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04-01-2010, 07:23 PM   #16
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I think whatever problems you may be having trying to focus the lamp post is due to the fact that even using the center AF point, the relative size of the object is very small because you're using an ultra wide angle lens.
So there is every chance that the camera is locking focus at the background as the AF point covers a relatively larger area due to the wider coverage that comes with the FOV of an ultra wide.

04-01-2010, 09:06 PM   #17
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The bad thing is the system could not even auto focus with infinity. I can get auto focus with closer range and indoor but not outside and the object far away from 10 feet (infinity focus).
04-01-2010, 10:38 PM   #18
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QuoteOriginally posted by vietnam74 Quote
The bad thing is the system could not even auto focus with infinity. I can get auto focus with closer range and indoor but not outside and the object far away from 10 feet (infinity focus).
Well I guess that's what you get when you buy current Tamron lenses... (debatable build quality, focus issues).
04-02-2010, 02:04 AM   #19
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Thank you all for helping me with this. I'll check with my seller tomorrow for a return or exchange of this lens.

04-02-2010, 08:14 AM   #20
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Everything tells me you have a serious problem with the lens or camera.

As others have said, unless there's major breakage with the aperture linkage or the lens contacts, Pentaxes will autofocus with the lens wide open regardless of aperture setting. They focus, calculate exposure, and then stop down when you actually take the shot. This means the autofocus mechanism should work the same no matter what your aperture setting is.

(K/M lenses are of course exceptions, as are extension tubes and such. But a new automatic lens should NOT behave the way you are describing.)
04-08-2010, 08:18 PM   #21
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Thank you. I've checked with Tamron and according to them, I've got the grey market version . I've worked with the seller The Camera Box to send it back for refund.

Base on my final tests, I concluded that this lens can only auto focus on anything within 7 feet. For anything further than that, I have ~10% of the time after several attempt to get the camera shutter actuate. This lens definitely have problem with infinity focus.

I'll try to go with reliable supplier next time. Anyone have experience with Sigma 10-20mm and Tamron 10-24mm? Amazon has the Sigma one while the Tamron is not in stock so I just want to know whether I can get better picture with Sigma lens or not before jumping into the water. Appreciate your inputs.
04-08-2010, 08:36 PM   #22
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it is good to hear you on the way to solving this problem.

I traded some IQ for a wider zoom range in choosing between the 10-24 over the 10-20, plus the 10-24 is the less expensive. I figured looking at prices on second hand lenses, often selling for full retail or more, if I ever tire of the 10-24, it can get a "100% refund".
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