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03-31-2013, 01:30 PM   #1
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Tamron 17-50 goes wacko

I recently bought a Tamron 17-50/2.8 from KEH (in LN- condition) and was very pleased with it for the first few weeks. Yesterday, I used it in manual focus (on my K-5) for the first time - for a period of a few hours - and now I'm seeing something that I can't figure out at all. I set the camera back to AF-S, and for the first few seconds it behaves normally. Then - while I'm focusing on a subject - all of a sudden, the MF indicator comes on in the viewfinder, the green "in focus" indicator starts flashing on and off as I move from one subject to another, and the focus confirmation beep is sounding every few seconds (presumably when it finds focus). While all this is happening, the MF indicator is lit steadily. It's as if the camera thinks that the lens has an AF/MF switch and that it's in the MF position, but this lens doesn't have such a switch. I've tried turning the camera off and back on again, taking the battery out for a couple minutes and then reinstalling it, recharging the battery, wiping the contacts, and turning the focus ring back and forth between stops a couple times. Nothing makes any difference -- when I turn it back on, everything's normal for the first few seconds, then it goes wacko again. With a Pentax lens on, everything works normally.

Has anyone else seen anything like this? I like this lens otherwise and, as I say, it worked fine in autofocus for the first few weeks. This didn't start until after I had used it in manual focus for a few hours.


Last edited by dshombert; 03-31-2013 at 01:58 PM.
03-31-2013, 01:57 PM   #2
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Hi. No I have not seen this and don't have this Tammy but the behaviour sounds like the camera really thinks its in manual focus mode. Some questions:
* Have you tried cycling the focus selector between M and AF-S a couple of times?
* Can't remember if the tammy has a AF / MF switch and if so is it in AF?
* Have you tried another lens - does the problem still happen?
03-31-2013, 02:05 PM   #3
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Send it back to KEH, either for refund or repair. You have a 6 month warranty on the lens.
03-31-2013, 03:03 PM   #4
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If I am correct, the lens has a MF/AF switch. To use the lens in MF mode, you must push both the lens switch and the camera switch to MF. Failure to do so might cause some damage when operating in MF mode. To revert back, you need to push back both lens switch and camera switch.

If you did the above, and you have still some problem, you may try to reset the camera. Switch off the camera. Take off the battery (and give it a full charge). Take off the lens. Check that all switches are to AF (both lens and camera). Once the battery is fully charged, try again.

Lastly, try with another lens before contacting Keh. Can you switch between AF and MF wiith your camera and another lens? Or do you have the same problem? You want to ascertain that the problem is with the lens, not with your camera.

If none of the above works and if you are confident that the problem is solely with the lens (not with your camera), contact Keh.

Hope that the comment may help.

04-01-2013, 02:31 AM   #5
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I'd also try cleaning the lens and camera contacts with alcohol.
04-01-2013, 05:22 AM   #6
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You have not mentioned the AF/MF switch on the lens. The lens has to have either a switch or a push/pull clutch. Sounds like you have it set somewhere in between or you have the lens set in MF with the camera set in AF at the same time.

Also, when you switched your camera to manual focus, did you also switch the lens to the same? If now some damage may have occurred.
04-01-2013, 05:55 AM   #7
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QuoteOriginally posted by stormtech Quote
You have not mentioned the AF/MF switch on the lens. The lens has to have either a switch or a push/pull clutch. Sounds like you have it set somewhere in between or you have the lens set in MF with the camera set in AF at the same time.

Also, when you switched your camera to manual focus, did you also switch the lens to the same? If now some damage may have occurred.
I believe this lens does not have a AF/MF switch, nor as far as I know does it have any kind of clutch. You just have to know not to turn the focus ring with the body set for AF. What would happen if you block rotation of both the ring and camera body (like holding the body while propping the lens up against a telephone pole - not that I've ever done that), I'm not sure. Something would have to give.

Paul
04-01-2013, 10:56 AM   #8
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QuoteOriginally posted by stormtech Quote
You have not mentioned the AF/MF switch on the lens. The lens has to have either a switch or a push/pull clutch. Sounds like you have it set somewhere in between or you have the lens set in MF with the camera set in AF at the same time.

Also, when you switched your camera to manual focus, did you also switch the lens to the same? If now some damage may have occurred.
As he said in his original post, the lens does NOT have a MF/AF switch. I have one myself and can confirm this. Others have suggested he try recharging the battery -- he said originally that he's already tried all those things. I agree with that he should just return it to KEH -- it's under warranty, after all.

04-01-2013, 06:18 PM   #9
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Thanks to all who tried to help. It's on its way back to KEH now.
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