Fred mused: > > > personally, I found the KA version less reliable, because often the > > contacts were just a tiny bit off and didn't make proper contact. It > > sure freaked me out when suddently I couldn't take a photo. I threw it > > out afterwards. Having to rotate the lens a bit on/off to be able to > > get a photograph is not my idea of good design... > > This is exactly the same as my experience with the Ka-mount version of the > Adaptall-2 mount - a little "flaky". And "flaky" does not make for > dependability. However, I do know that others have said they've never had > a problem.
Actually I suspect what you're running into here is a problem with the KA mount itself, not with the Adaptall-2 per se. I did notice that when I had the Tamron 300/2.8 with an Adaptall-2 mount I quite often got a bad contact somewhere; quite often the A pin itself would have a flaky contact, so the camera wasn't quite sure whether this was a lens set to the "A" position, or a lens with the aperture set to f32. This led to some rather interesting shots; I was expecting an exposure of something like 1/750 @ f4, and suddenly the viewfinder blanked out for 1/10 of a second or so! Third-party equipment (Tamron Adaptall lenses, Sigma AF teleconverters, etc.) do seem particularly susceptible to this problem, but I've even run into it using my Pentax 80-200/2.8 on my PZ-1p; if I hold the lens just the wrong way, and put just the wrong amount of stress on the lens-body coupling, then the "A" pin only makes intermittent contact.
