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09-26-2018, 08:22 AM   #1
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SMC Pentax-F 50mm F1.7 auto focus issue on K1 M2

Everytime when I put SMC Pentax-F 50mm F1.7 on k1 m2, this lens can not auto focus. I must turn the aperture ring from "A" to 1.7 and then turn it back to "A". After that auto focus started working.

I do not understand why. Is this lens just working like this? Or maybe I can change the setup on the camera to let auto focus work right away?


09-26-2018, 08:34 AM   #2
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The contacts probably could stand a cleaning. Try wiping them down with a microfiber cloth. Pay particularly close attention to the "data" and "A". The data pin corresponding to the 6 o'clock position of the camera face. The "A" should stick out a bit more than the other pins. It may retract a bit when you take the ring off the "A" setting and pop out a bit in the "A" setting. The pin might be a bit sticky so it doesn't pop out when you first mount the lens. Changing the ring setting might give it the nudge it needs to pop out. A tiny dab of alcohol or lighter fluid applied and immediately removed with a cotton swab might do the trick on cleaning away the stickiness.
09-26-2018, 09:20 AM   #3
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I agree that this is probably a contact issue. To expand on @Not_a_Number 's excellent advice, the camera attempts to detect the "A" contact followed by the "data" contact. If either is dirty or not functioning properly, AF will not work.

09-26-2018, 09:24 AM   #4
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I must turn the aperture ring from "A" to 1.7 and then turn it back to "A". After that auto focus started working.

Maybe the lens contact pins is not well aligned to the camera body. Try turning the lens a little bit left of A settings, if auto focus works , then turn a little bit of right if auto focus works... whichever.


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