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01-10-2011, 08:27 AM   #1
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Super A unable to read the minimal aperture from A lens


my Pentax Super A decided to not electrically accept any faster lens than f/3.5. I was using Tamron SP 24-48 3.5-3.8 lens with A end which works like a charm. During last few months it was starting to have problems with identifying faster lens. If I attach ex. Pentax-A 50/2 of Pentax-A 50/1.7 I am unable to select any combination having aperture set to anything below 3.5. The number on the display blinks and not decrease if I try to lower the time.

Is my Super A dying? Am I doing something wrong? Could you advise?

Thank you

01-10-2011, 08:35 AM   #2
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Welcome! :-)

Sounds like one or more of the mount contacts was not good. Cleaning them would be the first thing to try.
01-10-2011, 07:21 PM   #3
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Clean the contacts on the mounts, both body and lenses.
01-10-2011, 09:50 PM   #4
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If that doesn't work, you could try this. It looks to me from this page:

Features and Operation of the Ka Mount

that the contact furthest from the lens locking pin might be always reading 0. The contacts in the camera are on brass springs that conduct to a PC board in the camera. There might be a bad connection, dirt or corrosion there. You can check by unscrewing the screws in the lens mount. That means all the contacts come springing out, possibly with some other tiny parts. Also the screws are in pretty firmly, so they might require a good screwdriver and firm hand.

01-11-2011, 01:52 AM   #5
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From outside it seems that all contacts are clean and I was trying to clean all of them (on body and on lens) few times before I wrote this. So it seems that either the electronics inside is dying or there could be a dirt somewhere inside body or lens. I already have some experience with lens and camera cleaning so this is the way I will be trying now.

Just1MoreDave: You simply confirmed my doubts. Because I tried two different fast lens there having same problem I think the root cause is somewhere in the body. I will try to unmount the mount and I hope I will find something.

Thanks much for your hints. I will come back with my findings.
01-12-2011, 02:07 PM   #6
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Further observations

So according to

Features and Operation of the Ka Mount

r1 pin is affected and not shortened as should be. I have unscrewed the mount, cleaned up pin(s), spring and the contact under the spring. everything seems clean to me. That did not help.

Unfortunately there is not visible screws or anything to unmount here so I don't know where to continue. What I am a bit affraid of is that I would need to disassemble the camera from inside to get to the electrics to check it for resistance.

Do you know about any directions how to get Super A disassembled to reach this point, please?

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