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09-28-2012, 01:23 PM   #1
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Tamron-F TC 2X Pz-AF BBAR Broken?

This T/C seems to work ok on AF until I focus on something close and then try to re-focus out to infinity. It will just whirr and the camera flashes the MF signal in the view finder. If I put the lens and camera on manual and focus out to infinity, then switch back to AF it is good to go. Is this normal or is the T/C malfunctioning? Lenses both did the same thing: Tamron 70-200 f2.8 and Pentax DA 50-200WR.

10-03-2012, 10:30 AM   #2
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Sounds like there's a bad connection between the TC's and the lenses' AF drive screws. I believe it takes more power to focus from MFD to infinity on some lenses (not sure, but I read it somewhere), so when the AF mechanism resists more, it loses the link.


Your BBAR might be FUBAR. Badum tss.
10-03-2012, 10:40 AM   #3
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I haven't tried this myself, just brainstorming, so try it at your own risk.

You could do a little troubleshooting by mounting your TC to a lens, try a less expensive lens first, and then driving both lens and TC with a small screwdriver in the flat screwdrive location, instead of using the camera body to drive the focus train. See if you can detect a difference in the torque between using the TC and lens together and then just driving the lens itself. (You might be able to damage your lens by driving the screwdrive too hard against a stop - so don't attempt this if you can't be careful about it) - i'm sure the motor in the camera body doesn't put out much torque. If the TC requires a lot more force to turn the screw drive, then probably there is something wrong with it.
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