DA* 16-50 autofocus randomly working

jbriginshawphotograp · 06-10-2015, 11:12 AM

Originally posted by sterretje

Not knowing which camera you have is not helping. If you have e.g. a K100D, it's definitely not a SDM problem. If it's a camera that supports SDM, there is a thread how to disable the SDM, so the lens becomes screw-drive only. Might be a solution (if the problem is SDM). Or buy a K100D (not Super)

I'm shooting a K-5. I realized I haven't kept it up to date with firmware - though I doubt that would be the issue. Will update today and see (not getting my hopes up).

pentasonic49 · 06-17-2015, 12:15 PM

I have an early 16-50 which has problems from time to time and I find that if you point the camera at a plain surface which cannot be autofocussed upon, set the focus to infinity and press the focus button. Hopefully the lens will hunt from infinity to closest focus and back. Repeating this about ten times exercises the motor and it may improve the focussing reliability. The more often the lens is used the less problems with the motor. I have dismantled mine twice, the second time to drill holes in line with the axis of the motor to use a screwdriver to free up the motor. There is plenty of info on the forum on the SDM issue.

zoolander · 06-18-2015, 05:06 AM

I don't know if this will help.

I bought a 16-50 used with no history, and it works fine (early model). I bought the 50-135 and at first it was fine, but when it sits, it won't "fire up" straight away. I'll make sure I fire up both lenses 2 times a week. They say that a lazy SDM is a sign its on the way out. But before I fire them up, I'll turn the focus rings a few times, I remember reading somewhere there is a seal somewhere which gets sticky - despite the focus ring not turning during AF.

jbriginshawphotograp · 06-18-2015, 12:17 PM

Originally posted by zoolander

I don't know if this will help.

I bought a 16-50 used with no history, and it works fine (early model). I bought the 50-135 and at first it was fine, but when it sits, it won't "fire up" straight away. I'll make sure I fire up both lenses 2 times a week. They say that a lazy SDM is a sign its on the way out. But before I fire them up, I'll turn the focus rings a few times, I remember reading somewhere there is a seal somewhere which gets sticky - despite the focus ring not turning during AF.

Thanks for the tip! I'll try it out.

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06-10-2015, 11:12 AM	#16
jbriginshawphotograp Forum Member Join Date: Jan 2015 Location: Toronto, Canada Posts: 99	Originally posted by sterretje Not knowing which camera you have is not helping. If you have e.g. a K100D, it's definitely not a SDM problem. If it's a camera that supports SDM, there is a thread how to disable the SDM, so the lens becomes screw-drive only. Might be a solution (if the problem is SDM). Or buy a K100D (not Super) I'm shooting a K-5. I realized I haven't kept it up to date with firmware - though I doubt that would be the issue. Will update today and see (not getting my hopes up).

06-17-2015, 12:15 PM	#17
pentasonic49 Veteran Member Join Date: Oct 2012 Location: weston-super-mare Posts: 395	I have an early 16-50 which has problems from time to time and I find that if you point the camera at a plain surface which cannot be autofocussed upon, set the focus to infinity and press the focus button. Hopefully the lens will hunt from infinity to closest focus and back. Repeating this about ten times exercises the motor and it may improve the focussing reliability. The more often the lens is used the less problems with the motor. I have dismantled mine twice, the second time to drill holes in line with the axis of the motor to use a screwdriver to free up the motor. There is plenty of info on the forum on the SDM issue.

06-18-2015, 05:06 AM	#18
zoolander Veteran Member Join Date: Dec 2012 Location: Gold Coast Photos: Albums Posts: 351	I don't know if this will help. I bought a 16-50 used with no history, and it works fine (early model). I bought the 50-135 and at first it was fine, but when it sits, it won't "fire up" straight away. I'll make sure I fire up both lenses 2 times a week. They say that a lazy SDM is a sign its on the way out. But before I fire them up, I'll turn the focus rings a few times, I remember reading somewhere there is a seal somewhere which gets sticky - despite the focus ring not turning during AF.

06-18-2015, 12:17 PM	#19
jbriginshawphotograp Forum Member Join Date: Jan 2015 Location: Toronto, Canada Posts: 99	Originally posted by zoolander I don't know if this will help. I bought a 16-50 used with no history, and it works fine (early model). I bought the 50-135 and at first it was fine, but when it sits, it won't "fire up" straight away. I'll make sure I fire up both lenses 2 times a week. They say that a lazy SDM is a sign its on the way out. But before I fire them up, I'll turn the focus rings a few times, I remember reading somewhere there is a seal somewhere which gets sticky - despite the focus ring not turning during AF. Thanks for the tip! I'll try it out.

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