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05-20-2008, 01:13 AM   #1
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Tamron adaptall mount problem

Greetings to all!
This is my first post-forgive me if I screw it up!
I have been shooting with spotmatics and just got a KX. So just got an adaptall PKA mount to use my Tamron SP lenses. Mounted on the lens but with the lens not mounted to the camera the aperture gets stuck on f16. It does this on two different lenses. Mounting lens on the camera doesn't help. So....
1) Is the mount defective?
2) Does the lens have to be mounted on the camera for the aperture to work properly and I have the wrong mount?
3) do I need the PK (not PKA) mount or?
Thanks for any assistance!

05-20-2008, 02:29 AM   #2
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when a K mount lens is not on the camera, it will stop down to the apature set on the apature ring.

There are 2 couplings on a K mount, one recessed near the inner ring of the mount, which tells the body the apature set on the ring (for metering to work and calibrate properly. this is on the left side as you look at the back of the lens.

the other is more obvious, it sticks out from thebase, this is the apature activation lever.

If you move it the lens iwll open up .
05-20-2008, 07:54 AM   #3
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First, make sure the two feelers on the adapter fit into the correct slots on the lens, this ensures the apertures are registered. Second, there's a piece of bent metal, a button, that you push on the combined lens/mount that allows the ring to go all the way to the A setting. It isn't always obvious... and it is the fiddliest part of the process. Often it's easier to set this once the lens is mounted on the camera.

(You may need to try a couple of the buttons - on my adaptalls I think it's the black one, the silver ones are to unmount the adapter)

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adaptall, aperture, camera, k-mount, lens, lenses, mount, pentax lens, pka, slr lens, tamron
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