I think the PKA in this means Auto diaphram, or that the lens is wide open
for focusing and composing (and metering on most cameras), and stops down
automatically for the exposure. The earlier Tamron lenses were simple stop
down lenses. Something to check for is if the A contacts are present on
the mount of the lens.
I just thought of another way to possibly take a meter reading, which
involves using the lens release button, and twist the lens so it stops
down. Then the shutter speed it the meter displays should be accurate.
But this is tricky and risky in the sense you could easily drop the lens,
body, or both while trying this stunt.
Todd
At 08:52 AM 3/26/01 +1000, you wrote:
>Peter,
>
>forgive me, here I am totally confused and this is probably only due to my
>own lack of knowledge and experience here. The lens is a Tamron 135/2.5
>with the adaptall mount that says PKA on it. There is no "a" setting on the
>aperture ring. (I take it that this is what the "A" in PKA stands for?
>Shows how much I know). So if it is not a true PKA and it is not quite a
>PK, I guess I am stuck between a rock and a hardplace here. Can anybody
>else offer some suggestions? Well, at least I do know that I can use it in
>TV mode and compensate when I am not using it wide open. This was more than
>I could do a couple of days ago! Thanks everyone for the time you've spent
>with me on this....
>
>Tanya.
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