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03-10-2019, 08:03 AM   #1
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Adaptall 2 issues... operator error or bad adapter?

I just bought an Adaptall 2 70-150 f3.5 (the first one, with two-touch zoom and focus) and a PK-A adapter.

I really bought it for the adapter, but the lens looks interesting as well, as it would be nice to have something like my SMC 45-125 but with A-style metering.

I can verify it is a PK-A adapter with the presence of the contacts and the letters PK/A on the mount... and the lens slides over to "AE" when I push the button for that.

And some aspects of it work...

When I mount it, if I look at the screen on the back of my K1, everything looks good... aperture and shutter speed behave as they should, and the maximum aperture the camera will allow is f3.5... good...

But in the viewfinder, I get F--. I also get F-- on the top LCD, regardless of camera mode.

And while I haven't done completely exhaustive tests, if I leave the camera in Tav mode, it seems to want to shoot wide open, even if I give it plenty of light.
If I override the meter's first suggestion and adjust the aperture, it seems to adjust the aperture according to the exif, but the aperture does not appear to change...

In manual mode, it does appear to change, as I can hear it (and obviously see the exposure changes in manual mode as other things aren't altering to match).

I'll give the adapter a good cleaning this afternoon, but I wanted to check first if this is a common failure mode on these things or if there is something I should be doing that I'm overlooking.

Thanks,

-Eric

03-10-2019, 08:12 AM - 2 Likes   #2
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QuoteOriginally posted by TwoUptons Quote
I just bought an Adaptall 2 70-150 f3.5 (the first one, with two-touch zoom and focus) and a PK-A adapter.

I really bought it for the adapter, but the lens looks interesting as well, as it would be nice to have something like my SMC 45-125 but with A-style metering.

I can verify it is a PK-A adapter with the presence of the contacts and the letters PK/A on the mount... and the lens slides over to "AE" when I push the button for that.

And some aspects of it work...

When I mount it, if I look at the screen on the back of my K1, everything looks good... aperture and shutter speed behave as they should, and the maximum aperture the camera will allow is f3.5... good...

But in the viewfinder, I get F--. I also get F-- on the top LCD, regardless of camera mode.

And while I haven't done completely exhaustive tests, if I leave the camera in Tav mode, it seems to want to shoot wide open, even if I give it plenty of light.
If I override the meter's first suggestion and adjust the aperture, it seems to adjust the aperture according to the exif, but the aperture does not appear to change...

In manual mode, it does appear to change, as I can hear it (and obviously see the exposure changes in manual mode as other things aren't altering to match).

I'll give the adapter a good cleaning this afternoon, but I wanted to check first if this is a common failure mode on these things or if there is something I should be doing that I'm overlooking.

Thanks,

-Eric
Some TamronP/KA adapters have a bit of Loctite on a screw that needs to be shorted, which prevents transmission of the aperture position information. There’s a thread here somewhere on how to scrape off the Loctite, which solves the problem. I’ve tried to find it but can’t ATM - probably in Articles under Camera Help Central. Gotta run an errand now but I’ll look more later.

[EDIT] Found it.ClassA posted this: Fixing Tamron Adaptall P/KA Adapter - PentaxForums.com which links to the solution in a DPR post.

Last edited by monochrome; 03-10-2019 at 08:50 AM. Reason: Ctite
03-10-2019, 08:43 AM   #3
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What the adapter has is a variable resistor that gives a reading through the contact points on the mount. F-- tells you that it isn't making contact somewhere.
03-10-2019, 08:46 AM   #4
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Question : If you slightly and gently wiggle or womble the lens near the mount, does this change anything for you?

03-10-2019, 12:07 PM   #5
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I've had to gently abrade the 'A' contact on a couple of PK-A adapters - plus I buy an adapter for every Adaptall lens I have, so I'm not having to remove the lens from the adapter every time I want to change lenses....
03-10-2019, 04:41 PM   #6
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Original Poster
Thanks folks for the help.
I found the adaptall 2 troubleshooting guide in with the lens reviews, so it didnít show up in a forum search.

After dismounting the adapter, some cleaning and a bit of jiggling, it did start working as it should.
Iím not sure which did it, but I expect a bit of both...

Iíll see if I can narrow down the fix.

Thanks again,

-Eric
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