour that autofocus with this lens not to work, when SR is disabled?
SDM works fine with SR, but not when disabled? Does the camera behave the same problem between SR and auto focus with other lenses?
07-02-2019, 06:53 AM   #4
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I have just tried out my 16-50 with the K5 and K3ii with and without SR and the autofocus works.
My lens is one of the early ones and the SDM failed just out of guarantee. I followed the instructions on this forum to expose the SDM motor and turned it back and forth with a small JIS screwdriver. The fix worked for about a month, so I tried a more drastic approach. The lens mount now has a hole drilled in it (after dismantling) in line with the SDM motor so that the screwdriver trick can be carried out without dismantling the lens. The hole is inboard of the mount seal. Since then, the autofocus has worked flawlessly without ever having to use the screwdriver.
Why are you turning off the SR? I would only do that when using a tripod. Using a tripod, I would tend also to switch off the autofocus also.
Is the fault present when the body switch is in AFS as well as C? What about the AF button, is it affected also?

07-02-2019, 12:29 PM   #5
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Since we're on this topic, let me ask another question of the assembled Pentax Illuminati:

There has to be a pair of control functions, one in the camera and one in the lens. And I have no idea what either of them "really" are, I've only been dealing with them from a functional perspective.

So I had a lens start acting up, and I've sent it to Precision - they're waiting for over a month, now, for Ricoh to authorize repairs. I haven't had that trouble with other lenses, but just to be clear, when we talk about the SDM "block" (?) we're talking about stuff in the lens, right?

And what is it, exactly, in the two components that makes that SDM magic work?
07-06-2019, 12:12 PM   #6
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I tried to toggle the SR on and off a few times, and now SDM works just fine. I hope it's not a sign..!!! Lens was bought new, two years ago at SRS in England.
07-07-2019, 12:21 PM   #7
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Good result, quite often, just working a switch a few times cleans up its contacts.
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