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06-28-2010, 09:49 PM   #1
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Takumar manual/trap focus causes AF problems?

In an earlier thread I talked about getting a Takumar Bayonet 135mm f/2.8. I did, I like it and have had no problems using it with trap focus set to AF or straight Manual focus.

But since using the Tak, my other lens (DA-35 AF) is intermittently freezing, refusing to grab; mostly when wide open it just goes to infinity and sits there making that odd focusing buzzing noise. Also, now whenever I turn on the camera, regardless of the lens, I have to select the FL manually on the LCD before I can shoot.

I tried restoring, even tried downloading and reinstalling the 1.04 firmware, but the problem persists. Any ideas, lens or camera problem? I don't know which would be worse; if a camera problem, that means my K20 goes back in for the third time in the last three months,

06-29-2010, 05:14 AM   #2
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Sounds like a camera problem. Are you mounting your DA completely until it clicks?

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06-29-2010, 05:21 AM   #3
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Also, try cleaning the lens contacts with a q tip and a small dab of rubbing alcohol. Have you tried using your kit lens or other AF lenses to compare?
06-29-2010, 05:32 AM   #4
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Hangu beat me to the response. An old MF lens cannot modify the way a camera works or introduce problems with the camera, except at the contact surface.

One thing to consider when ever attaching a lens for the first time, is making sure it is clean. Sometimes, I have seen oil separate from the focusing helix grease, and aside from screwing up the aperture, it can migrate all the way down to the lens mount. Oil is NOT a conductor of small electrical signals like those used for the lens contacts

06-29-2010, 10:57 AM   #5
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Adam, I think so but it's a good reminder,
06-29-2010, 11:00 AM   #6
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hangu, lowell
I cleaned the contacts, and the contact-less mounting plate on the Takumar, as you both suggested; the problem went away but it was intermittent so I'll just keep an eye on it. It never occurred to me that there could be something on the Tak mounting plate that could get onto the camera contacts. Thanks for the advice and let's hope for the best,

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