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03-29-2017, 04:33 AM   #1
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misbehaving Tamron Adaptall-2 P-KA adapter

I own a few Tamron Adaptall-2 adapters (M42, M42 ES, PK, P-KA).
Most of them work as they should, a few are kind of lunatic.
Apart from a single PK adapter that for some reason won't fit any of my Adaptall lenses, i found that problems usually come from P-KA ones (those with electric contacts).
A couple of them need to be slightly turned, other way they don't "talk" with the camera. It happens only sometimes, and the remedy is simple. Not a big worry.
This time i found a more mysterious problem:
the adapter seems to work fine, but the set aperture is visible only on the back; in the viewfinder and on the top LCD of my K-1 the diaphragm value is empty

Is it a common problem? Any clue about the cause?

I have two identical adapters with me. One works fully okey, and is mounted on a 70-150mm Soft Focus, the funny one is a recent acquisition, and is fitted on a 17mm.
I could try to swap the adapters, but i am a little reluctant. I know from experience that when a P-KA ring works well, it's safer to leave everything as is. Especially if the lens is a valuable one, and i'm perfectly happy with the way it works.

Any idea is warmly welcomed.

cheers

Paolo

03-29-2017, 05:01 AM   #2
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I've had this happen: it means that the camera is registering a PKA mount, but the mount has not made a complete electrical connection.
Try the usual remedies: wiggling, switching on and off...also re-clean the screw stud next to the electrical contacts. Usually fixes things.

Fixing Tamron Adaptall P/KA Adapter - PentaxForums.com
03-29-2017, 05:17 AM   #3
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in my limited experience with PK-A adapters, I have had an adapter that seemed to prefer a specific lens over another one, so a swap may help...


I've also learned that is easier (although more expensive) to simply mount an adapter onto each Adaptall lens and just leave it, especially if it's working properly...
03-29-2017, 06:18 AM   #4
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Mine works the same way. I've never tried wiggling it to see if it makes a difference.

03-29-2017, 07:23 AM   #5
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Another thought: check that the wee auto aperture button is properly engaging - should click a little as the mount is engaged into "A" position.

Information page on Tamron adaptall, adaptall-2 system and lenses
03-29-2017, 08:19 AM   #6
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My pka adapter once needed the contacts cleaned with a pencil eraser just to get the A mode to show up on my MZ-6. The only thing I haven't been able to remedy was sometimes if you wiggle the lens clockwise a little it'll lose the connection and the camera will go back to treating it like a Pentax-M lens. Works well most the time since cleaning the contacts but it can be temperamental for me especially when trying to work quickly.

Only other issue I had with PK adaptall adapters in general is sometimes they don't push the internal button in far enough to correctly reach f/22 or f/16. Which usually isn't a problem when using a straight adaptall adapter (forcing it to always be stopped down such as on my digitals)
03-29-2017, 09:44 AM   #7
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I have one PK\A adapter that works well and another that can overexpose by 1.7 to 2ev on most lense and doesn't show on top lcd but does on back of my K3 II. Most irritating ;-) but it is old!
03-29-2017, 09:46 AM   #8
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QuoteOriginally posted by limestonecowboy Quote
I have one PK\A adapter that works well and another that can overexpose by 1.7 to 2ev on most lense and doesn't show on top lcd but does on back of my K3 II. Most irritating ;-) but it is old!
The over exposure sounds like the aperture pin isn't going down far enough, making the iris wider than the actual aperture, might need a cleaning where possible.

Similar to how I had to blow out my Pentax M 50/1.4 because the little aperture arm stopped down all the way stopped shy of what f/22 should be. Blowing out the little bit of dust or grit that got around the arm fixed that. I imagine a similar thing could be happening to that component on the adapter if it's consistently with just that adapter regardless of lens.

03-29-2017, 09:58 AM   #9
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QuoteOriginally posted by limestonecowboy Quote
and doesn't show on top lcd but does on back of my K3 II
I don' t think this mount will be stopping down. Take a sequence of shots with eg one of the f2.5 adaptalls of eg a whitewashed wall f2.5 - f4 - f5.6 - f8 - f11 in "A" mode to test.

I spent some time looking at overexposure issues with pka mounts without reaching any firm conclusion see my posts in the adaptal lens club.

Adaptall Mount Club (Tamron). - Page 198 - PentaxForums.com
03-29-2017, 01:35 PM   #10
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QuoteOriginally posted by cyberjunkie Quote
A couple of them need to be slightly turned, other way they don't "talk" with the camera
I had the similar issue of camera couldn't talk to lens appropriately. I saw some threads mentioned that some "new-looking" PKA adapters might still have some sealing on the contactors. I followed they instruction, scratched the surface of the connectors and the very near-by surrounding area using a knife. I ended up with some not very nice looking scratches on the adapters both both work great since then.
03-29-2017, 02:00 PM   #11
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This article in Camera Help Forum (linked above by @marcusBMG ) does the job.

Fixing Tamron P/KA Adapter

It links another old article and updates it. The two together are very helpful. The links further down are very helpful as well. Those old PDML guys did good work!

All my P/KA adapters work now!!

Last edited by monochrome; 03-29-2017 at 02:11 PM.
03-31-2017, 11:56 AM   #12
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I'll give a look to the links provided.
Thanks a lot!
BTW, of course i tried to see if the lens stops down in "A" position.
It does. If it's correctly exposed at mid aperture, it gets darker towards f/22 and whitewashed at full aperture.
It's just showing no F stop value inside the viewfinder and on the top LCD.
I guess the adapter is quite old, it came with a f/3.5 200mm Adaptall-2 lens that was purchased because of the presence of the P-KA adapter, rather than for the lens itself
I already cleaned the pins with a microfiber cloth. I don't think i took care of the head of the screw end next to the contact pins. I will try to clean it with a pencil eraser.
Before i have to check the links and see if i can get some more advice.
Thanks again

cheers

Paolo

Last edited by cyberjunkie; 03-31-2017 at 12:13 PM.
03-31-2017, 12:16 PM   #13
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QuoteOriginally posted by cyberjunkie Quote
I will try to clean it with a pencil eraser.
No - scratch it with eg knife point to remove possible thread locker.
03-31-2017, 12:31 PM   #14
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I tried twisting the lens slightly back to the right (with the camera turned on) once it was mounted. The aperture showed right up instead of F--.
03-31-2017, 05:21 PM   #15
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Problem fixed!
I scraped the end of the screw close to the electric contacts with a cutter. Quite hard, actually, a softer approach didn't work
I've saved the links you provided and the pics of the opened adapter. It will prove useful trying to fix a PKM adapter i have at home that can't be attached to any lens.
Probably something got bended, courtesy of the previous owner, but i'm hopeful.
Thanks again. Great forum!

cheers

Paolo
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